Co-reporter:Chao Liu, Huiyan Zhang, Rui Xiao, Shubin Wu
Carbohydrate Polymers 2017 Volume 156() pp:118-124
Publication Date(Web):20 January 2017
DOI:10.1016/j.carbpol.2016.09.024
•Enthalpies during the active pyrolysis of chitin and chitosan were revealed by DSC.•Potentials of chitin and chitosan to organonitrogen chemicals were evaluated by Py-GC/MS.•Selectivity of pyrazine compounds from chitosan pyrolysis was up to 22.99%.•Selectivity of acetamido acetaldehyde from chitin pyrolysis was up to 27.27%.Thermogravimetric characteristics of chitin and chitosan and their potentials to produce value-added organonitrogen chemicals were separately evaluated via TG/DSC-FTIR and Py-GC/MS. Results shown that chitin had the better thermal stability and higher activation energy than chitosan because of the abundant acetamido group. Furthermore, the dominated volatilization in active pyrolysis of chitin contributed to its endothermic property, whereas the charring in chitosan led to the exothermal. During fast pyrolysis, the acetamido group in chitin and chitosan was converted into acetic acid or acetamide. Typical products from chitosan pyrolysis were aza-heterocyclic chemicals, i.e. pyridines, pyrazines, and pyrroles, with the total selectivity of 50.50% at 600 °C. Herein, selectivity of pyrazine compounds was up to 22.99%. These aza-heterocyclic chemicals came from the nucleophilic addition reaction of primary amine and carbonyl. However, main reaction during chitin pyrolysis was ring-opening degradation, which led to the formation of acetamido chemicals, especially acetamido acetaldehyde with the highest selectivity of 27.27% at 450 °C. In summary, chitosan had the potential to produce aza-heterocyclic chemicals, and chitin to acetamido chemicals.
Co-reporter:Zhong Ma, Rui Xiao, Liangyong Chen
Fuel Processing Technology 2017 Volume 168(Volume 168) pp:
Publication Date(Web):15 December 2017
DOI:10.1016/j.fuproc.2017.08.029
•The sintering kinetics of iron oxide in the reduction process of chemical looping combustion was investigated.•The surface area decrease could be attributed to the coalescing and growth of particles.•The range of pore size distribution was increased and more macropores were formed during the reduction process.•Oxygen vacancies creation led to the forming of porous structure.The chemical looping combustion (CLC) is an advanced combustion technique that can separate carbon dioxide (CO2) simultaneously. The recyclability and stability of oxygen carriers is very important for the economical efficiency of CLC. The major factor for the deactivation of oxygen carriers is sintering. For most CLC studies, the focus were all on the reactivity of the oxygen carriers, but very few effort was contributed to the sintering properties of the oxygen carriers. This article addressed the characteristic and decay kinetics of surface area for iron oxide in the reduction process of CLC. The results showed that increasing the reaction temperature accelerated the decrease rate of surface area for iron oxide. In addition, with the reduction degree deepening, the grain size of iron oxide increased. Sintering kinetics of surface area decay based on a power law expression model was investigated. The activation energy for surface area decrease of iron oxide in the reduction process was calculated as 89.94 kJ/mol. Sintering and oxygen vacancies creation were the two causes for microstructural variation of iron oxide during the reduction process. Sintering leads to the decrease of surface area for iron oxide, while oxygen vacancies creation results in the porous structure forming.
Co-reporter:Huiyan Zhang, Xin Meng, Chao Liu, Yao Wang, Rui Xiao
Fuel Processing Technology 2017 Volume 167(Volume 167) pp:
Publication Date(Web):1 December 2017
DOI:10.1016/j.fuproc.2017.08.007
•LG and LGO were produced by cellulose selective pyrolysis in a fixed bed reactor.•Self-produced bio-char increased LG and especially LGO yields significantly.•The maximum LGO selectivity of 77.67% was obtained with H3PO4.•The highest LGO yield of 2.65 wt% was obtained with Fe2(SO4)3.•The catalytic reaction pathway for producing LGO and LG was proposed.Selective low-temperature pyrolysis of microcrystalline cellulose was carried out to produce levoglucosan (LG) and levoglucosenone (LGO) using a fixed bed reactor. The effects of temperature, self-produced bio-char, different catalysts and catalytic pattern on product's yields and selectivities were studied. The results showed the self-catalysis of bio-char increased LGO yield from 0.14 wt% to 1.35 wt% by increasing almost 10 times with reaction feedstock mass increasing 3 times. The maximum LGO selectivity of 77.67% was obtained with H3PO4 catalysts at 270 °C. Through comparing different catalysts including H3PO4, H2SO4, Fe2(SO4)3 and FePO4, the highest LGO yield of 2.65 wt% was obtained with Fe2(SO4)3. Acid catalysts can obviously increase LGO selectivity and in-situ pattern performed better than ex-situ pattern during the pyrolysis for LGO. Finally, the mechanism with bio-char effect for producing LGO and LG from selective pyrolysis of microcrystalline cellulose was proposed.
Co-reporter:Huiyan Zhang, Shanshan Shao, Yang Jiang, Tharapong Vitidsant, Prasert Reubroycharoen, Rui Xiao
Fuel Processing Technology 2017 Volume 159(Volume 159) pp:
Publication Date(Web):1 May 2017
DOI:10.1016/j.fuproc.2017.01.025
•Biomass two-step pyrolysis was conducted in a fluidized bed to improve hydrocarbon yield.•Low-temperature pyrolysis (LTP) reduced acetic acid and guaiacol yields of catalytic pyrolysis.•Aromatic yield boasted 30% compared with that without LTP pretreatment.•Catalyst coking problem weakened significantly after LTP pretreatment.Two-stage fast pyrolysis of pinewood, was investigated with and without catalysts in a fluidized-bed reactor. The method is using low-temperature pyrolysis (torrefaction) to remove unfavorable compounds firstly and then using high-temperature catalytic pyrolysis to produce hydrocarbons. The effects of torrefaction temperature, residence time and atmosphere on product distribution were investigated. The results show that the acidity of produced liquids reduced with increasing torrefaction temperature and residence time. Torrefaction pretreatment of pinewood reduced the yields of acetic acid and guaiacol effectively during catalytic pyrolysis. The highest aromatic yield was obtained with torrefied pinewood at 250 °C, which was boasted 30% of that without torrefaction. Besides, torrefied biomass can obviously reduce coke deposition on ZSM-5 in the catalytic pyrolysis process compared with raw pinewood. Therefore, the two-step pyrolysis can be considered as a more effective and promising method for producing high-quality liquid fuels and chemicals.
Co-reporter:Jimin Zeng, Rui Xiao, Huiyan Zhang, Yihong Wang, Dewang Zeng, Zhong Ma
Fuel Processing Technology 2017 Volume 168(Volume 168) pp:
Publication Date(Web):15 December 2017
DOI:10.1016/j.fuproc.2017.08.036
•Chemical looping pyrolysis-gasification of biomass is proposed.•H2/CO ratio of 2.45 mol mol− 1 is obtained in the syngas.•ΔG-T diagram concerning the H2 generation reactions is calculated.Chemical Looping Pyrolysis-Gasification (CLPG) of biomass is established as a novel concept for high quality syngas production. The process divides the main chemical reactions in different zones for biomass pyrolysis and gasification, then achieves residual char combustion and Oxygen Carrier (OC) regeneration consistently. The understanding of the process is first determined by calculation of possible chemical reactions using Gibbs Free Energy (ΔG). Experimental work for different effects of the fuel reactor (FR) temperature and the Steam-to-Biomass Mass Ratio (S/B) are then investigated in terms of syngas components, Hydrogen to Carbon Monoxide Molar Ratio (H2/CO), and Cold Gas Efficiency (CGE). Results show that at the FR temperature of 820 °C and S/B of 1.00 kg kg− 1, the optimized condition of H2/CO and CGE are obtained at 2.45 mol mol− 1 and 61.87%, respectively. With S/B increasing from 1.25 kg kg− 1 to 2.00 kg kg− 1, the H2/CO increases to 2.99 kg kg− 1, while the CGE decreases to 51.64%. The water-gas shift (WGS) reaction and the steam-iron reaction are approaching 0 kJ mol− 1 over the FR temperature of 820 °C in calculation, which confirms the contribution of these two reactions comparing with experimental tests. The research proposes an approach for efficient gasification of high volatile-content solid fuel using the advanced chemical looping technology.
Co-reporter:Shiliang Wu, Hongwei Yang, Jun Hu, Dekui Shen, Huiyan Zhang, Rui Xiao
Fuel Processing Technology 2017 Volume 161(Volume 161) pp:
Publication Date(Web):15 June 2017
DOI:10.1016/j.fuproc.2017.03.022
•The miscibility of ethylene glycol and 1,3-propylene glycol with diesel has been tested.•Diesel, ethanol-diesel, ethylene glycol-diesel, ethyl acetate-diesel blends have been tested and compared.•The engine performance of ethylene glycol is totally comparable to ethanol and ethyl acetate.•Ethylene glycol and hydrogenated bio-oil could be regarded as useful additives for diesel.In this work, the miscibility of hydrogenated biomass-pyrolysis-oil with diesel and its applicability in diesel engine has been tested by using its surrogate-ethylene glycol. The miscibility of ethylene glycol and 1,3-propylene glycol with diesel has been tested, finding that only 10% vol ethylene glycol could be mixed with diesel and 1,3-propylene glycol is immiscible with diesel. In order to make a direct comparison, 10% ethanol-90% diesel, 10% ethylene-90% diesel, and 10% ethyl acetate-90% diesel blends have been tested in a diesel engine under the same operation conditions. The engine performance of ethylene glycol is comparable to ethanol and ethyl acetate. There is no significant difference in brake specific fuel consumption and exhaust gas temperature for blends. The three oxygenated compounds all have lower CO emissions than diesel. Besides, ethylene glycol and ethyl acetate could reduce the NOx emission. All the three fuels have reported the reduction of soot emission. This work offers the possibility that ethylene glycol (hydrogenated bio-oil) could be used as a useful additive (up to 10% vol) in diesel.
Co-reporter:Jun Hu, Dekui Shen, Shiliang Wu, Rui Xiao
Journal of Analytical and Applied Pyrolysis 2017 Volume 127(Volume 127) pp:
Publication Date(Web):1 September 2017
DOI:10.1016/j.jaap.2017.07.005
•Effect of ZnCl2 on pyrolysis of cellulolytic enzyme corn stover lignin was studied.•ZnCl2 promoted the formation of solid char and non-condensable gases.•Pyrolysis of lignin with ZnCl2 exhibited higher activation energies (114–236 kJ/mol).•Formation of monomeric phenols was substantially suppressed with ZnCl2.•A possible mechanism of ZnCl2 on lignin pyrolysis was proposed.The target of this work is to investigate the effect of impregnated ZnCl2 on the analytical pyrolysis behavior of waste cellulolytic enzyme corn stover lignin (CECL). Pyrolysis of CECL in a thermogravimetric analyzer coupled with Fourier transform infrared spectroscopy (TG-FTIR) exhibited that ZnCl2 promoted the formation of solid product, resulted in high activation energies (114–236 kJ/mol). The evolution amount of CO2 and H2O increased 2–3 times with ZnCl2. Pyrolysis in a pyrolyzer coupled with gas chromatography/mass spectrometry (Py-GC/MS) showed that 4-vinylphenol and 4-vinylguaiacol exhibited high peak areas, and the formation of most monomeric phenols was substantially suppressed by ZnCl2. A possible mechanism was provided considering that ZnCl2 promoted the formation of char and non-condensable gases while suppressed the formation of bio-oil. The substantial evolution of gases could be responsible for the highly porous structure of activated carbon prepared with ZnCl2. Our work provides a foundation towards understanding the effect of ZnCl2 on lignin pyrolysis.
Co-reporter:Huiyan Zhang, Jun Hu, Jian Zheng, Rui Xiao
Journal of Analytical and Applied Pyrolysis 2017 Volume 128(Volume 128) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.jaap.2017.10.008
•Fast pyrolysis of residues (high lignin and ash) from non-grain fuel ethanol was conducted.•Light bio-oils (70–71 wt% water) and heavy bio-oils (9–11 wt% water) are separated automatically.•HHVs of oils reached 25.5–26.8 MJ/kg, which were significant higher than that of typical bio-oils.Pyrolysis of corn stalk residue (CSR) and cassava rhizome residue (CRR) to produce bio-oil were investigated using a fluidized bed reactor. Both feedstocks possessed low volatile matters and high ash contents. The results showed that the bio-oil yield of CSR reached the highest value (25.1%) at 700 °C, while that of CRR peaked (30.6%) at 600 °C. The obtained bio-oils were separated into light fraction and heavy fraction automatically. The light fraction mainly consisted of furan compounds and carboxylic acids, while the heavy fraction mainly consisted of aromatic compounds. Due to the abundant lignin in the residues, high heating values (HHVs) of the heavy fractions reached 25.5–26.8 MJ/kg which were significantly higher than typical bio-oils.
Co-reporter:Yuli Zhang, Rui Xiao, Mao Ye, Zhongmin Liu
Powder Technology 2017 Volume 314(Volume 314) pp:
Publication Date(Web):1 June 2017
DOI:10.1016/j.powtec.2016.08.059
•Evaluation of the traditional spectral data decomposition method•Obtain factors which dominate the amplitude of bubble induced pressure fluctuations.•Key points for improving the spectral data decomposition method•Bubble coalescence induces a kind of semi-global pressure wave.Pressure fluctuation analysis has been widely accepted as an efficient way for bubble size estimation in fluidized beds since the local bubble induced pressure fluctuation, which is believed to be a function of bubble size, can be separated away from the global pressure waves. The spectral data decomposition method developed by van der Schaaf et al. (2002) Van der Schaaf et al. (2002) has been widely used in this regard. However, it has been found in various experimental studies that the proportionality constant between the reference data (obtained via measurements by various techniques or predicted by well-established correlations) and the estimated bubble size differs significantly in different applications. In this work we try to understand the scattered proportionality constants via a numerical study based on the Euler-Euler two-fluid model. The simulation results indicate that the local bubble induced pressure fluctuation is affected not only by bubble size, but also by the lateral distance between the rising bubble and detecting point, bubble shape, bed diameter, and bubble coalescence. Without consideration of these factors, the spectral data decomposition method is subject to large deviation for bubble size estimation.Download high-res image (247KB)Download full-size image
Co-reporter:Huiyan Zhang, Yuna Ma, Shanshan Shao, Rui Xiao
Applied Energy 2017 Volume 208(Volume 208) pp:
Publication Date(Web):15 December 2017
DOI:10.1016/j.apenergy.2017.09.062
•Potassium effects during pyrolysis of agricultural and forest biomass was studied.•K increases furans and phenols yields, decreased aldehydes, esters and sugars yields.•K converts anhydrosugars to linear aldehydes and then to 5-hydroxymethylfurfural.•More polyphenols produced from small polymers with the assistance of K.•Reaction pathway of potassium influence on biomass pyrolysis was proposed.Potassium, due to its strong catalytic effects on biomass pyrolysis vapors, has great influence on the components of the obtained bio-oil. In this work, fast pyrolysis of acid washed and potassium salts impregnated feedstocks (camphor branch, corn cob and walnut shell) were carried out in a fluidized bed. The effects of potassium and the ash in biomass on yields and selectivities of bio-oil compounds were studied. The results showed that the walnut shells yielded the greatest amount of phenol and acids. Potassium promoted the conversion of large molecular compounds (such as levoglucosan) to furans. The existence of potassium reduced the yield of aldehydes and enhanced that of furfural. With the assistance of potassium, the selectivity of monophenols (phenol, methyl phenol, dimethyl phenol, etc.) decreased significantly to around half, while that of polyphenols (ethyl phenol, 2-allylphenol, 4-(2-propenyl)-phenol, 2-allyl-4-methylphenol, etc.) increased obviously. Finally, a possible reaction pathway indicating potassium influences on biomass pyrolysis was proposed according to the experimental results.
Co-reporter:Jimin Zeng, Rui Xiao, Huiyan Zhang, Xing Chen, Dewang Zeng, Zhong Ma
Biomass and Bioenergy 2017 Volume 104(Volume 104) pp:
Publication Date(Web):1 September 2017
DOI:10.1016/j.biombioe.2017.03.020
•The moisture content in biomass was used as a gasifying agent in gasification.•Lattice oxygen was used for increasing the H2/CO ratio.•The interaction between the oxygen carrier (OC) and biomass moisture was studied.Fresh biomass self-moisture gasification (BSMG) is a promising route for biomass utilization. Unlike conventional biomass steam gasification (BSG), BSMG used the moisture content in biomass as the gasifying agent. In this work, the performance of biomass self-moisture chemical looping gasification (BSM-CLG) was compared with dry biomass chemical looping gasification (DB-CLG) and biomass steam chemical looping (BS-CLG) gasification. The data analyzed was the gas cumulative compositions, the hydrogen-to-carbon monoxide ratio (H2/CO), the lower heating value (LHV) and the gas yield. Results showed that the moisture content increased the gas yield from 0.9927 Nm3 kg−1 to 1.1646 Nm3 kg−1, while the steam increased the H2/CO ratio from 0.6398 mol mol−1 to 0.7436 mol mol−1 in the process. The interaction between OC and biomass moisture increased the biomass reactivity. The differing gasification reactivity was due to different water diffusion between the methods of biomass gasification. The diffusion of moisture content and steam had opposite directions, and the different diffusion led to the moisture content impacted the initial gasification stage, but the steam influenced the biomass molecular structure rearrangement.
Co-reporter:Shiliang Wu, Dekui Shen, Jun Hu, Huiyan Zhang, Rui Xiao
Journal of Analytical and Applied Pyrolysis 2016 Volume 119() pp:147-156
Publication Date(Web):May 2016
DOI:10.1016/j.jaap.2016.03.006
•A new sample loading method has been introduced for Py-GC–MS.•Integrated TG-FTIR and Py-GC–MS method has been utilized for analysis.•Two mass loss peaks involving the breakage of β-O-4 glycosidic bond were observed for cellobiose.•Formation of furans from cellobiose was prominent over other products.•Four possible chemical pathways for the cleavage of β-O-4 glycosidic bond have been proposed.The pyrolytic characteristics of cellulose, cellobiose and glucose were examined by TG-FTIR combined with Py-GC–MS, in order to gain the effect of β-O-4 glycosidic bond on the pyrolysis process. In TG-FTIR analysis, two mass loss peaks were observed for cellobiose and glucose, indicating dehydration in low temperature stage and consequently intensive cracking of glycosidic bond and fragments for cellobiose. The samples were tested in Py-GC–MS at the temperature of 300, 500 and 900 °C according to their mass loss characteristics from TG-FTIR. Formation of furans from cellobiose, which involved the cracking of β-O-4 glycosidic bond, was prominent over other products, compared to that of cellulose and glucose. Four possible chemical pathways for the cleavage of β-O-4 glycosidic bond have been proposed with regard to the formation of furans and anhydrosugars from cellulose. Besides, another two reaction pathways leading to the formation of levoglucosan were also suggested.
Co-reporter:S. S. Shao, H. Y. Zhang, D. K. Shen and R. Xiao
RSC Advances 2016 vol. 6(Issue 50) pp:44313-44320
Publication Date(Web):21 Apr 2016
DOI:10.1039/C6RA05356D
In order to promote hydrocarbon production and catalyst stability in catalytic fast pyrolysis (CFP) of biomass, HZSM-5 catalysts were treated with alkali solutions to introduce mesopores into the microporous system. Parent and hierarchical catalysts were tested in catalytic conversion of furan as an important intermediate from biomass fast pyrolysis (BFP). Controlled desilication with mole concentration of NaOH of 0.3 M resulted in sheet-like mesopores on the external sphere, enhancing mass transfer in the catalyst, and it specifically promoted the carbon yield of hydrocarbons by 21.6%. Though the coke content on these HZSM-5-0.3M catalysts increased gradually by 11.6%, the tolerance toward deactivation by coke deposition was improved. Cyclic tests of catalysis-regeneration process over hierarchical HZSM-5-0.3M over 20 cycles revealed that it can withstand long-running with a stable yield of hydrocarbons being achieved. Thus, hierarchical HZSM-5 is a suitable catalyst for CFP of biomass and its derivatives to hydrocarbons by this simple synthetic process.
Co-reporter:De-Wang Zeng, Rui Xiao, Zhi-cheng Huang, Ji-Min Zeng, Hui-Yan Zhang
International Journal of Hydrogen Energy 2016 Volume 41(Issue 16) pp:6676-6684
Publication Date(Web):4 May 2016
DOI:10.1016/j.ijhydene.2016.03.052
•Non-aqueous phase bio-oil is used to produce hydrogen.•Hydrogen purity is enhanced by adjusting the steam.•Hydrogen purity is in a competing relationship with hydrogen yield.Chemical looping of bio-oil is a promising route to convert this low-quality fuel to pure hydrogen with inherent gas separation and low energy penalty. In that the oil is liable to form coke during the heating process, the current chemical looping cycles usually suffer from low hydrogen purity and poor OC recyclability. In this paper, we proposed a strategy of adding steam in FR to suppress coke formation and enhance the hydrogen purity. To perform the chemical looping cycles, we first built a dual fluidized bed and attained the optimal operating conditions. The results showed the higher hydrogen purity, yield and good recyclability at 950 °C. Afterward, we investigated effects of the steam to oil ratios on hydrogen purity, yield and the recyclability of oxygen carrier, and found adding steam in the fuel reactor was an efficiency way to enhance the hydrogen purity. The results suggested the hydrogen purity can reach 98%; nevertheless, it suppressed the hydrogen yield simultaneously. In terms of the redox performance of oxygen carrier, we also found the steam can weaken the reduction reactions, and therefore increased the particle recyclability. Our current study suggested the enhancement of the hydrogen purity was at the cost of the suppression in hydrogen yield, and we need to find a compromise between the hydrogen yield and the purity to pursue high system efficiency.
Co-reporter:De-Wang Zeng, Rui Xiao, Ji-Min Zeng, Hui-Yan Zhang
International Journal of Hydrogen Energy 2016 Volume 41(Issue 32) pp:13923-13933
Publication Date(Web):24 August 2016
DOI:10.1016/j.ijhydene.2016.07.019
•Oxygen carrier is prepared by liquid foam assisted sol–gel method.•The pore configuration is tuned by adding surfactant SDS in the precursor sols.•Material with 2D pores can better resist the particle sintering up to 900 °C.Chemical looping of iron oxides is capable of storing hydrogen with high capacity and low material costs. In this paper, we prepared iron oxides materials from the liquid foam templated sol–gel precursors and demonstrated its application in the chemical looping hydrogen storage process. By tuning the precursor chemistry, we obtained a series of materials with different pore configuration, and found this approach a convenient access to define the material configuration. With assistance of SDS, materials showed promoted porosity and better reactivity compared with the sample without SDS. In particular, samples with isolated pore structure were better able to limit the sintering. By characterizing the materials before and after cycles, we found the confinement effects of pore wall was capable of restraining the growth of the crystalline size, and thus mitigated the material deactivation in the high temperature redox cycles.
Co-reporter:Xin Meng, Huiyan Zhang, Chao Liu, and Rui Xiao
Energy & Fuels 2016 Volume 30(Issue 10) pp:8369
Publication Date(Web):September 14, 2016
DOI:10.1021/acs.energyfuels.6b01436
Levoglucosan (LG) and levoglucosenone (LGO) are two high-valued chemicals, which can be produced by catalytic fast pyrolysis of cellulose with proper catalysts. This work investigated the catalytic characteristics of different acids and metal salt catalysts to produce LG and LGO using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and thermogravimetric analysis (TGA). The results showed that weak acids (such as formic acid and acetic acid) enhanced LG yield, whereas sulfuric acid and phosphoric acid promoted the yield and selectivity of LGO with inhibitory effects on LG production. The maximum LGO selectivity of 61.8% was obtained with 10% phosphoric acid, while the maximum LG selectivity of 87.6% was obtained with 10% acetic acid. In comparison with two impregnation methods, the filtration method can increase LGO yield, while the evaporation method enhanced the selectivity of LGO (up to 82.6%) with lower concentration of phosphoric acid. The effects of metal salts on pyrolysis of cellulose were investigated by impregnating with different sulfates and chlorates. The results indicated that sulfates can increase the LGO yield significantly, which can be attributed to the effect of sulfate anions.
Co-reporter:Lijun Heng, Huiyan Zhang, Rui Xiao
International Journal of Hydrogen Energy 2016 Volume 41(Issue 40) pp:17771-17783
Publication Date(Web):26 October 2016
DOI:10.1016/j.ijhydene.2016.07.068
•Design of iron-based CLH production process from HFB using two-stage fluidized bed.•Design of complete self-sustaining operation with CO2 capture rate close to 100%.•Making a trade-off between two operation modes based on comparative analysis.The purpose of this work is to investigate the overall performance of the iron-based chemical looping hydrogen (CLH) production from the heavy fraction of bio-oil (HFB). The multiple ASPEN models are employed to simulate a two-stage fluidized bed reduction reactor considering the thermodynamic equilibrium limit. Several important factors are discussed to determine the suitable reactor operation conditions for the process simulation of two operation modes. The results show HFB CLH process has a maximum hydrogen efficiency of 73.1% (LHV) and a total thermal efficiency of 59.2% (LHV) at the cost of decreasing the CO2 capture efficiency under the condition of supplementary firing. Within the complete self-sustaining operation range, the highest hydrogen thermal efficiency is 57.8% (LHV) corresponding to a total thermal efficiency of 58.3% (LHV) and a CO2 capture efficiency of nearly 100%. This study indicates the CLH process has significant advantages over the conventional coal gasification (CG) for hydrogen production owing to its high energy conversion efficiency and high-efficient CO2 capture with low cost.
Co-reporter:Jimin Zeng, Rui Xiao, Dewang Zeng, Yang Zhao, Huiyan Zhang, and Dekui Shen
Energy & Fuels 2016 Volume 30(Issue 3) pp:1764
Publication Date(Web):January 6, 2016
DOI:10.1021/acs.energyfuels.5b02204
Chemical looping gasification (CLG) in a dual fluidized bed gasifier was proposed to increase the H2/CO ratio and to simplify the process in gasification. The gasifier offered two separate fluidized bed reactors, fuel reactor (FR) and steam reactor (SR), for biomass gasification and H2 production. Iron ore was used as the oxygen carrier (OC), providing lattice oxygen for gasification in the FR, transferring to the SR for reacting with steam to produce H2, and then achieving the circulation and reoxidation through the loop seal. The product gas from the FR and the SR could be controlled to make high H2/CO ratio syngas by this process. The experiment for the CLG of sawdust was conducted in a dual fluidized bed gasifier, regarding the influence of different FR temperatures, SR temperatures, steam/biomass (S/B) ratios, and steam preheating temperatures. The optimum operating condition was obtained by the analysis showed as follows: the FR temperature of 820 °C, the SR temperature of 910 °C, the S/B ratio of 1.50 kg kg–1, and the steam preheating temperature of 500 °C. At this condition, the cold gas efficiency in the FR was 77.21% and the H2 yield in the SR was 0.279 Nm3 kg–1. Overall, the CLG process of sawdust carried out in the present work suggests that a high H2/CO ratio syngas production was simple and promising.
Co-reporter:Chao Liu, Jun Hu, Huiyan Zhang, Rui Xiao
Fuel 2016 Volume 182() pp:864-870
Publication Date(Web):15 October 2016
DOI:10.1016/j.fuel.2016.05.104
•Aromatic units and side-chain linkages within lignin were analyzed by 2D HSQC NMR.•Relevance between lignin structure and pyrolysis behaviors was explored by Py–GC/MS.•Selectivities of phenols derived from AOL vs. SAL reached 86.73% vs. 87.37%.•More β-O-4′ linkages led to the easier pyrolysis conversion and less demethoxylation.In this study, the Fourier transform infrared (FTIR) spectrometry and the 13C–1H correlation two-dimensional (2D) heteronuclear single-quantum coherence (HSQC) nuclear magnetic resonance (NMR) were introduced to determine the chemical structure of soda alkali lignin (SAL) and Alcell organosolv lignin (AOL), and the relevance between chemical structure and pyrolysis behaviors was evaluated by thermogravimetric analysis (TGA) and pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS). Results showed that the two lignin samples had similar functional groups and S/G ratio, excepting side-chain linkages. SAL was mainly cross-linked by β-β′ linkages, while the main linkage within AOL was β-O-4′. This difference proposed that AOL had the worse thermal stability and was easier to be pyrolyzed to phenols than SAL. Herein, the pyrolysis transformation of SAL was always promoted by the increased temperature, whereas the generated phenols from AOL would be redecomposed at high pyrolysis temperature (800 °C). Moreover, the priority of demethoxylation occurring in SAL pyrolysis was higher than that in AOL pyrolysis. Further analysis on the types of phenols suggested that the formation of syringyl phenols benefitted from the increasing temperature. However, the formation of p-hydroxyphenyl phenols was inhibited as temperature increased, and the highest selectivity of guaiacyl phenols was obtained at 600 °C. The reveal of the relevance between lignin chemical structure and pyrolysis behaviors is meaningful for the efficient thermal conversion of lignin to phenol compounds.
Co-reporter:Jun Hu, Dekui Shen, Shiliang Wu, Huiyan Zhang and Rui Xiao
RSC Advances 2015 vol. 5(Issue 55) pp:43972-43977
Publication Date(Web):11 May 2015
DOI:10.1039/C5RA04974A
The microwave-assisted cleavage of C–O linkages in benzyl phenyl ether was investigated at 200 °C in the presence of ZrP or SBA-15 doped with or without metal catalyst (Pd/C or Ru/C). The total yield of phenol and benzyl alcohol from benzyl phenyl ether depolymerization with ZrP was 26.91%, while the yield of phenol reached 26.11% for that with Pd/C. Hybrid catalysts performed effectively for promoting the formation of phenol. A conversion of 85.70% was achieved with ZrP–Pd/C catalyst, and the selectivity to phenol reached 47.32%. The highest yield of phenol was obtained at 1 h, and repolymerization was remarkable at longer reaction time. Based on the reaction using phenol and benzyl alcohol as the reactants, benzyl phenyl ether might be decomposed into phenol and benzyl alcohol following with the repolymerization producing thermally stable polymers in the presence of Pd.
Co-reporter:Shanshan Shao, Huiyan Zhang, Yun Wang, Rui Xiao, Lijun Heng, and Dekui Shen
Energy & Fuels 2015 Volume 29(Issue 3) pp:1751-1757
Publication Date(Web):February 2, 2015
DOI:10.1021/ef5026505
A deactivation study of ZSM-5 in heterogeneous catalysis during the pyrolysis of a biomass-derived compound has been carried out. Experiments were performed in a gas–solid reactor with an online weighting system at varied temperatures, weight hourly space velocities, and partial pressures. Real-time catalyst weight monitoring during the catalytic conversion of furan as a main intermediate of biomass fast pyrolysis can be realized. The coke amount increased from 3.48% at a temperature of 300 °C to 9.81% at 700 °C and then declined slightly at 800 °C. The catalyst weight increment included active carbon species confined in the catalysts and inert carbon species of large unsaturated carbon molecules, which were defined as active coke and inert coke, respectively. Differentiation curves among displayed coke amount, active coke, and inert coke were described. Active coke accumulated quickly at the early stage; meanwhile, inert coke was dominant for its suppression on the catalysis reaction at the later stage, along with a slight decrease of active coke, namely, part of active coke was converted to inert species. An empirical and intrinsic model has been developed via an iterative process of model formulation, parameter estimation, and model validation with a final correlation coefficient of 0.968. To determine the kinetic parameters, several supposed deactivation functions Φ were introduced to the Arrhenius equation in a temperature-programmed reaction. Finally, a possible coking network was provided by introducing a multilayer theory, in which inert coke was supposed to be formed only on the surface of a microporous catalyst layer by layer.
Co-reporter:Shangzhe Sun, Ming Zhao, Liang Cai, Shuai Zhang, Dewang Zeng, and Rui Xiao
Energy & Fuels 2015 Volume 29(Issue 11) pp:7612-7621
Publication Date(Web):October 8, 2015
DOI:10.1021/acs.energyfuels.5b01444
The iron-based oxygen carrier with high oxygen transfer capacity has always been the key point in the chemical looping hydrogen generation (CLHG) process. In this study, CeO2-modified iron-based oxygen carriers with the porous reticular structure were prepared by the sol–gel method. Samples were tested in a thermogravimetric analyzer (TGA) and lab-scale fixed-bed reactor, respectively, to evaluate their capacities of hydrogen production and the resistance to carbon deposition or Fe3C formation. The effects of preparation conditions (CeO2 loading and [C6H8O7·H2O]/[PEG400] molar ratio) and experimental conditions (reducing atmosphere and temperature) on the physicochemical properties of CeO2-modified iron-based oxygen carriers were investigated. The initial screening test in TGA was done to select the samples with excellent reducibility and strong resistance to carbon deposition or Fe3C formation. Subsequent tests in the fixed-bed reactor were conducted to evaluate the redox characteristics and cyclic performance of the selected CeO2-modified samples. The results confirmed that iron-based oxygen carriers modified by CeO2 could effectively inhibit carbon deposition or Fe3C formation and the oxygen carrier prepared under the preparation conditions of Fe2O3/CeO2/Al2O3 = 65/5/30 and C6H8O7·H2O/PEG400 = 3 stood out from all the candidates by virtue of its high hydrogen production efficiency and the excellent recycle ability in the CLHG process. The oxygen carriers at the optimal reducing atmosphere (CO/H2/N2 = 40/30/30 and the steam oxidation reaction at 900 °C) showed the best performance with the highest hydrogen yield.
Co-reporter:Shuai Zhang, Sharmen Rajendran, Samuel Henderson, Dewang Zeng, Rui Xiao, and Sankar Bhattacharya
Energy & Fuels 2015 Volume 29(Issue 4) pp:2645-2655
Publication Date(Web):April 1, 2015
DOI:10.1021/acs.energyfuels.5b00194
Selection of low cost oxygen carriers with abundant reserves while being environmentally benign is preferred in the chemical looping combustion (CLC) process. Pyrite cinder is characterized as a waste material and poses potential environmental risk while having issues associated with disposal. In this study, pyrite cinder was utilized as a potential iron-based oxygen carrier. The reactivity, recyclability, and attrition behavior of pyrite cinder were evaluated in a laboratory scale fluidized bed reactor. The oxygen carrier to fuel ratio, steam concentration in the fluidization gas, fuel particle size, and temperature on the reactivity of pyrite cinder were investigated. The attrition behavior of pyrite cinder under both inert and reacting conditions was evaluated. The chemical and physical analyses of pyrite cinder confirmed it as a ready source of oxygen carrier. It displayed sufficient reactivity to convert char gasification products to CO2 and H2O. The performance of the system was found to be improved with respect to the carbon conversion rate and gasification rate under the following conditions: higher oxygen carrier to fuel ratio, higher steam concentration in the fluidization gas, smaller fuel particle size, and higher temperature. Cyclic redox tests of pyrite cinder over 20 cycles revealed that it behaved steadily with a stable CO2 yield being achieved. Additionally, pyrite cinder exhibited good resistance to sintering and agglomeration. The attrition behavior of pyrite cinder under inert conditions showed that the collisions of pyrite cinder particles with each other and with reactor wall at high superficial fluidization velocity was the predominant factor influencing its attrition behavior. The cyclic attrition tests showed that the attrition rate was higher in the initial cycle, but this reduced as the redox cycles progressed. It can be inferred from this study that pyrite cinder is a suitable iron-based oxygen carrier for CLC of coal while alleviating the environmental problems associated with its disposal.
Co-reporter:Jun Hu, Dekui Shen, Shiliang Wu, Huiyan Zhang, Rui Xiao
Journal of Analytical and Applied Pyrolysis 2014 Volume 106() pp:118-124
Publication Date(Web):March 2014
DOI:10.1016/j.jaap.2014.01.008
•Char produced at 330 °C has the largest surface area and the largest pore volume.•Crystalline structure of produced char is highly ordered with high hydrothermal temperature.•Char produced at higher hydrothermal temperature exhibited higher thermal-stability.•A possible mechanism was proposed for char structure evolution during lignin hydrothermal process.Hydrothermal degradation of lignin was carried out at 280–365 °C and the structure of solid char residue was extensively examined by means of scanning electron microscopy (SEM), nitrogen absorption/desorption, X-ray spectroscopy (XRD) and Fourier transform infrared spectroscopy (FTIR). The thermal stability of the produced char was estimated by Thermogravimetry–Fourier transform infrared spectroscopy (TG–FTIR). The char yield was 16.8% at 310 °C, which then increased with the temperature and reached the maxima value of 26.77% at 365 °C. SEM photo indicated that decomposition of lignin was enhanced with the increasing temperature, producing char with rough surface and few vesicles. The char at 330 °C had the largest surface area (2.5936 m2/g) and the largest pore volume (0.0189 cm3/g). XRD spectrum revealed that the char prepared at higher temperature produced higher ordered crystalline structure. Most of functional groups in char identified by FTIR were eliminated at 350 °C, except for the hydroxyl group. The char produced under high hydrothermal temperature exhibited high thermal-stability according to the right-shifted DTG curve against temperature. A mechanism was proposed to explain the possible steps for char structure evolution during lignin hydrothermal process in subcritical water, involving cleavage of the weak bonds at low temperature, and elimination of functional groups and carbonization at high temperature. The results would help improve the understanding of lignin degradation in subcritical water and optimize the hydrothermal process for producing value-added chemicals from lignin.
Co-reporter:Huiyan Zhang, Jianlong Nie, Rui Xiao, Baosheng Jin, Changqing Dong, and Guomin Xiao
Energy & Fuels 2014 Volume 28(Issue 3) pp:1940-1947
Publication Date(Web):January 29, 2014
DOI:10.1021/ef4019299
Biomass catalytic fast pyrolysis can produce aromatics and olefins, which are used as petrochemicals. However, the yields of aromatics and olefins are still very low. In this work, catalytic co-pyrolysis of pine sawdust and plastics (polyethylene, polypropylene, and polystyrene) was conducted in a fluidized-bed reactor to improve the yields of aromatics and olefins. The effects of different temperatures, polyethylene/pine sawdust ratios, different catalysts, and plastics on the product distributions were studied. The results show there are some positive synergistic effects between the two feedstocks. The maximum carbon yield of petrochemicals (71%) was obtained at 600 °C with a spent fluidized catalytic cracking (FCC) catalyst and polyethylene/pine sawdust ratio of 4:1. LOSA-1 presents better catalytic performances than Al2O3 and spent FCC catalysts. The petrochemical carbon yield with LOSA-1 is almost 2 times that without catalyst. Catalytic co-pyrolysis of polystyrene and pine sawdust produced the highest and lowest yields of aromatics (47%) and olefins (11.4%), respectively.
Co-reporter:Huiyan Zhang, Jian Zheng, Rui Xiao, Yixuan Jia, Dekui Shen, Baosheng Jin, and Guomin Xiao
Energy & Fuels 2014 Volume 28(Issue 7) pp:4294-4299
Publication Date(Web):April 25, 2014
DOI:10.1021/ef500176w
Catalytic fast pyrolysis of biomass with microporous ZSM-5 to produce aromatics is a promising technology for biomass use. To improve the aromatic yield, meso- and macroporous [CaO, MgO, and fluidized catalytic cracking (FCC)] catalysts were added in a microporous catalyst (ZSM-5). The added catalysts can crack large-molecule oxygenates from pyrolysis into small-molecule oxygenates, and then these small-molecule oxygenates were converted to aromatics over ZSM-5. The experiments of pine wood catalytic pyrolysis with two mixed catalysts were performed and analyzed using thermogravimetry–Fourier transform infrared spectroscopy (TG–FTIR) and pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS). The TG–FTIR results show that CaO and ZSM-5 mixed catalysts produced more aromatic rings and C–H bonds than pure ZSM-5. The Py–GC/MS results show that CaO and MgO mixed with ZSM-5 improved the aromatic yield significantly. The maximum aromatic yield that boosted 30% of that with pure ZSM-5 was obtained with CaO as the additive. It was obtained with a biomass/CaO/ZSM-5 mass ratio of 1:4:4. According to the disposal mode of feedstock and two catalyst studies, the completely separated mode of feedstock, CaO, and ZSM-5 (mode 3) produced the highest yield of indene and its derivatives and other hydrocarbons. This paper provides a simple way to improve the aromatic yield from biomass catalytic pyrolysis.
Co-reporter:Jun Hu, Dekui Shen, Shiliang Wu, Huiyan Zhang, and Rui Xiao
Energy & Fuels 2014 Volume 28(Issue 7) pp:4260-4266
Publication Date(Web):February 20, 2014
DOI:10.1021/ef500068h
The structural analysis and catalytic solvolysis performance of organosolv lignins from Chinese fir (softwood) and maple (hardwood) were investigated. Fourier transformation infrared spectroscopy (FTIR) analysis revealed that both Chinese fir lignin and maple lignin exhibited a guaiacyl–syringyl structure. Chinese fir lignin consisted of guaiacyl units principally, while maple lignin consisted of syringyl units mainly. The ratios of guaiacol-/syringol-type products obtained by pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS) were 2.53 for Chinese fir lignin and 0.29 for maple lignin, respectively. The catalytic solvolysis degradation was studied in supercritical ethanol/1-butanol at 300 °C with Ru/C to produce phenolic compounds. The degradation products of Chinese fir lignin were mainly guaiacol-type products, while the products of maple lignin consisted of both guaiacol- and syringol-type compounds. The yields of most products of maple lignin were much higher than those of Chinese fir lignin. The results show that the organosolv maple lignin is a potential feedstock for producing phenolic products through the solvolytic method.
Co-reporter:Rui Xiao, Shuai Zhang, Shaohua Peng, Dekui Shen, Kunlei Liu
International Journal of Hydrogen Energy 2014 Volume 39(Issue 35) pp:19955-19969
Publication Date(Web):3 December 2014
DOI:10.1016/j.ijhydene.2014.08.122
•Heavy fraction (HF) of bio-oil was used for hydrogen production in CLH process.•The reducibility and regenerability of ilmenite and three iron ores were examined.•The reactivity and recyclability of ilmenite was assessed in CLH of HF bio-oil.•HF bio-oil behaved the best at 950 °C in both pyrolysis and CLH processes.•The poor recyclability of ilmenite was due to its worse structure with cycles.Chemical looping hydrogen (CLH) process with renewable energy sources as fuel shows the potential of producing pure hydrogen with inherent capture of CO2 in a low-cost and sustainable way. The heavy fraction (HF) of bio-oil, derived from the fast pyrolysis of biomass and characterized as an energy carrier with difficulty in upgrading itself to bio-fuel or chemicals, was used in this study to generate H2. Four low-cost iron-based oxygen carriers including an ilmenite and three iron ores were initially evaluated with respect to their reducibility and the ability to minimize carbon or iron carbide (Fe3C) formation in a thermogravimetric analyzer (TGA). The reactivity and cyclic performance of the selected best candidate was then assessed in a laboratory scale fixed-bed reactor with HF bio-oil as fuel. The screening test in TGA showed that ilmenite was superior over the three iron ores in terms of promoting CO conversion and minimizing carbon or Fe3C formation. Ilmenite could maintain its increasing reducibility with the increase of surrounding CO concentration, in contrast with the iron ores that were deactivated seriously by the formed carbon or Fe3C. Subsequent CLH test with ilmenite and HF bio-oil showed that the reducibility and H2 production capacity of ilmenite were strongly dependent on the operating temperature. The steam oxidation step at 950 °C yielded H2 concentration and hydrogen yield exceeding all of those observed at the other investigated temperatures because of the deepest reduction degree of ilmenite at 950 °C. The decrease in the reducibility and H2 production capacity of ilmenite in the cyclic test could be ascribed to the poorer physical structure of ilmenite with cycles.
Co-reporter:Huiyan Zhang, Shanshan Shao, Rui Xiao, Dekui Shen, and Jimin Zeng
Energy & Fuels 2014 Volume 28(Issue 1) pp:52-57
Publication Date(Web):September 18, 2013
DOI:10.1021/ef401458y
Coke deposition on the zeolite catalysts in the conversion of furan (a main intermediate of biomass fast pyrolysis) is of serious concern for catalyst deactivation and product distribution. It is important to find out the nature and composition of coke on the spent ZSM-5 catalyst to study the coke-depositing behaviors. In this work, spent ZSM-5 catalysts obtained from furan catalytic conversion for chemicals at different reaction times and pyrolysis temperatures were characterized. The spent catalysts were first treated with hydrofluoric acid, and then the organics were extracted with CH2Cl2. The characterization of the origin coke and the treated insoluble coke were analyzed by the combination of some analytical techniques, including Fourier transform infrared spectroscopy (FTIR), high-performance liquid chromatography (HPLC), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The extracted organics were analyzed by HPLC to determine the chemical composition of the soluble coke. The results show that coke formation mainly involves condensation and rearrangement steps at a low reaction temperature (<200 °C). Coke components are polyaromatics, which formed by hydrogen transfer in addition to condensation and rearrangement steps at high temperatures (>200 °C). In the FTIR analysis, high aromaticity of coke species was obtained with increasing temperature, which indicates that the pyrolysis temperature plays a dominant role in the coke formation. TGA reveals that high temperature favors the formation of hard coke. The results enhance the understanding of coke formation and adjusting mechanism in biomass catalytic pyrolysis process.
Co-reporter:Shanshan Shao, Huiyan Zhang, Lijun Heng, Mengmeng Luo, Rui Xiao, and Dekui Shen
Industrial & Engineering Chemistry Research 2014 Volume 53(Issue 41) pp:15871-15878
Publication Date(Web):2017-2-22
DOI:10.1021/ie5024657
The present study describes the catalytic performance of acid treated HZSM-5 catalyst for the conversion of biomass derivates to olefins and aromatics. The ZSM-5 catalysts were prepared by changing several modifying parameters, such as the leaching agent, H+ concentration, processing temperature, and time. Fresh and modified catalysts were characterized by X-ray diffraction, scanning electron microscopy, surface area analysis, and NH3 temperature programmed desorption. The results show that modified ZSM-5 (leaching agent of H3PO4, H+ concentration of 2 mol/L, temperature of 20 °C, and time of 4 h) produced the maximum yield of chemicals (13.9% olefins and 31.8% aromatics), which are much higher than that obtained with the original ZSM-5 catalyst (9.8% olefins and 24.5% aromatics). The coke yield decreased from 44.1% with original ZSM-5 to 27.4% with modified ZSM-5. At the optimized dealumination condition, the selectivities of ethylene, propylene, and toluene increased, while those of butylene, C5, and benzene decreased compared with the original ZSM-5 catalyst.
Co-reporter:Dekui Shen, Jiangming Ye, Rui Xiao, Huiyan Zhang
Carbohydrate Polymers 2013 Volume 98(Issue 1) pp:514-521
Publication Date(Web):15 October 2013
DOI:10.1016/j.carbpol.2013.06.031
•Oxidative degradation of cellulose is investigated through TG-MS analysis.•A two-stage kinetic model was proposed for cellulose oxidative degradation.•Evolution of prominent volatiles and light gases was analyzed during the process.Cellulose degradation under inert (He) and oxidative atmospheres (7% O2, 20% O2 and 60% O2) was investigated through thermogravimetric (TG) equipped with mass spectroscopy (MS) system. Two mass loss stages were observed for cellulose degraded under oxidative atmosphere, where the first mass loss stage is close to that under inert atmosphere, and the second one designated to char oxidation was enhanced by the increased oxygen concentration. The evolution of prominent volatiles including furfural, acetone, 2/5-hydromethyl furfural, formaldehyde, CO and CO2 was examined considering the influence of oxygen concentration. The plateau for mass loss and evolution of some volatiles leads to the difficulty to determine the division-point for the two stages. However, the fitting parameter (Dev%) around 5% confirms the applicability of the proposed two-stage kinetic model accounting for partial pressure of oxygen.
Co-reporter:Jun Hu, Dekui Shen, Rui Xiao, Shiliang Wu, and Huiyan Zhang
Energy & Fuels 2013 Volume 27(Issue 1) pp:285-293
Publication Date(Web):December 10, 2012
DOI:10.1021/ef3016602
The chemical characteristics of lignin isolated from industrial black liquor were identified by gel permeation chromatography (GPC), Fourier transform infrared (FTIR) spectroscopy, and two-dimensional (2D) heteronuclear single-quantum coherence (HSQC) nuclear magnetic resonance (NMR), concerning its average molecular weight, distribution of typical interunit linkages, and functional groups. The frequency of β–O–4 linkage was determined to be 17–28/100 C9 units by 2D NMR, while the content of unit [guaiacol (G), syringol (S), and p-hydroxyphenyl (H)] presents a ratio of 7:2:1.5 for G/S/H. The mass-average molecular weight of lignin was characterized to be 2238 g/mol by GPC analysis. The low polymerization degree of the units in lignin leads to the substantial extent of interunit linkage cleavage at low temperatures. The guaiacol-, syringol-, and phenol-type compounds from fast pyrolysis of lignin in a pyroprobe at 500 °C were notably identified by gas chromatography–mass spectrometry (GC–MS) and presented a ratio of the peak area as 7:2:1. More fragments were observed at higher temperatures from pyrolysis (Py)–GC–MS analysis, because of the commencement of demethoxylation and cracking of side chains. The scheme concerning the cleavage of characterized interunit linkages in lignin was proposed to produce the free radicals. The side chains on the free radicals were preferably to crack on β-site bonds to produce a number of methyl phenolic compounds. The methoxyl group was intensively cracked with the increased temperature because of its high bond dissociation energy (BDE), giving rise to the notable increase of cresol-, phenol-, and catechol-type compounds under high temperatures.
Co-reporter:Huiyan Zhang, Jian Zheng, Rui Xiao, Dekui Shen, Baosheng Jin, Guomin Xiao and Ran Chen
RSC Advances 2013 vol. 3(Issue 17) pp:5769-5774
Publication Date(Web):27 Feb 2013
DOI:10.1039/C3RA40694F
The catalytic and co-catalytic pyrolysis of rice stalk and waste seed oil to produce olefins and aromatics were conducted in a novel reactor named the internally interconnected fluidized bed (IIFB) reactor. The IIFB system was specially designed for the catalytic pyrolysis of biomass, integrated with self-heating and catalyst regeneration functions in a single-bed reactor. The results show that catalytic fast pyrolysis of rice stalk produced up to a 20% total petrochemical (aromatic + olefin) carbon yield over an experimental time of 3 h. Co-catalytic fast pyrolysis of rice stalk and waste oil dramatically increased the petrochemical yield. A petrochemical yield of 64.8% was obtained at H/Ceff = 1.2. The pyrolysis and combustion temperatures were very stable, while char combustion and catalyst regeneration proceeded well in the reactor. This paper provides a new pathway for the catalytic fast pyrolysis of biomass and some insights into how biomass resources can be used more efficiently to produce renewable petrochemicals.
Co-reporter:S. Zhang;R. Xiao;Y. Yang;L. Chen
Chemical Engineering & Technology 2013 Volume 36( Issue 9) pp:1469-1478
Publication Date(Web):
DOI:10.1002/ceat.201200653
Abstract
Chemical looping combustion (CLC) of coal along with desulfurization was investigated in a fixed-bed reactor with anhydrite as oxygen carrier and CaO and CaCO3 as desulfurizers, regarding the influence of temperature, pressure, mass ratio of coal to CaSO4, and Ca/S ratio. CO2 concentration and fuel conversion increased with higher temperature and pressure but decreased with higher mass ratios of coal to CaSO4. Approximately 94 % outlet CO2 concentration and 83 % carbon conversion could be achieved under optimum operating conditions. Desulfurization tests proved the higher desulfurization efficiencies of both CaO and CaCO3 at elevated temperatures and pressures. CaO performed better than CaCO3, and an optimum value of Ca/S ratio existed for CaO. These findings demonstrate a good performance of anhydrite as oxygen carrier and the promising prospects of desulfurization in CLC of coal.
Co-reporter:Shanshan Shao;Huiyan Zhang;Dekui Shen;Jian Zheng
BioEnergy Research 2013 Volume 6( Issue 4) pp:1173-1182
Publication Date(Web):2013 December
DOI:10.1007/s12155-013-9303-x
The conversion of three major biomass derivates was conducted in a quartz tubular fixed bed reactor over a ZSM-5 catalyst. As the model compounds of polyols, saturated furans and unsaturated furans, ethylene glycol (EG), tetrahydrofuran (THF) and furan were pyrolyzed to find out the influence of chemical structure on the catalytic characteristics. The effect of pyrolysis temperature (400 ∼ 650 °C), weight hourly space velocity (2.9 ∼ 15.5 h−1) and partial pressure (2.12 ∼ 20.49 Torr) on the feed conversion, product yield and selectivity were investigated. The hydrogen to carbon effective ratio (H/Ceff) was referred to, to analyze the capacity of biomass derivates being converted to chemicals (olefins and aromatics). The results showed that the existence of rings and C=C had great effect on the catalytic characteristics. The conversion of furan was much lower (mainly less than 60 %) than that of EG and TH,F which were close to 100 %. It was also found that the chemical yield of THF was slightly more than that of EG, which can be attributed to its relative higher H/Ceff of 1.5. Furan produced the highest coke yield, which was more than 15 %, whereas that of EG and THF was only around 5 %. The serious coking of furan led to the lowest chemical yield, which was less than 35 %. This study paves a way for the mechanism study on catalytic characteristics of biomass-derived feedstocks over zeolite catalysts.
Co-reporter:Shuai Zhang, Chiranjib Saha, Yichao Yang, Sankar Bhattacharya, and Rui Xiao
Energy & Fuels 2011 Volume 25(Issue 10) pp:4357
Publication Date(Web):September 13, 2011
DOI:10.1021/ef2011595
Chemical-looping combustion (CLC), employing metal oxide(s) as the oxygen carrier for solid fuels (such as coal and biomass) combustion, is of growing interest thanks to its low cost of CO2 capture and the high system conversion efficiency. In this work, Fe2O3-containing wastes from the steel industry were applied as the oxygen carrier for chemical looping combustion with a Chinese bituminous coal in a bench-scale fixed-bed reactor. The performance of Fe2O3-containing industrial wastes was estimated with comparison to that of two other commercial iron ores (MAC iron ore from Australia and CVRD iron ore from Brazil). Effects of the operating pressure of the system (from 0.1 to 0.5 MPa) and cycle number (0–20) on the performance of the oxygen carriers were extensively studied, in terms of overall gas composition, carbon conversion, and its conversion rate. The Fe2O3-containing industrial wastes were remarkably sensitive with the operating pressure, as more pyrolysis gases and char gasification products were converted under higher pressure leading to higher concentration of CO2 and lower concentrations of CO and CH4. The elevated pressure also increased the carbon conversion and the overall reaction rate. The reactivity and porosity of the Fe2O3-containing industrial wastes under atmospheric pressure were notably enhanced by the reduction cycles, giving the concentration of 99% CO2 and the carbon conversion 81.41% after 20 cycles. Comparatively, the Fe2O3-containing industrial wastes exhibited better performance as oxygen carrier than the other two iron ores (MAC iron ore and CVRD iron ore), while the two iron ores behaved similarly to the Fe2O3-containing industrial waste with regard to the variation of operating pressure and cycles. It could be concluded that the Fe2O3-containing industrial wastes would be the outstanding oxygen carrier for chemical-looping combustion of coal over the other two iron ores.
Co-reporter:Huiyan Zhang, Shanshan Shao, Rui Xiao, Qiwen Pan, Ran Chen, and Jubing Zhang
Energy & Fuels 2011 Volume 25(Issue 9) pp:4077
Publication Date(Web):August 15, 2011
DOI:10.1021/ef200635v
A novel, self-heating biomass fast pyrolysis reactor named internally interconnected fluidized beds (IIFB) was proposed for the efficient production of bio-oils and chemicals by catalytic fast pyrolysis of biomass. The IIFB reactor mainly consisted of a pyrolysis bed (biomass pyrolysis) and a combustion bed (char burning and catalyst regeneration) connecting through a draft tube and a dipleg. Each bed was designed for the continuous operation. The hydrodynamic characteristics of the reactor, such as solid circulation rate, pressure distribution, and volume fraction of particles were performed using numerical simulation in this study. A non-steady-state, Eulerian multi-fluid model was used. The gas phase is modeled with a k–ε turbulent model, and the particle phase is modeled with the kinetic theory of granular flow. The experiments were carried out in an IIFB experimental system to verify the model. The simulation results show that the solid circulation rate was kept as a constant of 110 kg/h after 12 s of computational time compared to the value of 104.5 kg/h obtained in the experiments. The time-averaged values of the pressures at different positions after 12 s of computational time were also close to the experimental data. The particles in the dipleg were monitored to drop downward at a uniform speed of 0.07 m/s. In comparison to that in the draft tube, the velocity magnitude (including vertical or horizontal directions) of the particles decreased along the height of the draft tube, whereas the vertical velocity of the particles first underwent a disturbed flow because of the solid–solid and solid–wall collisions, then increased rapidly, and last were kept at an almost uniform magnitude. The results can provide a conceptual guide for designing, building, and operating the system of biomass (catalytic) fast pyrolysis.
Co-reporter:Denghui Wang, Rui Xiao, Huiyan Zhang, Guangying He
Journal of Analytical and Applied Pyrolysis 2010 Volume 89(Issue 2) pp:171-177
Publication Date(Web):November 2010
DOI:10.1016/j.jaap.2010.07.008
Pyrolysis of corncob with and without catalyst was investigated using thermogravimetry analyzer coupled with Fourier transform infrared spectroscopy (TGA–FTIR). The effects of two completely different catalysts, acid catalyst (MCM-41) and base catalyst (CaO), on the formation characteristics and composition of pyrolysis vapor were studied. The results show that these two catalysts give different product distributions. For catalytic run with MCM-41, the molality of carbonyl compounds decreases 10.2%, while that of phenols, hydrocarbons and CH4 increases 15.32%, 4.29% and 10.16% compared with non-catalytic run, respectively. The increase of phenols exhibits in a wide temperature range from about 295 °C to 790 °C in the catalytic run with MCM-41 catalyst. However, the use of CaO in pyrolysis of corncob leads to a huge change of product distribution. The molality of acids decreases 75.88%, while the molality of hydrocarbons and CH4 increases 19.83% and 51.05% compared with non-catalytic run, respectively. CaO is very effective in deacidification and the conversion of acids promotes the formation of hydrocarbons and CH4. Catalytic pyrolysis of corncob with CaO shows two main weight-loss stages. The first stage is from 235 °C to 310 °C with a weight loss of 31%. The second stage is from 650 °C to 800 °C with a weight loss of 21%.
Co-reporter:Rui Xiao, Qilei Song, Shuai Zhang, Wenguang Zheng and Yichao Yang
Energy & Fuels 2010 Volume 24(Issue 2) pp:1449-1463
Publication Date(Web):December 30, 2009
DOI:10.1021/ef901070c
A pressurized chemical-looping combustion combined cycle (PCLC) system is proposed for solid fuels combustion with potential high system efficiency, improving the fuel conversion and lowering the cost for CO2 sequestration. In this study, pressurized CLC of coal with Companhia Valedo Rio Doce (CVRD) iron ore was investigated in a laboratory fixed bed reactor focusing on cyclic performance. CVRD iron ore particles were exposed alternately for 20 cycles to reduction by 0.4 g of Chinese Xuzhou bituminous coal gasified with 87% steam/N2 mixture and oxidation with 5% O2 in N2 at 970 °C at atmospheric pressure (0.1 MPa) and a typical elevated pressure of 0.5 MPa. With increasing number of redox cycles, more pyrolysis gases are oxidized by the oxygen carrier. At elevated pressure, the char gasification is intensified with negligible gasification intermediate products released. The CO2 fraction increases from 80% to approximate 90% after 10 cycles at atmospheric pressure. At elevated pressures, the average CO2 fraction stabilizes at 95.75%, approximate to the equilibrium value. The carbon conversion at 0.1 MPa and 0.5 MPa is 76.48 and 84.65%, respectively, and maintains approximately the same during the cycles because excessive steam gasification agent used in this study. The oxygen carrier conversion determined from the oxygen mass balance verifies that reduction level increases with the cycle number. The physical and chemical properties of oxygen carrier particles were characterized. X-ray diffraction (XRD) analysis verifies the extent of reduction level increases with cycles. No detectable formation of compound of iron oxide and coal ash was observed. Scanning electron microscope (SEM) analyses show that the iron ore particles become porous and that more pores formed with cycles. Agglomeration of particles was not observed in all experiments at both pressures. Energy-dispersive X-ray spectroscopy (EDX) analysis show an increasing amount of coal ash on the oxygen carrier particles with increasing numbers of cycles. Pore size analyses show that the oxygen carrier particles maintained mesopores for both atmospheric and elevated pressure. The increase of both surface area and pore volume illustrates that the particles become more porous with redox cycles. This study show that pressurized CLC of coal is promising and a low-cost iron ore-based oxygen carrier may be suitable for pressurized CLC of coal.
Co-reporter:Huiyan Zhang, Rui Xiao, Denghui Wang, Zhaoping Zhong, Min Song, Qiwen Pan and Guangying He
Energy & Fuels 2009 Volume 23(Issue 12) pp:6199
Publication Date(Web):October 19, 2009
DOI:10.1021/ef900720m
The conversion of biomass into bio-oil using fast pyrolysis technology is one of the most promising alternatives to convert biomass into liquid products. However, substituting bio-oil for conventional petroleum fuels directly may be problematic because of the high viscosity, high oxygen content, and strong thermal instability of bio-oil. The focus of the current research is decreasing the oxygen and polymerization precursor content of the obtained bio-oil to improve its thermal stability and heating value. Catalytic fast pyrolysis of corncob with different percentages (5, 10, 20, and 30% by volume) of fresh fluidized catalytic cracking (FCC) catalyst (FC) and spent FCC catalyst (SC) in bed materials was conducted in a fluidized bed. The effects of the catalysts on the pyrolysis product yields and chemical composition of the bio-oil were investigated. A greater catalyst percentage lead to a lower bio-oil yield, while a lower catalyst percentage lead to little change of the composition of the bio-oil. The best percentages of FC and SC were 10 and 20%, respectively. FC showed more catalytic activation in converting oxygen into CO, CO2, and H2O than SC, but the oil fraction yield with FC was remarkably lower than that with SC because of more coke formation. The gas chromatography/mass spectrometry (GC/MS) analysis of the collected liquid in the second condenser showed that the most likely polymerization precursors, such as 2-methoxy-phenol, 2-methoxy-4-methyl-phenol, 4-ethyl-2-methoxy-phenol, 2-methoxy-4-vinylphenol, and 2,6-dimethoxy-phenol decreased, while monofunctional phenols, ketones, and furans increased compared to that in the noncatalytic experiment. The hydrocarbons increased with the increase of the catalyst percentages, and this contributed to the decrease of the oxygen content of the bio-oil. Multi-stage condensation achieved a good separation of the oil fraction and water.
Co-reporter:H.-Y. Zhang;R. Xiao;Q.-W. Pan;Q.-L. Song;H. Huang
Chemical Engineering & Technology 2009 Volume 32( Issue 1) pp:27-37
Publication Date(Web):
DOI:10.1002/ceat.200800541
Abstract
A novel biomass, autothermal, fast pyrolysis reactor with a draft tube and an internal dipleg dividing the reactor into two interconnected beds is proposed. This internally interconnected fluidized beds (IIFB) reactor is designed to produce high-quality bio-oil using catalysts. Meanwhile, the pyrolysis by-products, i.e., char, coke and non-condensable gases, are expected to burn in the combustion bed to provide the heat for the pyrolysis. On the other hand, the catalysts can be regenerated simultaneously. In this study, experiments on the hydrodynamics of a cold model IIFB reactor are reported. Geldart group B and D sand particles were used as the bed materials. The effects of spouting and fluidizing gas velocities, particle size, static bed height and the total pressure loss coefficient of the pyrolysis bed exit, on the flow patterns and pressure drops of the two interconnected beds are studied. Six distinct flow patterns, i.e., fixed bed (F), periodic spouted/bubbling bed (PS/B), spouted bed with aeration (SA), spout-fluidized bed (SF), spout-fluidized bed with slugging (SFS) and spouted bed with backward jet (SBJ) are identified. The investigations on the pressure drops of the two beds show that both of them are seen to increase at first (mainly in the F flow pattern), then to decrease (mainly in the PS/B and SA flow patterns) and finally to increase again (mainly in the SA and SF flow patterns), with the increase of the spouting gas velocity. It is observed that a larger particle size and lower static bed height lead to lower pressure drops of the two beds.
Co-reporter:Qilei Song, Rui Xiao, Zhongyi Deng, Wenguang Zheng, Laihong Shen and Jun Xiao
Energy & Fuels 2008 Volume 22(Issue 6) pp:3661-3672
Publication Date(Web):September 6, 2008
DOI:10.1021/ef800275a
Chemical-looping combustion (CLC) is a promising technology for the combustion of gas and solid fuel with efficient use of energy and inherent separation of CO2. In this study, the cyclic test of a CaSO4-based oxygen carrier (natural anhydrite) in alternating reducing simulated coal gas and oxidizing conditions was performed at 950 °C in a fluidized bed reactor at atmospheric pressure. A high concentration of CO2 was obtained in the reduction. The H2 and CO conversions and CO2 yield increased initially and final decreased significantly. The release of SO2 and H2S during the cyclic test was found to be responsible for the decrease of reactivity of a CaSO4 oxygen carrier. The oxygen carrier conversion after the reduction reaction decreased gradually in the cyclic test. Through the comparison of mass-based reaction rates as a function of mass conversion at typical cycles, it was also evident that the reactivity of a CaSO4 oxygen carrier increased for the initial cycles but finally decreased after around 15 cycles. The mass conversion rate of a CaSO4 oxygen carrier was considerably lower than that of metal oxides. X-ray diffraction analysis revealed that the presence and intensity of the reduction sulfur species was in accordance with the results of gas conversion. The content of CaO was higher than expected, suggesting the formation of SO2 and H2S during the cycles. Surface morphology analysis demonstrates that the natural anhydrite particle surface varied from impervious to porous after the cyclic test. It was also observed that the small grains on the surface of the oxygen carrier sintered in the cyclic tests. Energy-dispersive spectrum analysis also demonstrated the decrease of oxygen intensity after reduction, and CaO became the main component after the 20th oxidation. Pore structure analysis suggested that the particles agglomerated or sintered in the cyclic tests. The possible method for sulfur mitigation is proposed. Finally, some basic consideration on the design criteria of a CLC system for solid fuels using a CaSO4 oxygen carrier is discussed by the references and provides direction for future work.
Co-reporter:Zhongyi Deng, Rui Xiao, Baosheng Jin, He Huang, Laihong Shen, Qilei Song and Qianjun Li
Energy & Fuels 2008 Volume 22(Issue 3) pp:1560
Publication Date(Web):April 25, 2008
DOI:10.1021/ef7007437
Computational fluid dynamics (CFD) modeling, which has recently proven to be an effective means of analysis and optimization of energy-conversion processes, has been extended to coal gasification in this paper. A 3D mathematical model has been developed to simulate the coal gasification process in a pressurized spout-fluid bed. This CFD model is composed of gas−solid hydrodynamics, coal pyrolysis, char gasification, and gas phase reaction submodels. The rates of heterogeneous reactions are determined by combining Arrhenius rate and diffusion rate. The homogeneous reactions of gas phase can be treated as secondary reactions. A comparison of the calculated and experimental data shows that most gasification performance parameters can be predicted accurately. This good agreement indicates that CFD modeling can be used for complex fluidized beds coal gasification processes.
Co-reporter:Qilei Song, Rui Xiao, Zhongyi Deng, Laihong Shen, Jun Xiao and Mingyao Zhang
Industrial & Engineering Chemistry Research 2008 Volume 47(Issue 21) pp:8148-8159
Publication Date(Web):September 27, 2008
DOI:10.1021/ie8007264
Chemical-looping combustion (CLC) is a promising combustion technology for gaseous and solid fuel with efficient use of energy and inherent separation of CO2. The concept of a coal-fueled CLC system using calcium sulfate (CaSO4) as oxygen carrier is proposed in this study. Reduction tests of CaSO4 oxygen carrier with simulated coal gas were performed in a laboratory-scale fluidized bed reactor in the temperature range of 890−950 °C. A high concentration of CO2 was obtained at the initial reduction period. CaSO4 oxygen carrier exhibited high reactivity initially and decreased gradually at the late period of reduction. The sulfur release during the reduction of CaSO4 as oxygen carrier was also observed and analyzed. H2 and CO conversions were greatly influenced by reduction temperature. The carbon deposition ratio was found to be quite low. The oxygen carrier conversion and mass-based reaction rates during the reduction at typical temperatures were compared. Higher temperatures would enhance reaction rates and result in high conversion of oxygen carrier. An XRD patterns study indicated that CaS was the dominant product of reduction and the variation of relative intensity with temperature is in agreement with the solid conversion. The slight content of CaO in reduced oxygen carrier at high temperatures was due to the formation of SO2 and H2S during the reduction period. ESEM analysis indicated that the surface structure of oxygen carrier particles changed significantly from impervious to porous after reduction. Slight agglomeration of small grains occurred for reduced particles at 950 °C. EDS analysis also demonstrated the transfer of oxygen from the oxygen carrier to the fuel gas and a certain amount of sulfur loss and CaO formation on the surface at higher temperatures. The reduction kinetics of CaSO4 oxygen carrier was explored with the shrinking unreacted-core model. The apparent kinetic parameters were obtained, and the kinetic equation well predicted the experimental data. Finally, some basic considerations on the use of CaSO4 oxygen carrier in a CLC system for solid fuels were discussed.
Co-reporter:Qilei Song, Rui Xiao, Yanbing Li and Laihong Shen
Industrial & Engineering Chemistry Research 2008 Volume 47(Issue 13) pp:4349
Publication Date(Web):June 3, 2008
DOI:10.1021/ie800117a
The catalytic activity and kinetic behavior of catalytic reforming of methane with carbon dioxide over activated carbon were investigated as a function of reaction temperature, gas hourly space velocity (GHSV), and partial pressures of CH4 and CO2. The CH4 and CO2 conversions were greatly influenced by the reaction temperature in the range of 850−1050 °C. The apparent activation energies for CH4 and CO2 consumption and CO and H2 production were 32.63 ± 1.06, 25.54 ± 1.79, 24.81 ± 3.06, and 32.99 ± 2.58 kcal/mol, respectively. The curves of reaction rates versus GHSV showed various trends at different temperatures and indicated 7500 mL/h·g-cat was sufficient for operation in the kinetic regime. The reaction rate of methane and carbon dioxide over activated carbon was affected significantly by the partial pressures. Under a higher CO2 pressure, the excess CO2 reacted with H2 through the reverse water−gas shift (RWGS) reaction. The predictions of the CH4 and CO2 reaction rates based on a semiexperimental formula fitted satisfactorily with the experiments data. The results of mass balance, BET, XRD, and SEM studies in the deactivation test indicated that the catalyst deactivation was mainly attributed to the carbon deposition and might be alleviated at high temperatures. On the basis of the experimental results and Langmuir−Hinshelwood mechanism in the literature, a reaction mechanism was proposed. The overall reaction pathway involves the adsorption and cracking of methane and CO2 adsorption and gasification with carbon cracked. The RWGS reaction occurs simultaneously. Overall, a derived semitheoretical kinetic equation satisfactorily predicted the experimental results.
Co-reporter:Rui Xiao, Mingyao Zhang, Baosheng Jin, Yuanquan Xiaong, Hongcang Zhou, Yufeng Duan, Zhaoping Zhong, Xiaoping Chen, Laihong Shen, Yaji Huang
Fuel 2007 Volume 86(10–11) pp:1631-1640
Publication Date(Web):July–August 2007
DOI:10.1016/j.fuel.2006.11.014
The advanced high efficiency cycles are all based on gas turbine technology, so coal gasification is the heart of the process. A 2 MWth spout-fluid bed gasifier has been constructed to study the partial gasification performance of a high ash Chinese coal. This paper presents the results of pilot plant partial gasification tests carried out at 0.5 MPa pressure and temperatures within the range of 950–980 °C in order to assess the technical feasibility of the raw gas and residual char generated from the gasifiier for use in the gas turbine based power plant. The results indicate that the gasification process at a higher temperature is better as far as carbon conversion, gas yield and cold gas efficiency are concerned. Increasing steam to coal ratio from 0.32 to 0.45 favors the water–gas and water–gas shift reactions that causes hydrogen content in the raw gas to rise. Coal gasification at a higher bed height shows advantages in gas quality, carbon conversion, gas yield and cold gas efficiency. The gas heating value data obtained from the deep-bed-height displays only 6–12% lower than the calculated value on the basis of Gibbs free energy minimization. The char residue shows high combustion reactivity and more than 99% combustion efficiency can be achieved.
Co-reporter:Shiliang Wu, Dekui Shen, Jun Hu, Huiyan Zhang, Rui Xiao
Biomass and Bioenergy (December 2016) Volume 95() pp:55-63
Publication Date(Web):December 2016
DOI:10.1016/j.biombioe.2016.09.015
Co-reporter:Zhong Ma, Rui Xiao, Huiyan Zhang
International Journal of Hydrogen Energy (9 February 2017) Volume 42(Issue 6) pp:
Publication Date(Web):9 February 2017
DOI:10.1016/j.ijhydene.2016.11.107
•Bio-char was effective in catalytic steam reforming of bio-oil model compounds.•The effect of temperature, S/B and WHSV were investigated.•The inherent AAEM species have significant effect on the catalytic activity of bio-char.Hydrogen-rich gas production from the catalytic steam reforming of bio-oil model compounds was carried out in a fixed bed reactor. Bio-char, which was obtained from biomass gasification process and contained many alkali and alkaline metallic (AAEM) species, was used as a catalyst. The results showed that bio-char was effective in enhancing catalytic steam reforming of bio-oil model compounds and producing hydrogen rich gas. Temperature, S/B and WHSV were the operating variables which affected to a great extent of hydrogen production. The yield and concentration of hydrogen reached high values of 89.13% and 75.97%, respectively, under the condition of 900 °C, S/B of 3 and WHSV = 1. Acid treatment of bio-char was conducted to investigate the effect of inherent AAEM species on the catalytic activity of bio-char. It was found that the inherent AAEM species appear to have significant effect on the catalytic activity of bio-char especially the water-gas shift reaction under the current experimental conditions.
Co-reporter:De-Wang Zeng, Song Peng, Chao Chen, Ji-Min Zeng, Shuai Zhang, Hui-Yan Zhang, Rui Xiao
International Journal of Hydrogen Energy (28 December 2016) Volume 41(Issue 48) pp:
Publication Date(Web):28 December 2016
DOI:10.1016/j.ijhydene.2016.09.180
Chemical looping is a novel process in clean energy conversion with inherent CO2 sequestration. For successfully operating the chemical looping, the cyclic material must meet a variety of criteria, such as high dispersion of the cyclic phase on the support, large external surface area, and small crystallite size, etc. in attempt to better activity and stability. In this paper, we applied a colloidal crystal templated sol–gel synthesis route to produce materials for chemical looping with hydrogen storage. To understand the role of template in the sol–gel process, two samples prepared with or without template were investigated by various characterization techniques. The results showed the template could not only promote the homogeneity of the metallic precursors, but also efficiently control the material morphology. The resulting high dispersion and confinement effects endowed this material better activity and stability in chemical looping multicycles. Our current experiments demonstrated this strategy can be used as a platform for convenient incorporation of a variety of structural features, and we anticipated it can be extended to synthesis more chemical looping materials.
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