•A multi-stage stacked-tray solar seawater desalination still is designed and made.•A mathematical model of heat and mass transfer of multi-stage stacked-tray solar seawater desalination still is built.•The still performs well in water production and the performance coefficient can be up to 1.12 in an actual weather condition.In this paper, a multi-stage stacked-tray solar seawater desalination still was designed and used to assess heat and mass transfer mechanisms and test water production performance in both transient and steady states. A mathematical model of heat and mass transfer was developed and used to calculate the heat transfer velocity equation at each stage, the heat and mass transfer equation at the highest stage, and determine the performance coefficient of the still. The running of the still only needs the solar energy. It is showed that the water production rate became stable after 3 h and higher temperatures resulted in higher water production rates. Both the performance coefficient in steady state and performance coefficient were above 1 when the temperature above 70 °C. Under the practical weather, the smaller the seawater depth was, the bigger the accumulative water production and performance coefficient were. The total production was 8.1 kg/m2·d and the performance coefficient was 1.12 when the depth of seawater was 2 cm. The good agreement between the model predictions and experimental data shows the validity of the model.

•Hydrogen production of phenol was achieved via APR over Ni/ZSM-5.•Si/Al ratio of ZSM-5 strongly influenced the activity of catalyst.•Lower acidity of support was favored by APR of phenol.•240 °C, 4.9 MPa and phenol concentration of 0.2 mol/L were optimal to enhance H2 production.Hydrogen production from biomass in particular bio-oils appears interesting as bio-oils is easy to transport and storage with high conversion towards hydrogen. Phenol as presentation of lignin-derived bio-oils was chosen in this paper and was studied under aqueous phase reforming (APR) reaction using Nickel-based catalysts with ZSM-5 as support. The catalysts were synthesized by incipient wetness impregnation, and their physical and chemical properties were characterized by XRD, NH3-TPD, H2-TPR, SEM, TEM and N2 adsorption–desorption. Ni/ZSM-5 was studied with different Si/Al molar ratio and different Ni content on APR of phenol. The reactant concentration, reaction pressure and temperature were also evaluated. Ni/ZSM-5 with Si/Al molar ratio of 25 and nickel content of 16% exhibited the highest catalytic activity. Hydrogen production were maximized over the temperature of 240 °C, reaction pressure of 4 MPa and the phenol concentration of 0.2 mol/L.

•Water-wash and wrapping pretreatment on heavy metals was investigated.•Glass wrapping can effectively resist heavy metals volatilization.•After vitrification, the leachability of heavy metals is below the limit.•The optimum CAS ratio is 20–48% of CaO, 10–15% of Al2O3, 40–65% of SiO2.•The heavy metals in slag tendency is: Cr < Ni < Cd < Pb < Cu < Zn.Three fly ash samples collected from different waste incinerators were vitrified using a direct current arc plasma furnace at 1250–1400 °C. The influence of water-wash extraction and wrapping pretreatment on the volatilization and leaching behavior of heavy metals was investigated. Results showed: After thermal arc plasma treatment, the volume reduction and weight loss of fly ash were in the range of 68.7–82.2% and 23.8–56.7%, respectively. The residual fractions (wt.%) of heavy metals in slag are in the following sequence: Cr < Ni < Cd < Pb < Cu < Zn. Water-washing could reduce the volatilization rate of heavy metals due to some volatile salts removed by washing, while wrapping of fly ash could most effectively resist heavy metals against volatilizing, especially for Zn and Ni. The possible CaO – Al2O3 – SiO2 (CAS) ratio for successful melting of fly ash is suggested to be CaO in range of 20–48%, Al2O3 in range of 10–15%, and SiO2 in range of 40–65%. Moreover, toxicity characteristic leaching procedure results showed that the leaching of heavy metals in slags was much lower than the standard limit of toxicity characteristic leaching procedure (TCLP).

•A MFBR system was used for biodiesel production from waste cooking oil.•Reaction parameters were optimized by response surface methodology.•Transesterification using MWCBs in MFBR obtained a max yield of 91.8% after 48 h.•The MWCBs can be reused in MFBR for 10 cycles with maintaining 87.5% yield.•The MFBR using MWCBs was an efficient system for large-scale biodiesel industry.Biodiesel production from catalytic transesterification of waste cooking oil (WCO) was investigated in a magnetically fluidized bed reactor (MFBR) over Pseudomonas mendocina cells immobilized in magnetic microspheres. The effects of methanol to oil molar ratio (MOMR), magnetic field intensity, biocatalysts concentration and reactant flow rate on biodiesel production were investigated. Optimization of the selected parameters was carried out for maximum biodiesel production using response surface methodology with support of Design-Expert software. The parameters optimized with response surface methodology were MOMR of 3.74:1, magnetic field intensity of 136.63 Oe, biocatalysts concentration of 10.21 wt.% and reactant flow rate of 16.97 mL/min. An experimental biodiesel yield of 91.8% was obtained at 35 °C after 48 h with these optimized parameters. Moreover, the magnetic whole-cell biocatalysts (MWCBs) exhibited good reusability in MFBR that 87.5% biodiesel yield could still be achieved after 10 cycles. The results suggested that MWCBs catalyzed transesterification in the MFBR system would have broad application prospects in biodiesel production.Download high-res image (134KB)Download full-size image

•Catalytic co-cracking of distilled bio-oil and ethanol performed.•Reduced pressure distillation could remove oxygen and increase the (H/C)eff of bio-oil.•6% Ni-Z/M catalyst obtained minimum char formation and good bio-oil quality.The bio-oil from rice hull fast pyrolysis was distillated under reduced pressure at 0.005 Mpa, then mixed with ethanol (2:3 by weight). The mixture was subjected to catalytic co-cracking over Ni-ZSM-5/MCM-41 molecular sieves in a fixed-bed at 500 °C and 3.75 h−1 of the WHSV. The distillation results showed the distilled bio-oil, compared with raw bio-oil, contained lower oxygen content (decreased from 45.91 wt.% in raw bio-oil to 33.74 wt.%), higher (H/C)eff ratio (0.35) and HHV value (22.81 MJ/kg). The ethanol was involved in the ketonization, esterification, aromatization and dehydration during the catalytic co-cracking of distilled bio-oil and ethanol. The Ni loaded on ZSM-5/MCM-41 molecular sieves reduced char formation compared with ZSM-5/MCM-41. The ZSM-5/MCM-41 catalyst exhibited higher activity in the esterification and aromatization, which converted acids in upgraded bio-oil to esters, aromatics or phenols. The Ni-ZSM-5/MCM-41 catalysts showed excellent activity that transformed acids to ketones by ketonization process. The 6% Ni-ZSM-5/MCM-41 catalyst performed the good activity with the minimum char formation (7.3 wt.%) and higher upgraded bio-oil (40.8 wt.%). Moreover, the acid content in the upgraded bio-oil dropped to 0.1 wt.% and the total concentration of CO2 and CO in the gas products was 36.8 vol.%.

•CrOx–MnOx–TiO2 (CMT) adsorbent was synthesized by the sol–gel method to remove Hg0.•The addition of Cr into MnOx–TiO2 can significantly increase the activity of Hg0 removal.•The SO2 resistance performance can be greatly improved by the presence of Cr.•The mechanism for superior Hg0 removal and higher SO2 resistance over CMT was proposed.Chromium modified MnOx–TiO2 (CMT), MnOx–TiO2 (MT) and CrOx–TiO2 (CT) adsorbents were prepared by a sol–gel method and were investigated for Hg0 removal in the absence and presence of SO2. The fresh and used adsorbents were characterized by N2 physisorption, XRD, FTIR, H2-TPR, XPS and TG. The results showed that the addition of Cr into MT can not only increase the activity of Hg0 removal, but also improve its SO2 resistance performance. The amount of manganese sulfate formed onto spent CMT was much higher than that of chromium sulfate, meaning that sulfate species were formed preferentially on Mn rather than Cr.Download high-res image (162KB)Download full-size image

•Supercritical water pyrolysis of sewage sludge was studied.•The optimal temperature and moisture content were determined.•The bio-oil can be refined to use as fuel.•The non-condensable gas (NCG) and bio-char were analyzed.Municipal sewage sludge (SS) from wastewater treatment plant containing high water content (>85 wt.%), lead to the difficulty of co-combustion with MSW or coal due to the high cost of drying. This study explores an alternative method by supercritical water (SCW) pyrolysis of sewage sludge (SS) in a high pressure reaction vessel. The effects of temperature and moisture content of SS on yield and composition of the products (bio-oil, bio char and non-condensable gas) were studied. A temperature of 385 °C and moisture content of 85 wt.% were found to be the optimum conditions for the maximum bio-oil production of 37.23 wt.%, with a higher heating value of 31.08 MJ/kg. In the optimum condition, the yields of aliphatic hydrocarbon and phenols were about 29.23 wt.% and 12.51 wt.%, respectively. The physical and chemical properties of bio-char were analyzed by using XRF and BET. Results of GC analyses of NCG showed that it has the maximum HHV of 13.39 MJ/m3 at 445 °C and moisture content of 85 wt.%. The reaction path from SS to bio-oil through SCW pyrolysis was given. Moreover, carbon balance was calculated for the optimal condition, and finding out that 64.27 wt.% of the carbon content was transferred from SS to bio-oil. Finally, this work demonstrates that the SCW pyrolysis is a promising disposal method for SS.

•Novel heterogeneous rice rusk ash-based catalysts were developed.•The optimum catalyst is 30% RHA800-800.•Maximum biodiesel yield of 91.5% is achieved using the novel catalyst.•The novel catalyst can achieve a desirable recyclability.In the present study, rice husk ash (RHA, a solid waste from agriculture) was served as the support for loading calcined eggshell (another material derived from waste source) to prepare solid base catalyst. This catalyst was then applied for catalytically converting palm oil into biodiesel. The effects of catalyst preparation conditions (such as rice husk treatment temperature, the loading of calcined eggshell on the RHA, and the calcination temperature of eggshell-loaded RHA), reaction conditions (such as reaction time, methanol-to-oil molar ratio and catalyst loading) and the catalyst reusability were carefully studied. The experimental results revealed that 30% RHA800-800 exhibited the highest catalytic activity. More specifically, when the reaction was carried out with a reaction time of 4 h, methanol-to-oil molar ratio of 9:1, and catalyst loading of 7 wt.%, the biodiesel yield could reach 91.5%. Besides, after reused for more than 8 cycles, the catalyst could still possess a rather high biodiesel yield (above 80%).

•The lipid-extracted residue of T. minus was firstly used as the pyrolysis feedstock.•The lipid-extracted residue of T. minus has lower pyrolysis temperature than lignocellulosic material.•The maximum liquid product yield (29.82 wt.%) was achieved at 450 °C with 50 ml min−1 nitrogen flow rate.•The liquid product obtained from residue of T. minus contained more alkane/alkene than that from lignocellulose biomass.The pyrolysis of lipid-extracted residue of Tribonema minus has been performed in a fixed-bed reactor. In this paper the influence of nitrogen flow rate and pyrolysis temperature on products yields and composition were investigated. The maximum liquid yield of 29.82 wt.% was obtained at 450 °C with 50 ml min−1 nitrogen flow rate. The major compounds of liquid product from microalgae were carbonyls, hydrocarbons and nitrogenous compounds with a high proportion of oxygen. CO2 and CO were the main compositions of gas and their contents changed with pyrolysis temperature. The comparison of product yields and properties was made among lipid-extracted residue of T. minus, reeds and woody chips pyrolyzed under similar conditions. The liquid product from microalgal residue contained more alkane/alkene and less aromatics than that from lignocellulose biomass.

Ni/Zn/Al hydrotalcites (Ni/Zn/Al-HT) with different Ni/Zn ratios have been prepared by a coprecipitation method. The properties and microstructure of Ni/Zn/Al-HT precursors and derived catalysts were characterized by X-ray diffraction (XRD), H2-temperature programmed reduction (TPR), N2 physical adsorption analysis (BET), scanning electron microscopy (SEM) and particle size distribution. The results exhibited that the as-prepared samples consisted of a hydrotalcite phase and a ZnO phase, and Zn2+ was introduced into the layers. At the ratio of Ni/Zn = 1, the ZnAl2O4 phase emerged after calcination; Ni still remained in its original state after reaction, and ZnO always existed during the whole process. In aqueous-phase reforming (APR) of ethylene glycol, the H2 production rate over Ni/Zn/Al-HT was high, and the selectivity of H2 can almost reach 100% with a high conversion rate exceeding 99%.

The catalytic cracking of tar derived from biomass gasification was investigated, focusing on the catalyst performance of HZSM-5 (Si/Al = 25) loading with Ni or Ni and MgO, which was pre-calcined and reduced at 500 °C. The catalysts were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), and temperature-programmed desorption (TPD). The liquid and gaseous products were analyzed by gas chromatography–mass spectrometry (GC–MS) and gas chromatography (GC). The results showed that the catalytic activity of Ni–MgO/HZSM-5 was better than that of Ni/HZSM-5. When the loadings of Ni and MgO (mass %) were 6 and 2 wt %, respectively, tar conversion attained 91.03 wt % and the heating value of gas released reached 7.64 MJ/Nm3. Ni–MgO/HZSM-5 showed a stronger resistance to carbon deposition (11.69 wt %).

•Rice husk is burnt in a 500 kW fluidized bed combustor.•660–720 °C and fluidization velocity of 1.0–1.2 m s−1 appear to be the optimal.•Ash with amorphous SiO2 is over 93.8 wt.% and unburnt carbon less than 5%.•Combustion efficiency is ∼90% in all test runs.A 500 kW rice husk-firing fluidized bed combustor was designed for obtaining low carbon and high silicon ash in the amorphous form. The influence of operating condition (temperature, fluidizing velocity) on combustion efficiency and rice husk ash quality was experimentally investigated. Furthermore, the quality of rice husk ash collected from inner bed, two-stage cyclones and bag-house was analyzed using XRD, TEM and SEM instruments, in terms of amorphous silicon dioxide and unburnt carbon content. Comparative study was carried out between the rice husk ash produced in an electronic oven and that produced in the above-mentioned fluidized bed combustor. The results show that quality of ash from the industrial-scale fluidized bed is even better than that from electronic oven. Temperature of 660–720 °C and fluidization velocity of 1.0–1.2 m s−1 appear to be the favoring parameters for producing high quality rice husk ash with amorphous structure of silicon dioxide content over 93.8 wt.% and unburnt carbon context less than 4.5 wt.%. The fluidized bed combustor also assures combustion efficiency ∼90% in all test runs. This research indicates amorphous structure of silicon dioxide may be economically promisingly produced from the self-designed rice husk combustor.

To avoid lipase deactivation by methanol in the enzymatic transesterification process, a two-step biocatalytic process for biodiesel production from unrefined jatropha oil was developed.Unrefined jatropha oil was first hydrolyzed to free fatty acids (FFAs) by the commercial enzyme Candida rugosa lipase. The maximum yield achieved of FFAs 90.3 % at 40 °C, water/oil ratio 0.75:1 (v/v), lipase content 2 % (w/w) after 8 h reaction. After hydrolysis, the FFAs were separated and converted to biodiesel by using Rhizopus oryzae IFO4697 cells immobilized within biomass support particles as a whole-cell biocatalyst. Molecular sieves (3 Å) were added to the esterification reaction mixture to remove the byproduct water. The maximum fatty acid methyl ester yield reached 88.6 % at 35 °C, molar ratio of methanol to FFAs 1.2:1, molecular sieves (3 Å) content 60 % (w/w) after 42 h. In addition, both C. rugosa lipase and R. oryzae whole cell catalyst in the process showed excellent reusability, retaining 89 and 79 % yields, respectively, even after six batches of reactions.This novel process, combining the advantages of enzyme and whole cell catalysts, saved the consumption of commercial enzyme and avoid enzyme deactivation by methanol.

Biodiesel production by immobilized Rhizopus oryzae lipase in magnetic chitosan microspheres (MCMs) was carried out using soybean oil and methanol in a magnetically-stabilized, fluidized bed reactor (MSFBR). The maximum content of methyl ester in the reaction mixture reached 91.3 (w/v) at a fluid flow rate of 25 ml/min and a magnetic field intensity of 150 Oe. In addition, the MCMs-immobilized lipase in the reactor showed excellent reusability, retaining 82 % productivity even after six batches, which was much better than that in a conventional fluidized bed reactor. These results suggested that a MSFRB using MCMs-immobilized lipase is a promising method for biodiesel production.

Hydrogen production from renewable biomass is of great interests. Co-steam-reforming of biomass and crude glycerin with the ratio of 1:1(w/w) was investigated in a fixed-bed gasifier aiming at improving biomass to hydrogen conversion, focusing on the effects of temperature, pressure, H2O/C ratio and Ca/C ratio on producing gas composition. The results show that high temperature and low pressure favors hydrogen production. With temperature increasing from 650 to 825 °C, H2 yield shows a linear increase from 0.053 mol/kg to 0.059 mol/kg. Both H2 yield and its mole fraction increase obviously with the increasing H2O/C ratio. No influence on gas production is found for Ca/C ratio > 1. The study reveals the optimum condition for producing hydrogen is: temperature of 700–750 °C, pressure of 0.1 MPa, H2O/C ratio of 1.7–2.25 and Ca/C ratio of 1. Our experimental analysis shows co-steam-reforming of biomass and crude glycerin for hydrogen production is feasible and promising.Highlights► H2 production from co-gasification of biomass (corn cob) and crude glycerin has been studied. ► Reactor configuration is steam gasification followed by reforming over Ni-Ca/Al2O3. ► Effects of temperature, pressure, H2O/C ratio and Ca/C ratio have been investigated. ► High temperature, high H2O/C ratio, and low pressure favor H2 production. ► Optimum gasification condition is 700–750 °C, 0.1 MPa, H2O/C = 1.7–2.25, and Ca/C = 1.

•La1−xKxMnO3 perovskite-type catalysts were tested for bio-oil steam reforming.•The La0.8K0.2MnO3 catalyst exhibited the highest catalytic performance.•The H2 yield maximized at WCMR of 3 with 800 °C reactor temp and WbHSV of 12 h−1.•The activity of the catalysts decreases gradually, due to coke deposition.Hydrogen-rich syngas production from the catalytic steam reforming of bio-oil from fast pyrolysis of pinewood sawdust was investigated by using La1−xKxMnO3 perovskite-type catalysts. The effects of the K substitution, temperature, water to carbon molar ratio (WCMR) and bio-oil weight hourly space velocity (WbHSV) on H2 yield, carbon conversion and the product distribution were studied in a fixed-bed reactor. The results showed that La1−xKxMnO3 perovskite-type catalysts with a K substitution of 0.2 gave the best performance and had a higher catalytic activity than the commercial Ni/ZrO2. Both high temperature and low WbHSV led to higher H2 yield. However, excessive steam reduced hydrogen yield. For the La0.8K0.2MnO3 catalyst, a hydrogen yield of 72.5% was obtained under the optimum operating condition (T = 800 °C, WCMR = 3 and WbHSV = 12 h−1). The deactivation of the catalysts mainly was caused by coke deposition.

•A CCHP system with thermal energy storage is proposed.•Hourly operating strategies with different loads were analyzed.•Internal combustion engine is more suitable for the energy station.•Thermal energy storage can evidently reduce the installed capacity.Due to the national strategy of energy saving and environmental pollutant reduction, combined cooling, heating and power (CCHP) has been employed in China. A CCHP system with thermal energy storage (TES) is used as an energy station, usually consisting of a power generation unit (PGU), an absorption machine (AM), two ground source heat pumps (GSHPs), a storage tank (ST) and two electric chillers (ECs). The available PGU was compared between the gas turbine and the internal combustion engine (ICE), and the hourly operating strategies with different cooling and heating loads were analyzed. The environmental impacts were also calculated. The results show that the ICE is more suitable for the energy station. The TES reduces by 15.8% of the total installed cooling capacity and 37.5% of the total installed heating capacity of the CCHP system. The hourly operating strategies should be changed with the weather condition. The results are very valuable in guiding a CCHP system applied in engineering projects.