Cerium-modified Cu-SSZ-13 catalysts were synthesized by an in situ hydrothermal method, and Ce was incorporated through ion exchange. The catalytic performance and N2 selectivity over prepared catalysts were evaluated in the selective catalytic reduction (SCR) of NOx by NH3. The physicochemical properties of the samples were characterized using XRD, SEM, H2-TPR, XPS, NMR, XAS, and N2 adsorption. The results indicated that Cu-SSZ-13 modified by Ce showed better NOx removal efficiency and aging resistance. The optimized condition was ion exchanged for 2 h in a cerous nitrate solution. The introduction of Ce effectively restrained the conversion of an active Cu component (Cu2+ → Cu+) during the hydrothermal aging. Ce3+ species strongly associated with molecular sieve carriers and only slight skeleton dealumination was observed on the sample exchanged for 2 h, thus resulting in the further stabilization of catalyst active centers, which consequently maintained the catalytic activity and antiaging ability.

•Mesoporous magnetic Fe2O3 was prepared by one-step pyrolysis method without templates.•As-synthesized magnetic Fe2O3 has different crystalline structure.•Prepared α-Fe2O3 nanoparticles have a high saturation magnetization.•Prepared materials have high photocatalytic activity for degradation of organic dyes.•Catalyst and organic dye could be recovered by an external magnet field.Mesoporous magnetic Fe2O3 nanoparticles with different crystalline structure were facile prepared by environmental friendly one step pyrolysis method without any templates or surfactants. The product was characterized by means of XRD, N2 adsorption-desorption, SEM, TEM and VSM. And the photocatalytic activities of mesoporous Fe2O3 nanoparticles were also studied for degradation of organic dyes in aqueous solution. Results show that as-prepared mesoporous γ-Fe2O3 is a superparamagnetic material, mesoporous α-Fe2O3 also appears a stronger magnetic property. Some parameters of mesoporous Fe2O3 nanoparticles, such as specific surface areas, pore diameters, pore volumes and saturation magnetizations are as follows: γ-Fe2O3, 105.8 m2/g, 3.1 nm, 0.227 cm3/g and 32.0 emu/g; α-Fe2O3, 16.0 m2/g, 2.7 nm, 0.118 cm3/g and 19.5 emu/g. Furthermore, as-prepared mesoporous Fe2O3 nanoparticles have certain photocatalytic activities so that the methyl orange in model waste water could be removed completely under visible light irradiation, catalysts could be repeatedly recovered by an external magnetic field. In a word, this simple template-free preparation method of mesoporous magnetic nanomaterials is beneficial to large-scale production, and is a promising preparation method.Graphical abstractDownload high-res image (81KB)Download full-size image

•PHTS was synthesized using equal amount of TEOS, a little of P123 and PVA as preparing SBA-15.•Mesoporous size and plugged pore type could be simply adjusted by adding amount of P123 and PVA.•As-synthesized plugged materials exhibit a typical two-step desorption branch.•As-synthesized plugged SBA-15 maintains still ordered mesoporous structures.Ordered plugged SBA-15 mesoporous materials were successfully hydrothermal synthesized using equal amount of TEOS as silica sources, a little amount of P123 and different amount of PVA as co-templates agents as preparing of SBA-15. As-prepared materials were characterized by X-ray diffraction, nitrogen adsorption-desorption technique, transmission and scanning electron microscope. Results show that as-synthesized plugged SBA-15 materials exhibit ordered mesoporous characteristics and different plugged pores, viz, partially plugged or completed plugged, coexist in the mesopores channels; the pore sizes and plugged types can be expediently adjusted by simply changing addition amount of PVA; the adsorption-desorption isotherms of as-synthesized materials present a typical two-step desorption branch.

Pure benzene is an important chemical feedstock, and coking benzene is one of its sources. However, the industrialized coking benzene refining processes are not green and sustainable. To solve this problem, a green two-step process for the desulfurization of coking benzene with the advantages of easy operation, low environmental pollution and solid waste (sorbent/thiophene) recyclability was evaluated. The thiophene in coking benzene was first alkylated by the olefins present in it using a suitable AlCl3/silica gel catalyst to produce alkylthiophenes, which can be easily separated by distillation. The AlCl3/silica gel catalyst obtained by a novel green process was effective in catalyzing the alkylation of thiophene by 1-hexene with an efficiency of removing thiophene up to 94.2%. AlCl3 was grafted onto silica gel by reacting with hydroxyls on its surface, which could prevent the dissolution problem of AlCl3 in benzene. The residual thiophene with its concentration range of 100–1000 mg L−1 in benzene was then almost completely removed by adsorption using an ion-exchanged zeolite. The CeY zeolite sorbent showed excellent performance in deeply removing the residual thiophene in the benzene, in which the adsorption desulfurization over the CeY sorbent fits a Langmuir isotherm. The product met the requirements for a chemical feedstock, in that no thiophene was measured in the purified benzene by gas chromatography with a flame photometric detector. The CeY zeolite with adsorbed thiophene was used to prepare polythiophene–CeY composites by chemical oxidative polymerization using anhydrous FeCl3 as an oxidant at 0 °C. The decomposition temperature of the polythiophene–CeY composites is 480 °C, which is 60 °C higher than that of polythiophene.

•CFAs zeolites were prepared by using supercritical hydrothermal method in 5 min.•The CFAs zeolites have good activity for Hg removal.•Iron can be activated during the supercritical hydrothermal processing.The supercritical hydrothermal method was proposed as a new approach to synthesize zeolite from Coal fly ashes (CFAs). Eight kinds of CFAs from different power plants were used as raw material. The effects of the types of CFAs, the concentration of NaOH, liquid-solid volume ratio, reaction time and SCW temperature on the formation of zeolites and their properties were investigated. All the CFAs can form zeolite in supercritical conditions in 5 min at 400 °C, especially for the coal fly ash with medium mass ratio of SiO2/Al2O3 and low content of Fe2O3 and CaO. The different type of zeolites (cancrinite and sodalite) could be formed by changing the solution concentration of NaOH. The best crystallinity can be obtained under the conditions of the SCW temperature of 400 °C, liquid-solid volume ratio of 15:1 and NaOH concentration of 1 mol/L. The potential application of the products synthesized from CFAs was studied and the results suggested that CFA zeolites had a good activity for Hg removal from the simulation coal gas.

A series of MnOx/AC sorbents were prepared by a sub- or supercritical water impregnation method at different temperatures using three types of active carbons (ACs) as supports. The desulfurization activities of the MnOx/AC sorbents were studied, and the physicochemical properties of fresh and used sorbents were characterized by X-ray diffraction analysis, X-ray photoelectron spectroscopy, scanning electron microscopy, and X-ray absorption near edge structure. The results indicate that the AC composition and preparing temperature affect the desulfurization activity of prepared sorbent by changing the form and dispersion of the active component. MnOx/AC sorbent prepared at 350 °C and active carbon AC(Z) from walnut shell as support presents the best desulfurization activity, holding above 22 h under the desulfurization level of nearly entire removing H2S in hot coal-based gas with breakthrough sulfur capacity of 7.24 g of S/100 g of sorbent. It is found that the valence of Mn loaded on the different AC supports was various, which related directly to the activity and capacity of the H2S removal from hot coal-based gases. The species, content, and the dispersion of the manganese oxide on the surface of the supports were dominated by AC properties. In addition, Mn3O4 is the main active component for the H2S removal over MnOx/ACs sorbents.

M/γ-Al2O3 sorbents with different metals (Ag, Cu, Ni, Zn) as the active component loaded on a γ-Al2O3 support were prepared by the incipient wetness impregnation method, and their adsorption behavior for thiophene was investigated. The results show that all these metals can obviously promote the desulfurization activity of the prepared sorbents, and Ag is the best one. Then silver was selected to modify γ-Al2O3 with a different loading amount, and the desulfurization behavior of Ag/γ-Al2O3 series sorbents in a thiophene–benzene solution was evaluated. It was found that the silver content has a significant impact on desulfurization efficiency, and the A15 sorbent with 13.7 wt% silver has the best adsorption desulfurization performance. XRD results show that the simple Ag0 is the main active component in Ag/γ-Al2O3 sorbent. SEM/EDS and BET characterization show that the specific surface area and pore volume decrease obviously when the silver loading amount is more than 13.7 wt%, because of the agglomeration of silver. The desulfurization mechanism of the Ag/γ-Al2O3 sorbent was explored by using thiophene which has both a conjugated pi bond and sulfur, tetrahydrothiophene which has sulfur but no conjugated pi bond, benzene which has a conjugated pi bond but no sulfur, cyclohexane which has no conjugated pi bonds or sulfur as the model compounds. The desulfurization efficiencies of A15 sorbent in thiophene–benzene, thiophene–cyclohexane, thiophene–tetrahydrothiophene–benzene and thiophene–tetrahydrothiophene–cyclohexane solutions were compared. The results indicate that the thiophene adsorption on Ag/γ-Al2O3 sorbent is mainly dominated by two kinds of connection between thiophene and silver. One is the connection between the conjugated pi bond and silver (π-complexation), and the other one is the connection between sulfur and silver (S–metal bond). This is also the main reason that benzene has the competitive adsorption behavior on thiophene.

Poly(3-methylthiophene)/CeY zeolite nanocomposites (P3MT/CeY) were prepared by chemical oxidative polymerization using anhydrous FeCl3 as the oxidizing agent. The physical and chemical properties of the prepared samples were measured using various characterization techniques, such as conductivity measurements, Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and carbon–sulfur analysis. The prepared P3MT/CeY composites retained the crystalline structure of Y zeolite, which also enhanced thermostability. A 2000-fold increase in conductivity relative to a blank prepared using P3MT was observed for the composite prepared using a 3:1 g mL−1 ratio of CeY and P3MT.

Lignite with a high moisture content is needed to effectively remove water and maximally restrain the re-adsorption capacity of dewatered coal. The ambient gas during lignite drying is an important factor influencing the physical properties of dewatered samples. CO2 is the main component of exhaust gas, which has been reused in flash drying technology. The relationship between the drying characteristics of a typical Chinese lignite and the pore structure changes of dewatered coal in a CO2 atmosphere, and the effect on the behavior of re-adsorbing moisture were studied. Drying experiments of lignite samples under an Ar atmosphere were also carried out for comparison. The moisture re-adsorption experiments of dewatered coal samples were conducted at 30 °C under relative humidity of 75%. The results show that the drying efficiency of coal samples under a CO2 atmosphere is higher than that under an Ar atmosphere due to the swelling effect caused by the adsorption of CO2, but this difference between CO2 and Ar becomes gradually smaller with increase in the drying temperature. The dewatered coal sample obtained under a CO2 atmosphere shows a stronger ability to re-adsorb moisture caused by the swelling effect, which could be attributed to the changes of the structure of the coal sample in this atmosphere and the increase of the surface area where the moisture is primarily absorbed. The total moisture content in the coal sample after re-adsorbing moisture follows a linear relationship with the specific surface area of dewatered lignite.

The aim of this study is to develop a flame-retardant viscose fiber using the phosphazene derivative of a natural polymer. Hexachlorocyclotriphosphazene (HCCTP) and keratin were used as the raw materials to synthesize cyclotriphosphazenekeratin (CCTPK). The Fourier transform infrared spectroscopic results indicate that CCTPK was successfully synthesized. The thermal analysis shows that the introduction of phosphazene into keratin lowered the primary decomposition temperature, increased the decomposition rate, and caused less weight loss. CCTPK blended viscose fibers were prepared by the wet spinning method, and the properties of the fiber were investigated. Limiting oxygen index of the flame-retardant fiber containing 10 % flame retardant was 28.6 %, which decreased to 27.5 % after 30 washing cycles. After burning, the scanning electron microscopy image showed an inflated carbonized coat on the fiber surface. The effect of CCTPK on the mechanical properties of the fibers was insignificant. CCTPK was compatible with keratin, and the flame retardancy of the viscose fiber was significantly improved.

In this study, a series of zinc (Zn)-based sorbents were prepared by high-pressure impregnation under different conditions of time and pressure, followed by fixed-bed pyrolysis using lignite as a precursor of support and zinc nitrate [Zn(NO3)2] as an active component precursor. The desulfurization performances of lignite and sorbents were measured. Moreover, they were characterized by X-ray diffraction (XRD), atomic absorption spectroscopy (AAS), N2 adsorption, transmission electron microscopy–energy-dispersive X-ray (TEM–EDX), and scanning electron microscopy–energy-dispersive X-ray (SEM–EDX) techniques. The ambient conditions involved in hydrothermal synthesis are favorable for the efficient uploading of Zn(NO3)2 and the improvement of lignite texture during high-pressure impregnation. The content of Zn in prepared sorbent and the utilization rate of the active component can reach over 20 and 90%, respectively. The impregnation pressure and time are the main factors influencing the desulfurization performance and textural property of the sorbent through improving the content and distribution of the active component and specific surface area of sorbent. A sorbent prepared using Zn(NO3)2 solution (34 mL, 36 wt %) at 20 atm impregnation pressure and 5 h impregnation time exhibited the best desulfurization performance. The sulfur capacity and utilization rate of the active component were 10.05 g of S/100 g of sorbent and 93.40%, respectively.

CuSAPO-34/cordierite catalysts were prepared via in situ hydrothermal synthesis technique with and without HF. The morphology and structure of the synthesized samples were characterized in the present work. The NOx selective catalytic reduction (SCR) activities of the catalysts were evaluated with a fixed-bed reactor in simulated diesel vehicle exhaust. The results indicate that the addition of HF into the initial gel during the preparation of CuSAPO-34/cordierite can accelerate the crystallization and improve the relative crystallinity of CuSAPO-34, which lead to the compact morphology of the products. Furthermore, the existence of HF can increase the specific pore volume, BET surface area and CuSAPO-34 loading of the catalyst. For the crystallization time of 24 h, the loading amounts of CuSAPO-34 are 20.3 wt% and 13.6 wt% for the samples prepared with and without HF, respectively. The obvious improvement of the catalytic activities for NOx removal has been obtained over the catalysts prepared with HF. The active temperature window (NOx conversion rate > 95%) of the samples prepared with HF is wider (340–600 °C) than the samples prepared without HF (440–540 °C). The catalysts with HF present great endurance ability for the aging treatment at 650 °C with 15 vol.% H2O. The low temperature activity for NOx removal of the catalyst prepared with HF is not affected by the aging treatment and the maximum NOx conversion rate of the aging catalyst at the crystallization time of 12 h is about 96%, but only 80% for the catalyst without HF. The roles of HF and the different performances of the samples prepared with and without HF were discussed with the aid of X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) techniques.Highlights► HF added in the preparation CuSAPO-34/cordierite improves the crystallinity of CuSAPO-34. ► Catalyst prepared with HF has higher CuSAPO-34 loading amount, pore volume and BET surface area. ► Catalyst prepared with HF shows higher NOx SCR activity in the simulated diesel vehicle exhaust. ► Catalyst prepared with HF presents wider active temperature window of NOx conversion rate > 95%.

A series of sorbents were prepared by depositing the oxide particles of Cu, Mn, and Zn onto the activated carbon (AC) using the supercritical water impregnation (SCWI) method. The morphology and structure, amounts of loading metals, pore volume, and surface area of sorbents were characterized by X-ray diffraction (XRD), inductively coupled plasma−atomic emission spectrometry (ICP−AES), and nitrogen sorption measurements. The sulfidation tests of sorbents were performed using a fixed-bed reactor under ambient pressure and simulated coal-derived gas. The results show that the metal-active component, preparation temperature, and impregnation time during SCWI are the main influencing factors of the desulfurization activity of the sorbent. These factors behave mainly by changing the micropore volume and surface area of sorbents and the dispersion of metal oxide particles on the support. The optimal SCWI conditions for preparing Mn-based sorbents are 0.46 mol/L precursor solution concentration, 380 °C preparing temperature, and 30 min impregnation time. The addition of copper component could effectively promote the dispersion of manganese oxide. The Mn−Cu sorbents prepared by SCWI have high desulfurization efficiency and sulfur capacity compared to the single-metal sorbent. The desulfurization efficiency can be maintained at about 100% in the sulfidation time of 910 min, and the corresponding sulfur capacity is 5.58 g S/100 g sorbent for the sorbent with a 3:7 molar ratio of Mn/Cu prepared by SCWI.

Zn-based sorbent (Z20SC) prepared through semi-coke support in 20 wt% zinc nitrate solution by high-pressure impregnation presents an excellent desulfurization capacity in hot coal gas, in which H2S can not be nearly detected in the outlet gas before 20 h breakthrough time. The effects of the main operational conditions and the particle size of Z20SC sorbent on its desulfurization performances sorbent were investigated in a fixed-bed reactor and the desulfurization kinetics of Z20SC sorbent removing H2S from hot coal gas was calculated based on experimental data. Results showed that the conversion of Z20SC sorbent desulfurization reaction increased with the decrease of the particle size of the sorbent and the increases of gas volumetric flow rate, reaction temperature and H2S content in inlet gas. Z20SC sorbent obtained from hydrothermal synthesis by high-pressure impregnation possessed much larger surface area and pore volume than semi-coke support, and they were significantly reduced after the desulfurization reaction. The equivalent grain model was reasonably used to analyze experimental data, in which ks = 4.382×10−3 exp(−8.270×103/RgT) and Dep = 1.262×10−4exp(−1.522×104/RgT). It suggests that the desulfurization reaction of the Z20SC sorbent is mainly controlled by the chemical reaction in the initial stage and later by the diffusion through the reacted sorbent layer.

•Zero-value α-Fe microparticles were prepared by a cost-effective and safe method.•As-prepared samples have high antioxidation ability and paramagnetic properties.•As-synthesized α-Fe particles have high saturation magnetization 138.5 emu/g.•Prepared α-Fe samples have high specific surface area and adsorption capacity for heavy metal ions.α-Fe microparticles with high stability were expediently prepared by thermolysis directly of ammonium ferric citrate powders under inert atmosphere neither using any reductant nor by hydrogen reduction. The prepared samples were characterized by XRD, N2 adsorption-desorption isotherm, SEM, TEM, particle size distribution and VSM. And preliminary study of adsorption effect of as-prepared samples was still carried out. Results indicate that as-prepared α-Fe microparticles have irregular shape, bigger particle size of about 1.1 μm and higher oxidation resistant, which is really a core-shell structure material of Fe@C; they have higher saturation magnetization of 138.5 emu/g, lower remanet magnetization of 5.7 emu/g and coercive field of 66.8 Oe, which has the tendency of paramagnetization. Furthermore, as-prepared α-Fe microparticles have higher specific surface area of 57.2 m2/g and stronger adsorption capability for heavy metal ions in water.