Ethanol steam reforming over Ni/ZSM-5 nanosheet for hydrogen production

Compared to reforming reactions using hydrocarbons,ethanol steam reforming(ESR)is a sustainable alternative for hydrogen(H_(2))production since ethanol can be produced sustainably using biomass.This work explores the catalyst design strategies for preparing the Ni supported on ZSM-5 zeolite catalysts to promote ESR.Specifically,two-dimensional ZSM-5 nanosheet and conventional ZSM-5 crystal were used as the catalyst carriers and two synthesis strategies,i.e.,in situ encapsulation and wet impregnation method,were employed to prepare the catalysts.Based on the comparative characterization of the catalysts and comparative catalytic assessments,it was found that the combination of the in situ encapsulation synthesis and the ZSM-5 nanosheet carrier was the effective strategy to develop catalysts for promoting H_(2) production via ESR due to the improved mass transfer(through the 2-D structure of ZSM-5 nanosheet)and formation of confined small Ni nanoparticles(resulted via the in situ encapsulation synthesis).In addition,the resulting ZSM-5 nanosheet supported Ni catalyst also showed high Ni dispersion and high accessibility to Ni sites by the reactants,being able to improve the activity and stability of catalysts and suppress metal sintering and coking during ESR at high reaction temperatures.Thus,the Ni supported on ZSM-5 nanosheet catalyst prepared by encapsulation showed the stable performance with~88% ethanol conversion and~65% H_(2) yield achieved during a 48-h longevity test at 550-C.

Fe基催化剂物相演变及CO_(2)加氢反应性能影响

本研究使用原位X射线衍射(in-situ XRD)技术,对Na/Fe_(2)O_(3)样品的还原及活化过程进行了原位表征,探究了Na含量、预处理气氛对Fe基催化剂物相的影响,并研究了铁氧化合物与铁碳化合物在CO_(2)加氢过程中的协同作用。结合H_(2)-TPR、CO+H_(2)-TPSR-MS手段对催化剂样品进行了物化性质表征。结果表明,还原气氛为H_(2)时,Na助剂修饰会抑制Fe_(2)O_(3)催化剂还原;然而还原气氛为合成气(CO/H_(2)=1∶2)时,适量Na助剂会降低还原和活化温度,提高碳化铁含量。采用H_(2)和合成气分别对Fe基催化剂进行还原处理,低碳烯烃选择性由0.3%提高至20.2%,CO_(2)转化率由7.3%提升至25.8%;与纯Fe_(2)O_(3)相比,Na修饰后催化剂Fe_(5)C_(2)含量从8.5%提高到38.4%,C_(5+)选择性由7.8%提升至37.0%,CH_(4)选择性从43.2%降至14.9%。催化剂通过调节还原气氛和Na助剂修饰量有效调控Fe_(3)O_(4)和Fe_(5)C_(2)物相比例,提升Fe基催化剂CO_(2)加氢活性和产物选择性。

Fischer–Tropsch synthesis on impregnated cobalt-based catalysts:New insights into the effect of impregnation solutions and pH value

The Co-based catalysts were prepared with different cobalt acetate solutions. Effects of pH value were studied deeply on Fischer–Tropsch synthesis (FTS) through a semi-batch reactor. Among all impregnation solutions (water, butanol, amyl alcohol, acetic acid, nitric acid and ammonium nitrate), the catalyst prepared by NH4NO3solution showed the highest catalytic activity due to its small particle size and high reduction degree. However, the catalyst with the smallest particle size derived from water as impregnation solution exhibited low activity as well as high methane selectivity since it was difficult to be reduced and inactive in FTS. According to FT-IR spectra results, the low intensity of absorbed CO on the catalyst prepared from water solution resulted in low FTS activity. Whereas, the high activity of catalysts prepared from NH4NO3solution could be explained by the high intensity of absorbed CO on the catalysts. The cobalt species on the catalysts prepared under lower pH conditions exhibited smaller particle size distribution as well as lower CO conversion than those prepared at higher pH value. © 2016 Science Press

Active Fischer-Tropsch synthesis Fe-Cu-K/SiO_2 catalysts prepared by autocombustion method without a reduction step

The purpose of this study was to prepare iron-based catalysts supported on silica by autocombustion method for directly using for Fischer-Tropsch synthesis（FTS） without a reduction step. The effect of different citric acid（CA）：iron nitrate（N） molar ratios and acid types on the FTS performance of catalysts were investigated. The CA：N molar ratios had an important influence on the formation of iron active phases and FTS activity. The iron carbide（FexC）, which is known to be one of the iron active phases, was demonstrated by the X-ray diffraction and X-ray photoelectron spectroscopy. Increasing the CA：N molar ratios up to 0.1 increased CO conversion of catalyst to 86.5%, which was then decreased markedly at higher CA：N molar ratios. An excess of CA resulted in carbon residues covering the catalyst surface and declined FTS activity. The optimal catalyst（CA：N molar ratio = 0.1） achieved the highest CO conversion when compared with other autocombustion catalysts as well as reference catalyst prepared by impregnation method, followed by a reduction step. The autocombustion method had the advantage to synthesize more efficient catalysts without a reduction step. More interestingly, iron-based FTS catalysts need induction duration at the initial stage of FTS reaction even after reduction, because metallic iron species need time to be transformed to FexC. But here, even if without reduction, FexC was formed directly by autocombustion and induction period was eliminated during FTS reaction.

Analysis on the relationship between water resources and environmental change in Northern Thailand

How do people perceive environmental change when coping with scarcity? Previous studies on scarcity tend to overlook the aspect of perception. By analyzing repeated water conflicts in northern Thailand, this study sheds light on this aspect and solves the puzzle posed by repeated water conflicts in a small watershed.

Nanocellulose:Extraction and application

Recently,nanocellulose and its applications gain high attraction in both research and industrial areas due to its attractive properties such as excellent mechanical properties,high surface area,rich hydroxyl groups for modification,and natural properties with 100%environmental friendliness.In this review,the background of nanocellulose originated from lignocellulosic biomass and the typical extraction methods and general applications are summarized,in which the nanocellulose extraction methods related to ball milling are mainly introduced.Also,an outlook on its future is given.It is expected to provide guidance on the effective extraction of nanocellulose from biomass and its most possible applications in the future.

Glycerol valorization through production of di-glyceryl butyl ether with sulfonic acid functionalized KIT-6 catalyst

In this work,the etherification of glycerol with n-butanol catalyzed by sulfonic acid functionalized on KIT-6 mesoporous silica(SO_(3)H-KIT-6)was investigated for the production of valuable fuel additives.The SO_(3)H-KIT-6 catalyst was synthesized by co-condensation with different molar ratios of tetraethoxysilane and 3-mercaptopropyl(methyl)di-methoxy silane.The etherification reaction was systematically examined to determine the optimal reaction temperature,reaction time,catalyst loading,and glycerol to n-butanol ratio under autogenous pressure.The maximum glycerol conversion and di-glyceryl n-butyl ether(di-GNBE)selectivity were 59.09 and 51.50%,respectively,when the SO_(3)H-KIT-6 catalyst with the highest acidity was applied.Interestingly,the presence of a methyl group on the catalyst surface prevented glycerol adsorption during the reaction process,leading to the inhibition of undesired product formation.The SO_(3)H-KIT-6 catalyst could be reused up to three times,with only a 13%decrease in glycerol conversion being found.Moreover,the superior performance of the SO_(3)H-KIT-6 catalyst for di-GNBE production was also demonstrated compared with conventional solid acid catalysts including HZSM-5,H-beta zeolite,Amberlyst-35,and Amberlyst-36.

Fabrication of fluoroalkylsilane/zeolitic imidazolate framework composites for highly efficient superhydrophobic coating

Superhydrophobic bagasse paper was successfully engineered by facile spray coating with a zeolitic imidazolate framework composite modified by 3,3,3-trifluoropropyltrimethoxysilane(FAS)and used as a filter membrane with special wettability for oil/water separation.Surface characteristics such as surface morphology,surface moieties,roughness,and wettability were observed.The addition of FAS decreased the apparent surface energy between solid surfaces and liquids with a polar contribution of surface free energy as low as 0 mN m−1.The formation of the FAS layer was confirmed by transmission electron microscopy and X-ray photoelectron spectroscopy core-level spectra.Three-dimensional surface topography revealed an increase in the spray coating cycle that enhanced the hydrophobicity of the coated paper.The results confirmed that not only microstructures but also the presence of functional groups with low surface energy(such as FAS)can promote surface hydrophobicity.The spray-coated paper with FAS/ZIF in the presence of a small amount of nanocellulose provided a superhydrophobic surface after the first spray cycle.The separation efficiency was up to 85%and was slightly affected by oil viscosity.Moreover,this can be used as a filter membrane for water-in-oil emulsions.In the present work,simple spray-coated paper is a promising candidate material for gravity-driven oil/water separation and water repellent coating.