Xu Wu

A noble-metal free Cu-catalyst derived from hydrotalcite for highly efficient hydrogenation of biomass-derived furfural and levulinic acid

A Cu-catalyst derived from hydrotalcite precursor was highly selective for the hydrogenation of biomass-derived furfural and levulinic acid. 90% yield of furfuryl alcohol and 51% yield of 2-methylfuran were achieved selectively in the hydrogenation of furfural. 91% yield of γ-valerolactone was achieved in the hydrogenation of levulinic acid.

NOVEL PREPARATION OF NANO-COMPOSITE CuO-Cr2O3 USING CTAB-TEMPLATE METHOD AND EFFICIENT FOR HYDROGENATION OF BIOMASS-DERIVED FURFURAL

A simple route to fabricate nano-composite oxides CuO-Cr2O3 using hexadecyltrimethylammonium bromide (CTAB)-templated Cu-Cr hydrotalcite as the precursor is presented. This novel method is based on CTAB-templating effect for mesostructure directing and using the cheap metal nitrate, followed by removal of CTAB. It was indicated that the nano-composite CuO-Cr2O3 was formed during the removal of CTAB. X-ray diffraction (XRD) and transitional electronic microscopy (TEM) revealed nice nano-composite oxides CuO-Cr2O3 were formed with high crystallinity. N2 adsorption and desorption indicated that a high surface area of 170.5 m2/g with a pore size of 2.7 nm of the nano-composite CuO-Cr2O3 was facilely resulted. The as-synthesized nano-composite oxides CuO-Cr2O3 display good catalytic activities for hydrogenation of furfural to furfuryl alcohol, whereas 86% selectivity was achieved at 75% conversion of furfural.

Organotemplate-free synthesis of hollow Beta zeolite supported Pt-based catalysts for low-temperature ethanol steam reforming

A novel platinum-encapsulated hollow Beta zeolite (Pt@HBS) catalyst was successfully fabricated through an organotemplate-free and seed-directed route, with carbon spheres as a hard template. Pt@HBS not only exhibited excellent catalytic performance, but could also maintain the catalytic reaction for more than 28 h without losing its activity.

A new way to synthesize benzoin isopropyl ether on Cu-Fe-hydrotalcite

An efficient synthesis of benzoin isopropyl ether with benzaldehyde and propanol in the presence of heterogeneous recyclable Cu-Fe-hydrotalcite catalyst has been explored. Cu-Fe-hydrotalcite was firstly successfully synthesized over Jahn-Teller effect of Cu2+. The catalytic test result showed that Cu-Fe-hydrotalcite could be used as a good catalyst in the synthesis of benzoin isopropyl ether. The highest conversion of benzaldehyde was 59.7% and the selectivity of benzoin isopropyl ether was nearly 100%. By this new method, not only was the cyanide poisoning avoided, but also the synthesis of benzoin isopropyl ether could be completed in one step instead of traditional two steps with both condensation and etherification.

A novel BEA-type zeolite core–shell multiple catalyst for hydrogen-rich gas production from ethanol steam reforming

BEA-type core–shell catalysts consisting of a core supporting Cu and Fe and a Ni-based shell were investigated for their ethanol steam reforming (ESR) activity. The effect of the nature of the core–shell double-support and the promotion achieved by adding Ni, Cu and Fe were studied. The catalysts were characterized by XRD, BET, SEM, TEM, H2-TPR, CH4-TPD, CO-TPD and XAFS analyses. Compared to zeolite Beta as support, the core–shell catalysts exhibited excellent performance in ethanol reforming, leading to high selectivity to hydrogen through a multiple reaction system. This result indicated that the special structural advantages of the core–shell support could give full play to the properties of active phases and provide a one-step production process for high-purity hydrogen. The Ni-base shell was twice as active for the catalytic reaction, resulting in greatly improved catalytic activity and selectivity to hydrogen; in addition, the decrease of by-products could be attributed to the function of the Cu and Fe phases, improving the steam acetaldehyde reforming, steam methane reforming and water gas shift reactions. Furthermore, in the investigation of the effects of the amount of the Cu and Fe phases, the best catalytic performance was reported by the 2.5Fe2.5Cu-SB@NB catalyst.

Novel catalyst PTMA-PILC: structural properties and catalytic performance for the dehydration of bioethanol to ethylene

Novel phosphomolybdic acid-pillared interlayer clay (PTMA-PILC) catalysts were prepared by three steps: acid treatment, ion-exchange and impregnation method. The resulting catalysts were initially characterized by a combination of XRD analysis, FT-IR, TG, NH3-TPD, pyridine-IR, TEM, and N2 adsorption–desorption. The characterization results indicated that the sandwich structure of the montmorillonite was delaminated on acid treatment, resulting in a reduction of the surface area to 335 m2 g−1 and the formation of plate-like particles. Surprisingly, after ion-exchange and impregnation, the stratified structure was restored. The strong and weak acidity contents also changed. The catalytic properties of this series of catalysts were tested in the dehydration of ethanol to ethylene. A significant improvement in catalytic activity was observed in the dehydration of ethanol (30 vol%) to ethylene on the synthesized PTMA-PILC catalyst, from which 93.2% conversion and 99.1% selectivity of ethylene were achieved at 300 °C. The improved activities were attributed to the layer structure and the balance of Lewis and Bronsted acid sites.

Kinetics and mechanism of formation of benzoin ethyl ether from benzaldehyde and ethanol using heterogeneous Ni(HCO 3 ) 2 as catalyst

Ni(HCO3)2, with a unique phase and high crystallinity, was synthesised utilising urea hydrolysis. The physicochemical properties of the synthetic samples were characterised by X-ray diffraction, scanning electron microscopy and N2-adsorption – desorption measurements. The heterogeneous Ni(HCO3)2 catalysts presented high catalytic activity in the synthesis reaction of benzoin ethyl ether from benzaldehyde and ethanol. Furthermore, the catalysts could be recycled several times and showed stable activity without structural change. The kinetic parameters were obtained by the half-life law which showed that the reaction was belong first-order. The apparent activation energy was 42.72 kJ mol–1. The reaction mechanism was probed theoretically using the HF/3-21G method, which suggested that benzoin ethyl ether is formed via a series of states i.e. a complex, transition states and intermediates. Especially, the role of C6H5CHOC2H5OH as an intermediate is significant.

Oxidation of benzaldehyde to benzoic acid using heterogenous NiAl-hydrotalcite-like-compounds as the catalyst in acetic acid

NiAl-hydrotalcite-like-compounds (NiAl HTLcs) with a unique phase and high crystallinity were synthesized utilizing urea hydrolysis. The physicochemical properties of the synthetic samples were characterized by X-ray diffraction, scanning electron microscopy and N2-adsorption- desorption measurements. The catalysed oxidation of benzaldehyde to benzoic acid was performed using dissolved air as oxygen source in acetic acid under the following conditions: 0.1 g catalyst, the ratio V(benzaldehyde)/V(ethanoic acid) was 3/9, with a stirring speed of 800 rev min “1. The heterogeneous NiAl - HTLcs catalysts were recycled several times and showed stable activity without structural change. The reaction mechanism was elucidated via the determination of kinetic parameters. It was shown that the oxidation is of zero order, dominated by classic diffusion. The apparent activation energy was 14.13kJ mol-1.

Study on the Thermal Decomposition Behavior of MgAl-Hydrotalcite Compounds

MgAl-hydrotalcite compounds (MgAl-HT) with different n(Mg)/n(Al) ratios were synthesized by coprecipitation method. XRD and FT-IR were performed to characterize the structure of MgAl-HT. TG-DTG technology was adopted to study the thermal decomposition behavior. It was discovered that the thermal decomposition proceeded in two stages when the ratios of n(Mg) toward n(Al) being to 2~4. The kinetic parameters of the thermal decomposition procedure were also calculated by Ozawa method, which demonstrated that the value of active energy showed dynamic distribution. At each step of the decomposition behavior, the value of active energy decreased at first and then rose. The value of active energy for the deformation of the water in the interlayer was located within 45~90 kJ•mol-1 and within 150~230 kJ•mol-1 for the deformation of structure hydroxyl. Those characteristics were discussed and explained according to relative theory.

Synthesis and catalytic performance of hierarchically structured MOR zeolites by a dual-functional templating approach

Novel hierarchical MOR zeolites have been successfully synthesized via a one-step dual-functional templating strategy utilizing gemini organic surfactant (C18-2-8) through hydrothermal process. After a period of ∼96 h for crystallization, the hierarchy MOR zeolite with a larger BET (412.0 m2/g), abundant intracrystalline mesopores (average mesopore size distribution of 4.55 nm), and more accessible acid sites can be synthesized. The XRD study revealed a long range structural ordering of mesoporous and a good crystallinity of microporous structure. The results indicated that the surfactant acted as a dual-functional template for generating both micropores and mesopores simultaneously. Compared with conventional MOR zeolite, hierarchically structured MOR zeolite not only has higher activity and stability, but also can avoid side-reaction taking place in ethanol dehydration reactions. This hierarchical micro/mesostructured mordenite zeolite may be a candidate for practical industrial applications especially in those reactions where bulky molecules are involved.