Zhaoyin Hou

Characterization of Ca-promoted Ni/α-Al2O3 catalyst for CH4 reforming with CO2

In CH4 dry reforming, the influence of Ca on the activity of supported Ni catalyst depended on the properties of the supports (SiO2, α-Al2O3, γ-Al2O3) and on the amount of Ca added. Small amounts of Ca increased the activity and stability of Ni/α-Al2O3. Temperature-programmed reduction with H2 (H2-TPR), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) characterizations of Ca-promoted Ni/α-Al2O3 catalysts indicated that Ca improved the dispersion of Ni, strengthened the interaction between Ni and Al2O3, and retarded the sintering. A higher amount of Ca covered the surface of α-Al2O3 and enhanced the decomposition of CH4.

Biodiesel derived glycerol hydrogenolysis to 1,2-propanediol on Cu/MgO catalysts.

Hydrogenolysis of biodiesel derived glycerol to 1,2-propanediol (1,2-PDO) has attracted much attention in recent years. In this work, glycerol hydrogenolysis to 1,2-PDO was performed over CuO/MgO catalysts prepared by impregnation and coprecipitation at 180 degrees C and 3.0 MPa H(2). It was found that the Cu(15)/MgO catalyst prepared by coprecipitation had the best activity. The conversion of glycerol and the selectivity of 1,2-PDO over Cu(15)/MgO reached 72.0% and 97.6%, respectively. And the conversion of glycerol was further increased to 82.0% when small amount of NaOH was added in the reaction mixture. Those highly active catalysts were characterized by X-ray diffraction, transmission electron microscopy, N(2)-adsorption and temperature-programmed reduction with H(2). Characterization results revealed that the activity of the prepared catalysts depended strongly on the particle sizes of both Cu and MgO. Catalysts that have smaller sized Cu and MgO particles are more active for glycerol hydrogenolysis.

A sandwich N-doped graphene/Co3O4 hybrid: an efficient catalyst for selective oxidation of olefins and alcohols

A sandwich-like N-doped graphene/Co3O4 hybrid was prepared via a simple one-pot hydrothermal reaction in a solution of NH3. Characterizations disclosed that highly dispersed Co3O4 nanoparticles with dominant exposed {112} and {110} planes were fabricated on both sides of well-exfoliated N-doped graphene; N-dopants in the graphene matrix can prevent re-graphitization of graphene, strengthen the interaction between Co3O4 and the graphene matrix, and improve the dispersion of Co3O4. This hybrid (Co3O4/RGO-N) exhibited superior activity and stability for the epoxidation of styrene compared to bulk Co3O4 and N-free graphene supported Co3O4. At the same time, the resulting catalyst also showed high compatibility with various olefins and alcohols with good conversion and high selectivity. This synergistic strategy can provide simple, efficient and versatile blue-prints for low-cost fabrication of graphene-based nanocomposites for extending applications where graphene has rarely been exploited and beyond.

Characterization study of CeO2 supported Pd catalyst for low-temperature carbon monoxide oxidation

Catalysts consisting of palladium supported on cerium dioxide (Pd/CeO2) were prepared and used for carbon monoxide oxidation in a stoichiometric mixture of carbon monoxide and oxygen. Pd/CeO2 exhibits high catalytic activity for the oxidation of CO, showing markedly enhanced catalytic activities due to the combined effect of palladium and cerium dioxide. The Pd/CeO2 catalyst is superior to Pd/ZrO2, Pd/Al2O3, Pd/TiO2, Pd/ZSM-5 and Pd/SiO2 catalysts with regard to the activity under the conditions examined. The catalysts were characterized by means of XRD and TPR. The position of the H2-TPR peak shifts to lower temperature with increasing Pd loading from 0.25 to 2.0%. CeO2 inhibits the hydrogen reduction of PdO. CO-TPR measurements have shown the existence of three peaks. The low-temperature peak (α) is due to the Pd hydroxide species. The β peak has been attributed to finely dispersed PdO. The high-temperature peak (γ) has been attributed to crystal phase PdO. Crystal phase PdO is more difficult to reduce by CO than finely dispersed PdO. On the basis of the catalytic activity and CO-TPR results, we conclude α species (Pd hydroxide) mainly contribute to the catalytic activity for low-temperature CO oxidation.

Small amounts of Rh-promoted Ni catalysts for methane reforming with CO2

Small amounts of Rh-promoted Ni/α-Al2O3 catalysts possessed higher activity than pure Ni/α-Al2O3, Rhα-Al2O3 catalysts and exhibited excellent coke resistance ability in methane reforming with CO2. XRD, H2-TPR, CO2-TPD and coking reaction (via CH4 temperature-programmed decomposition) indicated that Rh improved the dispersion of Ni, retarded the sintering of Ni and increased the activation of CO2 and CH4 on the surface of catalyst.

A novel catalyst for DME synthesis from CO hydrogenation: 1. Activity, structure and surface properties

Abstract The effect of manganese on the dispersion, reduction behavior and active states of surfaces of γ-Al 2 O 3 supported copper catalysts was investigated by X-ray powder diffraction (XRD), temperature-programmed reduction (TPR) and XPS technologies. The relationship between the area of metallic copper and the activity of dimethyl ether (DME) synthesis from CO/H 2 was also investigated. The catalytic activity over Cu-MnO x /γ-Al 2 O 3 catalyst for CO hydrogenation is higher than that of Cu/γ-Al 2 O 3 . The adding of manganese increases the dispersion of the supported copper oxide. For the CuO/γ-Al 2 O 3 catalyst, there are two reducible copper oxide species; α- and β-peaks are attributed to the reduction of highly dispersed copper oxide species and bulk CuO species, respectively. For the CuO-MnO x /γ-Al 2 O 3 catalyst, four reduction peaks are observed. The α-peak is attributed to the reduction of high dispersed copper oxide species; β-peak is ascribed to the reduction of bulk CuO; γ-peak is ascribed to the high-dispersed CuO interacting with Mn; and δ-peak is attributed to the reduction of the manganese oxide interacting with copper oxide. XPS results showed that Cu + mostly existed on the working surface of the Cu-Mn/γ-Al 2 O 3 catalysts. Cu promoted the catalytic activity with positive charge, which was formed by means of long path exchange function between Cu O Mn. These results indicate that there are synergistic interactions between the copper and manganese oxide, which are responsible for the high activity of CO hydrogenation.

MnO2/graphene oxide: a highly active catalyst for amide synthesis from alcohols and ammonia in aqueous media

Rod-like MnO2 uniformly attached on both side of GO sheets (MnO2/GO) is an efficient heterogeneous catalyst for the synthesis of primary amides from primary alcohols and ammonia as well as from aldehydes or nitriles. Water is the best solvent for these reactions, analytically pure crystals of product could be isolated by simply cooling in ice and this catalyst has excellent recyclability.

Artificial neural network aided design of catalyst for propane ammoxidation

Abstract An artificial neural network (BP network) is applied to design a VSbWSn (P, K, Cr, Mo)/SIAL catalyst for acrylonitrile synthesis via propane. The conversion of propane and selectivity of acrylonitrile can be calculated as functions of the catalyst components by the BP network to be trained. After training, the network can simulate the catalytic system very well. If one takes the conversion of propane and selectivity of acrylonitrile as the two sub-objectives, a model for this catalytic system can be given as:Max(y1=X C3 ), Max(y2=S ACN ), y= F(W,X in ), 0≤y1≤1.0, 0≤y2≤1.0. A better catalyst could be found through optimization for propane ammoxidation to acrylonitrile. The best yield of acrylonitrile is 55.0%, which is higher than those reported in the literature.

Investigation of CH4 reforming with CO2 on meso-porous Al2O3-supported Ni catalyst

Meso-porous Al2O3-supported Ni catalysts exhibited the highest activity, stability and excellent coke-resistance ability for CH4 reforming with CO2 among several oxide-supported Ni catalysts (meso-porous Al2O3 (Yas1-2, Yas3-8), γ-Al2O3, α-Al2O3, SiO2, MgO, La2O3, CeO2 and ZrO2). The properties of deposited carbons depended on the properties of the supports, and on the meso-porous Al2O3-supported Ni catalyst, only the intermediate carbon of the reforming reaction formed. XRD and H2-TPR analysis found that mainly spinel NiAl2O4 formed in meso-porous Al2O3 and γ-Al2O3-supported catalysts, while only NiO was detected in α-Al2O3, SiO2, CeO2, La2O3 and ZrO2 supports. The strong interaction between Ni and meso-porous Al2O3 improved the dispersion of Ni, retarded its sintering and improved the activated adsorption of CO2. The coking reaction via CH4 temperature-programed decomposition indicated that meso-porous Al2O3-supported Ni catalysts were less active for carbon formation by CH4 decomposition than Ni/γ-Al2O3 and Ni/α-Al2O3.

Catalytic production of 1,2-propanediol from glycerol in bio-ethanol solvent.

Production of 1,2-propanediol (1,2-PDO) from glycerol hydrogenolysis was carried out in bio-ethanol solvent over small amount of Rh-promoted Cu/solid-base catalysts prepared via layered double hydroxide precursors. It was found that glycerol hydrogenolysis proceeded easily on Rh-Cu/solid-base catalysts than separated Rh and Cu/solid-base. The conversion of glycerol and selectivity to 1,2-PDO over Rh(0.02)Cu(0.4)/Mg(5.6)Al(1.98)O(8.57) reached 91.0% and 98.7%, respectively, at 2.0 MPa H(2), 180 °C. And this catalyst was stable in five consecutive hydrogenolysis tests in ethanol.