Nickel Magnesia Catalysts Research Articles

Butane Steam Reforming: Comparison of Two Ni/MgO-Pd Catalysts with YSZ and GDC Supports

Butane steam reforming with two different types of nickel magnesia catalysts is investigated. The catalytic and electrocatalytic properties of nickel magnesia with YSZ and GDC supports made using different calcinations temperatures; 673K, 873K, 973K, and 1073K are determined. A palladium doped catalyst sample is used to examine the effects of metals on the performance. Moreover, S/C ratio is also controlled from 4 to 6 to elucidate the mechanism of butane steam reforming. The effect of microstructural change and properties are observed using X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) to characterize the differences in reforming performance.

Dry reforming of methane to synthesis gas on NiO–MgO nanocrystalline solid solution catalysts

The catalytic performance of nickel–magnesia catalysts in CO2 reforming of methane and the factors influencing carbon deposition during the reaction were investigated by a comparative study of different reduced NixMg1−xO solid solution catalysts. With the characterization results of X-ray diffraction (XRD), BET surface area, scanning electron microscopy (SEM) and thermal gravimetric analysis (TGA) it was found that the excellent anti-coking performance of reduced solid solution catalyst with low Ni content is attributable to high dispersion of reduced Ni species, basicity of support surface and nickel–support interaction.

Nickel–Magnesia Catalysts: An Alternative for the Hydrogenation of 1,6-Hexanedinitrile

Two Ni–MgO systems were synthesized and characterized as nickel catalysts for the hydrogenation of 1,6-hexanedinitrile (adiponitrile) in the gas phase. The activity results were compared with those obtained for a commercial Raney–Ni. All three catalysts showed high selectivity to 1,6-hexanediamine, for a total conversion with a maximum of 96% for the Ni–MgO catalyst, which was made from a NiO–MgO solution. However, only Ni–MgO catalysts showed high selectivity to 6-aminohexanenitrile (83 and 77%, respectively) and high conversion (87 and 85%, respectively). The higher selectivity to 6-aminohexanenitrile could be related to the presence of octahedral crystallites in the Ni–MgO catalysts.

Nickel and Nickel–Magnesia Catalysts Active in the Hydrogenation of 1,4-Butanedinitrile

Several NiO–MgO systems were synthesized to be studied as nickel catalysts for the hydrogenation of 1,4-butanedinitrile in the gas phase and compared with a bulk NiO of controlled morphology. All samples were characterized by XRD, BET, TPR, TPD, SEM, and H2 chemisorption techniques. The Ni–MgO systems had higher activities than the Ni bulk catalyst. The most active catalyst at all reaction temperatures was type R4CB which had homogeneous particles of about 1000 Å, the highest metal surface area, and the highest coverage with weakly bound hydrogen. The presence of basic magnesia suppresses the condensation reactions and consequently favors the elimination of amines, and prevents catalyst deactivation. The selectivity toward the different products not only depends on the catalytic properties but can also be modified by controlling the hydrogen/dinitrile ratio. The highest selectivity to 4-aminobutanenitrile was achieved by catalyst R4CB, with 85% at 100% conversion and working at a space velocity of 13,000 h−1 and 343 K. This selectivity could be increased by lowering the hydrogen/butanedinitrile ratio.

Nickel–magnesia catalysts for the steam reforming of light hydrocarbons

The advantages of using magnesia prepared using two techniques as a support for nickel catalysts for the steam reforming of light hydrocarbons has been examined. The initial specific activities of nickel supported on alumina or magnesia were similar, but deactivation as a result of coke formation was significantly greater on alumina-supported nickel. The steam reforming of ethane and propane over nickel/magnesia catalysts was much less affected by coke formation over longer times-on-line. The effects of variation in the preparation of magnesia were small, differences only appearing in rates of coking of higher hydrocarbons.

Catalytic Performance and Catalyst Structure of Nickel–Magnesia Catalysts for CO2 Reforming of Methane

The catalytic performance of nickel–magnesia catalysts in CO2 reforming of methane and the factors influencing carbon deposition during the reaction were investigated by a comparative study of reduced NixMg1−xO solid solution and magnesia-supported Ni metal (Ni/MgO) catalysts. Reduced NixMg1−xO solid solution catalysts generally showed higher resistance to carbon formation than Ni/MgO. From the combination of catalytic properties with the characterization results of XRD, TEM, FTIR, and dispersion measurements, it was found that the excellent anticoking performance of reduced solid solution catalyst with low Ni content is attributable to high dispersion of reduced Ni species, basicity of support surface, and nickel-support interaction.

5-2.メタンの炭酸ガスリフォーミング反応における析出炭素生成(天然ガス科学,Session(5)天然ガス)

5-2.メタンの炭酸ガスリフォーミング反応における析出炭素生成(天然ガス科学,Session(5)天然ガス)

ChemInform Abstract: DEMETHYLATION OF 2,3‐XYLIDINE TO M‐TOLUIDINE

AbstractUntersucht wird das Hydrocracken von 2,3‐Xylidin über Nickel‐Metalloxid‐Katalysatoren.

DEMETHYLATION OF 2,3-XYLIDINE TO m-TOLUIDINE

Abstract Hydrocracking of 2,3-xylidine to m-toluidine over various metal oxide-supported nickel catalysts was examined. m-Toluidine was obtained in 65.3% of selectivity at 52.6% of 2,3-xylidine conversion by using basic nickel-magnesia catalyst. Nickel catalysts supported on strongly acidic metal oxides caused considerable extents of side reactions.

Chemisorption of hydrogen on nickel–magnesia catalysts. Part I. General kinetic characteristics

A detailed study of the kinetics of hydrogen chemisorption on 3 different nickel catalysts, supported on magnesia and prepared by coprecipitation, has been made over a wide range of pressures and temperatures. The results have been analyzed in the light of the Elovich equation. Experimental data obtained by variations of pressure and temperature indicate the existence of a number of stages in the chemisorption process and support the multiple kinetic stage hypothesis suggested by Low. The effect of temperature on the parameters has been studied, and relations obtained which have been used to calculate activation energies for each of the stages.

Hydrogenation of adiponitrile over a nickel-magnesia catalyst in absence of ammonia

1. A study was made of the effect of various factors on the course of the reduction of adiponitrile in absence of ammonia over a nickel-magnesia catalyst. 2. With change in the temperature, the nature of the solvent, and the concentration of the dinitrile in it, the course of the process changes, which is the result of the competition between the hydrogenation of 6-iminohexylamine and the condensation of the latter with amines. 3. The course of the process also depends on the amount of catalyst used, which points to the chemical nonequivalence of the hydrogen activated by the catalyst.

NICKEL–MAGNESIA CATALYST AS REVEALED BY ADSORPTION AND ELECTRON OPTICAL STUDIES

A combined electron diffraction and hydrogen adsorption study on a nickel–magnesia catalyst with 36% nickel is reported. A comparison of the adsorption results with those on the previously reported 79% and 18% catalysts indicates the possibility of the unreduced nickel in the catalysts taking part in high-temperature fast adsorption. The electron optical studies show that there are structural changes taking place during the reduction treatment the catalyst undergoes. However, diffraction study in situ appears to be necessary to show, beyond doubt, the presence of reduced and unreduced nickel on the catalyst's surface.

HYDROGEN CHEMISORPTION ON NICKEL–MAGNESIA CATALYSTS

The hydrogen adsorption activities, per gram of nickel, of two nickel–magnesia catalysts are compared and explained on the basis of different types of nickel being present. The application of the Elovich equation to interpret the kinetic data shows the possibility of the presence of three kinetic stages in the temperature and pressure range studied. A study of the effect, on the hydrogen adsorption, of deliberate oxygen addition to and re-reduction of the catalyst surface shows that the nature of the oxygen contamination in the catalyst is different from that of the added oxygen.