Preparation, activation and catalytic properties in the reactions between 2‐methyl pentane and hydrogen of group VIB metal carbides

Abstract

Journ6e de Conlacl en Calalyse de la CommunaulB Franpaise de Belgique : "Catalyse par les metaux" le 7 d6cembre 1995, Bruxelles red with an integrator (Spectra Physics 4290). 2-methyl pentane (purissimum gradepurity better than 99.5%) was provided from Fluka. Samples of about 3 g of W precursors were used in preparation and activation experiments and 0.6 g for catalytic tests, WO3 (Fluka, high purity grade 99.9%, BET surface area about 3 m2gm1, mixture of monoclinic and orthorhombic crystallographic phases), MOO3 (Fluka, puriss. grade 99.5%) and Cr203 (Prolabo, rectapur 99%) were used as carbide precursors. ProcedureCarburizations and hydrogen treatments were performed in temperature programmed experiments from room temperature up to temperatures ranging from 600 to 1000°C with a heating rate of 50°C h-. A more precise procedure can be found in ref. 30. From the areas of CH4, H20, CO and CO2 chromatographic peaks the amount of CH4 and 0 consumed in the different steps of carburization and reduction (30) or produced during the hydrogen treatments (31) can be measured.Catalytic experiments were performed after in situ carburization and hydrogen pretreatment in isotherm experiments. The hydrogen and 2-methyl pentane partial pressures were respectively 0.9 and 0.1 atm. X-Ray photoelectron spectroscopy (XPS)X-Ray photoelectron spectra were obtained with an A El ES 200 B Kratos electron spectrometer equipped with an aluminium anode (hv = 1486.6 eV). The anode was operated at 12 kV and 25 mA. CIS arising from in situ contamination (binding energy (B.E.) = 285 20.2 eV) was used as reference for the calculation of binding energies. Before fitting and integrating, the C I S photopeaks were smoothed bya least squares method and the background was linearly --107 -