Nickel-copper-chromium catalyst for selective methane oxidation to synthesis gas at short residence times

Data on the selective oxidation of methane to synthesis gas on a 9% NiCuCr/2% Ce/(I + alpha)-Al2O3 catalyst in dilute mixtures with Ar at short residence times (2-3 ms) are presented. The composition, structure, morphology, and adsorption properties of the catalyst with respect to oxygen and hydrogen before and after reaction were studied using XRD, BET, electron microscopy with electron microdiffraction, TPR, TPO, and TPD of oxygen and hydrogen. The following optimum conditions for the preparation and pretreatment of the catalyst for selective methane reduction were found: the incipient wetness impregnation of a support with aqueous nitrate solutions; drying; and heating in air at 873 and then at 1173 K (for 1 h at either temperature) followed by reduction with an H-2-Ar mixture at 1173 K for 1 h. At a residence time of 2-3 ms (space velocity to 1.5 x 10(6) h(-1)) and 1073-1173 K, the resulting catalyst afforded an 80-100% CH4 conversion in mixtures with O-2 (CH4/O-2 = 2: 1) diluted with argon (97.2-98.0%) to synthesis gas with H-2/CO = 2: 1. The selectivity of CO and H-2 formation was 99.6-100 and 99-100%, respectively; CO2 was almost absent from the reaction products. The catalyst activity did not decrease for 56 h; carbon deposition was not observed. A possible mechanism of the direct oxidation of CH4 to synthesis gas is considered.