INFLUENCE OF THE UREA CONTENT IN THE COMBUSTION SYNTHESIS FOR PREPARATION OF NiAI_2O_4 SUPPORT CATALYTIC TO STEAM REFORMING OF METHANE

摘要

The aim of this work is to evaluate the catalytic performance in steam reforming of methane of the MAl_2O_4 catalysts prepared by combustion reaction with different urea levels. The catalysts were prepared with urea in the stoichiometric proportion, and with excess of 10% and 20%. The samples were characterized by DRX, textural analysis by nitrogen adsorption, SEM, TPR, and then, catalytically evaluated in the methane reforming reaction. The results showed the presence of NiAl_2O_4 and traces of NiO for all the samples. The increase of the urea content caused an increase in the particle size and a reduction in the surface area, from 171 to 35 m~2/g. All the samples presented irregular morphology. The TPR curves showed peaks of reduction of the NiO species, and reduction of nickel present in the NiAl_2O_4. Regarding the conversion of methane to synthesis gas, it was observed that the increase of the urea content allowed obtaining higher conversion. However, it was also observed a rapid deactivation of these catalysts due to high coke deposition on the active phase's surfaces.