Influence of fuel additives in the urea-nitrates solution combustion synthesis of Ni-Al2O3 catalyst for slurry phase CO methanation

Urea-nitrates solution combustion system was facile modified by adding various fuel additives, and used for synthesizing nanosized Ni-Al2O3 catalysts. Among the three kind of fuel additives, i.e., ammonium acetate, starch and polyethylene glycol (PEG), the addition of ammonium acetate into urea-nitrates system results in numerous ignition points and uniform propagation of flames in gas-phase, which is conducive to the formation of small and dispersive NiO particles. Moreover, thermal analysis reveals that ammonium acetate, benefiting from its simultaneous decomposition With urea and metal nitrates as well as endothermic characteristic, serves as an inhibitor in combustion system that adsorbs the combustion heat to prevent the agglomeration of NiO particles. As a result, the optimum Ni-Al2O3 catalyst retains an desirable CO conversion of 92% and CH4 selectivity of 86% toward methane synthesis via slurry phase CO methanation at 260 degrees C, 1.0 MPa and 6000 mL/g(cat).h within 50 h. Taking ammonium acetate as a fuel additive, a solution combustion synthetic fashion is expected to optimize the nanostructure and activity of Ni-Al2O3 catalyst. (C) 2017 Elsevier B.V. All rights reserved.