SUSTAINABLE NI CA1-XSRXTIO3 CATALYST PREPARED IN-SITU FOR THE PARTIALOXIDATION OF METHANE TO SYNTHESIS GAS/

A series of mixed metal oxides of the compositions Ca1-xSrxTi1-xNiyO ( x = 0-1.0, y = 0-1.0) were prepared by the citrate method, and was tes ted for the oxidation of CH4 to synthesis gas. Analytical results clea rly showed the presence of Ca1-xSrxTi1-yNiyO perovskite structure, whe re Sr substituted all the Ca sites while Ni substituted the Ti sites i n the range of y < 0.1. Among the catalysts tested, the compositions o f x = y = 0.2 showed the highest activity. Either Ni species in the Ca 0.8Sr0.2Ti1-yNiyO perovskite structure or NiO originally separated fro m the perovskite structure during the preparation was in situ reduced to Ni metal during the CH4 oxidation. The Ni metal thus formed showed high activity for synthesis gas production, where Ca0.8Sr0.2TiO3 perov skite has an important role as a carrier of the Ni catalyst. Three cat alysts of the composition Ca0.8Sr0.2Ti1.0Ni0.2O were then prepared by citrate, impregnation and mixing methods. The highest activity was obt ained with the citrate, followed by the impregnation of Ni on Ca0.8Sr0 .2TiO3 perovskite. The catalyst prepared by the mixing method afforded no perovskite, resulting in low activity. The amount of coke formatio n over the Ni catalysts after the reaction for 150 h was as follows: c itrate < impregnation much less than Ni/gamma-Al2O3 as the comparison. Ca0.8Sr0.2TiO3 perovskite was effective as the carrier of the Ni cata lyst for the partial oxidation of CH4 to synthesis gas, Ni/Ca0.8Sr0.2T iO3 prepared by the citrate method is the most sustainable against cok e formation during the reaction. It is likely that the citrate method gave high Ni dispersion over the perovskite as well as strong metal-su pport interaction between Ni and the perovskite, resulting in both hig h activity and high sustainability against coke formation.