Utilization of carbon dioxide for the production of fuels and chemicals can be good alternative to reduce wide emission of CO2 from fossil fuels, which reflects as one of the source for the greenhouse gas effect. Fisher-Tropsch (FT) synthesis has been intensively studied over Co, Fe and Co-Fe based catalytic systems using syn-gas as a starting feedstock, these catalysts were used in the form of bulk or supported oxide catalysts. As reported, the residual alkali metals showed a negative effect on the catalyst structure and activity performance. However, use of alkali dopants K, Na and Cs during FT process would effectively help to reduce bulk Co-oxide species, also help to improve catalyst basic strengths. This clearly confirms with minimization of unwanted methane and production of hydrocarbons with high olefin/paraffin ratio. Hence, these target materials need to be investigates on the basis of active metal, easy reducibility and metal carbide species, which can effectively catalyzes CO2 hydrogenation to hydrocarbons. Here, CoCu supported ZrO2 catalysts prepared using potassium (K) as a precipitating agent by co-precipitation method with two different course of washing of the precipitates. In consideration, there is difficulty to remove the residual alkali metal thoroughly, this may influence the structure and performance of the catalysts. Therefore, we discuss the effect of residual potassium on the catalytic performance for CO2 hydrogenation to hydrocarbons. Monometallic Cu/ZrO2 effectively producing CO, while use of monometallic Co/ZrO2 favor to the formation of CH4 and C2-C4. However, the combination of CoCu (Cu2Co3/ZrO2) with high K loading showed gradual increase in CO2 conversion during time on stream activity, this may be due to the formation of active Co-carbide intermediate species. The influence high K loading on CO2 hydrogenation showed interesting observation, there is increase in olefin to paraffin ratio (C2-C4) with time on stream activity.

Effect of alkali metals on CO2 hydrogenation to hydrocarbons over zirconia supported CoCu bimetallic catalysts

255th National Meeting (2018)

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