Fischer-Tropsch Synthesis Coupling Carbon Dioxide Transforming Reaction

Fischer-Tropsch synthesis (FTS) has been an industrially established process for the production from synthesis gas(syngas) of mainly linear hydrocarbons having broad chain length distributions. Considering the increasing trend in crude oil price in recent years coupled with more stringent environmental regulations concerning sulfur content, FTS represents an alternative route for the production of petrochemical substitutes as well as high-quality fuels.However, the F-T synthesis has its disadvantages,strongly heat release,multi-byproducts and so on. While the carbon dioxide transforming reaction is an endothermal reaction, so Fischer-Tropsch synthesis coupling carbon dioxide transforming reaction is the solution of the thermal equilibrium, at the same time it is the trend of F-T synthesis in the future.This paper includes the aspects as following:(1) The influences of the different materials of carrier, cobalt loading,dipping order, catalyst particle size was investigated.The results showed that integral type of catalyst was a kind of catalyst with high strength and the result of synthesis was ideal. The effect of structured catalysts was unsatisfied and its intensity was lower than excepted. Comparing different carrier materials of catalyst, when Fe was the carrier, CO conversion rate is as high as98%, but it also increased the reduction temperature, sintering and the strong exothermic,these problems can not be ignored, when activated carbon introduced into the carrier, active component distribution more uniform, since its low strength and difficult to molding recycling, its still a though thing to be continute. The increasing of cobalt loading was benefit for the coupling synthesis. The CO and CO2conversion improved with the increasing of cobalt loading, selectivity of CH4was decreased,selectivity long chain hydrocarbon was increased. The smaller the size of catalyst,the higher the CO conversion and the selectivity of C5+hydrocarbon,the synthesis was more sufficient.(2)To further improve the coupling synthesis catalytic performance, a series of cobalt-iron based catalysts were prepared. First of all, different iron contents influence on the reaction performance of the catalysts were tested. The results indicate that:suitable Fe amount could improve the CO conversion,the3%Fe catlysis was suitable for the sythesis, the conversions of CO and CO2were high and the selectivity of CH4was low.With the5%Fe catalyst,the conversions of CO was high but the selectivity of CH4was high too, the result was incline to the short carbon chain. With the addition of kalium, the activity of catalysis was increased the component of products tend to the long carbon chain, it was good for the synthesis. (3)0n the basis of large amount of synthesis, feed gas was biomass gasfication and ayngas, the influences of reaction temperature and reaction pressure on the activity were studied and optimized. We can found the best reaction conditions were reduction temperature of400℃, feed gas space velocity of1SL/(h·g-cat), reaction temperature of230℃and reaction pressure of2.0MPa.(4) When the H/C ratio is2:1, the temperature decrease about30℃comparing with the fischer-tropsch synthesis period. It proves that the appropriate H/C ratio can decrease reaction exotherm, promote coupling reaction performance.