Preparation of Nanosized catalyst by supercritical fluid drying method and Its performance for Fischer-Tropsch synthesis

摘要

Nanosized Fe-Mn-Cu-K composite catalyst was prepared by sol-gel and supercritical fluid drying (SCFD) methods. The structural properties of catalyst were characterized by means of XRD, TEM and BET techniques and the catalytic performance was evaluated by supercritical phase Fischer-Tropsh synthesis. The results indicated that the activity of nanosized catalyst prepared by supercritical fluid drying method was improved greatly compared with the catalyst prepared by common drying method. The catalyst prepared by SCFD method possesses many excellent properties such as small particle diameter, narrow size distribution, large specific surface area, good dispersibility and the drying and crystallization of nanosized catalyst could be achieved in one step by SCFD technique. It was found that the catalyst prepared by SCFD method and supercritical phase Fischer-Tropsh synthesis was the best combination, the catalyst prepared by SCFD exhibited the higher activity and lower CO2 and CH4 selectivity. After approaching the steady state, the CO conversion was 98.90%, the light olefins selectivity in total hydrocarbon was 56.31% and the light olefins yield in total products was 50.59%. The SCFD method is a novel process and technique to prepare nanosized materials, and it is the advantage that the products are easy to be collected and the solvent can be recycled and reused.