The Influences Of CeO₂on The Properties Of Catalysts For Fischer-tropsch Synthesis

Fischer-tropsch synthesis is through a certain catalyst to synthesis gas (hydrogenand carbon monoxide) into liquid hydrocarbon fuel and high quality production way ofhigh value-added chemical raw materials.Especially in times of shortage of coalresources, to seek high efficiency and low cost of coal-to-liquid technology is a hotspotof current research.The core technology of Fischer-tropsch is the catalyst that is often incobalt and iron as a catalyst active component, when add a certain amount of promoter,the catalyst activity and selectivity of reaction products have certain improvementeffect.Rare earth elements because of its certain alkaline and REDOX properties,therefore, when used as a fee-tropsch catalyst agent can improve the activity andselectivity of catalyst.This paper was prepared by coprecipitation of CeO2nanoparticles, as a promoter tojoin in the catalyst, and through its different content, calcination temperature, etc., inorder to research assistant CeO2catalyst adsorption, stripping, such as catalyticperformance.By ultrasonic spray-coprecipitation method, the preparation of CeO2, theorthogonal experiment was designed through the powder particle size, morphologycharacterized in CeO2concentration is0.05mol/l, PH of7, water bath temperature was60℃, EDTA2000quality percentage of0.9experimental conditions, was prepared bypowder particle size is97nm, with irregular globular structure.Additives in the catalystCeO2content respectively:1%,2%,4%,8%,4%, by controlling the roastingtemperature:400℃,500℃,600℃,700℃to discuss the influences of additivecontent and temperature on the catalytic performance.The study found that CeO2addsmall amount (1%), the reduction performance of cobalt is restrained, the addingamount was4%and8%, the reduction peak temperature decreases; But too much theintroduction of additives (adding amount of12%), oxide additives will be covered on the surface of cobalt species, inhibit its adsorption performance.With the addition ofadditives, the CO conversion (CO/SiO2) increased by40%to75%(4%-Ce-CO/SiO2),then fell to61%(12%-Ce-CO/SiO2), C5+selectivity is (Ce-CO/SiO2) increased from62.5%to82.5%(8%-Ce-CO/SiO2), then fell to71.4%(12%-Ce-CO/SiO2).Roasting temperature rise, make the catalyst produces sintering phenomenon, with thedecrease of CO conversion, heat treatment (400℃) fell to39%from74%(700℃) heattreatment, the yield of C5+, too, fell, from85.4%(400℃) heat treatment, fell to83.5%(700℃) heat treatment.