碳球负载钴纳米颗粒的可控合成及其费-托合成催化性能

Controlled synthesis of cobalt nanparticles on the carbon spheres and Fischer-Tropsch synthesis performance

将热分解法应用于费-托合成模型催化剂的设计合成,并对一系列制备条件进行了系统的研究.结果显示,前驱体与载体物质的量比、搅拌速率和升温速率都对催化剂的分散度和颗粒的均一性有很大的影响.前驱体与载体比过大会导致颗粒致密堆叠,过小会导致颗粒过于分散.搅拌速率过慢会导致部分颗粒不依附载体生长,导致团聚;而转速过快会导致部分小颗粒形成大团簇.另一方面,升温速率会明显影响颗粒在载体上的成核结晶,进而影响颗粒的粒径大小,颗粒粒径会随着升温速率的增加而增加.当前驱体与载体物质的量比为0.024,搅拌速率为1 800 r/min,升温速率为8℃/min时,催化剂分散良好,粒径为16.9 nm,催化剂负载量为11%,将此催化剂进行费-托合成反应性能测试发现催化剂在210℃, 1.0 MPa时转化率达到28.5%,C_(5+)选择性达到85.5%,反应后催化剂形貌与结构得到了保持.

We applied thermal decomposition method in the designing of Fischer-Tropsch synthesis model catalysts,and explored a series of preparation conditions for current synthesis.The results shown that the amount-of-substance ratio of precursor to carrier,stirring speed and heating rate have great influence on the dispersion and uniformity of catalyst particles during the preparation of catalyst.The excessive amount-of-substance ratio of precursor to carrier leads to the dense stacking of particles and too small to excessive dispersion of particles.Slow stirring speed will cause some particles not growing on the carrier,leading to agglomeration,while some small particles will form large clusters for too fast rotating speed.On the other hand,the heating rate will obviously affect the nucleation and crystallization of particles on the carrier,and then affect the particle size of nanoparticles. The particle size will increase with the increase of the heating rate.Under the conditions of 0.024amount- of-substance ratio of precursor to CS,1 800r/min stirring rate and 8℃/min temperature ramp rate,CoO particles were in excellent dispersion with a size of 16.9nm,and the loading of Co was 11%.This catalyst presented a CO conversion of 28.5%and a C5+selectivity of 85.5%at 210℃and 1.0MPa.Morphology and structure of the catalyst were maintained after test.