等离子体法制备钴基费-托合成催化剂及性能表征

Preparation and Characterization of Co-Based Catalyst via Dielectric-Barrier Discharge Plasma Decomposition for Fischer-Tropsch Synthesis

钴基费-托合成催化剂以介质阻挡放电等离子体(DBD法)替代传统热焙烧过程来制备,从而可在低温分解前驱体以获得高分散催化剂.结果表明,DBD法分解前驱体效果与传统焙烧法相同,但更节能和快捷.尽管两种方法所得催化剂的比表面积相近,但DBD法制得催化剂的孔体积和孔径更大,Co分散度更高,且Co与载体间的相互作用更强,因而更难还原.同时,DBD法处理催化剂时硝酸钴分解产物以Co3O4为主,其粒径较小(达11.8nm),其团簇在催化剂表面分布比较均匀.因此,在费-托合成反应中DBD法制得的催化剂表现出较高的CO转化率和C5+选择性.

To obtain a highly dispersed Co-based catalyst,dielectric-barrier discharge （DBD） plasma instead of calcination was used to decompose the precursors at low temperature.It was found that DBD plasma can not only replace calcination to get catalyst precursor decomposed but also be quicker and more energy-saving.The catalyst samples treated by the two methods had similar surface area,while pore volume and pore size of the sample treated by DBD was larger than that by calcination.Temperature-programmed reduction results showed that the catalyst treated by DBD resulted in higher Co dispersion and stronger interaction between Co and the support than that by calcination.X-ray diffraction results indicated that Co3O4 was the main Co species after DBD treatment.The Co3O4 crystallite diameter was 11.8 nm,which was smaller than that of calcined counterparts.Transmission electron microscopy results proved that DBD treatment resulted in smaller Co oxide clusters,more homogeneous Co distribution,and less agglomeration.Fischer-Tropsch synthesis performance evaluation results showed that DBD treated catalyst had higher CO conversion and C5＋ selectivity than the calcined one.