K-Co-Mo-C催化剂的制备及其合成低碳醇的性能

 采用溶胶-凝胶法制备了含碳的K-Co-Mo-C催化剂,通过改变碳前驱体的添加量以获得不同的碳含量,测试了催化剂上合成气制混合醇的性能. 结果表明,适量的残留碳增加了催化剂中活性相的分散度,提高了合成醇的收率和选择性,但过量的碳导致烃的选择性增加而醇的选择性下降,这是由于随着碳前驱体添加量的增加,催化剂中的Mo物种更容易被还原成金属态. 与惰性气氛中焙烧的样品不同,空气中焙烧的样品中没有碳的存在,氧化物组分容易生成难以还原的物相,合成醇活性较低. 含碳量为2.8%的样品具有最大的比表面积和孔体积,同时也具有最高的醇收率和选择性. 惰性气氛中高温焙烧样品导致其合成醇活性明显降低,但同时高碳醇的选择性增加.

Preparation of K-Co-Mo-C Catalyst and Its Catalytic Performance for Mixed Alcohol Synthesis

A K-Co-Mo-C catalyst with remnant carbon was prepared by the sol-gel method. The carbon content was adjusted by adding different amounts of carbon precursor. Catalytic behavior of mixed alcohols synthesis from syngas was investigated over the catalysts. By combining different characterization techniques, such as X-ray diffraction, thermo-gravimetric analysis, N_2 adsorption isotherms method, and temperature-programmed desorption of hydrogen, it was revealed that the presence of appropriate content of remnant carbon increased the dispersion of active phase and improved the yield and selectivity for alcohol. For the catalysts with superfluous remnant carbon, the selectivity for alcohol decreased and the selectivity for hydrocarbon increased, which might be due to the fact that with the increase of amount of carbon precursors, Mo species was readily reduced to the metallic state. For the sample calcined in air, the metal oxide precursors were easily aggregated to irreducible compound, so the activity for alcohol synthesis was low. The sample with 2.8% carbon had the largest surface area and pore volume, and showed the highest activity for alcohol synthesis. Calcining sample at higher temperature in inert atmosphere also caused the activity for alcohol synthesis to decrease obviously, but the selectivity for C_ 2 alcohols increased markedly.