Co/SiO_2催化剂的表征和吸附量热研究

Studies of Microcalorimetric Adsorption and Characterization of Co/SiO_2 Catalysts

用溶胶-凝胶法制备了Co/S iO2系列的担载型催化剂,采用SBET、TPR、XRD、O2滴定及室温H2、O2、CO和C2H4微量吸附量热等技术进行了研究.结果表明:Co很好分散,S iO2的含量越高,样品的SBET越大;Co是经由Co3+→Co2+→Co0的还原过程;Co/S iO2系列催化剂上,CO、H2、O2和C2H4的初始吸附热数值均比较接近、饱和覆盖度以50Co/50S iO2最高,O2为多层吸附而H2、CO和C2H4为单层吸附,CO为线式吸附并发生歧化反应生成了C和CO2,C2H4吸附解离生成了H2、乙川(C2H3)和C2H6.

The catalysts of Co/SiO2 series were prepared by sol-gel method and characterized by the techniques of TPR, XRD, the titration of O2, the measurement of the specific area of BET （SRET） as well as the microcalorimetric adsorption of H2, O2, CO and C2H4at room temperature. The experimental results showed that the more of SiO2 content, the larger of the SBET of the sample, and on SiO2 support the dispersion of cobalt spicies was well. TPR results revealed that only cobalt species was reduced via Co^3＋→Co^2＋→Co^0 process. For Co/SiO2 catalysts, in the microcalorimetric adsorption cases of O2, CO, H2 and C2H4. the initial adsorption heats measured were nearly approximate, respectively, and the coverage on 50Co-50SiO2sample was the highest, the O2adsorption was the multilayer adsorption, but the adsorption cases of H2 etc. were the monolayer. The adsorption of CO on Co showed that the linear adsorption state existed, and during adsorption the disproportionation of CO might take place to form the C and CO2. The microcalorimetric adsorption measurement of C2H4 on Co/SiO2 exhibited the case that the H2, eth- ylidyne（ C2H3 ） and C2H6 were formed.