焙烧条件对浆态床CO甲烷化Ni-Al2O3催化剂性能的影响

结合行星式球磨机，采用机械化学法制备Ni-Al₂O₃催化剂，考察了焙烧温度和焙烧时间对Ni-Al₂O₃催化剂晶相结构、还原特征、孔道结构和浆态床CO甲烷化性能的影响。通过XRD、H₂-TPR、BET、XPS和TPH等方法对反应前后催化剂进行表征。结果表明，焙烧温度从350℃升高到700℃，活性前体NiO仍在载体表面高度分散，催化剂还原峰温向高温方向偏移。其中，450℃条件下焙烧所获得的cat-450试样比表面积最大，为350 m²/g。评价结果显示，焙烧温度从350℃升高到700℃，CO转化率、CH₄选择性和收率均呈先升高后降低的趋势，于450℃达到最大值，分别为97.8%、88.2%和86.2%。另外，焙烧时间对催化剂的还原性能影响较小，对载体Al₂O₃的晶相结构有一定影响。随焙烧时间延长，CO转化率稍有降低，而后增大；焙烧时间为4 h，CH₄选择性和收率均较大。

Influence of calcination conditions on the performance of Ni-Al2O3 catalyst for CO methanation in slurry-bed reactor

Effects of calcination temperature and calcination time on the crystal structure, reduction characteristics, pore structure and CO methanation performance of Ni-Al₂O₃ catalyst were investigated by using a mechanical-chemical method to prepare Ni-Al₂O₃ catalyst. The catalysts were characterized by XRD, H₂-TPR, BET, XPS and TPH. The results showed that the calcination temperature increased from 350℃ to 700℃, NiO was still well dispersed on the surface of the carrier, and the reduction peak temperature decreased to high temperature. The specific surface area of the cat-450 sample obtained by calcination at 450℃ was 350 m²/g. The results showed that with the calcination temperature increased from 350℃ to 700℃, CO conversion, CH₄ selectivity and yield were increased first and then decreased, reaching the maximum at 450℃, with 97.8%, 88.2% and 86.2%, respectively. In addition, the calcination time has little effect on the reduction performance of the catalyst, and has small influence on the crystal structure of the carrier Al₂O₃. With the increase of calcination time, CO conversion decreased slightly and then increased with the better calcination time of 4 h.