球磨时间对浆态床CO甲烷化Ni-Al_2O_3催化剂性能的影响

结合行星式球磨机,采用低温固相法制备Ni-Al_2O_3催化剂,考察了球磨时间对Ni-Al_2O_3催化剂晶相结构(XRD)、还原特征(H2-TPR)、孔道结构(BET)、粒径分布(PSD)、表面形貌(SEM)和浆态床CO甲烷化性能的影响.结果表明,球磨时间为60 min,催化剂(CT-60)平均粒径最小,为141 nm;比表面积最大,为329 m2/g.随球磨时间延长,Ni-Al_2O_3催化剂的甲烷化性能(CO转化率、CH_4选择性和CH_4收率)均先增加后减少.其中,球磨时间为60 min制备的催化剂(CT-60)甲烷化性能最佳,其CO转化率、CH_4选择性和CH_4收率分别达87.9%、8 6.8%和74.3%.结合催化剂表征可知,CT-60优异的性能与其具有较小的颗粒尺寸(141 nm)和较大的比表面积(329 m2·g-1)有很大的关联.即,催化剂颗粒尺寸越小,比表面积越大,其性能越好.

Influence of Milling Time on the Performance of Ni-Al2O3 Catalyst for CO Methanation Based on Slurry-bed Reactor

With planetary ball mill, the low temperature solid-state reaction method was used to prepare catalyst. The influence of milling time on the crystal structure (XRD), reduction performance (H₂-TPR), pore structure (BET), particle size distribution (PSD), surface morphology (SEM) and CO methanation performance in slurry bed was investigated in this paper. Results showed that, at the milling time of 60 min, the average particle size of the catalyst (CT-60) was only about 141 nm, and the specific surface area was up to 329 m²/g. With the extension of milling time, the methanation performance (CO conversion, CH₄ selectivity and CH₄ yield) of the Ni-Al₂O₃ ca-talyst (CT-60) was increased firstly and then decreased as the milling time over 60 min. That is, the CT-60 catalyst prepared at the milling time of 60 min presented the best methanation performance, with CO conversion, CH₄ selectivity and CH₄ yield of 87.9%, 86.8% and 74.3% respectively. The excellent performance of CT-60 was strongly correlated with its small particle size (141 nm) and its specific surface area (329 m²·g^-1). That is, the smaller the particle size of the catalyst, the larger the specific surface area, the better the performance.