二氧化碳甲烷化催化剂研究Ⅰ.担载型Ⅷ族金属催化剂的性能

A STUDY ON CATALYSTS FOR METHANATION OF CARBON DIOXIDE

采用水溶液浸渍法制备了一系列无机氧化物（ＳｉＯ２，Ａｌ２Ｏ３，ＴｉＯ２，ＺｒＯ２）担载的Ⅷ族金属（Ｆｅ，Ｃｏ，Ｎｉ，Ｒｕ，Ｐｄ）催化剂，研究了它们在二氧化碳甲烷化反应中的催化性能．结果表明，催化剂性能与金属本性有关．Ｒｕ在各种载体上均具有高活性；Ｆｅ的活性较低；Ｎｉ／Ａｌ２Ｏ３，Ｃｏ／ＳｉＯ２及Ｃｏ／Ａｌ２Ｏ３体系因在焙烧过程中生成尖晶石相而使活性受到影响．不同载体担载的体系有如下的活性次序：ＴｉＯ２＞ＺｒＯ２＞Ａｌ２Ｏ３＞ＳｉＯ２．金属与载体间的相互作用对催化活性有较强的影响．

Group Ⅷ metal (Fe, Co, Ni, Ru, Pd) catalysts supported on silica, alumina, titania and zirconia were prepared by impregnation. The catalytic methanation of carbon dioxide was carried out with a fixed bed reactor at atmospheric pressure. The results indicate that the catalytic activity varies with metal. Ru and Fe catalysts show the highest and lowest activity respectively. The catalytic activity of catalysts with different supports decreases in following sequence: titania>zirconia>alumina>silica. The electronic interaction between metal and support and support metal strong interaction (SMSI) play very important roles in the change of catalytic activity. The activity of Ni/alumina, Co/silica is decreased by the formation of spinel. Both the conversion of carbon dioxide and the selectivity for methane increase with the enhancement of reaction temperature in the range of 473 K to 773 K. And they decrease with the enhancement of space velocity and the ratio of carbon dioxide to hydrogen. The sequence of apparent activation energy tallies with the catalytic activity.