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制备了钼—碲—鈰多组份复氧化物催化剂,测定了其对异丁烯选择氧化反应的催化活性,发现添加鈰改善了钼—碲催化剂的表面状况:表面酸强度从403MV 提高到512MV,表面酸中心增大了1.3倍,Te富集在催化剂表面约为体相的1.2倍,比表面增大将近一倍。而且改变了催化剂的物相,形成复氧化物的结构,有助于防止碲的挥发流失。因此,这种催化剂具有很高的热稳定性:经500℃(持续受热时间128小时后产物—甲基丙烯醛的收率降低了15％,而未加Ce的催化剂64小时后收率巳降低了21％。
The multi-component molybdenum-tellurium-cerium complex oxide catalyst was prepared and its catalytic activity for selective oxidation of isobutylene was determined. It was found that the addition of cerium improved the surface condition of molybdenum-tellurium catalyst: the surface acid strength increased from 403MV to 512MV, The acid center increased by 1.3 times, Te enrichment in the catalyst surface is about 1.2 times the body phase, nearly double the surface. But also changes the phase of the catalyst to form a complex oxide structure, helping to prevent the loss of tellurium volatilization. Thus, this catalyst has a very high thermal stability: a reduction of 15% in product-methacrolein yield after 500 ° C (128 hours of sustained heat-up time) and a decrease in yield after 64 hours for the catalyst without Ce 21%.