丙烯醛与异丙醇均相氢转移制烯丙醇反应中催化剂失活及再利用研究

采用异丙醇铝为催化剂,丙烯醛与异丙醇进行均相氢转移反应合成烯丙醇,对催化剂的再利用及催化剂的失活原因进行了研究。研究发现,采用减压蒸馏的方法,可分离出催化剂。若在反应过程中加入高沸点溶剂,催化剂的第一次及第二次反应性能均有显著提高,并且随溶剂沸点升高,转化率及选择性呈上升趋势。当以邻二甲苯为溶剂时,第一次反应转化率、选择性分别为91%、92%;第二次反应转化率、选择性分别为80%、85%,可部分实现催化剂的再利用。催化剂失活的原因在于,原料中以及反应过程中产生的水对催化剂结构有破坏作用;另外,反应过程中产生的重组分副产物对催化剂的配合或包裹是造成催化剂失活的主要原因。

Studies on Deactivation and Recycle of Aluminium Isopropoxide in the Homogeneous Hydrogen Transfer Reaction of Acrolein to Allyl Alcohol

The homogeneous hydrogen transfer of aerolein to allyl alcohol was carried out with aluminium isopropoxide as catalyst. The recycle of catalyst and the cause of catalyst deactivation were studied. The catalyst could be separated by a distilled method. The catalytic performance could be enhanced obviously in the first and second cycle when a high boiling point solvent was introduced in to the reaction system. Furthermore, the conversion and selectivity were increased with the boiling point Of the solvent. When oxylene was applied as solvent, the conversion and selectivity in the first and second cycle could be 91%, 92% and 80%, 85%, respectively, which showed that the catalyst might be recycled partly. The reason for deactivation was that water in the raw material or produced during the reaction would destroy the structure of aluminium isopropoxide. On the other hand, the heavy by-products of the reaction would overlay on the surface of the catalyst or complex with the catalyst, which is the main reason for the deactivation of the catalyst.