酸碱双功能催化剂CaO/HMCM-22催化Knoevenagel缩合反应  

Knoevenagel Condensation Reaction over CaO/HMCM-22 with Acid-Base Bifunction

作　　者：任晓乾[1] 张文飞[1] 梁金花[2] 孙守飞[1] 刘艳秋[1] 姜岷[2] 

机构地区：[1]南京工业大学化学化工学院,江苏南京210009 [2]南京工业大学生物与制药工程学院,江苏南京210009

出　　处：《高校化学工程学报》2013年第6期998-1003,共6页Journal of Chemical Engineering of Chinese Universities

基　　金：材料化学工程重点实验室开放项目;国家重点基础研究规划973项目(2009CB724701)

摘　　要：以Ca(NO3)2为钙源,采用浸渍法制备了一系列Ca改性MCM-22分子筛催化剂,并采用XRD、FT-IR、TPD对催化剂进行了表征。结果表明,钙改性后MCM-22分子筛仍保持原有的结构;当负载量较低时,CaO在MCM-22分子筛表面高度分散;随着CaO负载量的增加,催化剂的碱强度和碱含量显著增加,而强酸含量明显减少,弱酸酸位有所增加。以苯甲醛与氰乙酸乙酯的Knoevenagel缩合反应为探针反应,考察了催化剂的性能。结果发现,当负载量为5.0%,反应物摩尔比1:1,催化剂用量为总反应物质量的3.0%,乙醇为溶剂,353 K下反应4 h时,苯甲醛转化率高达88.9%,优于未经改性的HMCM-22(6.6%)和单一钙改性的CaO/MCM-22(62.4%),体现出明显的酸碱协同催化作用。CaO/HMCM-22 molecular sieve catalysts were prepared by impregnating the catalyst MCM-22 with an aqueous solution of Ca（NO3）2. Catalysts were characterized by XRD, FT-IR, TPD. The results show that no significant structural change of MCM-22 was observed after modification. CaO could be highly dispersed on the surface of MCM-22 with low loading. The strength and content of base of the catalyst increase, while its content of strong acid decreased obviously with the increase of CaO loading. However, its amounts of weak acid sites increase slightly. The Knoevenagel condensation reaction of benzaldehyde and ethyl cyanoacetate was carried out over CaO/HMCM-22 catalysts. It was found that, 88.9% conversion of benzaldehyde can be obtained under conditions of reaction temperature of 353 K, reaction time of 4 h, the molar ratio of benzaldehyde to ethyl cyanoacetate equal to 1：1, mass fraction of catalyst to reactants 3.0% and ethanol as solvent. The catalytic performance of CaO/HMCM-22 is better than that of HMCM-22 and CaO/MCM-22, since the catalytic benzaldehyde conversion of HMCM-22 and CaO/MCM-22 are only 6.6% and 62.4%, respectively. The novel CaO/HMCM-22 molecular sieve catalysts exhibit the acid-base coordinative catalysis obviously.

关 键 词：MCM-22 钙 浸渍 酸碱双功能 KNOEVENAGEL缩合反应 

分 类 号：TQ032[化学工程]