一步酯交换法合成碳酸二甲酯非均相催化剂的研究  

Preparation and Evaluation of Heterogeneous Catalysts for One-Pot Synthesis of Dimethyl Carbonate

作　　者：崔洪友[1] 刘宁[1] 陈久标 姚德[1] 

机构地区：[1]山东理工大学化学工程学院,山东淄博255049 [2]山东工业职业学院,山东淄博256414

出　　处：《化学反应工程与工艺》2008年第2期140-146,共7页Chemical Reaction Engineering and Technology

基　　金：山东省中青年科学家科研奖励基金(2005BS05009)

摘　　要：以KI和K_2CO_3为双活性组分,分别以4A分子筛、硅胶、活性炭和活性氧化铝为载体,采用浸渍法制备了非均相催化剂。结果表明,在水溶液中浸渍制备的非均相催化剂比在甲醇溶液中浸渍的具有更高的催化活性,KI和K_2CO_3负载于4A分子筛的催化剂活性最高。采用傅立叶变换红外光谱(FT-IR)、热重分析(TG)和差热分析(DTA)等多种手段对催化剂进行结构表征,发现分子筛负载KI-K_2CO_3后晶型趋向规整化,KI和K_2CO_3在分子筛孔壁分散性良好,K_2CO_3分解产生的KOH增强了催化剂的碱性。以KI-K_2CO_3/4A分子筛为催化剂,考察了载体粒径、活性组分负载量、催化剂用量和反应时间对一步酯交换法合成碳酸二甲酯(DMC)的影响。结果表明,分子筛粒径为75～80μm及KI,K_2CO_3和分子筛质量配比为1:1.5:10的非均相催化剂催化性能较好。在以环氧丙烷、甲醇和CO_2为原料,催化剂与PO的质量比为1.25,140℃和7.5 MPa条件下一步合成DMC,反应5.5 h,PO转化率达100%,DMC收率达75%。A series of heterogeneous catalysts were prepared for one-pot synthesis of dimethyl carbonate （DMC） by loading KI and K2CO3 on 4A molecular sieve, silica gel, activated carbon and activated alumina by impregnation method respectively. The results showed that the catalytic activity of 4A molecular sieves loading KI and K2CO3 was the highest and the catalytic activity of catalysts perpared by impregnating in aqueous solution was higher than in methanol solution. The catalysts were characterized by XRD （X-ray diffraction）, SEM （scanning electron microscopy）, FT-IR （Fourier transformed infrared spectroscopy）, TG （thermogravimetric analysis） and DTA （differential thermal analysis）. The analysis results showed the microstructure of catalysts was more ordered after loading active components and KI/K2CO3 were well distributed on catalyst surface. KHCO3 and KOH from the metathetical reaction of K2CO3 with water strengthened the alkalscence of the catalysts and improved the catalytic performance. The effects of catalyst sizes loading amount of active components, catalyst dosage and reaction time on the one-pot synthesis of DMC form propylene oxide （PO）, methanol and CO2 over 4A molecular sieves loading KI/K2 CO3 were investigated. The results showed that the catalytic performance of the catalyst with mass ratio of KI and K2CO3 to moleculer sieve 1 ： 1.5 ： 10 and moleculer sieves 75--80 μm was very good. Under conditions of 140 ℃, 7.5 MPa and mass ratio of catalyst to PO 1. 25. The conversion of PO and yields of DMC and propylene carbonate were 100%, 75% and 24%, respectively, after reaction for 5.5 h.

关 键 词：碳酸二甲酯 非均相催化剂 酯交换 一步法 

分 类 号：TQ032.41[化学工程] TQ225.52