烯丙醇在Ti-MWW催化剂上的环氧化反应  

Epoxidation of Allyl Alcohol over Ti-MWW Molecular Sieve Catalyst

作　　者：陈晓晖[1] 范志勇[1] 魏可镁[1] 

机构地区：[1]福州大学化学化工学院化肥催化剂国家工程研究中心,福建福州350002

出　　处：《石油化工》2006年第3期255-259,共5页Petrochemical Technology

基　　金：国家自然科学基金青年科学基金项目(20306004);福建省青年科技人才创新项目(2002J009);福建省教育厅科技项目(JB02061)

摘　　要：以水热合成-酸处理法制得的T i-MWW分子筛为催化剂,研究了烯丙醇(AAL)和H2O2在水中的环氧化反应,考察了反应条件对AAL的转化率和环氧丙醇(GLY)选择性的影响。实验结果表明,AAL的浓度较低时有利于反应的进行,高浓度的H2O2则降低GLY的选择性,n(AAL)∶n(H2O2)=1时,GLY的选择性最高;当反应温度高于333K时,GLY的选择性随反应温度升高明显下降。当T i-MWW催化剂用量为50m g、AAL和H2O2的用量均为10mm ol、水量为20mL时,在333K下反应30m in,AAL的转化率达到96%,同时GLY的选择性可达98%以上。该反应的机理与TS-1催化剂催化烯烃环氧化反应类似,AAL和溶剂在活性位上存在竞争吸附。GLY的高选择性归因于T i-MWW催化剂中T i活性位与水、H2O2形成的五元环过渡态。Ti-MWW molecular sieve catalyst were prepared by hydrothermal synthesis and acid treatment. Epoxidation of allyl alcohol （AAL）by H2O2 over Ti-MWW molecular sieve catalyst was studied using water as solvent. The lower concentration of allyl alcohol helped increase reaction rate and higher concentration of H2O2 decrease selectivity to glycidol. Under suitable conditions： reaction temperature 333 K, reaction time 30 min, Ti-MWW molecular sieve catalyst dosage 50 mg, allyl alcohol 10 mmol, H2O2 10 mmol, and H2O 20 mE, conversion of allyl alcohol and selectivity to glycidol could reach 96% and 98% ,respectively. Selectivity to glycidol was the highest when n（AAL） ： n（ H2O2 ） = 1 ,but dropped quickly if reaction temperature increased above 333 K. The reaction mechanism was similar to that of alkene epoxidation on TS-1 molecular sieve catalyst, which involved a transition state of a 5-membered ring formed through a solvent molecule or an allyl alcohol molecule on Ti active site. High selectivity to glycidol was attributed to high structural stability of Ti species and nature of the 5-membered ring.

关 键 词：Ti—MWW分子筛 催化剂 烯丙醇 环氧丙醇 环氧化 

分 类 号：TQ032[化学工程]