微波固相法制备ZnCl_2/MCM-41催化剂及其催化性能  

Preparation of ZnCl_2/MCM-41 Catalysts by the Solid-state Interaction under Microwave Heating and Their Catalytic Performances

作　　者：银董红[1] 秦亮生[1] 刘建福[2] 尹笃林[1] 

机构地区：[1]湖南师范大学精细催化合成研究所,长沙410081 [2]白沙集团公司博士后科研工作站,长沙410007

出　　处：《物理化学学报》2004年第9期1150-1154,共5页Acta Physico-Chimica Sinica

基　　金：教育部留学回国人员科研启动基金(2001-498);湖南省自然科学基金(01JJY3008)资助项目~~

摘　　要：采用微波固相法、普通加热法和溶剂分散法等不同方法制备了ZnCl2/MCM-41催化剂,以XRD、FT-IR和TG-DSC等表征手段,比较了不同方法制备的催化剂中ZnCl2在分子筛表面的存在状态.XRD测定结果表明,微波固相法和溶剂分散法制备的样品可使ZnCl2完全分散于MCM-41分子筛表面,而加热法制备的样品中仍存在ZnCl2的晶相衍射峰.FT-IR、DSC和原子吸收光谱的测定结果表明,微波辐射可使ZnCl2与分子筛表面羟基发生固态相互作用形成O-Zn-Cl活性位,具有更加温和的Lewis酸性.考察了不同方法制备和不同ZnCl2负载量的催化剂在月桂烯与丙烯醛Diels-Alder反应中的催化性能,与普通加热法制备的催化剂相比,微波固相法与溶剂分散法制备的催化剂具有更好的催化活性和选择性,但微波固相法制备催化剂更为简单.ZnCl 2 /MCM-41catalysts are prepared by so lid-state interaction of ZnCl 2 and mesoporous MCM-41material using different method of m icrowave heating and conventional heating,as well as the method of solvent dispersion in toluene.The status of ZnCl 2 onto the surface of MCM-41in the samp les of ZnCl 2 /MCM-41is char-acterized by XRD,FT-IR,TG-DSC and a tomic absorption spectroscopy(AAS ).XRD patterns indicate that ZnCl 2 can be dispersed completely on the su rface of MCM-41at ZnCl 2 loading less than 4mmol ·g -1 if the samples pre-pared by the method of microwave heating and solvent dispersion.FT-IR sp ectra,DSC curves and AAS measure-ment results indicate that the new Le wis acid sites of O -Zn -Cl are formed b y the solid-state interaction betwe en ZnCl 2 and the surface hydroxyl (Si -OH)under microwave heating.The cataly tic performances of ZnCl 2 /MCM-41samples prepared by the diffe rent methods are also investigated i n the Diels-Alder reaction of myrcen e and acrolein for high regioselectiv e synthesis of para-myrac aldehyde.It was found that the activity,selectivity for cycloadducts and regiooselectivity of para-myrac aldehyde are higher over the c atalysts of ZnCl 2 /MCM-41pre-pared by the methods of microwave hea ting and solvent dispersion than that over ZnCl 2 /MCM-41prepared by conventional heating.Apparently,the catalyst preparation method of m icrowave heating is simpler than the method of solvent dispersion in toluene.Wi th an increase of ZnCl 2 loading,the catalytic activity increases but the selectivi-ty of cycloadducts decrease.The activity and regioselectivity of para /meta increase slightly with the selectiv ity for cycloadducts decrease markedly when ZnCl 2 loading over 4mmol ·g -1 ,which suggested that new active sites of O -Zn -Cl formed on the surface of MCM-41plays very important role for high regioselective synthesis of para-myrac aldehyde.

关 键 词：微波固相法 制备 二氯化锌/MCM-41催化剂 催化性能 DIELS-ALDER反应 月桂烯 丙烯醛 

分 类 号：O643[理学—物理化学]