Acta Phys. -Chim. Sin. ›› 2004, Vol. 20 ›› Issue (09): 1150-1154.doi: 10.3866/PKU.WHXB20040918

• ARTICLE • Previous Articles     Next Articles

Preparation of ZnCl2/MCM-41 Catalysts by the Solid-state Interaction under Microwave Heating and Their Catalytic Performances

Yin Dong-Hong;Qin Liang-Sheng;Liu Jian-Fu;Yin Du-Lin   

  1. Institute of Fine Catalysis and Synthesis, Hunan Normal University, Changsha 410081;Post-Doctoral Workstation for Science and Technology, Baisha Group, Changsha 410007
  • Received:2004-02-17 Revised:2004-06-17 Published:2004-09-15
  • Contact: Yin Dong-Hong E-mail:yindh@hunan.edu.cn

Abstract: ZnCl2/MCM-41 catalysts are prepared by solid-state interaction of ZnCl2 and mesoporous MCM-41 material using different method of microwave heating and conventional heating, as well as the method of solvent dispersion in toluene. The status of ZnCl2 onto the surface of MCM-41 in the samples of ZnCl2/MCM-41 is characterized by XRD, FT-IR, TG-DSC and atomic absorption spectroscopy (AAS).XRD patterns indicate that ZnCl2 can be dispersed completely on the surface of MCM-41 at ZnCl2 loading less than 4 mmol•g-1 if the samples prepared by the method of microwave heating and solvent dispersion. FT-IR spectra, DSC curves and AAS measurement results indicate that the new Lewis acid sites of O-Zn-Cl are formed by the solid-state interaction between ZnCl2 and the surface hydroxyl (Si-OH) under microwave heating. The catalytic performances of ZnCl2/MCM-41 samples prepared by the different methods are also investigated in the Diels-Alder reaction of myrcene and acrolein for high regioselective synthesis of para-myrac aldehyde. It was found that the activity, selectivity for cycloadducts and regiooselectivity of para-myrac aldehyde are higher over the catalysts of ZnCl2/MCM-41 prepared by the methods of microwave heating and solvent dispersion than that over ZnCl2/MCM-41 prepared by conventional heating. Apparently, the catalyst preparation method of microwave heating is simpler than the method of solvent dispersion in toluene. With an increase of ZnCl2 loading, the catalytic activity increases but the selectivity of cycloadducts decrease. The activity and regioselectivity of para/meta increase slightly with the selectivity for cycloadducts decrease markedly when ZnCl2 loading over 4 mmol•g-1,which suggested that new active sites of O-Zn-Cl formed on the surface of MCM-41 plays very important role for high regioselective synthesis of para-myrac aldehyde.

Key words: Microwave, MCM-41, Zinc Chloride, Myrcene, Diels-Alder reaction