Sulfated and persulfated TiO_2/MCM-41 prepared by grafting method and their acid-catalytic activities for cyclization of pseudoionone

摘要

Solid acid catalysts of SO_4~(2-)/TiO_2/MCM-41 and S_2O_8~(2-)/TiO_2/MCM-41 were prepared via grafting method and sulfate/persulfate promotion.The catalysts exhibited desirable activity and better selectivity for cyclization reaction of pseudoionone compared to traditional SO_4~(2-)/TiO_2.A combination of XRD,N_2 adsorption-desorption and FTIR spectroscopy indicated that the catalysts possess well-ordered mesostructure,and the grafted TiO_2 are in highly dispersed amorphous form rather than crystalline phase.For S_2O_8~(2-)/TiO_2/MCM-41 higher S content and more Bransted acid sites can be achieved by persulfation,which is favorable for the protons participated cyclization reaction.The similar Si-O-Ti-O-S =O structure of all acid sites on pore surface of the catalysts is attributed to the improvement of selectivity in comparison with SO_4~(2-)/TiO_2.