화학공학소재연구정보센터
Journal of Catalysis, Vol.319, 247-257, 2014
New Ti-incorporated MCM-36 as an efficient epoxidation catalyst prepared by pillaring MCM-22 layers with titanosilicate
A new Ti-incorporated MCM-36 material (shortly termed Si/Ti-MCM-36) with bimodal pore structures was prepared through sequential steps. The hexadecyltrimethylammonium swollen MCM-22 precursor was pillared with titanosilicate formed via hydrolysis of an interlayer mixture of tetraethylorthosilicate (TEOS) and tetrabutylorthotitanate (TBOT). Hydrolyzation of TEOS and TBOT was a key step for intercalation efficiency. The X-ray diffraction (XRD) patterns and N-2 sorption isotherm data confirmed the intercalation efficiency and the retention of basal layer MWW structure. A slightly ordered stacking of MWW sheets along c-direction was observed, generating mesopores of ca. 2 nm in diameter. Ti(IV) was well dispersed in the matrix of titanosilicate pillars, which expand the MWW layers apart. The Ti coordination environment examined by DR UV-Vis and Ti K-edge X-ray absorption spectroscopies was mainly in tetrahedral coordination. Post-treatment of the Si/Ti-MCM-36 materials with acid resulted in a new Ti-incorporated MCM-36 with good catalytic activities in cyclohexene epoxidation. (C) 2014 Elsevier Inc. All rights reserved.