Preparation of vanadium- and chromium-substituted KIT-1 disordered mesoporous material by direct incorporation

Vanadium- and chromium-substituted KIT-1 mesoporous materials were prepared by a direct hydrothermal synthesis for the first time and characterized by nitrogen physical adsorption, X-ray diffraction (XRD), and X-ray absorptio n near edge structure (XANES). These materials show narrow pore size distri butions centered at 3.77 nm for V-KIT-1 and 3.37 nm for Cr-KIT-1 and high s urface areas obtained from Nz adsorption and desorption isotherms, which su ggests that the incorporation of metal atoms does not much affect the mesop orous structure. It was determined from the XRD patterns that all samples h ad the KIT-I disordered mesoporous structure. The pre-edge peak was observe d in the XANES at the V and Cr K absorption edge, respectively, which sugge sts that V and Cr atoms have a tetrahedral coordination in the framework of the KIT-I mesoporous material. (C) 2001 Elsevier Science B.V. All rights r eserved.