Thermal Behavior Study of the MoVTeNb Oxide Catalyst for Selective Oxidation Process

摘要

Several parameters involved in preparing the multi metal oxide (MMO) catalysts (Mo_1 V_(0.3)Te_(0.23)Nb_(0.12)O_x) for selective oxidation of propane to acrylic acid (AA) were investigated. These included the proper pre-calcined and calcinations atmosphere effect on the performance of the catalysts. It was found that each metal element plays a critical role to the performance of an effective catalyst and also the calcinations under a non-flow inert atmosphere. The characterization results from XRD, SEM, TG and DSC show the important differences depending on the activation procedures of the MoVTeNb oxide catalyst. The XRD analysis is used to identify the phase inventory of the MoVTeNb oxide catalysts. The structure of orthorhombic Ml, M2, TeMo_5O_(16), V_(0.95)Mo_(0.97)O_5 and Mo_5O_(14) phase was investigated. The orthorhombic Ml phase is the most active and selective phase and is responsible for the major of the efficiently of the best catalyst for selective oxidation process. TGA and DTG allow the identification of the number and types, of reactions involving evaporation of small molecules from removal of ligands and water to condensation or drying processes . From all these analyses it was proven that the activation procedures would affect the performance of the MoVTeNb oxide catalyst.