Catalytic Consequences of a Revised Distribution of Key Elements at the Active Centers of the M1 Phase of the MoVNbTeO x System

摘要: In an earlier publication (Grasselli et al., Top Catal 54:595, 2011) [1] we analyzed the distribution of key catalytic elements at active site M1 phase MoVNbTeOx catalyst system based on definition this center put forth in our original work 23:5, 2003) [2]. From that analysis derived probabilities metal element distributions and its immediate surroundings, those results, proposed a model for propane ammoxidation M1. Recently, occupancies concomitant charges various have been revised (Li 54:614, [3]. Based structural now recalculated elemental describe here consequences mechanism these changes portend. Our (REV) predicts more closely actual experimental results over than does first (ORIG). The obtained are: ORIG Model: 41 % AN (acrylonitrile) concerted, 82 % total possible AN; REV 43 % 59 % experimental: 42 % 62 % using both M1 + M2 phases. Comparing [2] current [3] centers reaction pathways (from models), it is readily apparent higher concentrations V5+ lead to undesirable overoxidation thus lower selectivity. Therefore, decreasing surface concentration vanadium (to favor isolated sites) should be beneficial better selectivities yields. Additionally, selective doping or isomorphous substitution (and/or M2) also useful approaches towards improved