PREPARATION OF CATALYSTS BASED ON Fe VANADYL PHOSPHATES SUPPORTED ON γ-Al2O3 FOR OXIDATIVE DEHYDROGENATION OF ETHANE

Abstract

Catalysts based on vanadyl phosphates have been prepared for the oxidative dehydrogenation (ODH) of ethane to ethylene. The bulk catalysts VOP (VOPO4.2H2O), FeVOP(1) (Fe0.14VO0.86PO4) and FeVOP(2) (Fe0.21VO0.79PO4) have been synthesized by the Ladwig method, which consists in the preparation of vanadyl phosphate under reflux with phosphoric acid. The catalysts supported on γ-Al2O3 (FeVOP-Al) were prepared by the wet impregnation method. From XRD, the bulk catalysts presented crystalline structures described by the arrangement of the tetrahedral of PO4 and of the octahedral VO6. The TPR analysis revealed that the introduction of Fe to the structure of the VOP forms less reducible species and in the case of the supported samples, the increase of the active phase linearly increased the consumption of H2. The γ-Al2O3 support to the iron-vanadyl-phosphate catalysts allowed the formation of ethylene and active centers in the ODH of ethane due to the formation of weak and intermediate acid sites and the catalyst-support interactions. The activity and selectivity of reaction to ethylene in the best supported sample increased up to 46,8 and 27,3% against the equivalent bulk catalyst that was 9,8% and 21,4 %.