Oxoanion promoted transicion metal oxides for hydrocarbon isomerization

V.M. BENÍTEZ; J.C. YORI; C.R. VERA; C.L. PIECK; J.M. GRAU; J.M. PARERA

San Luis, Argentina

Workshop; Workshop on Molecular and Particle Processes at Solid Surface-MOLPPASS; 2004

Universidad Nacional de San Luis

Abstract             The catalytic activity of some transition metal oxides known to develop “superacidity” by promotion with certain oxoanions was compared with a set of acid-catalyzed test reactions.  They were further characterized by pyridine TPD, XRD and sortometry.  SO42--ZrO2, SO42--TiO2, SO42--Fe2O3, WO3-ZrO2, WO3-TiO2, WO3-Fe2O3, BO33--ZrO2, BO33--TiO2 and BO33--Fe2O3 were synthesized by impregnation of the oxoanion over a fresh xerogel.  Certain promoter-dependent orders could be elucidated:  (i) number of acid sites generated by promotion:  S > B > W; (ii) fraction of sites desorbing at high temperature:  S,B > W.  (iii) n-butane conversion B, S > W.  (iv) selectivity to isobutane:  W > B,S.  (v) iso-butene conversion: S > B,W. (vi) C5-C6 conversion: S > B,W. (vii) selectivity to isohexanes S,B > W.  ZrO2 yields the most active ones while Fe2O3 the least.