EXPERIMENTAL-EVIDENCE OF ALPHA-OLEFIN READSORPTION IN FISCHER-TROPSCHSYNTHESIS ON RUTHENIUM-SUPPORTED ETS-10 TITANIUM SILICATE CATALYSTS

Fischer-Tropsch synthesis seems to develop the following two consecuti ve paths: a primary process that involves the formation of alpha-olefi n products and a secondary process leading to the production of branch ed isomers and paraffins and requiring the readsorption of primary alp ha-olefin products. It was already shown by Iglesia et al. (E. Iglesia , S. C. Reyes, and R. J. Madon, J. Catal. 129, 238 (1991)) that such r eadsorption steps are of fundamental importance for Ru catalysts and t hat they occur due to the slow diffusive removal of alpha-olefins when the molecular size increases, this resulting in a long intraparticle residence time. In the present paper alpha-olefins readsorption was en hanced by changing the metal distribution inside the pores of a titani um silicate (ETS-10), modified by ion exchange with alkali metal ions, used as a support for Ru-based catalysts. (C) 1997 Academic Press.