Several gamma-Al2O3-supported tungsten oxide catalysts have been studi
ed in the skeletal isomerisation of l-butene. It appears that the pres
ence of small tungsten oxide particles induces skeletal isomerisation.
Large particles can be activated by prereduction treatment with hydro
gen. It was shown that the selectivity and stability of the catalysts
depend strongly on the tungstate loading. A sudden increase in selecti
vity is observed when dimeric WO42- species are formed. A low density
of active sites presents deactivation, which is caused by carbonizatio
n of the catalyst due to oligomerisation of isobutene. The main by-pro
ducts, C-3 and C-5 hydrocarbons, arise from the dimerisation and crack
ing of isobutene. (C) 1995 Academic Press, Inc.