| 摘要 |
A process for the isomerization of an acyclic unsaturated hydrocarbon which is capable of undergoing skeletal rearrangement and/or double bond shift comprises contacting the hydrocarbon with a catalyst consisting of a partially hydrated sulphate of a metal from Group II, III, IV, VI, VII or VIII of Mendeleef's Periodic Table. "Partially hydrated" sulphate means a sulphate containing a number of associated molecules of water of crystallization fewer than the maximum possible. Particular catalysts disclosed are FeSO42H2O (obtained from FeSO47H2O), MgSO41H2O (obtained from MgSO47H2O), Cr2(SO4)35H2O (from Cr2(SO4)315H2O), Al2(SO4)34H2O and Al2 (SO4)31H2O (from Al2(SO4)316H2O), the sulphates of chromium and aluminium being preferred. The sulphates may be prepared by partial dehydration of the fully dehydrated form and preferably have a surface area of at least 1 sq. m. per gm. The catalyst and hydro-carbon feed may be contacted when the latter is in the vapour phase, preferably above 50 DEG C., but essentially below the temperature at which the catalyst fully dehydrates. An L.H.S.V. of 0.1 to 10 vol./vol. may be used. Optionally, an inert diluent, e.g. N2, is added. The feed hydro-carbon preferably contains less than 20 carbon atoms and is particularly a C4 to C6 molecule, e.g. 3,3-dimethylbutene-1; 4-methylpentene-1. In Examples (1)-(7), 4-methylpentene-1 is contacted with partially dehydrated sulphates of Fe, Cr, Mg and Al at 150 DEG and 200 DEG C., and products containing amounts of 14-31% 2-methylpentene-2, 4-9% 2-methylpentene-1, 3-9% 3-methylpentene-2 (cis and trans forms) and from 54-79% unchanged feed plus 4-methylpentene-1 (cis a9d trans) are obtained (all percentages by volume). |
