Catalyst based on a halogenated alumina, its preparation and use for the isomerization of normal C4-C6 paraffins

A method of using a catalyst containing chlorine and a formed support comprising gamma alumina and optionally eta alumina in an isomerization process which comprises contacting a feed comprising at least 50% normal paraffins containing 4 to 6 combinations per molecule with said catalyst;

• the catalyst being characterized in that the smallest average dimension of said support is in the range of 0.8 mm to 2 mm and the chlorine content is in the range 4.5% to 15% by weight, said catalyst having been prepared by immersing spheres or extrudates comprising gamma alumina and optionally eta alumina, in an aqueous chloroplatinic acid solution, evaporating the solution to dryness, calcining the resultant dried impregnated spheres or extrudates in an air stream to remove chlorine, contacting the resultant platinum impregnated spheres or extrudates with carbon tetrachloride as the only halogenating agent, and removing unreacted carbon tetrachloride halogenating agent.