Process for the isomerization of olefins

Claim 1

A PROCESS FOR THE ISOMERIZATION OF A MONO-OLEFINIC HYDROCARON BY DOUBLE BOND MIGRATION WHICH COMPRISES PASSING SAID HYDROCARBON OVER A CATALYST AT A TEMPERATURE IN THE RANGE 140-180*C., SAID CATALYST COMPRISING NICKEL SUPPORTED ON A SUPPORT MATERIAL SELECTED FROM THE GROUP CONSISTING OF SEPIOLITE, ALUMINA, KIESELGUHR, CHALK, AND SILICA GEL, SAID NICKEL, IN SAID TEMPERATURE RANGE, BEING PRESENT IN A MAJOR PROPORTION AS AN ELEMENTAL NICKEL, SAID CATALYST HAVING BEEN PREVIOUSLY MODIFIED BY TREATMENT WITH AT LEAST ONE SULPHUR-CONTAINING MATERIAL SELECTED FROM THE GROUP CONSISTING OF ELEMENTAL SULPHUR, HYDROGEN SULPHIDE, CARBON DISULPHIDE, THIOPHENES THIACYYCLOALKANES, DIALKYLMONOSULPHIDES, MERCAPTANS, DIALKYLDISULPHIDES AND MIXTURES OF TH FOREGOING, AT A TEMPERATURE IN THE RANGE 0-300*C. SUCH THAT A MINOR PROPORTION OF THE NICKEL PRESENT IN THE CATALYST IS THEREBY COMBINED WITH SULPHUR, PASSING THE RESULTING REACTION PRODUCT OVER A CATALYST BED OF THE SAME COMPOSITION AS IN THE FIRST STAGE AT A TEMPERATURE IN THE RANGE 60-100*C. AND THEREAFTER RECOVERING ISOMERIZED OLEFIN AS THE PRODUCT.