Process for the preparation of hydrocarbons

A process for the preparation of C.sub.5.sup.+ hydrocarbons suitable for the production of middle distillates from C.sub.4.sup.- hydrocarbons comprising:

• (a) reforming C.sub.4.sup.- hydrocarbons at a pressure higher than 10 bar in the presence of carbon dioxide and steam into a mixture of carbon monoxide and hydrogen having a H.sub.2 /CO molar ratio between 0.25 and 2.25 by using a carbon dioxide/hydrocarbon ratio (a) higher than 0.1, but lower than 10 g mol CO.sub.2 /g atom C, a steam/hydrocarbon ratio (b) higher than 0.1, but lower than 1 g mol H.sub.2 O/g atoms C and a carbon dioxide/steam ratio chosen such that (2.times.a+3.times.b)>3, and
• (b) converting the product of (a) into a mixture of hydrocarbons substantially consisting of C.sub.5.sup.+ hydrocarbons by contacting it at a temperature of 105.degree.-305.degree. C. and a pressure, substantially corresponding with that used in the reforming, with a cobalt catalyst comprising 3-60 pbw of cobalt and 0.1-100 pbw of at least one other metal chosen from the group formed by zirconium, titanium, and chromium per 100 pbw silica, alumina or silica-alumina, wherein said catalyst has been prepared by kneading and/or impregnation, and that when the H.sub.2 /CO mixture has a H.sub.2 /CO molar ratio lower than 1.5, the cobalt catalyst is used in a catalyst mixture with a copper and zinc containing composition having CO-shift activity.