Process for the preparation of middle distillates

A process for the preparation of a hydrocarbon mixture, a major proportion of which is middle distillates boiling in the temperature range between about 140.degree. and about 370.degree. C., from a feed mixture of carbon monoxide and hydrogen, which comprises contacting an H.sub.2 - and CO-containing feed in a first stage at a temperature in the range of 125.degree.-350.degree. C. and pressure in the range of 1-150 bar with a first stage fixed bed catalyst (Co-impregnation catalyst) containing 10-40 parts by weight of cobalt and 0.25-5 parts by weight of zirconium, titanium or chromium per 100 parts by weight of silica, said first stage catalyst having been prepared by impregnating a silica carrier with one or more aqueous solutions of salts of cobalt and zirconium, titanium or chromium, followed by drying the composition, calcining at 350.degree.-700.degree. C. and reducing at 200.degree.-350.degree. C., with the proviso that if the feed has an H.sub.2 /CO molar ratio of less than 1.5, water is added to said feed and that in said first stage the Co-impregnation catalyst is used in combination with a CO-shift catalyst, and contacting at least a suitable distillate fraction of the reaction product of the first stage in a second stage in the presence of hydrogen at an elevated temperature and pressure with a fixed bed catalyst containing at least one metal with hydrogenation activity supported on a porous carrier.