| 摘要 |
Fuel gas is made by cracking hydrocarbons having a carbon number of C2 to C15 in the presence of steam over a nickel and/or cobalt catalyst which is maintained in two separate temperature zones, the first (which occupies from one-fifth up to four-fifths of the total catalyst volume) being kept at 350 DEG to 550 DEG C., and the second (which, however, must be nickel) at 560 DEG to 1000 DEG C. Preferred temperatures are 450 DEG C. and 700 DEG to 850 DEG C. respectively, and pressures may range from atmospheric to 100 atmospheres, preferably 20 to 60 atmospheres. The catalyst in the two zones may be the same or different, e.g. Ni (preferably 35 to 50% b.w.) or Al2O3, ZrO2, MgO, TiO2, or silicate carriers for the first zone, and Ni (preferably 15 to 25% b.w.) on Al2O3, ZrO2, MgO carriers, if desired with an alkali, for the second zone, and this catalyst may be calcined. A catalyst containing less than 10% b.w. Ni and free of silicates may be interposed between the two zones. All catalysts may have hydraulic binders. A specific example using a desulphured light naphtha is described. The invention permits lower steam ratios to be used.ALSO:Cracking catalysts is effected in two stages, a first zone containing less than 10% supported Ni in association with calcium aluminate and a second stage containing 15-30% Ni. The supports may be Al2O3, MgO, ZrO2. Silicates are absent but alkalis may be present. The catalysts may have a surface area of 6-30 m2/gm.
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