| 摘要 |
A process is described for preparing gaseous hydrocarbon mixtures having a high content of low-molecular weight olefins, especially C2-C4-olefins, by catalytic conversion of a gas, which contains carbon oxides, hydrogen and optionally inert gases, and whose carbon monoxide content is at most 5 % by volume, at a pressure from 1 to 150 bar, a temperature of from 200 to 600 DEG C and a space velocity of from 1000 to 50000 l(s.t.p.) of synthesis gas per kg of catalyst per hour, which process is carried out in the presence of a catalyst which consists of at least two intimately mixed heavy metals in free form or in the form of the carbides, carbonates and/or oxides or contains these, and which preferably also contains an alkali metal carbide, carbonate or oxide and, in particular, potassium carbonate, and which catalyst can be obtained by reduction and subsequent carbidisation of a precursor comprising one or more complex cyanides a) of an alkali metal or of ammonium, b) of one or more metals which form not readily reducible oxides and belong to group III of the Periodic Table of the Elements, and c) of one or more metals having atomic numbers of from 24 to 30, which cyanides have a cubic crystal structure with a lattice parameter of from approximately 0.5 to 1.0 nm (from 5 to 10 ANGSTROM ) and a crystallite size below 20 nm (200 ANGSTROM ). Preferably, the catalyst consists of potassium carbonate, aluminium and/or cerium oxide, iron carbide and, if appropriate, metallic copper and/or cobalt carbide. |
