A Method To Produce Synthetic Gasoline
A method is suggested for manufacturing synthetic gasoline by catalytic conversion of synthesis gas at elevated temperature. In order to improve the product quality, the process is performed in two stages. At the first stage, the synthesis gas is contacted with an oxide catalyst for methanol synthesis from carbon monoxide and hydrogen and with a solid acidic inorganic dehydration catalyst. This stage is run at a temperature of 149-372°C, pressure of 10.5-105.5 atmospheres and a space velocity of 500 hr-1. At the second stage, the products obtained at the first stage interact at a temperature of 260-455°C and a pressure of 211 atmospheres over a crystalline alumino-silicate zeolite having a silica to alumina ratio 12-30. The space velocity at the second stage is equal to 0.5-1000 hr-1. The activity of the second stage catalyst is characterized by the ratio of the first order cracking rate constants for n-hexane and 3-methylpentane equal to 1-12 at 288-510°C. A mixture of oxides of copper, chromium, zinc and lanthanum composed of 50-70, 5-15, 15-25, 5-15 wt. parts, respectively, is used as the catalyst for methanol synthesis.
Contacting snythesis gas (mixed carbon monoxide and hydrogen) with a mixture of a carbon monoxide hydrogenation catalyst and an acid dehydration catalyst to produce a first stage product comprising dimethyl ether and contacting this first stage product, preferably in its entirety, with a crystalline aluminosilicate having a silica to alumina ratio of at least about 12 and a constraint index of about 1 to 12 to convert it to high octane gasoline.