Methanol prepd. with lower energy requirements - by catalytic cleavage of hydrocarbons, followed by synthesis of methanol from hydrogen and carbon oxides obtd.

摘要

The prepn. of methanol from gaseous and liq. hydrocarbons (I) with a C/H ratio higher than that stoichiometrically reqd. for methanol prodn. by (i) catalytic cleavage of (I) in one- or 2-step process by the addn. of steam at 350-900 degrees C and 5-30 bar to give a gas consisting essentially of H2 and oxides of carbon and (ii) catalytic synthesis of methanol from H2 and oxides of carbon at 230-280 degrees C and 30-150 bar, is improved by removing carbon-contg. gaseous components (II) from the waste-gas from step (ii) and mixing the remaining H2-rich gaseous components (III) with (I) provided that the resulting mixt. has C/H ratio is not 5.7. Pref. (II) are removed without expenditure of energy esp. by using a mol. sieve. The heat/energy requirements (based on MeOH prodn.) are lowered. The deleterious effects of by-products (esp. high-boiling aromatics) is reduced, the catalysts have a longer life. It is also possible to use S-contg. starting materials; as part or all of (III) can be used to remove sulphur from (I) by hydrogenation. (II) consists primarily of CO2,CO and CH4 and can be used to heat (I) before the second catalytic cleavage step.