PURPOSE: To produce a hydrocarbon mixture rich in lower paraffins in a good yield with one-stage reaction, by using zeolite having a specified pore size as a methanol conversion catalyst in the titled method using a catalyst mixture of a methanol synthesis catalyst and a methanol conversion catalyst.
CONSTITUTION: A synthesis gas is catalytically treated by using a catalyst mixture (or pellet) obtd. by physically mixing a methanol synthesis catalyst (A) (e.g. CuO-ZnO-Al2O3 catalyst or Pd-SiO2 catalyst) with a methanol conversion catalyst (B) composed of zeolite having an average pore size of 10 Angstrom or above [e.g. Y type zeolite (which has been subjected to an aluminum removal treatment or steam treatment)]. Preferably the treatment is carried out under such conditions that the temp. is 250-450oC, the pressure is 5-100 kg/cm2 and the H2/CO ratio of the raw synthesis gas is 4-1.