PROCESS AND PLANT FOR PRODUCING METHANOL FROM SUBSTOICHIOMETRIC SYNTHESIS GAS

Proposed is a process for producing methanol from synthesis gas by means of multi-stage, for example two-stage, heterogeneously catalyzed methanol synthesis, wherein the methanol product formed in every synthesis stage is separated by condensation and the remaining residual gas is supplied to the downstream synthesis stage or after separation of a purge stream recycled to the first synthesis stage as a recycle stream. According to the invention after each synthesis stage the residual gas streams have separated from them a respective purge stream, from which, using one or more hydrogen recovery apparatuses, hydrogen is separated and recycled to the first synthesis stage. The ratio of the individual purge streams and their total molar flow may optionally be varied to allow better control of the reaction in the individual synthesis stages and to allow reaction to the advancing deactivation of the catalysts present therein.