NOVELTY - Forming ethanol, comprises: (a) carbonylating methanol in the presence of a carbonylation catalyst in a carbonylation reactor (1) to form acetic acid; (b) hydrogenating the acetic acid in the presence of a hydrogenation catalyst in a hydrogenation reactor (7) to form a crude ethanol stream; (c) separating the crude ethanol stream into a vapor stream comprising hydrogen and carbon monoxide (2) and an ethanol product stream; (d) separating carbon monoxide from the vapor stream; and (e) directing the separated carbon monoxide to the carbonylation reactor.    USE - The process is useful for forming ethanol (claimed), where the ethanol is useful as fuels or for human consumption.    ADVANTAGE - The process having high convertibility and selectivity is capable of easily, reliably and energy efficiently forming ethanol in an economical manner.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) a reaction system for forming ethanol, comprising a carbonylation reactor for carbonylating methanol in the presence of a carbonylation catalyst to form acetic acid, a hydrogenation reactor for hydrogenating the acetic acid in the presence of a hydrogenation catalyst to form a crude ethanol stream and a tail gas stream, a separator for separating the crude ethanol stream into a vapor stream comprising hydrogen and carbon dioxide and a liquid ethanol product stream, a separation unit for separating the vapor stream into a hydrogen stream (8) comprising hydrogen and a separated carbon monoxide stream, and a conduit in fluid communication between the separation unit and the carbonylation reactor for directing the separated carbon monoxide to the carbonylation reactor; and    (2) a process-I for forming ethanol from methanol, comprising carbonylating the methanol to form acetic acid and hydrogenating the acetic acid to form ethanol, where a crude ethanol product from the hydrogenating step is separated into a vapor stream and an ethanol product stream, and at least some carbon monoxide for the carbonylating step is derived from the vapor stream.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of a device for forming ethanol.    Carbonylation reactor (1)    Carbon monoxide stream (2)    Methanol stream (3)    Hydrogenation reactor (7)    Hydrogen stream. (8)