Process for producing 1,4-butanediol and tetrahydrofuran by hydrogenating dialkyl maleate in mixed phase

A process is described for the production of 1,4-butanediol and tetrahydrofuran by catalytic hydrogenation of dialkyl maleates. The process consists essentially in the following steps: a) hydrogenating a stream of dialkyl maleate in a first stage of reaction over suitable catalysts to produce dialkyl succinate; b) further hydrogenating the dialkyl succinate in a second stage of reaction, by using a different suitable catalyst, for producing mainly 1,4-butanediol, together with gamma-butyrolactone and tetrahydrofuran as co-products. In both stages of reaction the conditions, as hydrogen/ organic feed ratio, pressure and temperature, are such to maintain the reactors in mixed liquid/vapor phase.