To produce 1,4 butanediol (BDO) from butane via maleic anhydride and hydrogen using ester hydrogenation.
Maleic anhydride is first esterified with methanol in a reaction column (1) to form the intermediate dimethyl maleate. The methanol and water overhead stream is separated in the methanol column (2) and water discharged.
The ester is then fed directly to the low-pressure, vapor-phase hydrogenation system where it is vaporized into an excess of hydrogen in the vaporizer (3) and fed to a fixed-bed reactor (4), containing a copper catalyst. The reaction product is cooled (5) and condensed (6) with the hydrogen being recycled by the centrifugal circulator (7).
The condensed product flows to the lights column (8) where it is distilled to produce a co-product tetrahydrofuran (THF) stream. The heavies column (9) removes methanol, which is recycled to the methanol column (2). The product column (10) produces high-quality butanediol (BDO). Unreacted ester and gamma butyralactone (GBL) are recycled to the vaporizer (3) to maximize process efficiency.
The process can be adapted to produce up to 100% of co-product THF and/or to extract the GBL as a co-product if required.
Economics: per ton of BDO equivalent:
Maleic anhydride 1.125
Electric power, kWh 160
Steam, ton 3.6
Water, cooling, m3 320
Licensor: Davy Process Technology, UK