Green methanol production

Abstract

Steam reforming, water separation, and hydrogen separation by membrane can be performed sequentially on a mixture of steam and a hydrocarbon. A hydrogen-rich permeate stream from the hydrogen membrane can be used as fuel for combustion heating, leaving a retentate mixture of a prescribed ratio of hydrogen to oxides of carbon. The retentate can be compressed and synthesized to methanol in a methanol synthesis reactor. The synthesized methanol can be separated into a methanol-rich stream and a tail gas stream containing the remaining outlet gas from the synthesis reactor. The methanol-rich stream can be refined. The tail gas stream can be divided into a methanol loop recycle stream, an SMR recycle stream, and a nitrogen purge stream. The methanol loop recycle stream is compressed and recycled to the methanol synthesis reactor. The SMR recycle stream is recycled as feedstock to the reformer. The nitrogen purge stream is combusted in a burner. Carbon dioxide may be separated from combustion products and sequestered.