Published June 2009
Methanol is an important feedstock for making many other chemicals. It has also been considered as a fuel additive and as a fuel with some success. As oil prices continue to rise, its usage as a fuel alternative will become more viable. Currently, the US methanol market is in a period of oversupply as the global recession has caused the demand to decrease. Methanol plants in North America have closed due to high production costs and similar things may happen in the global market. As auto manufacturers in the US and the rest of the world develop next generation flex fuel cars, methanol demand may revive if methanol is accepted as a fuel additive in the fuels industry. In any case, being able to lower the manufacturing costs in a methanol plant is going to be of paramount importance as the chemical industry survives through the demand slump.
Methanol is most commonly produced by a multi-step process: natural gas or coal gas and steam are reformed in a furnace to produce hydrogen and carbon oxides; then, hydrogen and carbon oxides react under pressure in a gas phase reactor in the presence of a catalyst to produce methanol. Crude methanol as produced is purified by fractional distillation. While gas phase methanol reactors are used in almost all commercial plants, a liquid phase methanol synthesis process was successfully demonstrated by Air Products and Chemicals in partnership with the US Department of Energy. The liquid phase methanol process offers some benefits compared to the gas phase process including the ability to process syngas rich in CO and CO2 content, excellent reactor thermal management, and the ability to add and withdraw catalyst from the system without the necessity of a shutdown.
In this review, we examine the technology and economics of methanol production starting from natural gas as a raw material. Syngas is generated from natural gas using the commercially available ICI/Synetix process as a front end. Liquid phase methanol technology is then utilized to synthesize methanol followed by methanol purification. We also present a conceptual design and economic evaluation of a 5000 metric ton-per-day methanol plant using integrated ICI/Synetix syngas generation technology and liquid phase methanol synthesis technology.