The most important development in methanol technology in recent years has been the widespread acceptance of low and intermediate pres- sure processes for methanol production. Before 1960, all synthetic methanol was made at pressures in excess of 200 atmospheres. During the 196Os, Imperial Chemical Industries (ICI) recognized that the sulfur con- tent of natural gas could now be reduced to very low levels. Thus, very active copper catalysts, which were formerly unsuitable because they were easily poisoned by sulfur compounds, could now be used for methanol synthesis. Since the copper catalysts were more active than the established zinc oxide and chrome oxide catalysts, it was commercially practical to synthesize methanol at lower temperatures and pressures than formerly,
The first nonlicensor-operated low pressure methanol plant was built for the Chang Chun Petrochemical Company in Taiwan, using the ICI process, and operation began in September 1970. Since that time, low and inter- mediate pressure processes have captured most of new methanol production, and several other licensers have entered the field with similar processes.
The first ICI low pressure process, operating at about 50 atm and 550�F, was intended for competition with high pressure processes at capacities below 500 ton/day. In this range, the low pressure process with its larger feed gas discharge volume was able to use centrifugal gas compressors, whereas the high pressure processes were limited to the more costly and less efficient reciprocating compressors. Subsequent improvements in the life of the copper catalyst and in the efficiency of the lower pres- sure processes have extended their size range so that they now compete with high pressure processes at any capacity,
Methanol process technology was last reviewed by SRI's Process Economics Program in October 1968 (58038). At that time, the ICI low pressure process was still undergoing development, and only limited information was available. Thus, the object of this study is to evaluate the changes in ICI low pressure methanol technology that have taken place since 1968. Copper catalyzed low and intermediate pressure processes available from other licensers are also considered, but in lesser detail.
A recent ICI patent for the direct oxidation of methane to methanol and formaldehyde is examined in a separate section of this report.
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