Around 1913, A. Mittasch at BASF noticed the presence of oxygen-containing compounds during experiments on the NH₃ synthesis. Systematic research and development in Germany led in 1923 to the first large scale (CH₃OH) manufacture based on synthesis gas:



If the synthesis gas is manufactured from methane-rich natural gas, then its composition (CO + 3H₂) does not correspond to stoichiometric requirements. In these cases, CO, is added to the feed as it consumes more H₂ (cf. eq 12) than CO (cf. eq 11).

The BASF process is conducted at 320-380°C and ca. 340 bar. The ZnO-Cr₂O₃ catalyst has a maximum activity when the Zn/Cr ratio is about 70: 30. Cold gas is injected at many places in the catalyst bed to avoid high temperatures that would shift the equilibrium away from methanol. Being very resistant to the usual catalyst poisons at low concentrations, the oxide mixture has a service life of several years. Byproducts such as , methyl formate, and the higher alcohols are separated by distillation with a low- and high-boiling column. In order to suppress side reactions, a short residence time (1 -2 s), which completely prevents equilibration from taking place, is employed. Conversions of only 12- 15% are usual for a single pass through reactor.

The industrial process has been made highly efficient. The use of high pressure centrifugal compressors - normally employed in NH₃ plants - has made a particularly strong contribution.

UK Wesseling has developed a process operating at a low CO partial pressure (13 bar in gas recycle). The reaction conditions (300 bar and 350 °C) are similar to those of the BASF process. The ZnO-Cr₂O₃ catalyst is arranged in stages in the reactor. steel can serve as construction material as no Fe(CO)₅ is formed at the low CO partial pressure used. Methanol is obtained in high purity with only a small amount of byproducts. Using this high pressure modification, more than a million tonnes of methanol had been produced worldwide by the end of 1970. Recently, the conventional processes have been complemented by others operating at low and medium pressures. This transition to lower operating pressure was made possible by the introduction of more active Cu-based catalysts. These are, however, extremely sensitive to sulfur and require that the total sulfur content in synthesis gas be less than 1 ppm.

The ICl low pressure process, first operated in a pilot plant in 1966, plays a dominant role. Today, about 65% of the world methanol production is based on the ICl process, which is characterized by lower investment and process costs. In 1972, the prototype of a large scale plant (310000 tonnes per year) went on stream in Billingham, United Kingdom. Modern plants have an annual production capacity of about one million tonnes. The Cu-Zn-Al-oxide-based catalyst requires a synthesis gas particularly free of sulfur and chlorine. A new generation of catalysts with a 50% longer lifespan was recently introduced.

The usual process conditions in the converter are 50-100 bar and 240-260°C. Methanol can be obtained with a purity up to 99.99 wt%. The reactor is extremely simple; it contains only one catalyst charge which can be quickly exchanged. As in the high pressure process, cold gas is introduced at many places to absorb the reaction heat.

A similar low pressure process with a tubular bundle reactor was developed by Lurgi. The temperature is controlled by flowing boiling water around the entire length of the tubes. It employs a modified CuO-ZnO catalyst at 50-80 bar and 250-260°C.

In 1973, a 200000 tonne-per-year plant, in combination with a 415 000 tonne-per-year NH₃ plant, went into operation employing this principle. In the period following, Lurgi reactors were used more and more, and in 1984 their market share had already reached 50% of all methanol plants.

Recently, there has been a trend toward a medium pressure process. A number of companies are employing Cu as well as Zn-Cr oxide-based catalysts as shown in the table below:



For the sake of completeness, it must be mentioned that since 1943 Celanese (now Hoechst Celanese) has produced not only acetic acid, formaldehyde and , but also methanol and numerous other components from the oxidation of a propane-butane mixture. The reaction products must undergo an involved distillative separation.