Methanol is an alternative, clean burning fuel source currently used as an additive to gasoline as well as a solvent in chemical processes, an alcohol denaturant, antifreeze, and in the biodiesel production process. This simplest of alcohols is also commonly known as methyl alcohol, wood alcohol, wood naphtha, and wood spirits. The names wood alcohol, wood naphtha, and wood spirits are commonly used because methanol was once produced exclusively from wood.
Early Methanol Production Methods
From the early 1800’s through the mid 1920’s, the major method of methanol production was wood distillation. This process used heat to produce charcoal and methanol from wood. As the wood was heated, it slowly burned down releasing methanol gas. The gas was collected and condensed to make liquid methanol. By 1923, methanol production had reached 30,000 tons, using over 6 tons of wood feedstock. This method was extremely inefficient and was replaced in the late 1920’s by a large scale methanol production process which used hydrogen-carbon oxide mixtures.
Early Synthesis Gas Methanol Production
In 1923, while wood distillation was at its peak, German chemists Alwin Mittasch and Mathias Pier developed a method of methanol production using synthesis gas – a carbon monoxide, carbon dioxide, and hydrogen mixture. This method used a chromium and manganese oxide catalyst and required pressures from 50 atm to as high as 220 atm. Extremely high temperatures of up to 450° C.
Modern Methanol Production
Today, the synthesis gas methanol production method is still in use. Over the years, however, it has been modified to be easier, faster, and safer than the original method.
Modern Synthesis Gas Methanol Production
Modern synthesis gas methanol production uses a copper catalyst, which allows the process to take place at lower pressures. This modern low pressure method – LPM – was developed in the late 1960’s by ICI.
During the process, synthesis gas is produced in a reformer. To accomplish this, hydrocarbon feedstock and steam are passed through a heated reformer tube. Ratios may need to be adjusted through purging excess hydrogen or adding carbon dioxide.
The resulting syngas is then cooled and compressed, after which it is fed to the methanol converter. It is here that methanol synthesis takes place using a copper based catalyst. The crude methanol is then recovered and distilled down to a purified form.
Methanol Production Feedstocks
Methanol can and has been produced from a variety of substances over the years including:
- Natural gas
- Crop residues
- Forest residues
- Cellulosic parts of municipal solid wastes
Although all of these methods have been used at one time or another, today the main feedstock used for methanol production is natural gas. This is because it is the most cost effective, convenient, and effective method. Recently other biomass sources have been receiving attention as possible methanol production feedstocks.
Currently, there are 18 methanol production plants in the United States which produce over 2.6 billion gallons of methanol per year. Additionally there are over 90 methanol production plants worldwide which produce over 11 billion gallons of methanol per year. Globally, the methanol industry generates $12 billion dollars a year and creates nearly 100,000 jobs.
The worldwide methanol market is expected to reach sales in excess of 55 million metric tons by the year 2015. The major factor in this industry’s unbelievable growth is the increasing consumption of methanol in the Asia-Pacific region, especially China. Also predicted to fuel methanol’s high demand and huge sales is the rising use of methanol in end-use industries such as alternative fuel and acetic acid production.