Methanol to gasoline

The methanol to gasoline process is a method of producing liquid hydrocarbons for use as synthetic fuel from methanol by heating with ZSM-5 zeolite catalyst. It was developed by Mobil in early 1970s.

The Process

Methanol is made from methane (natural gas) in a series of three reactions:
# Steam reforming: CH₄ + H₂O → CO + 3 H₂ ΔrH = +206 kJ mol-1
# Water shift reaction CO + H₂O → CO₂ + H₂ ΔrH = +206 kJ mol-1
# Synthesis 2 H₂ + CO → CH₃OH ΔrH = -92 kJ mol-1

The methanol thus formed may be converted to gasoline by the Mobil process. Firstmethanol is dehydrated to give dimethyl ether::2 CH₃OH → CH₃OCH₃ + H₂OThis is then further dehydrated over a zeolite catalyst, ZSM-5, to give a gasoline with 80% (by weight based on the organics in the product stream) C5+ hydrocarbon products.

Deactivation

ZSM-5 is deactivated by a carbon build-up ("coking") over time in converting methanol to gasoline. The catalyst can be re-activated by burning off the coke in a stream of hot (500C) air; however, the number of re-activation cycles is limited.

ee also

* Fischer-Tropsch process
* Synthetic Liquid Fuels Program
* Synthetic petrol

External links

* [http://chemelab.ucsd.edu/methanol/indexMTG/main.html University of California San Diego webpage]
* [http://www.nzic.org.nz/ChemProcesses/energy/7D.pdf The production of methanol and gasoline]