DKRW Advanced Fuels (DKRW) has selected ExxonMobil Research and Engineering Company’s (EMRE) methanol-to-gasoline (MTG) technology as part of DKRW’s coal to liquids (CTL) project in Medicine Bow, WY. DKRW recently stated that it has switched the initial finished product of its planned CTL plant from diesel to gasoline. (Earlier post.)
The Medicine Bow project will gasify the coal, convert the synthetic gas to methanol, and then convert the methanol to gasoline via the MTG process. The plant will produce up to 20,000 barrels per day of transportation fuels, electricity, steam, off-gas, slag, chemicals (including sulfur), other fuels and energy products which will be sold into the market. The plant intends to capture CO2 emissions from the process and send it to northeast Wyoming for use in enhanced oil recovery projects.
The approximately 15,000 barrel per calendar day MTG unit will be based on commercially proven technology which incorporates improvements since the technology was originally commercialized by Mobil 20 years ago in New Zealand.
Mobil (now ExxonMobil) began with a 4 bpd pilot plant in the US, then scaled up pilot operations to 100 bpd in Germany (with Uhde). In 1979, the New Zealand government decided to build a commercial 14,500 bpd plant in Montunui, NZ, owned 75% by the NZ government, 25% by Mobil. The plant started up in 1985 and operated successfully for ~10 years till conversion to chemical grade Methanol production.
The conversion of methanol to hydrocarbons and water is virtually complete and essentially stoichiometric in the MTG process. The reaction is exothermic with the reaction heat managed by splitting the conversion in two parts. In the first part, methanol is converted to an equilibrium mixture of methanol, dimethyl ether (DME), and water. In the second part, the equilibrium mixture is mixed with recycle gas and passed over a shape-selective catalyst to form hydrocarbons and water. Most of the hydrocarbon product boils in the gasoline boiling range. The low-sulfur, low-benzene gasoline product from the process is a premium quality clean gasoline and can be blended with refinery gasoline directly or sold separately.
From 1,000 tons of methanol, the process will produce 387 tonnes of gasoline, 46 tonnes of LPG, 7 tonnes of fuel gas and 560 tonnes of water, which is recycled as process water.
|Comparison of Fischer-Tropsch with MTG|
|Compound||Low Temp FT|
Co Catalyst @428F
|High Temp FT|
Fe Catalyst @644F
|C5 - 160C||19||36||82.3|
In 2006, China-based JAM (Shanxi Jincheng Anthracite Coal Mining Co. Ltd. ) awarded a contract to Uhde for the engineering and supply of a coal-based MTG plant. (Uhde licenses the MTG technology from EMRE.)
The new MTG plant is part of a complex on a pilot-plant scale, which is being constructed at Jincheng, Shanxi Province, some 600km south-west of Beijing. This complex also includes a fluidized-bed hard-coal gasification plant and a methanol plant. It is planned to produce 100,000 tonnes of gasoline annually from the year 2008.
Sigmund M. Csicsery, “Catalysis by shape selective zeolites — science and technology” Pure & Appl. Chem., Vol. 58, No. 6, pp. 841—856, 1986.