Synthetic fuels (Methanol to gasoline)  

ExxonMobil’s methanol to gasoline (MTG) process selectively converts methanol to a single fungible liquid fuel and a small LPG stream. The liquid product is conventional gasoline with virtually no sulfur and low benzene, which can be sold as-is or blended with ethanol, methanol or with petroleum refinery stocks. This minimizes offsite and logistic complexity and investment for synthetic fuel distribution.

Methanol-to-gasoline chemistry was discovered by ExxonMobil scientists in the 1970s. Over years of extensive studies and pilot plant operations, ExxonMobil developed an understanding of the MTG reactions and process conditions necessary to consistently produce motor gasoline. In 1979, a fixed bed design was completed and thoroughly demonstrated at 4 BPD capacity (today proven scalable up to 15 KBD).

In this design, methanol is first dehydrated over an amorphous alumina catalyst to an equilibrium mixture of di-methyl ether (DME), methanol and water. The DME reactor effluent is introduced into the MTG reactors, wherein methanol and DME are completely dehydrated by a proprietary catalyst forming light olefins and water. At the MTG reactor conditions, light olefins oligomerize into higher olefins, which combine through various reaction paths into paraffins, naphthenes, and methylated aromatics. The shape-selective MTG catalyst limits the hydrocarbon synthesis reactions to about C₁₁.

ExxonMobil commercialized the first gas-to-gasoline plant in New Zealand in 1985. The New Zealand plant produced 14,500 BPD of gasoline and was operated by the New Zealand Synthetic Fuels Corporation, a joint venture between the government of New Zealand and ExxonMobil, until 1995. Operation of the first coal-to-gasoline plant via 2nd generation MTG technology began in 2009 in China by Jincheng Antracite Mining Group (JAMG). This 2,500 BPD gasoline plant began operations in 2009 and successfully demonstrated the coal-to-gasoline concept. After two years of operation, JAMG and ExxonMobil agreed to license an engineering agreement for two additional MTG units at 12,500 BPD each.

The conversion of methanol to hydrocarbons and water is virtually complete with the product being a mixture of synthesis hydrocarbons and water with a limited amount of C₂- gases. Production yields, product qualities and catalyst performance are stable during operation with little variation in the product. The liquid product is conventional gasoline with virtually no sulphur and low benzene, which can be sold as-is or blended with ethanol or methanol or with petroleum refinery feedstocks.

In March 2015 ExxonMobil and Sinopec Engineering Group (SEG) announced a joint technology development agreement for advancement of a fluidized-bed MTG technology. The goal is to develop a fluidized bed MTG design that will cost significantly less to construct and operate, and significantly improve energy efficiency versus the fixed bed design.