|Methanol-to-gasoline process flow diagram. Source: EMRE. Click to enlarge.|
At a recent hearing of the Alaska state legislature’s House Resources Committee, Deo van Wijk, chairman of Swiss company Janus Methanol AG (formed in 2007), outlined a potential approach to converting North Slope gas to gasoline via the combination of a new methanol production technology (GigaMethanol) and the Methanol-to-Gasoline (MTG) process developed by ExxonMobil Research and Engineering (EMRE).
Under van Wijk’s concept, a plant would produce methanol from natural gas on the North Slope using the proposed GigaMethanol technology. The resulting methanol would be blended with crude and transported via the trans-Alaska oil pipeline to Valdez, where it would be extracted from the oil and processed via Methanol-to-Gasoline technology into gasoline.
|Janus subsidiary acquiring Eastman methanol plant|
|In January, ICIS reported that Eastman Chemical reached an agreement to sell a mothballed Texas methanol and ammonia plant to Pandora Methanol, a subsidiary of Janus Methanol.|
|The plant will have a capacity of 850,000 tonnes/year of methanol and 250,000 tonnes/year of ammonia, according to van Wijk.|
|Van Wijk at the time said the new plant might consider the methanol-to-gasoline MTG process pioneered by ExxonMobil.|
|Eastman originally bought the plant in 2007 for a $1.6-billion coal-gasification project, but called off the project in late 2009 due to high capital requirements, the narrow difference between petroleum and natural gas prices and uncertain US energy policy.|
Costs for a 63,000 barrel (of gasoline) per day system would be approximately $5.2 billion, he said. Gasoline could be delivered from Valdez at $2.65 to $2.85 per gallon, including a $1.45 margin.
In addition to providing a market for North Slope gas, the mix of methanol in the pipeline flow would help prevent problems with ice forming in the line, van Wijk, a former Methanex executive, suggested. If the entire daily output of North Slope gas (4.5 billion cubic feet, bcf) were converted to gasoline, it would produce 450,000 barrels per day, he suggested.
Janus, GigaMethanol and MTG. Janus Methanol is a methanol and chemical development and operating company. van Wijk, a former Methanex executive, formed Saturn Methanol which subsequently built Titan Methanol, a 2,500 tonne per day methanol production facility in Trinidad, and began Atlas Methanol, also in Trinidad. van Wijk sold Saturn to Methanex in 2000 due to funding issues. Atlas is now owned by Atlas Methanol Company, a joint venture between Methanex (63.1%) and BP Trinidad and Tobago (bpTT) (36.9%).
Atlas uses Lurgi’s MegaMethanol technology, which allows the cost-effective production of methanol from natural gas. Major process elements of the MegaMethanol technology are:
Oxygen-blown natural gas reforming, either in combination with steam reforming, or as pure autothermal reforming.
Two-step methanol and synthesis in water- and gas-cooled reactors operating along the optimum extraction route.
Adjustment of syngas composition by hydrogen recycle.
MegaMethanol technology supports the production of 5,000 tonnes of methanol per day in a single train. van Wijk is now proposing the commercialization of GigaMethanol technology, targeted to deliver 10,000 tonnes of methanol per day in a single train configuration based on Atlas. GigaMethanol would use Lurgi’s high-pressure autothermal reforming technology and two-stage methanol synthesis.
The resulting economy of scale would deliver a significant reduction in investment cost, van Wijk argues.
Given cost-effective methanol production, there are several established pathways for converting the methanol into fuels and chemicals: MTG; methanol to propylene (MTP); and methanol to olefins (MTO). MTG, which can be licensed from Exxon Mobil (earlier post) currently is the only commercially proven methanol conversion technology. MTG is in use in new Zealand, and now in China.
MTG synthesis reactions convert methanol into a mixture of C1-C10 hydrocarbons and free water; approximately 89% of the hydrocarbons are in the gasoline boiling range with 87 octane value ((R+M)/2). LPG accounts for the other major product stream (about 10%). By contrast, the Fischer-Tropsch process produces a range of hydrocarbons and oxygenates, with yields dependent on catalyst, temperature and specific technology. The products also require refining processes to convert the F-T liquids to conventional fuels.
The MTG reactor operates under moderate temperature and pressures, and the design allows for on-stream MTG catalyst regeneration and replacement. The current, second-generation technology now being applied in China is based on the more than 10 years of learnings from the New Zealand operation, and features improved heat integration and improved process efficiency.
A 2009 National Research Council study examining fuels from coal/biomass found that an MTG-based plant had slightly higher overall efficiency than F-T plants.
|NRC comparison of F-T and MTG. Source: EMRE. Click to enlarge.|