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Ionic Liquids

Chevron embraces ionic liquids

Oil company uses the novel salts as alkylation catalyst in place of hydrofluoric acid

by Michael McCoy
October 3, 2016 | APPEARED IN VOLUME 94, ISSUE 39

Credit: Honeywell
The demonstration alkylation unit at Chevron’s Salt Lake City refinery.

Chevron will convert the alkylation catalyst used in its Salt Lake City refinery from the toxic and corrosive chemical hydrofluoric acid to an ionic liquid. The planned switch takes ionic liquids a step closer to becoming mainstream materials and could presage big changes in the refining industry as well.

The big oil firm began developing ionic liquids as alkylation catalysts in 1999 and has run a demonstration unit in Salt Lake City for the past five years. It plans to start building a full-scale alkylation plant next year. After the plant is completed in 2020, Chevron will remove all HF-specific equipment and its inventory of HF from the site.

Ionic liquids, salts that are liquid at temperatures below 100 °C, have long fascinated chemists, but they have often seemed like a technology in need of an application. Two successful applications are BASF’s use of ionic liquids as acid-scavenging agents and Petronas’s ionic-liquid-based process for removing mercury from natural gas.

Tom Welton, a professor at Imperial College London who studies ionic liquids, says Chevron’s project will represent the largest-scale chemical synthesis using ionic liquids to date. “It will certainly have the greatest impact of any process introduced so far,” he says, noting that the new facility’s output will end up in the fuel that powers our cars.

The Chevron technology could also have a big impact on how the refining industry carries out alkylation. Refiners use alkylation to combine low-molecular-weight alkanes and alkenes into high-octane gasoline components. Today, more than half of the alkylation capacity in the U.S. is based on HF, according to the energy consulting firm Stratas Advisors. HF releases in Texas and Pennsylvania have prompted calls for the phaseout of HF in refineries.

Chevron says it developed the new process not for safety reasons but for the lower catalyst consumption and ease of on-site regeneration it offers. Chevron has licensed the technology to Honeywell UOP, which will market it to the refining industry and supply the catalyst, a chloroaluminate ionic liquid with a proprietary composition.

Honeywell calls the process, named Isoalky, the first successful liquid alkylation technology to be introduced in 75 years.



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Robert Buntrock (October 5, 2016 4:33 PM)
No information on the composition of the ionic liquids. Please furnish.
Michael McCoy (October 5, 2016 4:41 PM)
In the story above I write that it is "a chloroaluminate ionic liquid with a proprietary composition." That's all Chevron would reveal. One of its patents says:

Non-limiting examples of chloroaluminate ionic liquid catalysts that may be used in alkylation processes according to embodiments of the instant invention include those comprising 1-butyl-4-methyl-pyridinium chloroaluminate, 1-butyl-3-methyl-imidazolium chloroaluminate, 1-H-pyridinium chloroaluminate, N-butylpyridinium chloroaluminate, and mixtures thereof.
Peter Klusener (October 6, 2016 3:17 AM)
The authors of the article overlooked the fact that in China a few years ago the first alkylation plant using ionic liquid was successfully started up. The statement of Honeywell by being the first successful liquid alkylation technology being introduced in 75 years is not true. (in Chinese, translation below)
October 08, 2013, source: Treasure Island
Shandong Deyang Chemical Co Ltd (Deyang) held on Sept 29, 2013 a ceremony in Dongying on the start up of the first Ionic Liquid Alkylation (ILA) plant in the world, with a capacity of 120 kt/a. The ceremony was attended by Shandong provincial party Committee and municipal leaders and by Prof Xu Chunming, president of China Petroleum University in Beijing (CUP).
Deyang invested 875 M RMB in the unit, which took 2 years to build. The income will be 3000 M RMB with a profit tax of 320 M RMB. The ILA technology was developed by the national heavy oil laboratory at CUP. Advances of the ILA technology above the traditional HF and sulphuric acid alkylation are: almost no corrosion, much safer for human and environment, and thus double green. The high octane alkylate product (RON up to 97) meets EU VI emission standards and is free of sulphur, olefin and aromates. In comparison with traditional technologies the alkylate yield is 5% higher and the catalyst can be recycled, resulting in a lower catalyst loss of about 100 t/a.
This new launched technology received already wide attention by petrochemical companies such as in Shanghai and Suzhou. The ILA technology is more desirable in the southern coastal areas because it could solve environmental issues.
In China there are about 36 alkylation plants with a total capacity of 7630 kt/a; such as 8 plants in Shangdong province, 2 in Henan and 1 in Hubei. The capacity will be increased as alkylate use will increase due steadily upgrading of gasoline.

See also a more recent conference paper:
Michael McCoy (October 11, 2016 12:34 PM)
Hi Peter,
Thanks for pointing out the China project. I did come upon references to it in researching the article and should have mentioned it. I don't know why Honeywell is making the "first time in 75 years claim" if in fact Deyang Chemical is already using ionic liquid-based alkylation.
Danny E (October 13, 2016 12:25 PM)
Not all alky unit's or HF . Our refinery alk unit had Iso butane , BB and sulphuric acid.
Sophie (October 14, 2016 6:33 PM)
What is the patent # for the process? How many barrels of alkylate per day will the Salt Lake City plant produce? How much would it cost to convert a 25,000 bpd HF alkylation unit to the new isoalky technology?

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