Jan. 8 (Bloomberg) -- Ineos Group Holdings Plc, a closely held chemicals company, will shut a unit that makes gasoline additives at its refinery in Grangemouth, Scotland, for maintenance next month.

The catalytic reformer unit, which also processes naphtha into petrochemical products such as ethylene, will be closed for 24 days in February, according to an official who declined to be identified, citing company policy.

David East, a spokesman for the refinery in central Scotland, declined to comment on the plant's ``day-to-day operations.''

Ineos completed the purchase of the 200,000-barrel-a-day Grangemouth plant from BP Plc in December 2005. At the same time, it bought BP's refinery in Lavera, France.

Morgan Stanley Commodities Group said in July last year it would sell Ineos's products from the Grangemouth and Lavera plants in a long-term agreement starting April 1.

The Scottish refinery, the U.K.'s sixth-largest, processes Forties oil from the North Sea into fuels such as diesel and gasoline, according to the Web site of the U.K. Petroleum Industry Association. Britain's biggest refinery is Exxon Mobil Corp.'s plant at Fawley in Hampshire, England.

Ineos, based in Lyndhurst, England, has 73 production facilities in 19 countries, according to the company's Web site.

Gasoline additives improve fuel performance. Ethylene is used in making plastics.

To contact the reporter on this story: Nidaa Bakhsh in London at nbakhsh@bloomberg.net

Last Updated: January 8, 2008 08:09 EST