Adds company statement

By Nicole Jao

NEW YORK, May 22 (Reuters) - Exxon Mobil XOM.N was operating the catalytic cracker unit at its 275,000 barrel-per-day Joliet, Illinois refinery at reduced rates earlier this week, IIR Energy said on Thursday.

The refinery ran its 98,000-bpd catalytic cracker unit at approximately 50% capacity due to unspecified mechanical issues, the industry monitor said.

"We are conducting maintenance at our Joliet refinery, and we are working to complete it as safely and quickly as possible," an Exxon Mobil spokesperson said. They declined to comment on the specifics of operational maintenance.

The company said on Tuesday it was working to resolve an operational issue at the Joliet refinery.

(Reporting by Nicole Jao in New York; Editing by Chris Reese)

((Nicole.Jao@thomsonreuters.com; Twitter/X: @ByNicoleJao; +1 646 540 2216;))