D. Michael Wilson, one of Albemarle Corp.’s top executives, has resigned to take the job as CEO of Richmond, Virginian-based WestRock Co.’s specialty chemical business.

WestRock said it expects that business will be spun off into a publicly traded company, Ingevity, early next year. Wilson starts on Sept. 1.

Wilson has been president of Albemarle’s Performance Chemicals segment, which includes the lithium business Albemarle acquired in a $6 billion deal for Rockwood Holdings.

Wilson’s resignation was accepted Aug. 3 and is effective on Aug. 31, according to a Tuesday filing with the U.S. Securities and Exchange Commission. Albemarle did not give an explanation for Wilson’s departure in the filing.

Chief Executive officer and President Luther Kissam IV will take over those responsibilities on an interim basis, the company said. In the meantime, Albemarle will conduct an internal and external search for a permanent replacement.

Kissam said he is happy for and proud of Wilson.

Wilson was instrumental in driving Albemarle’s growth strategy and supporting the company’s transformation through the Rockwood acquisition, Kissam said.

Wilson joined Albemarle on Oct. 1, 2013, as senior vice president and president of Catalyst Solutions. When Albemarle realigned its business into three global business units in January, Wilson was named president of the Performance Chemicals unit. The unit includes catalyst solutions, lithium, specialty chemicals, flame retardants and fine chemistry services.