<p>This invention is a process for producing diisobutylene from isobutylene. The process comprises contacting isobutylene with a solid adsorbent to remove sulfur and/or nitrogen impurities from the isobutylene, followed by oligomerizing the isobutylene to diisobutylene using a sulfonic acid-type ion exchange resin. The solid adsorbent removes sulfur and/or nitrogen impurities from the isobutylene and surprisingly increases both catalyst activity and catalyst life of the sulfonic acid-type ion exchange resin.</p>
