Original sentence: Halloysite also has been used as a petroleum cracking catalyst in the past, <ref>US Patent #3515682, </ref, Exxon have developed one based on synthetic halloysite;
Edited sentence: Halloysite also has been used as a petroleum cracking catalyst in the past,  but was surpassed by synthetic halloysite developed by Exxon; however, due to improvements in technology there are lower cost methods of converting halloysite to Zeolite-a and also potential applications for low cost plastics recycling