Preparation and characterization of pillared hectorite catalysts

Abstract

Reaction of natural hectorite with Al, ZrAl, and Zr polyoxycations generate pillared hectorites which after heating in air at 400 °C/4 h have Langmuir surface areas of 260–300 m 2/g thermally stable to 600–700 °C. Spectroscopic studies of sorbed pyridine indicate that these pillared hectorites (like pillared bentonites) contain both Lewis and Brønsted acid sites distributed as in the parent (acidwashed) hectorite. Above 300 °C, in vacua, pyridine is sorbed mainly on Lewis sites. Pillared hectorites are not as active as the corresponding pillared bentonites in cracking 260–426 °C boiling range gas oils but exhibit greater gasoline selectivity and minimize light gases (C 2–C 4) generation. Cracking activity depends mostly on the surface area generated by pillaring and the parent hectorite low iron content did not affect the catalyst's carbon selectivity.