PREPARATION AND CHARACTERIZATION OF LANTHANUM-DOPED PILLARED CLAYS

A series of Lanthanum-doped hydroxyalumia pillared clays (LaAl-PILC) with basal spacing of 1.80-1.87nm were first prepared by two different routes. The pillar structure, thermal stability and surface acidity of the pillared clays have been determined using Al-27-NMR, x-ray diffraction (XRD), DTA, IR and temperature-programmed desorption (TPD) measurements. The results suggest that the thermal stability of the pillared clays was improved by doping lanthanum(III) and the pillars have the Keggin structure, whereas their surface acidity was slightly decreased compared with that of hydroxy-Al pillared clays.The cracking of cumene, disproportionation and alkylation of 1,2,4-trimethylbenzene were carried out in a pulse reaction system at 400-degrees-C over the pillared clay catalysts. Incorporating La(III) into an alumina pillar increased the cracking activity of cumene and selectivity for disproportionation of 1,2,4-trimethylbenzene compared to hydroxy-Al pillared clay containing no lanthanum.