Rectorite, pillared, hydrothermal stability

Pillared rectorites are expanded clay minerals with a surface area in the 150-220 mVg range, and thermal and hydrothermal stability similar to that of zeolites with the faujasite structure (1-4). After steaming at 760°C/5h (100% steam, 1 atm), these materials retain their pillared structure, and at microactivity test conditions (MAT) they are as active as commercial fluid cracking catalysts (FCC) for gas oil conversion... 

X-ray diffraction (XRD), pyridine chemisorption, and microactivity test (MAT) results have been used to characterize a sample of natural rectorite pillared with alumina clusters. After reaction with chlorhydrol, a pillared product was obtained that after drying at 100°C/10h had d(OOl) spacing of 28.7 A. The pillared rectorite retained its structure even after calcining in air at 800 C/5h or after steam aging at 760°C/5h with steam at 1 atm. Thus, pillared rectorites have thermal and hydrothermal stability comparable to that of zeolites with the Faujasite structure. 

Pillared rectorites have thermal and hydrothermal stability much superior to that of similarly prepared montmorilIonites and hectorite catalysts. In fact, ACH-rectorites retain their pillared structure even after calcination in air at 800°C/5h or after steam-aging with 100% steam at 760°C/5h, Fig. 3. High temperature (800°C) calcination or steaming has little effect on the shape and intensity of the clay 001 and 002 reflections. Fig. 3. At 800°C the d(OOl)... 

Natural rectorites pillared with alumina clusters have thermal as well as hydrothermal stability far superior to that of similarly prepared montmorilIonite catalysts. Their stability is comparable to that of zeolites with the Faujasite structure. Pyridine chemisorption experiments have indicated that these materials contain both B and L acid sites and that at cracking conditions acidity is essentially of the L-type. Steam-aged (760°C/5h) pillared rectorites at MAT conditions have cracking activity comparable to that of similarly steam-aged commercial FCC containing an estimated 35% CREY. Coke selectivity (as well as particle density) will have to be improved for ACH-rectorites to compete with zeolite-containing FCC. 

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