Preparation of hydroxyl-rich zeolites
AssigneeMobil Oil Corporation
InventorsClarence D. Chang, Stuart D. Hellring
Life of this patent
Estimating the term…
Abstract
Zeolites (e.g. ZSM-5 and zeolite beta) enriched with hydroxyl groups are prepared by ammonia treatment of sieves which have suffered loss of tetrahedral aluminum from framework positions followed by careful calcination (200.degree.-450.degree. C.). The hydroxyl group created by this method are stable only to 500.degree. C.
Claims28
A method of preparing hydroxyl-rich zeolites comprising providing as a reactant, a zeolite, which has suffered a loss of tetrahedral aluminum, and has been subjected to an elevated temperature of at least 500.degree. C., and then subjecting the reactant zeolite to ammoniation;
- subjecting the ammoniated zeolite to conditions equivalent to second elevated temperature which ranges up to 450.degree. C. whereby ammonia is evolved and the zeolite contains hydroxyl groups absent from the reactant zeolite.
A zeolite exhibiting the X-ray diffraction pattern of ZSM-5, having suffered loss of framework aluminum, the Fourier Transform Infrared Spectrograph of which exhibits absorbance at about 3720 cm.sup.-1 and at about 3745 cm.sup.-1.
A zeolite, having a characteristic X-ray diffraction pattern, exhibiting a constraint index within the approximate range of about 1 to about 12 measured at 500.degree. F. to 950.degree. F., having suffered loss of framework aluminum, the Fourier Transform infrared spectrogram of which exhibits absorbance at about 3720 cm.sup.-1 and at about 3745 cm.sup.31 1.
A zeolite, having a characteristic X-ray diffraction pattern;
- exhibiting a constraint index within the approximate range of about 1 to about 12, measured at 500.degree. F. to 950.degree.;
- having suffered loss of framework aluminum and the Fourier Transform Infrared Spectrograph of which exhibits hydroxylgroup absorbance, different from the absorbance either of the as-synthesized zeolite or of the as-synthesized zeolite subsequently heated to temperatures exceeding 500.degree. C. and at about 3745 cm.sup.-1.
A zeolite, exhibiting the X-ray diffraction pattern of zeolite Beta, having suffered loss of framework aluminum and the Fourier Transform Infrared Spectrograph of which exhibits hydroxyl group absorbance different from that of the zeolite as-synthesized and different from that of the as-synthesized zeolite calcined at temperatures greater than 500.degree. C. and at about 3745 cm.sup.-1.
Dependencies are inferred from the claim text.