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US 5,783,168 AGranted
ZSM-22 zeolite
AssigneeExxon Chemical Patents Inc.
InventorsJohannes Petrus Verduijn, Luc Roger Marc Martens
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Abstract
ZSM-22 zeolite which is particularly pure and whose synthesis does not require the synthesis mixture to be stirred can be produced by the addition to the synthesis mixture of a small quantity e.g. 1000 ppm, of preformed ZSM-22 zeolite seed crystals.
Claims6
A process for preparing a ZSM-22 zeolite comprising crystallizing a synthesis mixture comprising:
- (i) a source of silicon and/or germanium;
- (ii) a source of aluminum, iron, chromium, vanadium, molybdenum, arsenic, antimony, manganese, gallium or boron;
- (iii) a source of monovalent cation;
- and
- (iv) an organic structure agent;
- wherein seeds of preformed ZSM-22 are included in the initial synthesis mixture, and crystallization is carried out by agitating under conditions effective for forming a zeolite comprising ZSM-22 ingrown needles of crystals of less than 1 micron and having a ZSM-5/ZSM-22 peak height ratio less than 0.04;
- and wherein the mixture is stirred at a rate of less than 50 rpm during crystallization so that the level of agitation is reduced compared to a process in which such ZSM-22 crystals are formed under identical reaction conditions, using an initial synthesis mixture containing no seeds of preformed ZSM-22.
4 more elements
A process according to one of claims 1 to 6 in which the crystallisation temperature is not more than 160.degree. C.
Dependencies are inferred from the claim text.