MFI With Unusual Morphology

摘要

A method of making a crystalline molecular sieve of MFI framework type, preferably ZSM-5, from a synthesis mixture comprising at least one source of tetravalent element (Y), at least one source of trivalent element (X), at least one source of alkali metal hydroxide (MOH), at least one structure directing agent (R) and water, said synthesis mixture having the following molar composition: YO2:(p) X2O3:(q) MOH:(r) R:(s) H2O, wherein (p) is from 0.005 to 0.025, (q) is from 0.05 to 0.5, (r) is from 0.05 to 0.15 and (s) is from 35 to 45, wherein the ratio of the largest dimension (L) to the smallest dimension (S) of each crystal of the molecular sieve product is at least 5, and the smallest dimension (S) is from 20 nm to 200 nm.

主权项

1. A method of making a crystalline molecular sieve of MFI framework type, said method comprising the steps of:
(a) providing a synthesis mixture comprising at least one source of tetravalent element (Y), at least one source of trivalent element (X), at least one source of alkali metal hydroxide (MOH), at least one structure directing agent (R) and water, said synthesis mixture having the following molar composition (expressed in terms of oxide):
YO2:(p)X2O3:(q)MOH:(r)R:(s)H2Owherein (p) is in the range from 0.005 to 0.025, (q) is in the range from 0.05 to 0.5, (r) is in the range from 0.05 to 0.15, (s) is in the range from 35 to 45; and wherein said structure directing agent (R) is a compound having a cation of the general formula R1R2R3N+(CH2)nN+R4R5R6A− with n equal to 4, 5 or 6, R1, R2, R3, R4, R5 and R6 independently representing an alkyl group having 1 to 4 carbon atoms, and A− representing a hydroxide or a halide ion; and
(b) treating said synthesis mixture under crystallization conditions to form crystals of molecular sieve of MFI framework type, wherein the ratio of the largest dimension (L) to the smallest dimension (S) of each crystal is at least 5, and the smallest dimension (S) is from 20 nm to 200 nm, wherein said crystallization conditions comprise a temperature in the range of 90 to 200° C. applied for 24 to 240 hours.