Patent ID: 8853117

Claim:
A method of making a crystalline molecular sieve of MFS 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 alkali metal (M) being a mixture of sodium and potassium, said synthesis mixture having the following molar composition (expressed in terms of oxide): YO 2 :(p) X 2 O 3 :(q) MOH:(r)R:(s)H 2 O wherein (p) is in the range from 0.005 to 0.05,(q) is in the range from 0.01 to 3, (r) is in the range from 0.03 to 2, (s) is in the range from 10 to 75 and the molar ratio of sodium (q 1 ) divided by the molar ratio of potassium (q 2 ,) is less than or equal to 2.0; and (b) treating said synthesis mixture under crystallization conditions to form crystals of molecular sieve of MFS framework type, said crystals having an average diameter (D) of less than or equal to 1.5 micron and an average thickness (T) of less than or equal to 300 nanometers.