Molybdenum-exchanged crystalline aluminosilicate zeolite
AssigneeUnion Oil Company of California
InventorEric L. Moorehead
Life of this patent
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Abstract
Molybdenum is ion exchanged into a crystalline aluminosilicate zeolite, replacing metals such as sodium, calcium, and potassium, by contacting the zeolite with an aqueous solution containing molybdenyl cations (i.e., MoO.sub.2.sup.2+) and having a pH below 7.0 but higher than that which would substantially affect the crystallinity of the zeolite. The resulting zeolite, when calcined or sulfided, is useful as a catalyst for hydrocarbon conversion reactions, particularly with respect to the hydrodealkylation of toluene to benzene and methane.
Claims26
A crystalline aluminosilicate zeolite having a composition expressed in molar ratios of oxides as:
- ##EQU3## where cM.sub.2/n O represents the sum of all components, on a per mole of Al.sub.2 O.sub.3 in the crystal framework basis, required to balance that portion of the charge on the crystal framework not balanced by molybdenum constituents, with the valence of M being represented by n, and where MoO.sub.3 represents all molybdenum constituents balancing a charge on the crystal framework, and c, b, x, and y represent the moles of M.sub.2/n O, MoO.sub.3, SiO.sub.2, and the water of hydration, H.sub.2 O, respectively, present in the zeolite to each mole of Al.sub.2 O.sub.3 in the crystal framework, x being between 2 and 100, y being a non-negative number, c being 0 or a positive number less than 1, and b being a positive number no greater than 1, with c+b being a positive number no greater than 1.0, said zeolite being characterized by the ion exchange of molybdenum-containing cations from the zeolite when the zeolite is immersed for at least one hour in an aqueous sodium salt solution having a temperature in the range of 20.degree. to 80.degree. C. and an initial pH between 6.0 and 8.5, said solution containing sodium ions in a concentration between 1.0 and 15.0% by weight, calculated as Na, and said immersion being such that the weight ratio of zeolite to solution is between about 1:4 and 1:12.
A molybdenum-containing crystalline alumino-silicate zeolite characterized by the ion exchange of molybdenum-containing cations from the zeolite when the zeolite is immersed for at least one hour in an aqueous sodium salt solution having a temperature in the range of 20.degree. to 80.degree. C. and an initial pH in the range of 6.0 to 8.5, said solution containing sodium ions in a concentration between 1.0 and 15.0% by weight, calculated as Na, and said immersion being such that the weight ratio of zeolite to solution is between about 1:4 and 1:12.
A molybdenum-containing crystalline aluminosilicate zeolite having an ordered crystalline structure and containing ion-exchangeable molybdenum-containing cations prepared by the method of contacting a crystalline aluminosilicate zeolite having an ordered crystalline structure with an aqueous solution containing a precursor of MoO.sub.2.sup.+2 ions, said solution having sufficient of an organic base added thereto to maintain the pH of the solution during said contacting below 7.0 but higher than that which would substantially affect the crystalline structure of the zeolite, said contacting being under conditions sufficient to replace at least some of the cations in the zeolite with molybdenum-containing cations and increase the molybdenum-containing cation content of the zeolite.
A catalyst composition comprising a molybdenum-containing crystalline aluminosilicate zeolite having an ordered crystalline structure prepared by the method comprising (1) contacting a crystalline aluminosilicate zeolite having a substantially ordered crystalline structure with an aqueous solution containing a precursor of MoO.sub.2.sup.+2 cations, said solution having sufficient of an organic base added thereto to maintain the pH of the solution below 7.0 but higher than that which would substantially affect the crystalline structure of the zeolite, said contacting being under conditions sufficient to replace at least some of the cations in the zeolite with molybdenum-containing cations and increase the molybdenum-containing cation content of the zeolite, and (2) subsequently calcining the zeolite containing the molybdenum-containing cations in an oxygen-containing oxidizing atmosphere.
A catalyst composition comprising a molybdenum-containing crystalline aluminosilicate zeolite having an ordered crystalline structure prepared by the method comprising:
- (1) contacting a crystalline aluminosilicate zeolite having an ordered crystalline structure with an aqueous solution containing a precursor of MoO.sub.2.sup.+2 cations, said solution having sufficient of an organic base added thereto to maintain the pH of the solution below 7.0 but higher than that which would substantially affect the crystal structure of the zeolite, said contacting being under conditions sufficient to replace at least some of the cations in the zeolite with molybdenum-containing cations and increase the molybdenum-containing cation content of the zeolite, and
- (2) subsequently exposing the zeolite to an atmosphere containing one or more components selected from the group consisting of sulfur and its compounds under conditions sufficient to convert at least some of the molybdenum-containing cations to components containing sulfur and molybdenum.
A method for ion-exchanging molybdenum-containing cations into a crystalline aluminosilicate zeolite having an ordered crystalline structure comprising contacting a crystalline aluminosilicate zeolite having an ordered crystalline structure with an aqueous solution containing a precursor of MoO.sub.2.sup.+2 cations, said solution having sufficient of an organic base added thereto to maintain the pH of the solution during said contacting below 7.0 but higher than that which would substantially affect the crystal structure of the zeolite, said contacting being under conditions sufficient to replace at least some of the cations in said zeolite with molybdenum-containing cations, and recovering the zeolite containing the molybdenum-containing cations from said solution.
Dependencies are inferred from the claim text.