Synthesis Of Aluminosilicate Molecular Sieves Having The Ifr Structure Type (Chevron)

CATEGORY: MOLECULAR SIEVES
Synthesis Of Aluminosilicate Molecular Sieves Having The Ifr Structure Type (Chevron)
United States Patent Application 20160185610
Elomari; Saleh Ali ;   et al.   June 30, 2016
Assignee: Chevron U.S.A.
Abstract
This disclosure is directed to a method for directly preparing pure phase aluminosilicate molecular sieves having the IFR framework type using a colloidal aluminosilicate composition in the presence of N-benzyl-4-aza-1-azoniabicyclo[2.2.2]octane cations as a structure directing agent.
TECHNICAL FIELD
[0001] This disclosure relates generally to methods for preparing pure phase aluminosilicate molecular sieves having the IFR structure type using a colloidal aluminosilicate composition in the presence of N-benzyl-4-aza-1-azoniabicyclo[2.2.2]octane cations as a structure directing agent.
BACKGROUND
[0002] Molecular sieve materials, both natural and synthetic, have been demonstrated in the past to be useful as adsorbents and to have catalytic properties for various types of hydrocarbon conversion reactions. Certain molecular sieves, zeolites, aluminophosphates, mesoporous materials, are ordered, porous crystalline materials having a definite crystalline structure as determined by X-ray diffraction (XRD). Within the crystalline molecular sieve material there are a large number of cavities which may be interconnected by a number of channels or pores. These cavities and pores are uniform in size within a specific molecular sieve material. Because the dimensions of these pores are such as to accept for adsorption molecules of certain dimensions while rejecting those of larger dimensions, these materials have come to be known as "molecular sieves" and are utilized in a variety of industrial processes.
[0003] Molecular sieves are classified by the Structure Commission of the International Zeolite Association according to the rules of the IUPAC Commission on Zeolite Nomenclature. According to this classification, framework type zeolites and other crystalline microporous molecular sieves, for which a structure has been established, are assigned a three letter code and are described in the "Atlas of Zeolite Framework Types," Sixth Revised Edition, Elsevier, 2007.
[0004] One known molecular sieve for which a structure has been established is the material designated as IFR, which is a molecular sieve having an undulating, one-dimensional 12-membered channel system. Examples of IFR framework type molecular sieves include ITQ-4, MCM-58 and SSZ-42.
[0005] PCT Publication No. WO98/29332 discloses ITQ-4 and its synthesis in a fluoride medium using N-benzylquinuclidinium cations or N-benzyl-1,4-diazabicyclo[2.2.2]octane cations as a structure directing agent.
[0006] U.S. Pat. No. 5,437,855 discloses MCM-58 and its synthesis in the presence of N-benzylquinuclidinium cations as a structure directing agent. U.S. Pat. No. 5,441,721 discloses the synthesis of MCM-58 using N-benzyltropanium cations as a structure directing agent.
[0007] U.S. Pat. No. 5,653,956 discloses SSZ-42 and its synthesis using N-benzyl-1,4-diazabicyclo[2.2.2]octane cations or N-benzyl-1-azabicyclo[2.2.2]octane cations as a structure directing agent. The SSZ-42 can contain oxides of boron, aluminum, gallium, iron or titanium, but at least 50% of those oxides must be boron oxide. In Example 14, an aluminum-containing SSZ-42 is made, but the aluminum is added to the SSZ-42 by post-synthetic treatment of the boron-containing SSZ-42.
[0008] U.S. Pat. No. 6,821,502 discloses the direct synthesis of aluminosilicate IFR framework type materials using a zeolite as the source of aluminum, a separate source of silicon, and a structure directing agent selected from N-benzylquinuclidinium cations and N-benzyl-1,4-diazabicyclo[2.2.2]octane cations.
[0009] Attempts to grow pure phase aluminosilicate IFR framework type crystals have been problematic, typically resulting in the formation of undesired impurities. The typical impurities found in the synthesized products include, for example, unreacted source zeolite and the competitive phases of beta zeolite, mordenite and/or ZSM-12, which can be identified in X-ray diffraction patterns.
[0010] The preparation of aluminosilicate IFR framework type molecular sieves using colloidal aluminosilicate compositions as a source of aluminum and silicon has not been previously reported. The present disclosure is based on the discovery that the preparation of aluminosilicate IFR framework type molecular sieves from a synthesis mixture containing a colloidal aluminosilicate composition allows for the preparation of aluminosilicate IFR framework type molecular sieve crystals free of impurities.
SUMMARY
[0011] In one aspect, there is provided a method of preparing an aluminosilicate molecular sieve having the IFR framework type by contacting under crystallization conditions (1) a colloidal aluminosilicate composition; (2) at least one source of an element selected from Groups 1 and 2 of the Periodic Table; (3) N-benzyl-4-aza-1-azoniabicyclo[2.2.2]octane cations; and (4) hydroxide ions.
[0012] In another aspect, there is provided a process for preparing an aluminosilicate type molecular sieve having the IFR framework type by: (a) preparing a reaction mixture containing (1) a colloidal aluminosilicate composition; (2) at least one source of an element selected from Groups 1 and 2 of the Periodic Table; (3) N-benzyl-4-aza-1-azoniabicyclo[2.2.2]octane cations; (4) hydroxide ions; and (5) water; and (b) subjecting the reaction mixture to crystallization conditions sufficient to form crystals of the molecular sieve.
[0013] The present disclosure also provides an aluminosilicate molecular sieve having the IFR framework type and having a composition, as-synthesized and in the anhydrous state, in terms of mole ratios, as follows:
TABLE-US-00001 Broad Exemplary SiO.sub.2/Al.sub.2O.sub.3 5 to 200 15 to 100 Q/SiO.sub.2 0.02 to 0.20 0.05 to 0.15 M/SiO.sub.2 0.01 to 0.20 0.05 to 0.20
wherein (1) Q is an N-benzyl-4-aza-1-azoniabicyclo[2.2.2]octane cation and (2) M is selected from the group consisting of elements from Groups 1 and 2 of the Periodic Table.
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