Mtw framework-type molecular sieves, and methods of making and using the same
AssigneeBraskem America, Inc.
InventorsDan Xie, Ishant Khurana, Graham Gregorich, Richard Opfer
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Abstract
The disclosure provides an MTW framework-type molecular sieve with crystallites having an average size of 70 nm or below. The sieve includes a structure-directing composition comprising 2-pyrrolidone or its N-alkyl derivative and a quaternary ammonium cation. A method for preparing the sieve and its use in producing olefins from alkanes are also described.
Claims24
An MTW framework-type molecular sieve, comprising:
- a plurality of crystallites of a Mobil TWelve (MTW) framework-type zeolite, wherein the crystallites have an average crystal size of 70 nm or below, as measured by X-ray powder diffraction;
- and
- a structure-directing composition (SDC) present within the zeolite's pore structures, wherein the structure-directing composition comprises (1) 2-pyrrolidone or its N-alkyl derivative, and (2) a quaternary ammonium cation represented by N+R1R2R3R4, wherein R1, R2, R3, and R4 are each independently an alkyl.
An MTW framework-type molecular sieve, comprising:
- a plurality of crystallites of a Mobil TWelve (MTW) framework-type zeolite, wherein the crystallites exhibit an X-ray powder diffraction having at least three peaks at the following 2θ diffraction angles:
- 7.4, 7.6, 8.8, 15.3, 18.8, and 20.0° 2θ+0.2°2θ;
- and
- a structure-directing composition (SDC) present within the zeolite's pore structures, wherein the structure-directing composition comprises (1) 2-pyrrolidone or its N-alkyl derivative, and (2) a quaternary ammonium cation represented by N+R1R2R3R4, wherein R1, R2, R3, and R4 are each independently an alkyl.
A method for preparing a molecular sieve having a MTW framework type, comprising:
- providing a mixture comprising:
- i. a source of silicon oxide (SiO2),
- ii. a source of aluminum (Al2O3),
- iii. a source of hydroxide ions (OH−)
- iv. a source of alkali or alkaline earth metal ions (M),
- v. a structure-directing composition (SDC) comprising (1) 2-pyrrolidone or its N-alkyl derivative, and (2) a quaternary ammonium cation represented by N+R1R2R3R4, wherein R1, R2, R3, and R4 are each independently an alkyl, and
- vi. water;
- and
- subjecting the mixture to crystallization conditions sufficient to form a plurality of crystallites of an MTW framework-type zeolite, having the structure-directing composition within the zeolite's pore structures.
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Dependencies are inferred from the claim text.