Silicoaluminophosphate molecular sieve

Chemistry of hydrocarbon compounds – Unsaturated compound synthesis – From nonhydrocarbon feed

Reexamination Certificate

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

C423S327100, C423S328200, C423S329100, C502S214000, C585S639000

Reexamination Certificate

active

06812372

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to new silicoaluminophosphate molecular sieves, to methods of making them and to their use in a method of making an olefin product by contacting these silicoaluminophosphate molecular sieves with an oxygenate feedstock. In particular, this invention relates to silicoaluminophosphate molecular sieves comprising at least one intergrown phase of AEI and CHA molecular sieves.
BACKGROUND OF THE INVENTION
Silicoaluminophosphate (SAPO) molecular sieves contain a three-dimensional microporous crystal framework structure of [SiO
2
], [AlO
2
] and [PO
2
] corner sharing tetrahedral units. The [PO
2
] tetrahedral units are provided by a variety of compositions including phosphoric acid, organic phosphates such as triethyl phosphate, and aluminophosphates. The [AlO
2
] tetrahedral units are provided by a variety of compositions including aluminum alkoxides such as aluminum isopropoxide, aluminum phosphates, aluminum hydroxide, sodium aluminate, and pseudoboehmite. The [SiO
2
] tetrahedral units are provided by a variety of compositions including silica sols and silicon alkoxides such as tetraethylorthosilicate and fumed silica.
Aluminophosphate (ALPO) molecular sieves are crystalline microporous oxides which can have an AlPO
4
framework. ALPOs can have additional elements within the framework, typically have uniform pore dimensions ranging from about 3 Angstroms to about 10 Angstroms.
Light olefins, particularly ethylene and propylene, can be produced by contacting a feedstock containing oxygenated organic compounds, such as methanol or dimethyl ether, with a SAPO and/or ALPO-containing catalyst. See for example U.S. Pat. No. 4,499,327.
SAPO-34 and SAPO-18 have been reported as suitable catalysts for light olefin production from methanol. SAPO-34 belongs to the family of molecular sieves having the structure type of the zeolitic mineral chabazite (CHA). The preparation and characterization of SAPO-34 has been reported in several publications, including U.S. Pat. No. 4,440,871; J. Chen et al. in “Studies in Surface Science and Catalysis”, Vol. 84, pp. 1731-1738; U.S. Pat. No. 5,279,810; J. Chen et al. in “Journal of Physical Chemistry”, Vol. 98, pp. 10216-10224 (1994); J. Chen et al. in “Catalysis Letters”, Vol. 28, pp. 241-248 (1994); A. M. Prakash et al. in “Journal of the Chemical Society, Faraday Transactions” Vol. 90(15), pp. 2291-2296 (1994); Yan Xu et al. in “Journal of the Chemical Society, Faraday Transactions” Vol. 86(2), pp. 425-429 (1990), all of which are herein fully incorporated by reference.
SAPO-18 belongs to the family of molecular sieves having the AEI structure type. Other molecular sieves with the AEI structure type are ALPO-18 and RUW-18. The preparation and characterization of molecular sieves with AEI structure type has been reported in several publications, including U.S. Pat. No. 4,440,871; J. Chen et al. in “Studies in Surface Science and Catalysis”, Vol. 84, pp. 1731-1738; U.S. Pat. No. 5,279,810; J. Chen et al. in “Journal of Physical Chemistry”, Vol. 98, pp. 10216-10224 (1994); J. Chen et al. in “Catalysis Letters”, Vol. 28, pp. 241-248 (1994); pp. 2291-2296 (1994); Yan Xu et al. in “Journal of the Chemical Society, Faraday Transactions” Vol. 86(2), pp. 425-429 (1990); U.S. Pat. No. 5,609,843, all of which are herein fully incorporated by reference.
International Application PCT/NO97/00272, published as WO 98/15496, relates to a molecular sieve that is a mixed phase comprising silicoaluminophosphates of AEI and CHA structure, referred to as RUW-19. RUW-19 is said to produce an X-ray diffractogram that includes peaks at the following 2&thgr; values: 9.3-9.5, 10.4-10.6, 12.7-12.9, 13.8-14.0, 15.9-16.1, 16.7-16.9, 18.9-19.0, 20.5-10.7, 21.0-21.3, 23.7-24.0, 25.7-26.0, 30.9-31.1.
FIG. 1
of this publication shows the XRD-traces in the 15-33 (2&thgr;) region for RUW-19 (examples 1 to 3), SAPO-18 (example 4), SAPO-34 (example 5) and a physical mixture of SAPO-18 and SAPO-34 (example 6). This publication suggests that RUW-19 is different from a physical mixture of SAPO-18 and SAPO-34. RUW-19 has peaks characteristic of an AEI structure type molecular sieve, except that the broad feature centered at about 16.9 (2&thgr;) in RUW-19 replaces the pair of reflections centered at about 17.0 (2&thgr;) in SAPO-18 or AEI. Also, RUW-19 does not have the reflections associated with SAPO-34 or CHA centered at 17.8 (2&thgr;) and 24.8 (2&thgr;). According to WO 98/15496, RUW-19 is suitable for the conversion of methanol to olefins.
In the conversion of methanol to olefins, SAPO-34 exhibits relatively high product selectivity to ethylene and propylene, and low product selectivity to paraffin and olefin with four or more carbons (C
4
+
olefin). Catalysts containing SAPO-34 are thus particularly suited for the conversion of methanol to olefin. Despite its good performances, carbonaceous deposits, commonly referred to as coke, quickly form in the catalytic cages of SAPO-34. Eventually, the presence of too much coke will clog up the cage and deactivate the catalyst. Also, despite its low product selectivity to paraffin, SAPO-34 still produces by-products. Separating by-products from the desired ethylene and propylene adds additional cost to the methanol to olefin conversion process. Therefore, there is a need to find new molecular sieves that have good product selectivity and produce few by-products.
SUMMARY OF THE INVENTION
The present invention relates to silicoaluminophosphate molecular sieves comprising at least one intergrown phase of molecular sieves having AEI and CHA framework types, wherein said intergrown phase has an AEI/CHA ratio of from about 5/95 to 40/60 as determined by DIFFaX analysis, using the powder X-ray diffraction pattern of a calcined sample of said silicoaluminophosphate molecular sieve.
The silicoaluminophosphate molecular sieves of the present invention exhibit characteristic X-ray diffraction features. In an embodiment of the invention, the molecular sieves of the invention possess silica to alumina ratios ranging from 0.01 to 0.25.
The silicoaluminophosphate molecular sieves of the present invention are prepared by submitting a mixture comprising a reactive source of silicon, a reactive source of aluminum and a reactive source of phosphorus, in the presence of an organic structure directing agent (template) to hydrothermal treatment under autogenous pressure. In an embodiment of the invention, the organic structure directing agent is a tetraethylammonium compound.
The silicoaluminophosphate molecular sieves of the present invention exhibit good catalytic performances in processes for making olefin products from an oxygenate feedstock, such as a feedstock comprising methanol.


REFERENCES:
patent: 3258455 (1966-06-01), Natta et al.
patent: 3305538 (1967-02-01), Natta et al.
patent: 3364190 (1968-01-01), Emrick
patent: 3635803 (1972-01-01), Binns et al.
patent: 3645992 (1972-02-01), Elston
patent: 4068136 (1978-01-01), Minami
patent: 4076698 (1978-02-01), Anderson et al.
patent: 4243691 (1981-01-01), Mohlenkamp, Jr et al.
patent: 4302565 (1981-11-01), Goeke et al.
patent: 4440871 (1984-04-01), Lok et al.
patent: 4499327 (1985-02-01), Kaiser
patent: 4659685 (1987-04-01), Coleman, III et al.
patent: 5279810 (1994-01-01), Calabro
patent: 5324493 (1994-06-01), Mueller et al.
patent: 5324800 (1994-06-01), Welborn, Jr. et al.
patent: 5609843 (1997-03-01), Wendelbo
patent: 5649843 (1997-07-01), Elger
patent: 5892079 (1999-04-01), Wilson, Jr.
patent: 6294493 (2001-09-01), Strohmaier et al.
patent: 6514899 (2003-02-01), Mertens et al.
patent: WO 98/15496 (1998-04-01), None
“Free Fall Reactor”,Fluidization Engineering, D. Kunii and O. Levenspiel, Robert E. Krieger Publishing Co. NY, 1977, no month.
“Riser Reactor”,Fluidization and Fluid-Particle Systems, pp. 48-59, F. A. Zenz and D. F. Othmo, Reinhold Publishing Corp., NY 1960, no month.
J. Chen et al. “Studies in Surface Science and Catalysis”, vol. 84, pp. 1731-1738, no month.
Xu, Yan, et al, “The Synthes

LandOfFree

Say what you really think

Search LandOfFree.com for the USA inventors and patents. Rate them and share your experience with other people.

Rating

Silicoaluminophosphate molecular sieve does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Silicoaluminophosphate molecular sieve, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Silicoaluminophosphate molecular sieve will most certainly appreciate the feedback.

Rate now

     

Profile ID: LFUS-PAI-O-3277645

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.