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Composite molecular sieve as well as preparation method and application thereof

A composite molecular sieve and molecular sieve technology, applied in molecular sieve catalysts, chemical instruments and methods, hydrocarbons, etc., can solve problems such as low atom utilization, poor cycle performance, and small effective active surface area

Pending Publication Date: 2022-04-19
UNIV OF SCI & TECH OF CHINA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] At present, metal catalysts generally used for dehydrogenation of low-carbon alkanes have low activity, and metal particles are easy to agglomerate at high temperatures, resulting in small effective active surface area, low atom utilization, and easy to generate carbon deposits, poor cycle performance

Method used

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  • Composite molecular sieve as well as preparation method and application thereof
  • Composite molecular sieve as well as preparation method and application thereof
  • Composite molecular sieve as well as preparation method and application thereof

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preparation example Construction

[0028] The application also provides a preparation method for a composite molecular sieve, comprising the following steps:

[0029] Mix the structure directing agent, silicon source and water, and heat to obtain the initial sol;

[0030] crystallizing the initial sol, transition metal salt and mineralizer to obtain a solid product;

[0031] The solid product is calcined to obtain a composite molecular sieve.

[0032] In the process of preparing the composite molecular sieve, the applicant first mixes the structure-directing agent, silicon source and water, and heats to obtain the initial sol; during this process, the above-mentioned raw materials synthesize the molecular sieve precursor. The structure directing agent is a nitrogen-containing organic compound containing a tertiary amine center or a quaternary ammonium center; in a specific embodiment, the structure directing agent is specifically selected from tetrapropylammonium hydroxide, tetrapropylammonium bromide or pyrid...

Embodiment 1

[0043] Weigh 3.22g tetrapropylammonium hydroxide, 4.91g tetraethyl orthosilicate and 4.55g H 2 After mixing O, stir at a constant temperature of 50°C for 14h at a speed of 350r / min to obtain a molecular sieve precursor; weigh 0.23g Fe(NO 3 ) 3 9H 2 O was added to the precursor, transferred to a hydrothermal kettle for crystallization at 160 °C for 28 h; the crystallized sample was washed until the pH was less than 8, and dried at 80 °C for 14 h; finally, the sample was calcined at 500 °C for 3 h to obtain Fe-MFI catalyst A.

[0044] figure 1 The EXAFS result (dotted line) of the composite molecular sieve prepared for the present embodiment and the theoretical calculation fitting result (solid line) contrast graph; figure 2 The spherical aberration electron microscope picture (wherein the red dot is skeleton Fe) of the composite molecular sieve prepared for the present embodiment; figure 1 and figure 2 It can be explained that the transition metal Fe in the composite mol...

Embodiment 2

[0046] Weigh 4.05g tetrapropylammonium bromide, 5.32g gaseous silicon dioxide and 5.89g H 2 After mixing O, stir at a constant temperature of 70°C for 12h at a speed of 450r / min to obtain a molecular sieve precursor; weigh 0.59g of CuSO 4 ·5H 2 O was added to the precursor, transferred to a hydrothermal kettle for crystallization at 170 °C for 25 h; the crystallized sample was washed to pH less than 8, and dried at 85 °C for 13 h; finally, the sample was calcined at 560 °C for 2.5 h to obtain Cu-*BEA catalyst B.

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Abstract

The invention provides a composite molecular sieve which is composed of transition metal and a molecular sieve, and the transition metal exists in a molecular sieve framework in a monodisperse tetrahedral coordination form. The composite molecular sieve provided by the invention is a transition metal composite molecular sieve containing a single-site framework confinement. The invention also provides a preparation method of the low-carbon olefin. According to the preparation method, low-carbon alkane is dehydrogenated on the catalyst to generate the low-carbon olefin and hydrogen. Experiments prove that the selectivity of the low-carbon olefin prepared by the method disclosed by the invention can reach 99.9%. The method is simple in process and simple and convenient in reaction equipment; the composite molecular sieve catalyst has the advantages of acid and alkali resistance, oxygen and sulfur resistance, water resistance, carbon deposition resistance, long service life, high reaction activity and product selectivity, and suitableness for industrial production.

Description

technical field [0001] The invention relates to the technical field of olefin preparation, in particular to a composite molecular sieve, its preparation method and its application. Background technique [0002] Light olefins are one of the most important raw materials for modern chemical industry. For example: ethylene is the basic chemical raw material for synthetic fibers, synthetic rubber, synthetic plastics (polyethylene and polyvinyl chloride), synthetic ethanol (alcohol), and is also used to manufacture vinyl chloride, styrene, ethylene oxide, acetic acid, and acetaldehyde It can also be used as a ripening agent for fruits and vegetables; propylene can be used to produce dozens of valuable fine chemical intermediates such as polypropylene, plastic or fiber, acrylonitrile, and propylene oxide; n-butene can mainly be used It is used in the manufacture of butadiene, followed by the manufacture of methyl ethyl ketone, sec-butanol, butylene oxide and butene polymers and co...

Claims

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Application Information

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IPC IPC(8): B01J29/46B01J29/76C07C11/06C07C11/08C07C11/09C07C11/04C07C11/02C07C5/333
CPCB01J29/46B01J29/76B01J29/7676B01J29/763C07C11/06C07C11/08C07C11/09C07C11/04C07C11/02C07C5/333B01J2229/183Y02P20/52
Inventor 傅尧张翔许光月
Owner UNIV OF SCI & TECH OF CHINA
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