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A kind of iron-based catalyst and its preparation method and application

An iron-based catalyst, technology for catalyzing saturated alkane liquid, applied in oxidation reaction preparation, molecular sieve catalyst, chemical instruments and methods, etc., can solve the problems of poor catalyst stability, low product selectivity, low selectivity, etc., and achieve high practical value , high selectivity, easy separation effect

Active Publication Date: 2022-05-10
SHANXI INST OF COAL CHEM CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In the early days, researchers used iron powder, iron alloy, iron oxide, supported iron oxide or iron / metal oxide as catalysts to realize alkane oxidation (SchuchardtU., et al.Appl.Catal.A:Gen.2001; 221(1 ): 1-17), but the above-mentioned method exists problems such as low alkane conversion rate, target product (alcohol, aldehyde, ketone or acid etc.) selectivity is not high and catalyst stability is poor
Since then, researchers have used impregnation methods, ion exchange methods, and isomorphic substitution methods to introduce active center iron into the pores of molecular sieves (ZSM-5, SBA-15, MCM-41, and TS-1, etc.) (Dapurkar S.E., et al. al.J.Mol.Catal.A:Chem.2004; 223(1-2):241-250; SinghaS., et al.J.Porous Mater.2010; 18(6):707-714), however these Traditional methods are still difficult to precisely control the size and chemical state of Fe in the pores of molecular sieves, resulting in low product selectivity and difficult control of catalyst activity and stability

Method used

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  • A kind of iron-based catalyst and its preparation method and application
  • A kind of iron-based catalyst and its preparation method and application
  • A kind of iron-based catalyst and its preparation method and application

Examples

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preparation example Construction

[0032] The invention provides a method for preparing an iron-based catalyst, comprising the following steps:

[0033] Based on the atomic layer deposition method, by sequentially pulsing gaseous iron-based precursors and gaseous oxidants, deposition is performed on the surface of the carrier material, and iron active centers are formed on the surface of the carrier material to obtain iron-based catalysts;

[0034] Wherein, the carrier material is a microporous material or a mesoporous material, and the carrier material contains silicon element and / or aluminum element;

[0035] The iron active center is iron oxide, and the iron in the iron active center is ferric iron, or ferric iron and ferrous iron coexist.

[0036] In the present invention, unless otherwise specified, the preparation raw materials used are commercially available products well known to those skilled in the art.

[0037] The invention is based on the atomic layer deposition method, by sequentially pulsing gas...

Embodiment 1

[0070] (1) Weigh 500mg ZSM-5 molecular sieve (the mass percentages of Al element and Si element are 2.33% and 41.6% respectively), and place it in the atomic layer deposition vacuum reaction chamber, the chamber pressure is 70Pa, the deposition process The medium carrier gas flow rate is fixed;

[0071] (2) Deposit FeO on the surface of ZSM-5 molecular sieve by atomic layer deposition technology x species, the set deposition parameters are: reaction temperature is 270°C, reaction source is ferrocene and ozone, ferrocene heating temperature is 100°C, ozone temperature is 25°C, nitrogen flow rate is 70sccm; Iron vapor pulses into the atomic layer deposition vacuum reaction chamber, the pulse time is 10s, the hold time is 30s, and the purge time is 300s; then the ozone pulse is entered into the atomic layer deposition vacuum reaction chamber, the pulse time is 1s, the hold time is 10s, blowing The sweeping time is 150s, and one deposition process has been completed so far; the d...

Embodiment 2～6

[0073] The preparation method of the iron-based catalyst in Examples 2-6 is basically the same as that in Example 1, except that the number of deposition treatments in Examples 2-6 is 20 times, 30 times, 40 times, 50 times and 60 times respectively , and the mass percentages of Fe element in the finally obtained iron-based catalyst were 0.12%, 0.18%, 0.27%, 0.29% and 0.31%, respectively. The active center of iron in the iron-based catalysts of Examples 2-6 is mainly trivalent iron.

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Abstract

The invention provides an iron-based catalyst and its preparation method and application, belonging to the technical field of catalytic materials. The present invention adopts the atomic layer deposition method to prepare iron-based catalysts. During the atomic layer deposition process, the functional groups on the surface of the iron-based precursor and the carrier material will form stable chemical bonds, such as Fe-O-Al and / or Fe-O-Si bonds, which can be obtained Stable, sub-nanometer (<1nm) highly dispersed iron active centers; at the same time, based on the self-limiting growth characteristics of atomic layer deposition, the iron active centers are highly dispersed on the carrier material, and it is easy to achieve the content and size of the iron active centers by adjusting the operating parameters And the precise regulation of the iron valence state, so that the final iron-based catalyst has better catalytic activity and stability. Furthermore, the present invention uses atomic layer deposition as a deposition aid to modify the iron active center, which is beneficial to further improving the performance of the iron-based catalyst.

Description

technical field [0001] The invention relates to the technical field of catalytic materials, in particular to an iron-based catalyst and its preparation method and application. Background technique [0002] Alkanes are the main components of natural gas and petroleum, and can also be produced by converting coal. They are not only the main raw materials for the chemical industry, but also important energy molecules. Direct catalytic oxidation of alkanes to corresponding chemical organic products such as alcohols, aldehydes, ketones and acids has high atom economy and is an important way to alleviate energy shortages, realize clean, efficient and high-value utilization of fossil energy, and solve environmental pollution problems. However, the C-H bond energy of alkane is large, and it usually needs to be activated under severe conditions of high temperature and high pressure, so that the product is prone to over-oxidation, and the product selectivity is difficult to control (Ch...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B01J29/46B01J29/03C07C31/04C07C29/50C07C45/28C07C49/303
CPCB01J29/46B01J29/0333C07C29/48C07C45/28B01J35/394C07C31/04C07C49/303Y02P20/52
Inventor 张斌翟黎明赵世超覃勇
Owner SHANXI INST OF COAL CHEM CHINESE ACAD OF SCI