Method for preparing pure alpha-phase molybdenum carbide catalyst through one-step carbonization, catalyst and application

Abstract

The invention discloses a method for preparing a pure alpha-phase molybdenum carbide catalyst through one-step carbonization induced by precious metal rhodium and application. The preparation method comprises the following steps: (1) preparing molybdenum trioxide powder by adopting a flame jetting method; (2) dipping molybdenum trioxide powder into a rhodium salt solution, and drying to obtain molybdenum trioxide loaded with noble metal; and (3) carbonizing the sample obtained in the step (2) in the presence of carbon source gas. According to the method, the molybdenum trioxide nanoparticles are prepared by utilizing a flame jetting method, the carbonization process of the molybdenum trioxide can be obviously changed by using trace precious metal rhodium, the alpha-phase molybdenum carbide with relatively high purity is obtained through one-step carbonization, and a high-pollution ammonification process is omitted. The invention also discloses a rhodium-loaded alpha-phase molybdenum carbide catalyst and an application thereof in a water-gas shift reaction, and a result shows that the molybdenum carbide catalyst prepared by the method has higher activity and stability.

Description

technical field [0001] The present invention relates to molybdenum oxide loaded with precious metal rhodium and transformed into a rhodium-supported molybdenum carbide catalyst through one-step embodiment 1, as well as a preparation method and application thereof, in particular to a preparation method for obtaining pure α-phase molybdenum carbide catalyst by one-step carbonization and the same Applications in the water vapor shift reaction. Background technique [0002] The water vapor shift reaction (WGS) is a commonly used reaction for industrial hydrogen production, and is mainly used in the hydrogen production and ammonia synthesis industry using coal, oil and natural gas as raw materials. Among the existing catalysts in the past, copper-based and iron-based catalysts are mainly used in industry, and the activity is poor. In recent years, transition metal carbides have gradually become an emerging catalytic material system, among which molybdenum carbide has attracted m...

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Problems solved by technology

[0003] However, the preparation and application of α-phase molybdenum carbide catalysts are relatively difficult: (1) Because α-phase molybdenum carbide has a face-centered cubic structure (FCC), its preparation method is mostly a two-step carbonization process of high-temperature ammoniation-cooling-high-temperature carbonization. However, the method has complicated steps and high cost, and high-purity ammonia gas needs to be used at high temperature during the preparation process, which is very easy to cause environmental pollution, has potential safety hazards, and requires high corrosion resistance of the equipment; (2) α-phase molybdenum carbide although for dissociated H 2 O has an advantage, but it is also easily absorbed by H during the reaction 2 O is oxidized to molybdenum oxide, and then loses its activity. Poor stability is one of the bottlenecks in the practical application of α-phase molybdenum carbide catalysts.

[0004] The patent application published by Ishikawa et al. "A pure α-phase molybdenum carbide supported noble metal catalyst and its preparation method and application" (patent publication number: CN104923274A) adopts a one-step carbonization method to synthesize pure α-phase molybdenum carbide supported by precious metal gold, platinum or palladium Catalyst, from the given XRD spectrum, it can be seen that the crystal form of the obtained molybdenum carbide is molybdenum carbide of pure α phase, but this method needs to carry out non-equilibrium plasma treatment instead of roasting process before carbonization, although this method can not Pure α-phase molybdenum carbide is obtained through the ammoniation process, but the catalyst preparation cycle is long and the preparation process is relatively complicated

[0005] The patent application published by Martin et al. "Pt / α-MoC 1-x Supported catalyst and its synthesis and application" (patent publication number: CN104707636A) adopts a one-step carbonization method to synthesize a noble metal platinum-supported α-phase molybdenum carbide catalyst, and applies the catalyst to the aqueous phase methanol reforming reaction. From the given data and It can be seen from the XRD spectrum that the crystal form of the obtained molybdenum carbide is pure α-phase molybdenum carbide, but in the preparation process of the catalyst, high-temperature roasting treatment is required, and the content of noble metal Pt is high, which increases the cost.

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