A kind of ruthenium dioxide catalyst of methane oxychlorination and preparation method thereof

Abstract

The invention discloses a ruthenium dioxide catalyst applied to oxychlorination of methane. The ruthenium dioxide catalyst comprises a carrier, an active component loaded on the carrier, co-catalysiscomponents and a carrier modification additive, wherein the carrier comprises titanium dioxide; the active component is ruthenium dioxide; the co-catalysis components comprise alkali metal componentsand rare-earth metal components; the carrier modification additive is silicon dioxide. The invention also discloses a preparation method of the ruthenium dioxide catalyst. According to the catalyst, through the co-catalysis components including alkali metal components and rare-earth metal components, the dispersibility of ruthenium dioxide as the active component is improved; the active site structure of ruthenium dioxide is changed; the catalyst has two high-activity sites for activating C-H bonds and activating O2; the activation of methane is facilitated; the excessive oxidization of the product is avoided; the catalyst also has high methane conversion rate and monochloro methane selectivity; the catalyst obtained by the preparation method can be directly used for catalyzing oxychlorination reaction of methane without pretreatment.

Description

technical field [0001] The invention belongs to the technical field of catalysts, and in particular relates to a ruthenium dioxide catalyst for methane oxychlorination and a preparation method thereof. Background technique [0002] Methane is the main component of natural gas. In recent years, with the increasing depletion of petroleum resources and the increase of proven reserves and production of natural gas, the use of natural gas instead of petroleum as a raw material for the petrochemical industry to reduce the dependence of basic chemicals on petroleum resources has gradually attracted people's attention. However, the highly symmetrical tetrahedral structure and high bond energy of methane greatly increase the difficulty of selectively activating its C-H bonds. At present, methane is converted into synthesis gas through high-temperature steam reforming firstly in industry, and then the synthesis gas is further converted into methanol and other chemical products. Howe...

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Problems solved by technology

[0004] Chinese patent CN104549307A discloses a preparation method of a copper-based methane oxychlorination catalyst. In this method, the active component and the carrier are directly mixed and roasted to obtain the catalyst. The catalyst is kept at 450°C and the space velocity is 5000mL·h -1 g -1 and gas composition V(CH 4 ):V(HCl):V(O 2 )=5:4:2 under the condition that methane is carried out oxychlorination, methane conversion rate is 28.6%, and the selectivity of monochloromethane is 37.6%; But the reaction temperature of copper-based catalyst is high, and selectivity is poor, and easily occurs Bulk phase chlorination leads to poor thermal stability and easy deactivation; in addition, the CuCl in the copper-based catalyst 2 The melting points of CuCl and CuCl are only 498°C and 430°C, and they are easily volatile and lost at the reaction temperature of 450°C

Compared with other catalysts, RuO 2 When used in methane oxychlorination, the reaction temperature is low, and its melting point is as high as 1200°C, so the catalyst is not easy to sinter, but its monochloromethane selectivity is much lower than other types of catalysts

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