A kind of highly active propylene gas phase epoxidation catalyst and preparation method thereof

Abstract

The invention discloses a high-activity propylene gas-phase epoxidation catalyst, TiO2-MoO3-Bi2SiO5 / SiO2, for preparing propylene oxide and a preparation method thereof. The catalyst is used for a propylene gas-phase epoxidation reaction for preparing the propylene oxide, which takes molecular oxygen (O2) or nitric oxide (NO) as an oxidant; reaction conditions are moderate and no inhibitor is needed; the catalyst has high catalytic activity. The catalyst takes a SiO2 mesoporous material Bi2SiO5 / SiO2 containing bismuth silicate (Bi2SiO5) as a carrier, MoO3 as an active component and TiO2 as an auxiliary agent. The catalyst comprises following components in percentage by mass: 64.6%-98.8% of the carrier Bi2SiO5 / SiO2, 1.1%-22.8% of the MoO3 and 0.1%-12.6% of the TiO2. The mol ratio of Si to Bi in the carrier Bi2SiO5 / SiO2 is 30-200. The catalyst is synthesized by using a hydrothermal method; molybdenum and titanium precursors in the active component MoO3 and the auxiliary agent titanic oxide are immersed into the carrier by an ultrasonic-assisted immersion method to prepare the catalyst.

Description

technical field [0001] The invention belongs to the field of petrochemical catalyst preparation methods, and more specifically relates to a catalyst for preparing propylene oxide and a preparation method thereof, especially a catalyst for preparing propylene oxide by gas-phase epoxidation of propylene and a preparation method thereof. Background technique [0002] Propylene oxide, referred to as PO, is an important chemical raw material, a very important organic compound raw material, and the third largest propylene derivative after polypropylene and acrylonitrile. At present, the main methods of producing PO in industry are chlorohydrin method and co-oxidation method. Among them, the chlorohydrin method is still the main production method of PO, which has the advantages of short process, low investment, good selectivity, and high efficiency. However, the hypochlorous acid produced in the production process of this process severely corrodes equipment, and produces a large am...

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Problems solved by technology

With TS-1 molecular sieve as catalyst, the reaction conditions are mild and the PO yield is high, but due to TS-1 and H 2 o 2 The cost is higher, and H 2 o 2 There are potential safety hazards in storage and transportation, even if a factory is built nearby, there will be H 2 o 2 The problem of high production energy consumption and high cost limits its industrialization process to a certain extent

M. Haruta et al. (Journal of Catalysis, 1998, 178(2): 566-575) synthesized Au / TiO by deposition-precipitation method for the first time 2 Catalyst, in H 2 with O 2 Under coexistence conditions, a PO selectivity as high as 93% was obtained, but the conversion of propylene was less than 2.5%

The Si / Bi for dear catalytic materials is low, the Bi content is high, carcinogenic organic amines are used in the synthesis method, the cost is high, and the pollution is large

Y. J. Pang et al. (ChemCatChem, 2014, 6(3):876-884) MoO synthesized by simple impregnation method 3 -Bi 2 SiO 5 / SiO 2 Has good propylene gas phase epoxidation activity, but the catalyst Mo content is relatively high, with MoO 3 Calculated as 18.1wt%, and PO selectivity needs to be further improved

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