An ionic liquid-promoted palladium-based catalyst and its application in catalyzing the hydrohalogenation of unsaturated hydrocarbons

Abstract

The invention discloses a porous solid carrier-supported ionic liquid-promoted palladium catalyst. The catalyst is prepared according to the following method: mixing a prepared palladium-containing solution and an ionic liquid to obtain a mixed solution; dropwise adding the mixed solution to a porous solid carrier at a temperature of 20-60 DEG C under action of ultrasonic waves, and performing impregnation under the effect of ultrasonic waves for 0.5-6 hours by employing an equivalent-volume impregnation method; dropwise adding an inorganic salt solution to the porous solid carrier impregnatedwith the mixed solution under the action of ultrasonic waves at a temperature of 20-60 DEG C, and performing impregnation under the action of ultrasonic waves for 1 to 20 hours; and performing vacuumdrying at a temperature of 60-120 DEG C for 3 to 30 hours, so as to obtain the supported type ionic liquid-promoted palladium catalyst. The active components of the catalyst are not easily sublimated. The catalyst has good stability, long running time, high catalytic activity, simple preparation and convenient operation.

Description

Background technique [0001] Polyvinyl chloride (PVC) is an important general-purpose plastic. Due to the energy storage characteristics of rich coal, poor oil and little gas in my country, the preparation of vinyl chloride by calcium carbide acetylene method is the mainstream process of polyvinyl chloride production in my country. Mercury chloride is currently used as a catalyst for the synthesis of vinyl chloride in the industry. Because it causes serious pollution to the environment, and the synthesized polyvinyl chloride contains a small amount of mercury, the application of polyvinyl chloride is limited. Therefore, the mercury chloride catalyst will be gradually eliminated, and the synthesis of vinyl chloride under the condition of mercury-free catalyst will become the main direction for the future sustainable development of calcium carbide method PVC. Mercury-free catalysts mainly use metal chlorides as active components, among which noble metal chlorides exhibit the bes...

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Problems solved by technology

[0004] The literature (Catalysis Communications 83 (2016) 9-13) reported that adding KCl to the Pd / NFY catalyst can improve the stability of the catalyst, but at 160 °C, V(HCl) / V(C 2 h 2 )=1.25 After reacting for 10h, there is still 37.8% Pd species loss in the Pd-K / NFY catalyst

[0005] Chinese patent application (CN 101716508 A) discloses that palladium chloride is used as an active component, lanthanum chloride is used as an auxiliary agent, and the raw material gas ratio V(HCl) / V(C 2 h 2 )=1.05, the acetylene hydrochlorination reaction performance test was carried out at 150°C, and the reaction tail gas was analyzed. The acetylene conversion rate of the catalyst was 98.2%, and the vinyl chloride selectivity was 98%. Although the catalyst has high stability and activity, the precious metal High load mass fraction, which makes it expensive and impractical for industrial applications

[0014] Chinese patent application (CN 102357336 A) discloses that molecular sieves such as HZSM-5, NaZSM-5, and zeolite are used as carriers to support PdCl 2 Prepared catalyst, in raw gas ratio V(HCl) / V(C 2 h 2 ) = 1.15 under the condition of 160 ℃ for acetylene hydrochlorination reaction performance test, analysis of the reaction tail gas, the initial conversion rate of acetylene of the catalyst is 89.78%, the selectivity of vinyl chloride is 98.62%, the activity of the catalyst is relatively low, and does not meet the requirements of industrialization

[0018] Chinese patent application (CN 101716528 A) discloses an ionic liquid dissolving metal chlorides such as gold, platinum, palladium, tin, mercury, copper or rhodium as a catalyst system, which is applied to acetylene hydrochlorination, but the reaction system belongs to gas liquid reaction system, there are deficiencies such as low mass transfer efficiency of reactants and products, and easy loss of active components of the catalyst due to stirring or pneumatic stirring. bed or fluidized bed

[0019] Chinese patent application (CN 105001040 A) discloses the Pd catalyst prepared by the metal nanoparticle / ionic liquid system, at the feed gas ratio V(HCl) / V(C 2 h 2 )=1.2 under the condition of 140-220 ℃ for acetylene hydrochlorination reaction performance test, analysis of reaction tail gas, the acetylene conversion rate of the catalyst is 88%, the selectivity of vinyl chloride is 99.5%, no catalyst deactivation is seen after the reaction for 15 hours, the improved Catalysts still have a low conversion rate of acetylene

[0020] It has been reported in the literature (ACS Catal.2015, 5, 6724-6731) that dispersing Pd active components in ionic liquids can effectively catalyze the hydrochlorination of acetylene. 2 h 2 )=1.2 under the condition of 180 ℃ for acetylene hydrochlorination reaction performance test, analysis of reaction tail gas, the initial conversion rate of acetylene of the catalyst is 97.3%, vinyl chloride selectivity is 99.5%; but, in the open reaction system (gas- In liquid reaction), it is still found that 24.6% of active components are lost after reacting for 50 hours

[0021] Chinese patent CN104703953 A discloses a method for solid-loaded ionic liquid and metal and applied to acetylene hydrochlorination reaction. The selected solid carrier has a specific surface area greater than 0.1m 2 / g, pore volume greater than 0.02ml / g, the cation of the selected ionic liquid is imidazolium cation, pyridinium cation or pyrrolidinium cation, the anion can be any anion, and the selected metal is mainly represented by Pd Precious metals, etc., but the evaluation results show that the conversion rate of acetylene is only about 60% after 500 hours of reaction

However, it can be seen that neither the gas-liquid reaction of the ionic liquid as a solvent nor the introduction of the ionic liquid phase on the solid surface has completely suppressed the loss of the Pd active component, and the catalyst performance has not been fundamentally improved.