Alkaline earth metal-doped phosphate catalysts, methods of making and use in allyl alcohol synthesis

Abstract

An alkaline earth metal doped phosphate catalyst, a preparation method and application in allyl alcohol synthesis are disclosed. The catalyst is composed of a carrier of silicon dioxide and a main catalyst of alkaline earth metal doped phosphate, wherein the mass ratio of the main catalyst to the carrier is 10:1-1:10, and the doping amount of the alkaline earth metal is 0.1wt.%-20wt.%. The preparation method comprises the following steps: firstly, preparing the alkaline earth metal doped phosphate by using a coprecipitation method, and then loading the alkaline earth metal doped phosphate on the silicon dioxide to obtain the supported catalyst. The catalyst prepared by the method has excellent catalytic stability and carbon deposition resistance in the preparation of allyl alcohol by isomerization of propylene oxide, the conversion rate is greater than 95%, the selectivity is greater than 95%, and the catalyst can be used stably for 400-500 hours.

Description

Technical Field

[0001] This invention belongs to the field of catalytic materials and applications, and relates to a supported catalyst, its preparation method and application. Background Technology

[0002] Allyl alcohol, as an important chemical raw material, is currently produced industrially primarily through four methods: allyl chloride hydrolysis, propylene oxide isomerization, acrolein reduction, and propylene acetate hydrolysis. Among these, propylene oxide isomerization is widely used in industry due to its simplicity, high selectivity, and non-corrosiveness to experimental equipment. However, this method suffers from two significant problems. First, the conversion rate is relatively low. Second, during the isomerization reaction, the catalyst activity easily decreases over time due to factors such as carbon poisoning and varying physicochemical conditions, leading to catalyst deactivation. Patent US 7847135 B1 proposes using a boron- and sodium-containing lithium phosphate catalyst for propylene oxide isomerization, achieving a conversion rate of only 37% or even lower. Patents US 5262371 and US 5262371, using α-alumina-supported aluminum phosphate and high-purity silica-supported lithium phosphate as catalysts respectively, achieve conversion rates of 80% in allyl alcohol production, but catalyst stability is difficult to maintain. Therefore, there is an urgent need to develop a catalyst that is both highly active and highly stable against carbon deposition. Summary of the Invention

[0003] The purpose of this invention is to provide an alkaline earth metal-doped phosphate catalyst, its preparation method, and its application in the synthesis of allyl alcohol. It also provides a supported catalyst for the isomerization of propylene oxide and its preparation method. The catalyst prepared by this method is used in the isomerization of propylene oxide to prepare allyl alcohol, and the catalyst exhibits both high activity and high stability.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solutions.

[0005] The alkaline earth metal-doped phosphate catalyst of the present invention is composed of silica as support and alkaline earth metal-doped phosphate as main catalyst, wherein the mass ratio of main catalyst to support is 10:1 to 1:10, and the doping amount of alkaline earth metal is 0.1 wt.% to 20 wt.%.

[0006] The alkaline earth metal is one or more of magnesium, calcium, strontium, and barium.

[0007] The phosphates mentioned include, but are not limited to, sodium phosphate, lithium phosphate, iron phosphate, cobalt phosphate, nickel phosphate, copper phosphate, or zinc phosphate.

[0008] The present invention discloses a method for preparing an alkaline earth metal-doped phosphate catalyst, comprising the following steps.

[0009] (1) Preparation of alkaline earth metal-doped phosphate by co-precipitation method: A solution containing alkaline earth metal ions is mixed with a metal hydroxide solution, and then the mixed solution is added to a diammonium hydrogen phosphate solution to produce a precipitate. The precipitate is filtered, washed and calcined to obtain alkaline earth metal-doped phosphate.

[0010] (2) The silica and alkaline earth metal doped phosphate are physically mixed and then calcined to obtain an alkaline earth metal doped phosphate / silica catalyst.

[0011] The doping amount of alkaline earth metal in step (1) is 0.1%~20%, the temperature required to produce precipitation is 80 ℃, the reaction time is 90 min, and the precipitation calcination temperature is 280 ℃.

[0012] In step (2), the types of silicon dioxide include, but are not limited to, crystalline silicon dioxide, amorphous silicon dioxide, irregularly shaped silicon dioxide, fumed silicon dioxide, and mesoporous silicon dioxide.

[0013] Furthermore, the preferred mass ratio of the main catalyst to the support is 5:1 to 1:5, and the preferred doping amount of alkaline earth metal is 5%. wt. %~15 wt. %.

[0014] The application of the alkaline earth metal-doped phosphate catalyst of the present invention is to use the alkaline earth metal-doped phosphate catalyst for the isomerization of propylene oxide to prepare allyl alcohol.

[0015] The propylene oxide isomerization reaction is carried out in a fixed-bed reactor. The catalyst is placed in the middle of the reactor, and propylene oxide is bubbled into the reactor by an inert gas. Finally, the product is collected by condensation in a cold trap, and the collected product is analyzed by gas chromatography.

[0016] The mass ratio of catalyst to reaction substrate is 5-20; the reaction temperature is 260-380℃; and the injection rate of propylene oxide in the reaction is 0.1-5 ml / min.

[0017] The beneficial effects of the present invention.

[0018] (1) This invention regulates the phosphate synthesis process environment by doping phosphate with an appropriate amount of alkaline earth metal, thereby adjusting the pH value or ion concentration of the reaction system and influencing the catalyst formation process. A suitable pH value or ion concentration helps the catalyst precursor to disperse more uniformly in the solution, causing the synthesized phosphate to change from a complete spherical shape to a fine particle composition, thus promoting the dispersion of phosphate on the support surface. Furthermore, doping with alkaline earth metal can increase the alkaline sites on the catalyst surface, achieving control over the acidity and alkalinity of the catalyst surface and effectively inhibiting the formation of carbon deposits, thereby endowing the catalyst with superior catalytic performance and anti-carbon deposition ability.

[0019] (2) The alkaline earth metal doped phosphate / silica catalyst prepared by the present invention has both high activity and high stability in the reaction of propylene oxide isomerization to prepare allyl alcohol, with a conversion rate of >95%, selectivity of >95%, and can be used stably for 400h~500h. Attached Figure Description

[0020] Figure 1 This is a comparison of the conversion rates of propylene oxide isomerization between the comparative catalyst of this invention and the catalyst of the embodiments of this invention.

[0021] Figure 2 This is a comparison of the selectivity of the comparative catalyst of the present invention and the catalyst of the embodiments of the present invention for the isomerization of propylene oxide to prepare allyl alcohol.

[0022] Figure 3 This is a SEM image of phosphate without alkaline earth metal doping.

[0023] Figure 4 This is a SEM image of phosphates doped with alkaline earth metals.

[0024] Figure 5 The CO2-TPD diagrams of phosphates before and after doping with alkaline earth metals are shown. Detailed Implementation

[0025] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention. Example 1

[0026] A method for preparing an alkaline earth metal-doped phosphate catalyst includes the following steps.

[0027] (1) Preparation of sodium phosphate doped with alkaline earth metals: 10 g of sodium hydroxide and 2.4 g of magnesium hydroxide were dissolved in 60 ml of deionized water. The resulting mixed solution was added to 60 ml of solution containing 8.8 g of diammonium hydrogen phosphate. The mixture was stirred at 80 °C for 90 min to generate a white precipitate. The precipitate was then filtered, dried in a vacuum drying oven at 100 °C for 10 h, and then calcined in a high-temperature furnace at 280 °C for 4 h to obtain magnesium-doped sodium phosphate.

[0028] (2) Preparation of sodium phosphate supported on silica and doped with alkaline earth metal: 5 g of magnesium-doped sodium phosphate and 10 g of silica were added to a 250 ml three-necked flask, 150 ml of deionized water was added, and the mixture was stirred at 110 °C for 120 min. The product was filtered, dried in a vacuum drying oven at 100 °C for 6 h, and then calcined in a high-temperature furnace at 300 °C for 6 h to obtain magnesium-doped sodium phosphate / silica catalyst. Example 2

[0029] A method for preparing an alkaline earth metal-doped phosphate catalyst includes the following steps.

[0030] (1) Preparation of sodium phosphate doped with alkaline earth metals: 10 g of sodium hydroxide and 5.1 g of strontium hydroxide were dissolved in 60 ml of deionized water. The resulting mixed solution was added to 60 ml of a solution containing 8.8 g of diammonium hydrogen phosphate. The mixture was stirred at 80 °C for 90 min to generate a white precipitate. The precipitate was then filtered, dried in a vacuum drying oven at 100 °C for 10 h, and then calcined in a high-temperature furnace at 280 °C for 4 h to obtain strontium-doped sodium phosphate.

[0031] (2) Preparation of sodium phosphate with alkaline earth metal supported on silica: 5 g of strontium-doped sodium phosphate and 10 g of silica were added to a 250 ml three-necked flask, 150 ml of deionized water was added, and the mixture was stirred at 110 °C for 120 min. The product was filtered, dried in a vacuum drying oven at 100 °C for 6 h, and then calcined in a high-temperature furnace at 300 °C for 6 h to obtain strontium-doped sodium phosphate / silica catalyst. Example 3

[0032] A method for preparing an alkaline earth metal-doped phosphate catalyst includes the following steps.

[0033] (1) Preparation of sodium phosphate doped with alkaline earth metals: 10 g of sodium hydroxide and 3.1 g of calcium hydroxide were dissolved in 60 ml of deionized water. The resulting mixed solution was added to 60 ml of solution containing 8.8 g of diammonium hydrogen phosphate. The mixture was stirred at 80 °C for 90 min to generate a white precipitate. The precipitate was then filtered, dried in a vacuum drying oven at 100 °C for 10 h, and then calcined in a high-temperature furnace at 280 °C for 4 h to obtain calcium-doped sodium phosphate.

[0034] (2) Preparation of sodium phosphate supported on silica and doped with alkaline earth metal: 5 g of calcium-doped sodium phosphate and 10 g of silica were added to a 250 ml three-necked flask, 150 ml of deionized water was added, and the mixture was stirred at 110 °C for 120 min. The product was filtered, dried in a vacuum drying oven at 100 °C for 6 h, and then calcined in a high-temperature furnace at 300 °C for 6 h to obtain calcium-doped sodium phosphate / silica catalyst. Example 4

[0035] A method for preparing an alkaline earth metal-doped phosphate catalyst includes the following steps.

[0036] (1) Preparation of sodium phosphate doped with alkaline earth metal: 10 g of sodium hydroxide and 0.71 g of barium hydroxide were dissolved in 60 ml of deionized water. The resulting mixed solution was added to 60 ml of solution containing 8.8 g of diammonium hydrogen phosphate. The mixture was stirred at 80 °C for 90 min to generate a white precipitate. The precipitate was then filtered, dried in a vacuum drying oven at 100 °C for 10 h, and then calcined in a high-temperature furnace at 280 °C for 4 h to obtain barium-doped sodium phosphate.

[0037] (2) Preparation of sodium phosphate supported on silica and doped with alkaline earth metal: 5 g of barium-doped sodium phosphate and 10 g of silica were added to a 250 ml three-necked flask, 150 ml of deionized water was added, and the mixture was stirred at 110 °C for 120 min. The product was filtered, dried in a vacuum drying oven at 100 °C for 6 h, and then calcined in a high-temperature furnace at 300 °C for 6 h to obtain barium-doped sodium phosphate / silica catalyst. Example 5

[0038] A method for preparing an alkaline earth metal-doped phosphate catalyst includes the following steps.

[0039] (1) Preparation of sodium phosphate doped with alkaline earth metals: 10 g of sodium hydroxide and 3.6 g of barium hydroxide were dissolved in 60 ml of deionized water. The resulting mixed solution was added to 60 ml of solution containing 8.8 g of diammonium hydrogen phosphate. The mixture was stirred at 80 °C for 90 min to generate a white precipitate. The precipitate was then filtered, dried in a vacuum drying oven at 100 °C for 10 h, and then calcined in a high-temperature furnace at 280 °C for 4 h to obtain barium-doped sodium phosphate.

[0040] (2) Preparation of sodium phosphate supported on silica and doped with alkaline earth metal: 5 g of barium-doped sodium phosphate and 10 g of silica were added to a 250 ml three-necked flask, 150 ml of deionized water was added, and the mixture was stirred at 110 °C for 120 min. The product was filtered, dried in a vacuum drying oven at 100 °C for 6 h, and then calcined in a high-temperature furnace at 300 °C for 6 h to obtain barium-doped sodium phosphate / silica catalyst. Example 6

[0041] A method for preparing an alkaline earth metal-doped phosphate catalyst includes the following steps.

[0042] (1) Preparation of sodium phosphate doped with alkaline earth metal: 10 g of sodium hydroxide and 7.2 g of barium hydroxide were dissolved in 60 ml of deionized water. The resulting mixed solution was added to 60 ml of solution containing 8.8 g of diammonium hydrogen phosphate. The mixture was stirred at 80 °C for 90 min to generate a white precipitate. The precipitate was then filtered, dried in a vacuum drying oven at 100 °C for 10 h, and then calcined in a high-temperature furnace at 280 °C for 4 h to obtain barium-doped sodium phosphate.

[0043] (2) Preparation of sodium phosphate supported on silica and doped with alkaline earth metal: 5 g of barium-doped sodium phosphate and 10 g of silica were added to a 250 ml three-necked flask, 150 ml of deionized water was added, and the mixture was stirred at 110 °C for 120 min. The product was filtered, dried in a vacuum drying oven at 100 °C for 6 h, and then calcined in a high-temperature furnace at 300 °C for 6 h to obtain barium-doped sodium phosphate / silica catalyst. Example 7

[0044] A method for preparing an alkaline earth metal-doped phosphate catalyst includes the following steps.

[0045] (1) Preparation of sodium phosphate doped with alkaline earth metals: 10 g of sodium hydroxide and 10.7 g of barium hydroxide were dissolved in 60 ml of deionized water. The resulting mixed solution was added to 60 ml of solution containing 8.8 g of diammonium hydrogen phosphate. The mixture was stirred at 80 °C for 90 min to generate a white precipitate. The precipitate was then filtered, dried in a vacuum drying oven at 100 °C for 10 h, and then calcined in a high-temperature furnace at 280 °C for 4 h to obtain barium-doped sodium phosphate.

[0046] (2) Preparation of sodium phosphate supported on silica and doped with alkaline earth metal: 5 g of barium-doped sodium phosphate and 10 g of silica were added to a 250 ml three-necked flask, 150 ml of deionized water was added, and the mixture was stirred at 110 °C for 120 min. The product was filtered, dried in a vacuum drying oven at 100 °C for 6 h, and then calcined in a high-temperature furnace at 300 °C for 6 h to obtain barium-doped sodium phosphate / silica catalyst. Example 8

[0047] A method for preparing an alkaline earth metal-doped phosphate catalyst includes the following steps.

[0048] (1) Preparation of sodium phosphate doped with alkaline earth metals: 10 g of sodium hydroxide and 14.3 g of barium hydroxide were dissolved in 60 ml of deionized water. The resulting mixed solution was added to 60 ml of solution containing 8.8 g of diammonium hydrogen phosphate. The mixture was stirred at 80 °C for 90 min to generate a white precipitate. The precipitate was then filtered, dried in a vacuum drying oven at 100 °C for 10 h, and then calcined in a high-temperature furnace at 280 °C for 4 h to obtain barium-doped sodium phosphate.

[0049] (2) Preparation of sodium phosphate supported on silica and doped with alkaline earth metal: 5 g of barium-doped sodium phosphate and 10 g of silica were added to a 250 ml three-necked flask, 150 ml of deionized water was added, and the mixture was stirred at 110 °C for 120 min. The product was filtered, dried in a vacuum drying oven at 100 °C for 6 h, and then calcined in a high-temperature furnace at 300 °C for 6 h to obtain barium-doped sodium phosphate / silica catalyst. Example 9

[0050] A method for preparing an alkaline earth metal-doped phosphate catalyst includes the following steps.

[0051] (1) Preparation of sodium phosphate doped with alkaline earth metal: 10 g of sodium hydroxide and 7.2 g of barium hydroxide were dissolved in 60 ml of deionized water. The resulting mixed solution was added to 60 ml of solution containing 8.8 g of diammonium hydrogen phosphate. The mixture was stirred at 80 °C for 90 min to generate a white precipitate. The precipitate was then filtered, dried in a vacuum drying oven at 100 °C for 10 h, and then calcined in a high-temperature furnace at 280 °C for 4 h to obtain barium-doped sodium phosphate.

[0052] (2) Preparation of sodium phosphate doped with alkaline earth metal supported on amorphous silica: 5 g of barium-doped sodium phosphate and 10 g of amorphous silica were added to a 250 ml three-necked flask, 150 ml of deionized water was added, and the mixture was stirred at 110 °C for 120 min. The product was filtered, dried in a vacuum drying oven at 100 °C for 6 h, and then calcined in a high-temperature furnace at 300 °C for 6 h to obtain barium-doped sodium phosphate / amorphous silica catalyst. Example 10

[0053] A method for preparing an alkaline earth metal-doped phosphate catalyst includes the following steps.

[0054] (1) Preparation of sodium phosphate doped with alkaline earth metal: 10 g of sodium hydroxide and 7.2 g of barium hydroxide were dissolved in 60 ml of deionized water. The resulting mixed solution was added to 60 ml of solution containing 8.8 g of diammonium hydrogen phosphate. The mixture was stirred at 80 °C for 90 min to generate a white precipitate. The precipitate was then filtered, dried in a vacuum drying oven at 100 °C for 10 h, and then calcined in a high-temperature furnace at 280 °C for 4 h to obtain barium-doped sodium phosphate.

[0055] (2) Preparation of sodium phosphate doped with alkaline earth metal supported on shaped silica: 5 g of barium-doped sodium phosphate and 10 g of shaped silica were added to a 250 ml three-necked flask, 150 ml of deionized water was added, and the mixture was stirred at 110 °C for 120 min. The product was filtered, dried in a vacuum drying oven at 100 °C for 6 h, and then calcined in a high-temperature furnace at 300 °C for 6 h to obtain barium-doped sodium phosphate / shaped silica catalyst. Example 11

[0056] A method for preparing an alkaline earth metal-doped phosphate catalyst includes the following steps.

[0057] (1) Preparation of sodium phosphate doped with alkaline earth metal: 10 g of sodium hydroxide and 7.2 g of barium hydroxide were dissolved in 60 ml of deionized water. The resulting mixed solution was added to 60 ml of solution containing 8.8 g of diammonium hydrogen phosphate. The mixture was stirred at 80 °C for 90 min to generate a white precipitate. The precipitate was then filtered, dried in a vacuum drying oven at 100 °C for 10 h, and then calcined in a high-temperature furnace at 280 °C for 4 h to obtain barium-doped sodium phosphate.

[0058] (2) Preparation of sodium phosphate doped with alkaline earth metal supported on fumed silica: 5 g of barium-doped sodium phosphate and 10 g of fumed silica were added to a 250 ml three-necked flask, 150 ml of deionized water was added, and the mixture was stirred at 110 °C for 120 min. The product was filtered, dried in a vacuum drying oven at 100 °C for 6 h, and then calcined in a high-temperature furnace at 300 °C for 6 h to obtain barium-doped sodium phosphate / fumed silica catalyst. Example 12

[0059] A method for preparing an alkaline earth metal-doped phosphate catalyst includes the following steps.

[0060] (1) Preparation of sodium phosphate doped with alkaline earth metal: 10 g of sodium hydroxide and 7.2 g of barium hydroxide were dissolved in 60 ml of deionized water. The resulting mixed solution was added to 60 ml of solution containing 8.8 g of diammonium hydrogen phosphate. The mixture was stirred at 80 °C for 90 min to generate a white precipitate. The precipitate was then filtered, dried in a vacuum drying oven at 100 °C for 10 h, and then calcined in a high-temperature furnace at 280 °C for 4 h to obtain barium-doped sodium phosphate.

[0061] (2) Preparation of sodium phosphate supported on mesoporous silica and doped with alkaline earth metal: 5 g of barium-doped sodium phosphate and 10 g of mesoporous silica were added to a 250 ml three-necked flask, 150 ml of deionized water was added, and the mixture was stirred at 110 °C for 120 min. The product was filtered, dried in a vacuum drying oven at 100 °C for 6 h, and then calcined in a high-temperature furnace at 300 °C for 6 h to obtain barium-doped sodium phosphate / mesoporous silica catalyst. Example 13

[0062] A method for preparing an alkaline earth metal-doped phosphate catalyst includes the following steps.

[0063] (1) Preparation of sodium phosphate doped with alkaline earth metals: 10 g of sodium hydroxide, 7.2 g of barium hydroxide and 0.24 g of magnesium hydroxide were dissolved in 60 ml of deionized water. The resulting mixed solution was added to 60 ml of solution containing 8.8 g of diammonium hydrogen phosphate. The mixture was stirred at 80 °C for 90 min to generate a white precipitate. The precipitate was then filtered and dried in a vacuum drying oven at 100 °C for 10 h. Finally, it was placed in a high-temperature furnace and calcined at 280 °C for 4 h to obtain sodium phosphate doped with barium and magnesium.

[0064] (2) Preparation of sodium phosphate doped with alkaline earth metals supported on fumed silica: 5 g of sodium phosphate doped with barium and magnesium and 10 g of fumed silica were added to a 250 ml three-necked flask, 150 ml of deionized water was added, and the mixture was stirred at 110 °C for 120 min. The product was filtered, dried in a vacuum drying oven at 100 °C for 6 h, and then calcined in a high-temperature furnace at 300 °C for 6 h to obtain a barium and magnesium doped sodium phosphate / fumed silica catalyst. Example 14

[0065] A method for preparing an alkaline earth metal-doped phosphate catalyst includes the following steps.

[0066] (1) Preparation of sodium phosphate doped with alkaline earth metals: 10 g of sodium hydroxide, 7.2 g of barium hydroxide and 0.31 g of calcium hydroxide were dissolved in 60 ml of deionized water. The resulting mixed solution was added to 60 ml of solution containing 8.8 g of diammonium hydrogen phosphate. The mixture was stirred at 80 °C for 90 min to generate a white precipitate. The precipitate was then filtered, dried in a vacuum drying oven at 100 °C for 10 h, and then calcined in a high-temperature furnace at 280 °C for 4 h to obtain sodium phosphate doped with barium and calcium.

[0067] (2) Preparation of sodium phosphate doped with alkaline earth metals supported on fumed silica: 5 g of sodium phosphate doped with barium and calcium and 10 g of fumed silica were added to a 250 ml three-necked flask, 150 ml of deionized water was added, and the mixture was stirred at 110 °C for 120 min. The product was filtered, dried in a vacuum drying oven at 100 °C for 6 h, and then calcined in a high-temperature furnace at 300 °C for 6 h to obtain a barium and calcium doped sodium phosphate / fumed silica catalyst. Example 15

[0068] A method for preparing an alkaline earth metal-doped phosphate catalyst includes the following steps.

[0069] (1) Preparation of sodium phosphate doped with alkaline earth metals: 10 g of sodium hydroxide, 7.2 g of barium hydroxide, 0.31 g of calcium hydroxide and 0.51 g of strontium hydroxide were dissolved in 60 ml of deionized water. The resulting mixed solution was added to 60 ml of solution containing 8.8 g of diammonium hydrogen phosphate. The mixture was stirred at 80 °C for 90 min to generate a white precipitate. The precipitate was then filtered, dried in a vacuum drying oven at 100 °C for 10 h, and then calcined in a high-temperature furnace at 280 °C for 4 h to obtain sodium phosphate doped with barium, calcium and strontium.

[0070] (2) Preparation of sodium phosphate doped with alkaline earth metals supported on fumed silica: 5 g of sodium phosphate doped with barium, calcium and strontium and 10 g of fumed silica were added to a 250 ml three-necked flask, 150 ml of deionized water was added, and the mixture was stirred at 110 °C for 120 min. The product was filtered, dried in a vacuum drying oven at 100 °C for 6 h, and then calcined in a high-temperature furnace at 300 °C for 6 h to obtain sodium phosphate / fumed silica catalyst doped with barium, calcium and strontium. Example 16

[0071] A method for preparing an alkaline earth metal-doped phosphate catalyst includes the following steps.

[0072] (1) Preparation of sodium phosphate doped with alkaline earth metals: 10 g of sodium hydroxide, 7.2 g of barium hydroxide, 0.31 g of calcium hydroxide and 0.24 g of magnesium hydroxide were dissolved in 60 ml of deionized water. The resulting mixed solution was added to 60 ml of solution containing 8.8 g of diammonium hydrogen phosphate. The mixture was stirred at 80 °C for 90 min to generate a white precipitate. The precipitate was then filtered, dried in a vacuum drying oven at 100 °C for 10 h, and then calcined in a high-temperature furnace at 280 °C for 4 h to obtain sodium phosphate doped with barium, calcium and magnesium.

[0073] (2) Preparation of sodium phosphate doped with alkaline earth metals supported on fumed silica: 5 g of sodium phosphate doped with barium, calcium and magnesium and 10 g of fumed silica were added to a 250 ml three-necked flask, 150 ml of deionized water was added, and the mixture was stirred at 110 °C for 120 min. The product was filtered, dried in a vacuum drying oven at 100 °C for 6 h, and then calcined in a high-temperature furnace at 300 °C for 6 h to obtain sodium phosphate / fumed silica catalyst doped with barium, calcium and magnesium.

[0074] Comparative Example 1.

[0075] (1) Preparation of sodium phosphate: Dissolve 10 g of sodium hydroxide in 60 ml of deionized water, add the obtained sodium hydroxide solution to 60 ml of solution containing 8.8 g of diammonium hydrogen phosphate, stir at 80 ℃ for 90 min to generate a white precipitate, filter the precipitate, dry it in a vacuum drying oven at 100 ℃ for 10 h, and then calcine it in a high-temperature furnace at 280 ℃ for 4 h to obtain sodium phosphate.

[0076] (2) Preparation of sodium phosphate supported on fumed silica: 5 g of sodium phosphate and 10 g of fumed silica were added to a 250 ml three-necked flask, 150 ml of deionized water was added, and the mixture was stirred at 110 °C for 120 min. The product was filtered, dried in a vacuum drying oven at 100 °C for 6 h, and then calcined in a high-temperature furnace at 300 °C for 6 h to obtain sodium phosphate supported on fumed silica.

[0077] Comparative Example 2.

[0078] (1) Preparation of lithium phosphate: 10 g of lithium hydroxide was dissolved in 60 ml of deionized water. The resulting lithium hydroxide solution was added to 60 ml of a solution containing 8.8 g of diammonium hydrogen phosphate. The mixture was stirred at 80 °C for 90 min to generate a white precipitate. The precipitate was then filtered, dried in a vacuum drying oven at 100 °C for 10 h, and then calcined in a high-temperature furnace at 280 °C for 4 h to obtain lithium phosphate.

[0079] (2) Preparation of lithium phosphate supported on fumed silica: 5 g of lithium phosphate and 10 g of fumed silica were added to a 250 ml three-necked flask, 150 ml of deionized water was added, and the mixture was stirred at 110 °C for 120 min. The product was filtered, dried in a vacuum drying oven at 100 °C for 6 h, and then calcined in a high-temperature furnace at 300 °C for 6 h to obtain lithium phosphate supported on fumed silica.

[0080] Comparative Example 3.

[0081] (1) Preparation of ferric phosphate: 10 g of ferric hydroxide was dispersed in 60 ml of deionized water. The resulting ferric hydroxide solution was added to 60 ml of solution containing 8.8 g of diammonium hydrogen phosphate. The mixture was stirred at 80 °C for 90 min to generate a white precipitate. The precipitate was then filtered, dried in a vacuum drying oven at 100 °C for 10 h, and then calcined in a high-temperature furnace at 280 °C for 4 h to obtain ferric phosphate.

[0082] (2) Preparation of ferric phosphate supported on fumed silica: 5 g of ferric phosphate and 10 g of fumed silica were added to a 250 ml three-necked flask, 150 ml of deionized water was added, and the mixture was stirred at 110 °C for 120 min. The product was filtered, dried in a vacuum drying oven at 100 °C for 6 h, and then calcined in a high-temperature furnace at 300 °C for 6 h to obtain ferric phosphate supported on fumed silica.

[0083] Comparative Example 4.

[0084] (1) Preparation of cobalt phosphate: 10 g of cobalt hydroxide was dispersed in 60 ml of deionized water. The resulting cobalt hydroxide solution was added to 60 ml of a solution containing 8.8 g of diammonium hydrogen phosphate. The mixture was stirred at 80 °C for 90 min to generate a white precipitate. The precipitate was then filtered, dried in a vacuum drying oven at 100 °C for 10 h, and then calcined in a high-temperature furnace at 280 °C for 4 h to obtain cobalt phosphate.

[0085] (2) Preparation of cobalt phosphate supported on fumed silica: 5 g cobalt phosphate and 10 g fumed silica were added to a 250 ml three-necked flask, 150 ml deionized water was added, and the mixture was stirred at 110 °C for 120 min. The product was filtered, dried in a vacuum drying oven at 100 °C for 6 h, and then calcined in a high-temperature furnace at 300 °C for 6 h to obtain cobalt phosphate supported on fumed silica.

[0086] Comparative Example 5.

[0087] (1) Preparation of nickel phosphate: 10 g of nickel hydroxide was dispersed in 60 ml of deionized water. The obtained nickel hydroxide solution was added to 60 ml of solution containing 8.8 g of diammonium hydrogen phosphate. The mixture was stirred at 80 °C for 90 min to generate a white precipitate. The precipitate was then filtered, dried in a vacuum drying oven at 100 °C for 10 h, and then calcined in a high-temperature furnace at 280 °C for 4 h to obtain nickel phosphate.

[0088] (2) Preparation of nickel phosphate supported on fumed silica: 5 g of nickel phosphate and 10 g of fumed silica were added to a 250 ml three-necked flask, 150 ml of deionized water was added, and the mixture was stirred at 110 °C for 120 min. The product was filtered, dried in a vacuum drying oven at 100 °C for 6 h, and then calcined in a high-temperature furnace at 300 °C for 6 h to obtain nickel phosphate supported on fumed silica.

[0089] Comparative Example 6.

[0090] (1) Preparation of copper phosphate: 10 g of copper hydroxide was dispersed in 60 ml of deionized water. The resulting copper hydroxide solution was added to 60 ml of solution containing 8.8 g of diammonium hydrogen phosphate. The mixture was stirred at 80 °C for 90 min to generate a white precipitate. The precipitate was then filtered, dried in a vacuum drying oven at 100 °C for 10 h, and then calcined in a high-temperature furnace at 280 °C for 4 h to obtain copper phosphate.

[0091] (2) Preparation of copper phosphate supported on fumed silica: 5 g of copper phosphate and 10 g of fumed silica were added to a 250 ml three-necked flask, 150 ml of deionized water was added, and the mixture was stirred at 110 °C for 120 min. The product was filtered, dried in a vacuum drying oven at 100 °C for 6 h, and then calcined in a high-temperature furnace at 300 °C for 6 h to obtain copper phosphate supported on fumed silica.

[0092] Comparative Example 7.

[0093] (1) Preparation of zinc phosphate: 10 g of zinc hydroxide was dispersed in 60 ml of deionized water. The resulting zinc hydroxide solution was added to 60 ml of solution containing 8.8 g of diammonium hydrogen phosphate. The mixture was stirred at 80 °C for 90 min to generate a white precipitate. The precipitate was then filtered, dried in a vacuum drying oven at 100 °C for 10 h, and then calcined in a high-temperature furnace at 280 °C for 4 h to obtain zinc phosphate.

[0094] (2) Preparation of zinc phosphate supported on fumed silica: 5 g of zinc phosphate and 10 g of fumed silica were added to a 250 ml three-necked flask, 150 ml of deionized water was added, and the mixture was stirred at 110 °C for 120 min. The product was filtered, dried in a vacuum drying oven at 100 °C for 6 h, and then calcined in a high-temperature furnace at 300 °C for 6 h to obtain zinc phosphate supported on fumed silica.

[0095] Comparative Example 8.

[0096] (1) Preparation of sodium phosphate doped with alkaline earth metal: 10 g of sodium hydroxide and 7.2 g of barium hydroxide were dissolved in 60 ml of deionized water. The resulting mixed solution was added to 60 ml of solution containing 8.8 g of diammonium hydrogen phosphate. The mixture was stirred at 80 °C for 90 min to generate a white precipitate. The precipitate was then filtered, dried in a vacuum drying oven at 100 °C for 10 h, and then calcined in a high-temperature furnace at 280 °C for 4 h to obtain barium-doped sodium phosphate.

[0097] (2) Preparation of γ-alumina supported sodium phosphate: 5 g of barium-doped sodium phosphate and 10 g of γ-alumina were added to a 250 ml three-necked flask, 150 ml of deionized water was added, and the mixture was stirred at 110 °C for 120 min. The product was filtered, dried in a vacuum drying oven at 100 °C for 6 h, and then calcined in a high-temperature furnace at 300 °C for 6 h to obtain barium-doped sodium phosphate / γ-alumina catalyst.

[0098] Comparative Example 9.

[0099] (1) Preparation of sodium phosphate doped with alkaline earth metal: 10 g of sodium hydroxide and 7.2 g of barium hydroxide were dissolved in 60 ml of deionized water. The resulting mixed solution was added to 60 ml of solution containing 8.8 g of diammonium hydrogen phosphate. The mixture was stirred at 80 °C for 90 min to generate a white precipitate. The precipitate was then filtered, dried in a vacuum drying oven at 100 °C for 10 h, and then calcined in a high-temperature furnace at 280 °C for 4 h to obtain barium-doped sodium phosphate.

[0100] (2) Preparation of sodium phosphate supported on titanium dioxide: 5 g of barium-doped sodium phosphate and 10 g of titanium dioxide were added to a 250 ml three-necked flask, 150 ml of deionized water was added, and the mixture was stirred at 110 °C for 120 min. The product was filtered, dried in a vacuum drying oven at 100 °C for 6 h, and then calcined in a high-temperature furnace at 300 °C for 6 h to obtain barium-doped sodium phosphate / titanium dioxide catalyst.

[0101] Comparative Example 10.

[0102] (1) Preparation of sodium phosphate doped with alkaline earth metal: 10 g of sodium hydroxide and 7.2 g of barium hydroxide were dissolved in 60 ml of deionized water. The resulting mixed solution was added to 60 ml of solution containing 8.8 g of diammonium hydrogen phosphate. The mixture was stirred at 80 °C for 90 min to generate a white precipitate. The precipitate was then filtered, dried in a vacuum drying oven at 100 °C for 10 h, and then calcined in a high-temperature furnace at 280 °C for 4 h to obtain barium-doped sodium phosphate.

[0103] (2) Preparation of sodium phosphate supported on zirconium dioxide: 5 g of barium-doped sodium phosphate and 10 g of zirconium dioxide were added to a 250 ml three-necked flask, 150 ml of deionized water was added, and the mixture was stirred at 110 °C for 120 min. The product was filtered, dried in a vacuum drying oven at 100 °C for 6 h, and then calcined in a high-temperature furnace at 300 °C for 6 h to obtain a barium-doped sodium phosphate / zirconium dioxide catalyst.

[0104] Application of alkaline earth metal-doped phosphate catalysts in the isomerization of propylene oxide to prepare allyl alcohol.

[0105] The isomerization reaction of propylene oxide is carried out in a fixed-bed reactor. The catalyst is placed in the middle of the reactor, and propylene oxide is bubbled into the reactor through an inert gas. Finally, the product is collected by condensation in a cold trap and analyzed by gas chromatography.

[0106] Application Comparative Example 1.

[0107] The catalyst described in Example 11 was used in the reaction, wherein the mass ratio of reactants to catalyst was 5, the reactor heating temperature was 320 °C, and the propylene oxide injection rate was 1 ml / min.

[0108] Comparative Example 2.

[0109] The catalyst described in Example 11 was used in the reaction, wherein the mass ratio of reactants to catalyst was 10, the reactor heating temperature was 320 °C, and the propylene oxide injection rate was 1 ml / min.

[0110] Application Comparative Example 3.

[0111] The catalyst described in Example 11 was used in the reaction, wherein the mass ratio of reactants to catalyst was 15, the reactor heating temperature was 320 °C, and the propylene oxide injection rate was 1 ml / min.

[0112] Application Comparative Example 4.

[0113] The catalyst described in Example 11 was used in the reaction, wherein the mass ratio of reactants to catalyst was 10, the reactor heating temperature was 280 °C, and the propylene oxide injection rate was 1 ml / min.

[0114] Application Comparative Example 5.

[0115] The catalyst described in Example 11 was used in the reaction, wherein the mass ratio of reactants to catalyst was 10, the reactor heating temperature was 360 °C, and the propylene oxide injection rate was 1 ml / min.

[0116] Application Comparative Example 6.

[0117] The catalyst described in Example 11 was used in the reaction, wherein the mass ratio of reactants to catalyst was 10, the reactor heating temperature was 320 °C, and the propylene oxide injection rate was 0.5 ml / min.

[0118] Application Comparative Example 7.

[0119] The catalyst described in Example 11 was used in the reaction, wherein the mass ratio of reactants to catalyst was 10, the reactor heating temperature was 320 °C, and the propylene oxide injection rate was 3 ml / min.

[0120] Table 1 Comparison of catalytic performance data for Comparative Examples 1-7

[0121] serial number propylene oxide conversion rate / % Allyl alcohol selectivity / % Application Comparative Example 1 28 90 Application Comparative Example 2 53 88 Application Comparative Example 3 50 82 Application Comparative Example 4 30 92 Application Comparative Example 5 42 70 Application Comparative Example 6 40 90 Application Comparative Example 7 35 85

[0122] As can be seen from the results in Table 1, the catalyst exhibits the best catalytic performance when the mass ratio of reactants to catalyst is 10, the reactor heating temperature is 320℃, and the propylene oxide injection rate is 1 ml / min. Therefore, Examples 1-16 and Comparative Examples 1-10 were all carried out under these reaction conditions.

[0123] Table 2 Comparison of catalytic performance data between Examples 1-16 and Comparative Examples 1-10

[0124] serial number propylene oxide conversion rate / % Allyl alcohol selectivity / % Stability / h Example 1 76 90 50~80 Example 2 81 91 100~150 Example 3 70 87 60~130 Example 4 85 91 200~320 Example 5 89 95 260~400 Example 6 94 93 280~350 Example 7 88 96 250~370 Example 8 83 91 180~310 Example 9 94 97 300~450 Example 10 91 95 200~400 Example 11 96 98 400~500 Example 12 93 95 300~350 Example 13 90 90 200~300 Example 14 88 92 250~310 Example 15 85 88 180~250 Example 16 90 92 200~260 Comparative Example 1 53 88 30~50 Comparative Example 2 46 80 20~30 Comparative Example 3 37 78 15~20 Comparative Example 4 30 81 15~20 Comparative Example 5 18 70 3~5 Comparative Example 6 22 66 5~10 Comparative Example 7 13 80 3~5 Comparative Example 8 82 85 100~300 Comparative Example 9 80 92 80~270 Comparative Example 10 78 96 160~300

[0125] As shown in Table 2, sodium phosphate exhibits the best catalytic performance when using different phosphates as catalysts. Furthermore, doping it with alkali metals significantly improves its performance compared to undoped phosphates. Under the same catalyst synthesis and catalytic reaction conditions, barium-doped sodium phosphate demonstrates higher activity and stronger stability.

[0126] Furthermore, as shown in Tables 2 (Examples 4-8), we used different mass fractions of barium to dope sodium phosphate. The optimal performance was observed when the barium doping concentration was 10%, achieving a propylene oxide conversion rate of 94% and a selectivity for allyl alcohol of 93%. Next, as shown in Tables 2 (Examples 13-16), we compared the effects of simultaneously doping sodium phosphate with more than one alkaline earth metal, and found that barium alone provided the best performance.

[0127] Based on the results of Examples 9-12 in Table 2, we selected different types of silica to support barium-doped sodium phosphate. Finally, we found that when fumed silica was used as a support, the catalyst performance was further improved, with a propylene oxide conversion rate of 96%, a selectivity for allyl alcohol of 98%, and stable operation for 400-500 h.

[0128] Meanwhile, we selected other supports: γ-alumina, titanium dioxide, and zirconium dioxide to load barium-doped sodium phosphate to compare catalytic activity. The catalyst supported on silica showed particularly outstanding advantages in catalytic activity and stability.

[0129] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. The application of an alkaline earth metal-doped phosphate catalyst in the isomerization of propylene oxide to prepare allyl alcohol, characterized in that... The catalyst is composed of silica as a support and alkaline earth metal-doped phosphate as the main catalyst, wherein the mass ratio of the main catalyst to the support is 10:1 to 1:10, and the doping amount of alkaline earth metal is 0.1 wt.% to 20 wt.%.

2. The application according to claim 1, characterized in that: The alkaline earth metal in the catalyst is one or more of magnesium, calcium, strontium, and barium.

3. The application according to claim 1, characterized in that: The catalyst phosphate includes sodium phosphate, lithium phosphate, iron phosphate, cobalt phosphate, nickel phosphate, copper phosphate, or zinc phosphate.

4. The application according to claim 1, characterized in that: The method for preparing the catalyst includes the following steps: (1) Preparation of alkaline earth metal-doped phosphate by co-precipitation method: A solution containing alkaline earth metal ions is mixed with a metal hydroxide solution, and then the mixed solution is added to a diammonium hydrogen phosphate solution to produce a precipitate. The precipitate is filtered, washed and calcined to obtain alkaline earth metal-doped phosphate. (2) Physically mix silica with alkaline earth metal-doped phosphate and then calcine to obtain alkaline earth metal-doped phosphate / silica catalyst. The amount of alkaline earth metal doping in step (1) is 0.1 wt.%~20 wt.%, the temperature required to produce precipitation is 80 ℃, the reaction time is 90 min, and the precipitation calcination temperature is 280 ℃; The types of silicon dioxide mentioned in step (2) include crystalline silicon dioxide, amorphous silicon dioxide, shaped silicon dioxide, fumed silicon dioxide, or mesoporous silicon dioxide.

5. The application according to claim 4, characterized in that: In the preparation method, the mass ratio of the main catalyst to the support is 5:1 to 1:5, and the doping amount of alkaline earth metal is 5 wt.% to 15 wt.%.

6. The application according to claim 1, characterized in that: The propylene oxide isomerization reaction is carried out in a fixed-bed reactor. The catalyst is placed in the middle of the reactor, and propylene oxide is bubbled into the reactor through an inert gas. Finally, the product is collected by condensation through a cold trap, and the collected product is analyzed by gas chromatography. The mass ratio of catalyst to reaction substrate is 5-20; the reaction temperature is 260-380℃; and the injection rate of propylene oxide in the reaction is 0.1-5 ml / min.

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