A catalyst for preparing 1,3-propylene glycol from glycerol and a method for preparing 1,3-propylene glycol using a loop reactor

Abstract

The present invention discloses a catalyst for preparing 1,3-propylene glycol from glycerol and a method for preparing 1,3-propylene glycol using a loop reactor. The catalyst is powdered Pt / WO3-ZrO2, prepared from WO3-ZrO2 composite oxide and chloroplatinic acid, wherein the element Pt in chloroplatinic acid is 1.5% of the mass of the WO3-ZrO2 composite oxide, and the WO3-ZrO2 composite oxide is prepared using ammonium tungstate and zirconium hydroxide powder as main raw materials. The mass ratio of element W to element Zr in the raw materials ammonium tungstate and zirconium hydroxide is measured according to the mass ratio of WO3:ZrO2 of (3-20):100. The present invention uses a platinum catalyst supported by a doped tungsten-zirconium carrier as a catalyst, and combines a loop reactor to carry out a glycerol hydrogenation reaction to prepare 1,3-propylene glycol, effectively improving the glycerol conversion rate and the selectivity of the product 1,3-propylene glycol, the utilization rate of the catalyst, effectively reducing production costs, and achieving green energy saving.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical production, and in particular relates to a method for preparing 1,3-propylene glycol by an intermittent process of glycerol hydrogenation using a new type of reactor equipment, namely a loop reactor. Background Art

[0002] 1,3-Propanediol is an important, high-value-added organic chemical raw material, widely used in chemical industries such as inks, coatings, cosmetics, pharmaceuticals, and antifreeze. Its most important use is as a monomer in the synthesis of high-performance polymer materials, such as the high-performance new polyester fiber PTT (poly(1,3-trimethylene terephthalate)).

[0003] Glycerol, a renewable resource, can be converted into high-value-added 1,3-propylene glycol through a series of chemical or biological reactions. U.S. Patent No. 5,426,249 uses a 10-40 wt% aqueous glycerol solution. In the first step, glycerol is dehydrated over an acidic solid catalyst at 250-340°C to produce acrolein and hydroxyacetone. In the second step, acrolein is hydrated over an acidic catalyst at 20-120°C to produce 3-hydroxypropionaldehyde. In the third step, 1,3-propylene glycol and 1,2-propylene glycol are produced through a two-stage catalytic hydrogenation reaction of 3-hydroxypropionaldehyde and hydroxyacetone.

[0004] Glycerol can be synthesized into 1,3-propylene glycol in one step by catalytic hydrogenation of glycerol. The existing reports on the preparation of 1,3-propylene glycol by catalytic hydrogenation of glycerol mainly use Pt / WO3 / support series catalysts in fixed bed or reactor batch process: Pt / WO3 / Al2O3 catalyst is dissolved in 10% glycerol aqueous solution at a mass space velocity of 0.09h -1 The reaction temperature was 160°C, the pressure was 5 MPa, the optimal glycerol conversion was 64.2%, and the 1,3-propylene glycol selectivity was 66.1% (Journal of Molecular Catalysis A: Chemical 398 (2015) 391–398); Pt-WO3 / ZrO2 catalyst was used in 60% glycerol aqueous solution as raw material, and the volume space velocity was 0.25 h -1 , reaction temperature 130℃, pressure 4MPa, optimal glycerol conversion rate 70.2%, 1,3-propylene glycol selectivity 32% (Green Chem 2010,12,1466–1472); glycerol hydrogenation in a Pt / WO3 / ZrO2 catalyst tank reactor, reaction pressure 5.5MPa, reaction time 12h, glycerol conversion rate 31.6%, 1,3-propylene glycol selectivity 11%, 1,2-propylene glycol selectivity 8.7% (Chinese J Catal,2009,30(12):1189–1191).

[0005] While the above preparation methods can directly synthesize 1,3-propylene glycol in a single step, the catalyst preparation and catalyst utilization are limited by the reactor vessel, resulting in certain drawbacks. In fixed-bed reports, the precious metal catalysts were only subjected to laboratory tableting and screening to obtain particles of a certain particle size before being loaded into the fixed-bed reactor. Without industrial forming, they have poor mechanical strength and are easily pulverized upon collision. Furthermore, during long-term continuous hydrogenation processes, catalyst powder may be lost after being wetted, limiting their practical industrial application. Furthermore, in fixed-bed hydrogenation processes, the catalyst is solid and the glycerol reactant is a fluid. The fluid feedstock flows into contact with the catalyst, resulting in a low mass transfer rate between the gas-liquid-solid three-phase system. This significantly limits the glycerol hydrogenation reaction and results in low catalyst utilization (low reactant conversion per unit mass of catalyst per unit time). Using another reactor, a kettle reactor, results in longer reaction times and, due to the limitations of solid-liquid-gas mass transfer, makes it difficult to conduct small-scale, kilogram-scale experiments.

[0006] In the glycerol hydrogenation reaction, glycerol undergoes selective hydrogenation to produce 1,3-propylene glycol (the main product) and 1,2-propylene glycol as a byproduct. Continuous deep hydrogenation can then yield n-propanol and isopropanol as byproducts. Of these, 1,3-propylene glycol has the highest economic added value. High catalyst activity and extended reaction times (or increased temperature and pressure) promote deep hydrogenation to produce n-propanol (or isopropanol) and reduce 1,3-propylene glycol selectivity. However, weak catalyst activity and short reaction times result in low glycerol conversion. This makes it difficult to achieve both glycerol conversion and main product selectivity, limiting its potential for industrial application. Summary of the Invention

[0007] The present invention provides a novel catalyst suitable for a new process for preparing 1,3-propylene glycol. The catalyst is a powdered Pt / WO3-ZrO2 catalyst, which is used in conjunction with a loop reactor for glycerol hydrogenation preparation, thereby improving the utilization rate of the catalyst, the conversion rate of the reactants, and the selectivity of the target product 1,3-propylene glycol.

[0008] In order to achieve the above object, the technical solution of the present invention is as follows:

[0009] A catalyst for preparing 1,3-propylene glycol from glycerol is provided. The catalyst is powdered Pt / WO3-ZrO2 prepared from a WO3-ZrO2 composite oxide and chloroplatinic acid. The element Pt in the chloroplatinic acid accounts for 1.5% of the mass of the WO3-ZrO2 composite oxide. The WO3-ZrO2 composite oxide is prepared using zirconium hydroxide powder and ammonium tungstate as main raw materials. The mass ratio of the element W to the element Zr in the raw materials, ammonium tungstate and zirconium hydroxide, is measured at a WO3:ZrO2 mass ratio of (3-20):100. In some embodiments, the preferred stoichiometric ratio is 9:100.

[0010] The powdered Pt / WO3-ZrO2 catalyst is a platinum catalyst supported on a doped tungsten-zirconium carrier. The specific preparation method is as follows:

[0011] (1) Using an ammonia precipitation method, concentrated ammonia was added dropwise to an aqueous zirconium nitrate solution to adjust the pH value to 9-10, and the mixture was stirred for 0.5 h and then aged at room temperature for 4 h. The mixture was filtered and washed until the pH value of the filtrate was 7. The filter cake was dried at 110°C for 5 h and ground into a fine powder to obtain zirconium hydroxide powder;

[0012] (2) The zirconium hydroxide powder prepared in step (1) is placed in a reaction vessel, and a mixed aqueous solution of ammonium tungstate and oxalic acid is added under vacuum (oxalic acid is used as an auxiliary agent, and its addition amount is suitable for the dissolution of ammonium tungstate in water), stirred and evaporated in a water bath, dried and ground, and placed in a tube furnace, heated to 480°C to 520°C, kept at a constant temperature for 1.5h to 2.5h, and cooled to room temperature to obtain a WO3-ZrO2 composite oxide sample;

[0013] (3) The WO3-ZrO2 composite oxide powder obtained in step (2) is added to a glass container, and a measured amount of H2PtCl6 solution is added under vacuum conditions. The mixture is stirred and evaporated to dryness in a water bath. After drying and grinding, the mixture is placed in a tube furnace for dechlorination treatment to obtain the catalyst Pt / WO3-ZrO2.

[0014] The present invention also provides a method for preparing 1,3-propylene glycol from glycerol using the above catalyst. The method uses glycerol as a raw material and Pt / WO3-ZrO2 as a catalyst to carry out a hydrogenation reaction in a loop reactor to prepare 1,3-propylene glycol.

[0015] The specific steps of the method for preparing 1,3-propylene glycol from glycerol of the present invention are as follows:

[0016] Analytical pure glycerol was dissolved in methanol to prepare a glycerol methanol solution, which was added to the reactor of the loop reactor. Pt / WO3-ZrO2 powder catalyst pre-reduced with hydrogen at 200°C for 2h was quickly added to the reactor for hydrogenation reaction; the reaction pressure during the hydrogenation reaction was 2MPa, the reaction temperature was 160±1°C, and the reaction time was 1h.

[0017] The mass concentration of the glycerol methanol solution is 20%, and the added amount of the catalyst Pt / WO3-ZrO2 accounts for 4% of the mass of the glycerol.

[0018] In the loop reactor adopted by the present invention, the ratio of the opening inner diameter of the inlet section of the Venturi injector: the inner diameter of the nozzle: the inner diameter of the air chamber closing: the length of the mixing section: the length of the diffusion section is 38: (1.5-4): (2-6): (20-80): (600-1700); the opening angle of the diffusion section is 10° to 35°; and the linear velocity of the fluid at the nozzle of the Venturi injector during the hydrogenation reaction is 80 to 125 m / s.

[0019] In some embodiments, preferably, the ratio of the inner diameter of the inlet section opening of the Venturi injector in the loop reactor: the inner diameter of the nozzle: the inner diameter of the gas chamber closing: the length of the mixing section: the length of the diffusion section is 38:3:4:45:1100, and the opening angle of the diffusion section is 17°; the linear velocity of the fluid at the nozzle of the Venturi injector during the hydrogenation reaction is 105 m / s.

[0020] At the same time, compared with the existing technology, the present invention has the following advantages:

[0021] 1. The catalyst used in the present invention is a platinum catalyst supported on a doped tungsten-zirconium carrier. Compared with the catalyst supported on a supported tungsten-zirconium carrier for platinum, it has better glycerol conversion rate, 1,3-propylene glycol conversion rate and catalyst utilization rate.

[0022] 2. The present invention also combines a loop reactor as a key process equipment to carry out glycerol hydrogenation to prepare 1,3-propylene glycol. The micron-level bubbles generated by the Venturi ejector are dispersed into the liquid phase, which can effectively cause a very high local gas-liquid mass transfer rate. At the same time, the liquid phase turbulence caused by the introduction into the reactor improves the mixing efficiency of the catalyst solid phase and the raw material glycerol liquid phase in the reactor, accelerates the multiphase reaction rate, and the mixed phase is sprayed into the reactor of the loop reactor to form a good circulation therein, which promotes the continuous reaction and further improves the rate of the catalytic reaction.

[0023] 3. The present invention further improves the glycerol conversion rate and the selectivity of the product 1,3-propylene glycol, and the utilization rate of the catalyst by screening the catalyst preparation raw materials and preparation process, as well as designing the Venturi ejector, a key equipment of the loop reactor, thereby effectively reducing production costs and achieving green energy conservation.

[0024] 4. The present invention can achieve a good catalytic effect by using only powdered catalysts, does not involve catalyst molding, saves catalyst production costs, and has a high catalyst utilization rate (reactants converted per unit mass of catalyst per unit time). BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic structural diagram of a loop reactor for preparing 1,3-propylene glycol by hydrogenation of glycerol according to the present invention;

[0026] Figure 2 For the present invention Figure 1 Schematic diagram of the structure of the Chinese Qiuli injector.

[0027] In the figure, 1-reactor, 2-Venturi ejector, 3-heat exchanger, 4-circulation pump; 21-inlet section, 22-mixing section, 23-diffusion section, 24-nozzle, 25-gas circulation pipe, 26-gas chamber. DETAILED DESCRIPTION

[0028] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] like Figure 1 As shown, the 1,3-propylene glycol production of the present invention adopts a loop reactor for batch reaction. The loop reactor includes four parts: a reactor 1, a circulation pump 4, a heat exchanger 3 and a venturi ejector 2.

[0030] When the reactor is operating, the circulation pump is activated. The reaction liquid circulates at a high flow rate within the loop, and Venturi ejector 2 injects liquid at high speed, creating negative pressure at the working nozzle, drawing gas (hydrogen) into the Venturi ejector. A branch pipe is installed on one side of the top of reactor 1, connected to the air inlet, allowing for localized air circulation. Tiny bubbles with a large specific surface area form in the Venturi ejector, increasing gas-liquid contact and accelerating the reaction. The lower end of the Venturi ejector is located below the liquid surface, where the gas-liquid-solid mixture impacts the materials within the reactor, promoting dispersion and mixing, and further advancing the reaction. The materials enter the heat exchanger from the bottom of the reactor via circulation pump 4 and then enter Venturi ejector 2 from the top of reactor 1. Heat exchanger 3 removes or supplies heat released or absorbed during the reaction, controlling reaction temperature fluctuations within ±1°C. As the reaction proceeds, the reactants gradually decrease, while the products gradually increase. Once the reaction is complete, the products are discharged from the bottom of the reactor.

[0031] The heat exchanger in this patent can be a tubular heat exchanger or a plate heat exchanger.

[0032] For a specific chemical reaction process under certain pressure and temperature conditions, the design structure and size of the Venturi ejector greatly affects the effect of mutual dispersion and contact between the reactants, which ultimately affects the chemical production efficiency. Figure 2 In this patent, the Wenqiuli ejector 2 is specifically composed of a tapered tube-shaped inlet section 21, a nozzle 24, a mixing section 22, a diffusion section 23 and an air chamber 26. Figure 1 As shown, a gas circulation pipe 25 is provided on the side of the gas chamber 26 and is connected to the top of the reactor 1 to provide a local gas circulation space.

[0033] In the initial stage of glycerol hydrogenation, analytically pure glycerol was dissolved in methanol to a glycerol content of 20 wt%. Catalyst powder, pre-reduced by dechlorination, was added, mixed thoroughly, and then added to the loop reactor via the feed port. H₂ was introduced into the reactor through the air inlet to a system pressure of 1 MPa. Circulation pump 4 was started to slowly flow the liquid in the reactor, then vented. This process was repeated six times to displace the air in the loop reactor. After heating to the preset reaction temperature (heating time approximately 15 minutes), H₂ was immediately introduced to the reaction pressure. Circulation pump 4 was then adjusted until the flow rate reached a certain value, which was recorded as the reaction start time.

[0034] At the end of the reaction, immediately reduce the flow rate of circulating pump 4 and quickly cool to room temperature (cooling time is about 15 minutes). Vent the gas in the kettle, release the liquid in the kettle, filter and separate, and take the liquid for GC analysis. Specifically, a Nanjing Kejie GC-5890 gas chromatograph, a PEG-20M polar capillary column, a vaporization chamber temperature of 290°C, an FID detector temperature of 290°C, and a column box program temperature increase from 50°C to 200°C at 10°C / min and then constant temperature. In addition to the main product 1,3-propylene glycol, the product also contains by-products 1,2-propylene glycol, n-propanol, isopropanol, etc. Some experimental products contain glycerol cracking products such as ethanol and ethylene glycol. Methanol is used as a reference substance, and a measured product substance and methanol mixed solution is prepared for gas chromatography analysis. The relative correction factor of each product is calculated based on the relative quantitative relationship between concentration and peak area. A relative correction factor was introduced to calculate the relative proportions of the products based on the peak area ratios of the components in the experimental sample. This was used to calculate the glycerol conversion and product selectivity, with the ratio of 1,3-propylene glycol to 1,2-propylene glycol selectivity being recorded as 1,3 / 1,2. Catalyst utilization is the mass of glycerol processed per unit catalyst per unit time, expressed in g / (g·h).

[0035] Catalyst Preparation Example

[0036] 1. Experimental materials

[0037] Ammonium tungstate H 40 N 10 O 41 W 12 xH2O (Sinopharm Group Chemical Reagent Co., Ltd. AR);

[0038] Oxalic acid H2C2O4·2H2O (Sinopharm Chemical Reagent Co., Ltd. AR);

[0039] Zirconium nitrate Zr(NO3)4·5H2O (Sinopharm Chemical Reagent Co., Ltd. AR);

[0040] Chloroplatinic acid H2PtCl6·6H2O (Aladdin).

[0041] 2. Preparation process

[0042] Dissolve the measured amount of zirconium nitrate in deionized water, wherein the zirconium nitrate accounts for 4-7wt% of the mass of the aqueous solution, add concentrated ammonia water dropwise, adjust the pH value to 9-10, continue stirring for 0.5h, then age at room temperature for 4h, filter and wash until the pH value of the filtrate is 7, dry the obtained filter cake at 110°C for 5h, grind into fine zirconium hydroxide powder.

[0043] The amount of ammonium tungstate H 40 N 10 O 41 W 12xH2O (AR from Sinopharm Chemical Reagent Co., Ltd.) and oxalic acid H2C2O4·2H2O (AR from Sinopharm Chemical Reagent Co., Ltd.) were dissolved in a certain amount of deionized water at a mass ratio of 1:1 to prepare a solution with a W atomic concentration of 0.08 mol / L.

[0044] Weigh a measured amount of zirconium hydroxide powder and add it to a glass container. After evacuating the container for 1 hour, add a certain volume of the above-mentioned ammonium tungstate solution. Stir and evaporate to dryness in a 95℃ water bath, and air-dry at 110℃ for 5 hours. After grinding the sample, place it in a tube furnace and heat it to 500℃ at a rate of 3℃ / min, keep it at this temperature for 2 hours, and cool it to room temperature to obtain a WO3-ZrO2 composite oxide sample. Under the same calcination conditions, the weight loss ratio of zirconium hydroxide powder to zirconium oxide is determined by gravimetric method. This is used to calculate the amount of zirconium hydroxide powder to be added. Combined with the concentration of ammonium tungstate solution, the mass ratio of WO3:ZrO2 in the obtained WO3-ZrO2 composite oxide is controlled to be (3-20):100.

[0045] Weigh a measured amount of WO3-ZrO2 composite oxide powder into a custom glass container. After evacuating the container for 1 hour, add a precisely measured amount of H2PtCl6 solution (0.13 mol / L), with the Pt element representing 1.5% of the WO3-ZrO2 composite oxide sample mass. Evaporate the mixture to dryness in a 95°C water bath with stirring, and air-dry at 110°C for 5 hours. Grind the sample and dechlorinate it in a tube furnace using the following steps to obtain the dechlorinated catalyst powder:

[0046]

[0047] Example 1

[0048] To a 5L loop reactor (5L reactor volume), 3000g of 20wt% glycerol methanol solution was added, and 24g of Pt / WO3-ZrO2 powder, a catalyst pre-reduced at 200°C for 2h, was added, i.e., the relative ratio of catalyst to reactant glycerol was 4wt%. The amount of the raw material zirconium hydroxide powder added and the amount of ammonium tungstate solution added were measured at a mass ratio of WO3 to ZrO2 of 4:100, and the amount of H2PtCl6 added accounted for 1.5% of the mass of the WO3-ZrO2 composite oxide sample with the mass of element Pt. Hydrogen was introduced into the reactor through the air inlet to a system pressure of 1MPa, a circulating pump was turned on to allow the liquid in the kettle to flow slowly, and the reactor was vented. After the air in the replacement loop reactor was heated to a preset reaction temperature of 160°C (heating time of about 15min), hydrogen was immediately added to the reaction pressure of 2MPa, and the circulating pump 4 was adjusted to a flow velocity of 90m / s, which was recorded as the reaction start time. During the reaction, the hydrogen pressure in the connected reactor was maintained at a constant 2 MPa and the temperature at 160 ± 1°C. After 1 h of reaction, the flow rate of circulating pump 4 was immediately reduced and the temperature was rapidly cooled to room temperature (cooling time was approximately 15 min). After venting, the liquid product was collected and analyzed to calculate the conversion and selectivity.

[0049] During the reaction process, the linear velocity of the fluid at the nozzle of the Venturi ejector is controlled to be 90 m / s. The detailed design dimensions are as follows: the ratio of the inlet section opening inner diameter D1: the nozzle inner diameter D2: the air chamber closing inner diameter D3: the mixing section length L1: the diffusion section length L2 is 38:3:4.5:30:1250, and the diffusion section opening angle α is 20°. Figure 2 Analysis of the reaction products showed a glycerol conversion of 44.5%, a selectivity of 30.2% for 1,3-propylene glycol, and a selectivity of 50.9% for 1,2-propylene glycol, with a ratio of 1,3 / 1,2 = 0.6. The catalyst utilization, i.e., the amount of glycerol processed per unit catalyst and per unit time, was 11.1 g / (g·h).

[0050] Example 2

[0051] To a 5L loop reactor (5L reactor volume), 3000g of 20wt% glycerol methanol solution was added, along with 24g of Pt / WO3-ZrO2 powder, a catalyst pre-reduced at 200°C for 2h, i.e., a 4wt% relative ratio of catalyst to reactant glycerol. The catalyst preparation raw material, zirconium hydroxide powder, and ammonium tungstate solution were measured in a mass ratio of WO3 to ZrO2 of 7:100, and the amount of H2PtCl6 was measured in an amount of 1.5% of the mass of the WO3-ZrO2 composite oxide sample, based on the mass of the element Pt. Hydrogen was introduced into the reactor through the air inlet to a system pressure of 1MPa. A circulating pump was turned on to allow the liquid in the reactor to flow slowly, followed by emptying. The air in the replacement loop reactor was repeated six times, followed by heating to a preset reaction temperature of 160°C (heating time of approximately 15min), followed by immediate addition of hydrogen to a reaction pressure of 2MPa. The circulating pump 4 was adjusted to a flow velocity of 90m / s, which was recorded as the reaction start time. During the reaction, the hydrogen pressure in the connected reactor was maintained at a constant 2 MPa and the temperature at 160 ± 1°C. After 1 h of reaction, the flow rate of circulating pump 4 was immediately reduced and the temperature was rapidly cooled to room temperature (cooling time was approximately 15 min). After venting, the liquid product was collected and analyzed to calculate the conversion and selectivity.

[0052] During the reaction process, the linear velocity of the fluid at the nozzle of the Venturi ejector is controlled to be 90 m / s. The detailed design dimensions are as follows: the ratio of the inlet section opening inner diameter D1: the nozzle inner diameter D2: the air chamber closing inner diameter D3: the mixing section length L1: the diffusion section length L2 is 38:3:4.5:30:1250, and the diffusion section opening angle α is 20°. Figure 2 Analysis of the reaction products showed a glycerol conversion of 56.1%, a selectivity of 47.9% for 1,3-propylene glycol, and a selectivity of 34.1% for 1,2-propylene glycol, with a ratio of 1,3 / 1,2 = 1.4. The catalyst utilization rate, i.e., the amount of glycerol processed per unit catalyst per unit time, was 14 g / (g·h).

[0053] Example 3

[0054] To a 5L loop reactor (5L reactor volume), 3000g of 20wt% glycerol methanol solution was added, and 24g of Pt / WO3-ZrO2 powder, a catalyst pre-reduced at 200°C for 2h, was added, i.e., the relative ratio of catalyst to reactant glycerol was 4wt%. The amount of the raw material zirconium hydroxide powder added and the amount of ammonium tungstate solution added were measured at a mass ratio of WO3 to ZrO2 of 9:100, and the amount of H2PtCl6 added accounted for 1.5% of the mass of the WO3-ZrO2 composite oxide sample with the mass of element Pt. Hydrogen was introduced into the reactor through the air inlet to a system pressure of 1MPa. A circulating pump was turned on to allow the liquid in the kettle to flow slowly, and the reactor was vented. After the air in the replacement loop reactor was heated to a preset reaction temperature of 160°C (heating time of about 15min), hydrogen was immediately added to the reaction pressure of 2MPa. The circulating pump 4 was adjusted to a flow velocity of 90m / s, which was recorded as the reaction start time. During the reaction, the hydrogen pressure in the connected reactor was maintained at a constant 2 MPa and the temperature at 160 ± 1°C. After 1 h of reaction, the flow rate of circulating pump 4 was immediately reduced and the temperature was rapidly cooled to room temperature (cooling time was approximately 15 min). After venting, the liquid product was collected and analyzed to calculate the conversion and selectivity.

[0055] During the reaction process, the linear velocity of the fluid at the nozzle of the Venturi ejector is controlled to be 90 m / s. The detailed design dimensions are as follows: the ratio of the inlet section opening inner diameter D1: the nozzle inner diameter D2: the air chamber closing inner diameter D3: the mixing section length L1: the diffusion section length L2 is 38:3:4.5:30:1250, and the diffusion section opening angle α is 20°. Figure 2 Analysis of the reaction products showed a glycerol conversion of 67.2%, a selectivity for 1,3-propylene glycol of 62.9%, a selectivity for 1,2-propylene glycol of 20.4%, a ratio of 1,3 / 1,2 = 3.1, and a catalyst utilization rate of 16.8 g glycerol / (g·h) per unit catalyst and per unit time.

[0056] Example 4

[0057] To a 5L loop reactor (5L reactor volume), 3000g of 20wt% glycerol methanol solution was added, and 24g of Pt / WO3-ZrO2 powder, a catalyst pre-reduced at 200°C for 2h, was added, i.e., the relative ratio of catalyst to reactant glycerol was 4wt%. The amount of the raw material zirconium hydroxide powder added and the amount of ammonium tungstate solution added were measured at a mass ratio of 13:100 for WO3 and ZrO2, and the amount of H2PtCl6 added accounted for 1.5% of the mass of the WO3-ZrO2 composite oxide sample with the mass of elemental Pt. Hydrogen was introduced into the reactor through the air inlet to a system pressure of 1MPa. A circulating pump was turned on to allow the liquid in the kettle to flow slowly, and the reactor was vented. After the air in the replacement loop reactor was heated to a preset reaction temperature of 160°C (heating time of about 15min), hydrogen was immediately added to the reaction pressure of 2MPa. The circulating pump 4 was adjusted to a flow velocity of 90m / s, which was recorded as the reaction start time. During the reaction, the hydrogen pressure in the connected reactor was maintained at a constant 2 MPa and the temperature at 160 ± 1°C. After 1 h of reaction, the flow rate of circulating pump 4 was immediately reduced and the temperature was rapidly cooled to room temperature (cooling time was approximately 15 min). After venting, the liquid product was collected and analyzed to calculate the conversion and selectivity.

[0058] During the reaction process, the linear velocity of the fluid at the nozzle of the Venturi ejector is controlled to be 90 m / s. The detailed design dimensions are as follows: the ratio of the inlet section opening inner diameter D1: the nozzle inner diameter D2: the air chamber closing inner diameter D3: the mixing section length L1: the diffusion section length L2 is 38:3:4.5:30:1250, and the diffusion section opening angle α is 20°. Figure 2 Analysis of the reaction products showed a glycerol conversion of 50.8%, a selectivity of 60.5% for 1,3-propylene glycol, and a selectivity of 19.6% for 1,2-propylene glycol, with a ratio of 1,3 / 1,2 = 3.1. The catalyst utilization, i.e., the amount of glycerol processed per unit catalyst and per unit time, was 12.7 g / (g·h).

[0059] Example 5

[0060] To a 5L loop reactor (5L reactor volume), 3000g of 20wt% glycerol methanol solution was added, and 24g of Pt / WO3-ZrO2 powder, a catalyst pre-reduced at 200°C for 2h, was added, i.e., the relative ratio of catalyst to reactant glycerol was 4wt%. The amount of the raw material zirconium hydroxide powder added and the amount of ammonium tungstate solution added were measured at a mass ratio of 17:100 for WO3 and ZrO2, and the amount of H2PtCl6 added was measured at 1.5% of the mass of the WO3-ZrO2 composite oxide sample based on the mass of the element Pt. Hydrogen was introduced into the reactor through the air inlet to a system pressure of 1MPa. A circulating pump was turned on to allow the liquid in the kettle to flow slowly, and the reactor was vented. After the air in the replacement loop reactor was heated to a preset reaction temperature of 160°C (heating time of about 15min), hydrogen was immediately added to the reaction pressure of 2MPa. The circulating pump 4 was adjusted to a flow velocity of 90m / s, which was recorded as the reaction start time. During the reaction, the hydrogen pressure in the connected reactor was maintained at a constant 2 MPa and the temperature at 160 ± 1°C. After 1 h of reaction, the flow rate of circulating pump 4 was immediately reduced and the temperature was rapidly cooled to room temperature (cooling time was approximately 15 min). After venting, the liquid product was collected and analyzed to calculate the conversion and selectivity.

[0061] During the reaction process, the linear velocity of the fluid at the nozzle of the Venturi ejector is controlled to be 90 m / s. The detailed design dimensions are as follows: the ratio of the inlet section opening inner diameter D1: the nozzle inner diameter D2: the air chamber closing inner diameter D3: the mixing section length L1: the diffusion section length L2 is 38:3:4.5:30:1250, and the diffusion section opening angle α is 20°. Figure 2 Analysis of the reaction products showed a glycerol conversion of 43.5%, a selectivity of 51.3% for 1,3-propylene glycol, and a selectivity of 28.4% for 1,2-propylene glycol, with a ratio of 1,3 / 1,2 = 1.8. The catalyst utilization, i.e., the amount of glycerol processed per unit catalyst and per unit time, was 10.9 g / (g·h).

[0062] It can be seen from Examples 1 to 5 that under the same reaction conditions, as the WO3 content in the WO3-ZrO2 composite oxide support increases, the glycerol conversion rate (catalyst utilization) and the selectivity of the product 1,3-propylene glycol reach optimal values ​​(see Example 3).

[0063] Comparative Examples 6 to 10 use Pt / WO3 / ZrO2 catalysts, and their preparation methods are as follows:

[0064] Dissolve the measured amount of zirconium nitrate in deionized water, wherein the zirconium nitrate accounts for 4-7wt% of the mass of the aqueous solution, add concentrated ammonia water dropwise, adjust the pH value to 9-10, continue stirring for 0.5h, then age at room temperature for 4h, filter and wash until the pH value of the filtrate is 7, dry at 110℃ for 5h, grind into powder, heat to 500℃ at a rate of 3℃ / min, keep constant temperature for 2h, and naturally cool to room temperature to obtain ZrO2 powder.

[0065] The amount of ammonium tungstate H 40 N 10 O 41 W 12 xH2O (AR from Sinopharm Chemical Reagent Co., Ltd.) and oxalic acid H2C2O4·2H2O (AR from Sinopharm Chemical Reagent Co., Ltd.) were dissolved in a certain amount of deionized water at a mass ratio of 1:1 to prepare a solution with a W atomic concentration of 0.08 mol / L.

[0066] Weigh a measured amount of zirconium oxide powder into a glass container. After evacuating the container for 1 hour, add a predetermined volume of the aforementioned ammonium tungstate solution. Stir and evaporate to dryness in a 95°C water bath, then air-dry at 110°C for 5 hours. After grinding, place the sample in a tube furnace and heat to 500°C at a rate of 3°C / min. Maintain the temperature for 2 hours, then cool to room temperature to obtain a WO3 / ZrO2 sample. Subsequent Pt loading and dechlorination steps are identical to those used in the preparation of the Pt / WO3-ZrO2 catalyst of the present invention.

[0067] Comparative Example 6

[0068] To a 5L loop reactor (5L reactor volume), 3000g of 20wt% glycerol methanol solution was added, along with 24g of Pt / WO3 / ZrO2 powder, a catalyst pre-reduced at 200°C for 2h, i.e., a 4wt% relative ratio of catalyst to reactant glycerol. The catalyst preparation raw material zirconium oxide powder and ammonium tungstate solution were measured at a mass ratio of WO3 to ZrO2 of 4:100, and the amount of H2PtCl6 added was measured with the mass of elemental Pt accounting for 1.5% of the mass of the WO3 / ZrO2 sample. Hydrogen was introduced into the reactor through the air inlet to a system pressure of 1MPa. A circulating pump was turned on to allow the liquid in the reactor to flow slowly, followed by emptying. This process was repeated six times, with the air in the replacement loop reactor heated to a preset reaction temperature of 160°C (heating time of approximately 15min). The reactor was immediately filled with hydrogen to a reaction pressure of 2MPa. The circulating pump 4 was adjusted to a flow velocity of 90m / s, which was recorded as the reaction start time. During the reaction, the hydrogen pressure in the connected reactor was maintained at a constant 2 MPa and the temperature at 160 ± 1°C. After 1 h of reaction, the flow rate of circulating pump 4 was immediately reduced and the temperature was rapidly cooled to room temperature (cooling time was approximately 15 min). After venting, the liquid product was collected and analyzed to calculate the conversion and selectivity.

[0069] During the reaction process, the linear velocity of the fluid at the nozzle of the Venturi ejector is controlled to be 90 m / s. The detailed design dimensions are as follows: the ratio of the inlet section opening inner diameter D1: the nozzle inner diameter D2: the air chamber closing inner diameter D3: the mixing section length L1: the diffusion section length L2 is 38:3:4.5:30:1250, and the diffusion section opening angle α is 20°. Figure 2Analysis of the reaction products showed a glycerol conversion of 22.1%, a product 1,3-propylene glycol selectivity of 25.5%, a 1,2-propylene glycol selectivity of 46.2%, a ratio of 1,3 / 1,2 = 0.6, and a catalyst utilization rate of 5.5 g glycerol / (g·h) per unit catalyst and unit time.

[0070] Comparative Example 7

[0071] To a 5L loop reactor (5L reactor volume), 3000g of a 20wt% glycerol methanol solution was added, along with 24g of a catalyst Pt / WO3 / ZrO2 powder pre-reduced at 200°C for 2h, i.e., a 4wt% relative ratio of catalyst to reactant glycerol. The catalyst preparation raw material zirconium oxide powder and ammonium tungstate solution were measured at a mass ratio of WO3 to ZrO2 of 7:100, and the amount of H2PtCl6 was measured with the mass of elemental Pt accounting for 1.5% of the mass of the WO3 / ZrO2 sample. Hydrogen was introduced into the reactor through the air inlet to a system pressure of 1MPa. A circulating pump was turned on to allow the liquid in the reactor to flow slowly, and the reactor was vented. This was repeated six times to replace the air in the loop reactor until it was heated to a preset reaction temperature of 160°C (heating time of approximately 15min). Hydrogen was then added immediately to a reaction pressure of 2MPa. The circulating pump 4 was adjusted to a flow rate of 90m / s, which was recorded as the reaction start time. During the reaction, the hydrogen pressure in the connected reactor was maintained at a constant 2 MPa and the temperature at 160 ± 1°C. After 1 h of reaction, the flow rate of circulating pump 4 was immediately reduced and the temperature was rapidly cooled to room temperature (cooling time was approximately 15 min). After venting, the liquid product was collected and analyzed to calculate the conversion and selectivity.

[0072] During the reaction process, the linear velocity of the fluid at the nozzle of the Venturi ejector is controlled to be 90 m / s. The detailed design dimensions are as follows: the ratio of the inlet section opening inner diameter D1: the nozzle inner diameter D2: the air chamber closing inner diameter D3: the mixing section length L1: the diffusion section length L2 is 38:3:4.5:30:1250, and the diffusion section opening angle α is 20°. Figure 2 Analysis of the reaction products showed a glycerol conversion of 40.2%, a selectivity of 31.6% for 1,3-propylene glycol, and a selectivity of 29.3% for 1,2-propylene glycol. The ratio 1,3 / 1,2 was 1.1, and the catalyst utilization rate was 10 g of glycerol per unit catalyst per unit time / (g·h).

[0073] Comparative Example 8

[0074] To a 5L loop reactor (5L reactor volume), 3000g of 20wt% glycerol methanol solution was added, along with 24g of Pt / WO3 / ZrO2 powder, a catalyst pre-reduced at 200°C for 2h, resulting in a 4wt% catalyst to reactant glycerol ratio. The catalyst preparation raw material, zirconium oxide powder, and ammonium tungstate solution were measured at a mass ratio of WO3 to ZrO2 of 9:100, and H2PtCl6 was measured at a mass of elemental Pt relative to the mass of the WO3 / ZrO2 sample. Hydrogen was introduced into the reactor through the air inlet to a system pressure of 1MPa. A circulating pump was turned on to allow the liquid in the reactor to flow slowly, followed by venting. This process was repeated six times, with the air in the replacement loop reactor heated to a preset reaction temperature of 160°C (heating time of approximately 15min). The reactor was immediately filled with hydrogen to a reaction pressure of 2MPa. The circulating pump 4 was adjusted to a flow rate of 90m / s, which was recorded as the reaction start time. During the reaction, the hydrogen pressure in the connected reactor was maintained at a constant 2 MPa and the temperature at 160 ± 1°C. After 1 h of reaction, the flow rate of circulating pump 4 was immediately reduced and the temperature was rapidly cooled to room temperature (cooling time was approximately 15 min). After venting, the liquid product was collected and analyzed to calculate the conversion and selectivity.

[0075] During the reaction process, the linear velocity of the fluid at the nozzle of the Venturi ejector is controlled to be 90 m / s. The detailed design dimensions are as follows: the ratio of the inlet section opening inner diameter D1: the nozzle inner diameter D2: the air chamber closing inner diameter D3: the mixing section length L1: the diffusion section length L2 is 38:3:4.5:30:1250, and the diffusion section opening angle α is 20°. Figure 2 Analysis of the reaction products showed a glycerol conversion of 53.2%, a selectivity for 1,3-propylene glycol of 43.1%, a selectivity for 1,2-propylene glycol of 18.4%, a ratio of 1,3 / 1,2 = 2.3, and a catalyst utilization rate of 13.3 g glycerol / (g·h) per unit catalyst and per unit time.

[0076] Comparative Example 9

[0077] To a 5L loop reactor (5L reactor volume), 3000g of 20wt% glycerol methanol solution was added, along with 24g of Pt / WO3 / ZrO2 powder, a catalyst pre-reduced at 200°C for 2h, resulting in a 4wt% catalyst to reactant glycerol ratio. The catalyst preparation raw material, zirconium oxide powder, and ammonium tungstate solution were measured at a mass ratio of 13:100 for WO3 and ZrO2, and H2PtCl6 was measured at a mass of 1.5% of the WO3 / ZrO2 sample mass based on the mass of elemental Pt. Hydrogen was introduced into the reactor through the air inlet to a system pressure of 1MPa. A circulating pump was turned on to allow the liquid in the reactor to flow slowly, followed by venting. This process was repeated six times, with the air in the replacement loop reactor heated to a preset reaction temperature of 160°C (heating time of approximately 15min). The reactor was immediately filled with hydrogen to a reaction pressure of 2MPa. The circulating pump 4 was adjusted to a flow rate of 90m / s, which was recorded as the reaction start time. During the reaction, the hydrogen pressure in the connected reactor was maintained at a constant 2 MPa and the temperature at 160 ± 1°C. After 1 h of reaction, the flow rate of circulating pump 4 was immediately reduced and the temperature was rapidly cooled to room temperature (cooling time was approximately 15 min). After venting, the liquid product was collected and analyzed to calculate the conversion and selectivity.

[0078] During the reaction process, the linear velocity of the fluid at the nozzle of the Venturi ejector is controlled to be 90 m / s. The detailed design dimensions are as follows: the ratio of the inlet section opening inner diameter D1: the nozzle inner diameter D2: the air chamber closing inner diameter D3: the mixing section length L1: the diffusion section length L2 is 38:3:4.5:30:1250, and the diffusion section opening angle α is 20°. Figure 2 Analysis of the reaction products showed a glycerol conversion of 38.7%, a selectivity for 1,3-propylene glycol of 40.5%, a selectivity for 1,2-propylene glycol of 19.6%, a ratio of 1,3 / 1,2 = 2.1, and a catalyst utilization rate of 9.7 g glycerol / (g·h) per unit catalyst and per unit time.

[0079] Comparative Example 10

[0080] To a 5L loop reactor (5L reactor volume), 3000g of 20wt% glycerol methanol solution was added, along with 24g of Pt / WO3 / ZrO2 powder, a catalyst pre-reduced at 200°C for 2h, resulting in a 4wt% catalyst to reactant glycerol ratio. The catalyst preparation raw material, zirconium oxide powder, and ammonium tungstate solution were measured at a mass ratio of 13:100 for WO3 and ZrO2, and H2PtCl6 was measured at a mass of 1.5% of the WO3 / ZrO2 sample mass based on the mass of elemental Pt. Hydrogen was introduced into the reactor through the air inlet to a system pressure of 1MPa. A circulating pump was turned on to allow the liquid in the reactor to flow slowly, followed by venting. This process was repeated six times, with the air in the replacement loop reactor heated to a preset reaction temperature of 160°C (heating time of approximately 15min). The reactor was immediately filled with hydrogen to a reaction pressure of 2MPa. The circulating pump 4 was adjusted to a flow rate of 90m / s, which was recorded as the reaction start time. During the reaction, the hydrogen pressure in the connected reactor was maintained at a constant 2 MPa and the temperature at 160 ± 1°C. After 1 h of reaction, the flow rate of circulating pump 4 was immediately reduced and the temperature was rapidly cooled to room temperature (cooling time was approximately 15 min). After venting, the liquid product was collected and analyzed to calculate the conversion and selectivity.

[0081] During the reaction process, the linear velocity of the fluid at the nozzle of the Venturi ejector is controlled to be 90 m / s. The detailed design dimensions are as follows: the ratio of the inlet section opening inner diameter D1: the nozzle inner diameter D2: the air chamber closing inner diameter D3: the mixing section length L1: the diffusion section length L2 is 38:3:4.5:30:1250, and the diffusion section opening angle α is 20°. Figure 2 Analysis of the reaction products showed a glycerol conversion of 35.6%, a selectivity for 1,3-propylene glycol of 35.8%, a selectivity for 1,2-propylene glycol of 26.7%, a ratio of 1,3 / 1,2 = 1.3, and a catalyst utilization rate of 8.9 g glycerol / (g·h) per unit catalyst and unit time.

[0082] From the test results of Example 1 and Comparative Example 6, Example 2 and Comparative Example 7, Example 3 and Comparative Example 8, Example 4 and Comparative Example 9, and Example 5 and Comparative Example 10, it can be seen that when other reaction conditions are the same, the preparation method of the catalyst has a greater influence on the glycerol hydrogenation reaction performance of the final catalyst, and the Pt / WO3-ZrO2 catalyst obtained by loading tungsten salt with zirconium hydroxide as the carrier is more suitable for the loop reactor glycerol hydrogenation process.

[0083] Example 11

[0084] To a 5L loop reactor (5L reactor volume), 3000g of 20wt% glycerol methanol solution was added, along with 24g of Pt / WO3-ZrO2 powder pre-reduced at 200°C for 2h, i.e., a 4wt% relative ratio of catalyst to reactant glycerol. The catalyst preparation raw material, zirconium hydroxide powder, and ammonium tungstate solution were measured in a mass ratio of WO3 to ZrO2 of 9:100, and the amount of H2PtCl6 was measured in an amount where the mass of elemental Pt accounted for 1.5% of the mass of the WO3-ZrO2 composite oxide sample. Hydrogen was introduced into the reactor through the air inlet to a system pressure of 1MPa. A circulating pump was turned on to allow the liquid in the reactor to flow slowly, followed by emptying. The air in the replacement loop reactor was heated to a preset reaction temperature of 160°C (heating time of approximately 15min) six times, followed by the addition of hydrogen to a reaction pressure of 2MPa. The circulating pump 4 was adjusted to a flow rate of 105m / s, which was recorded as the reaction start time. During the reaction, the hydrogen pressure in the connected reactor was maintained at a constant 2 MPa and the temperature at 160 ± 1°C. After 1 h of reaction, the flow rate of circulating pump 4 was immediately reduced and the temperature was rapidly cooled to room temperature (cooling time was approximately 15 min). After venting, the liquid product was collected and analyzed to calculate the conversion and selectivity.

[0085] During the reaction process, the linear velocity of the fluid at the nozzle of the Venturi ejector is controlled to be 105 m / s. The detailed design dimensions are as follows: the ratio of the inlet section opening inner diameter D1: the nozzle inner diameter D2: the air chamber closing inner diameter D3: the mixing section length L1: the diffusion section length L2 is 38:3:4:45:1100, and the diffusion section opening angle α is 17°. Figure 2 Analysis of the reaction products showed a glycerol conversion of 84.2%, a 1,3-propylene glycol selectivity of 72.3%, and a 1,2-propylene glycol selectivity of 18.3%, with a ratio of 1,3 / 1,2 = 4. The catalyst utilization rate, i.e., the amount of glycerol processed per unit catalyst per unit time, was 21 g / (g·h).

[0086] Example 12

[0087] To a 5L loop reactor (5L reactor volume), 3000g of 20wt% glycerol methanol solution was added, along with 24g of Pt / WO3-ZrO2 powder, a catalyst pre-reduced at 200°C for 2h, i.e., a 4wt% relative ratio of catalyst to reactant glycerol. The catalyst preparation raw material, zirconium hydroxide powder, and ammonium tungstate solution were measured in a mass ratio of WO3 to ZrO2 of 9:100, and the amount of H2PtCl6 was measured in an amount of 1.5% of the mass of the WO3-ZrO2 composite oxide sample based on the mass of the element Pt. Hydrogen was introduced into the reactor through the air inlet to a system pressure of 1MPa. A circulating pump was turned on to allow the liquid in the reactor to flow slowly, followed by emptying. The air in the replacement loop reactor was heated to a preset reaction temperature of 160°C (heating time of approximately 15min) six times, followed by the addition of hydrogen to a reaction pressure of 2MPa. The circulating pump 4 was adjusted to a flow velocity of 83m / s, which was recorded as the reaction start time. During the reaction, the hydrogen pressure in the connected reactor was maintained at a constant 2 MPa and the temperature at 160 ± 1°C. After 1 h of reaction, the flow rate of circulating pump 4 was immediately reduced and the temperature was rapidly cooled to room temperature (cooling time was approximately 15 min). After venting, the liquid product was collected and analyzed to calculate the conversion and selectivity.

[0088] During the reaction process, the linear velocity of the fluid at the nozzle of the Venturi ejector is controlled to be 83 m / s. The detailed design dimensions are as follows: the ratio of the inlet section opening inner diameter D1: the nozzle inner diameter D2: the air chamber closing inner diameter D3: the mixing section length L1: the diffusion section length L2 is 38:2:3.5:50:1500, and the diffusion section opening angle α is 24°. Figure 2 Analysis of the reaction products showed a glycerol conversion of 52.4%, a product 1,3-propylene glycol selectivity of 50.9%, a 1,2-propylene glycol selectivity of 36.4%, a ratio of 1,3 / 1,2 = 1.4, and a catalyst utilization rate of 13.1 g glycerol / (g·h) per unit catalyst and per unit time.

[0089] Example 13

[0090] To a 5L loop reactor (5L reactor volume), 3000g of a 20wt% glycerol methanol solution was added, along with 24g of a catalyst Pt / WO3-ZrO2 powder pre-reduced at 200°C for 2h, i.e., a 4wt% relative ratio of catalyst to reactant glycerol. The catalyst preparation raw material zirconium hydroxide powder and ammonium tungstate solution were measured at a mass ratio of WO3 to ZrO2 of 9:100, and the amount of H2PtCl6 was measured at a mass of elemental Pt accounting for 1.5% of the mass of the WO3-ZrO2 composite oxide sample. Hydrogen was introduced into the reactor through the air inlet to a system pressure of 1MPa. A circulating pump was turned on to allow the liquid in the reactor to flow slowly, followed by venting. This process was repeated six times, with the air in the replacement loop reactor heated to a preset reaction temperature of 160°C (heating time of approximately 15min). The reactor was immediately filled with hydrogen to a reaction pressure of 2MPa. The circulating pump 4 was adjusted to a flow rate of 110m / s, which was recorded as the reaction start time. During the reaction, the hydrogen pressure in the connected reactor was maintained at a constant 2 MPa and the temperature at 160 ± 1°C. After 1 h of reaction, the flow rate of circulating pump 4 was immediately reduced and the temperature was rapidly cooled to room temperature (cooling time was approximately 15 min). After venting, the liquid product was collected and analyzed to calculate the conversion and selectivity.

[0091] During the reaction process, the linear velocity of the fluid at the nozzle of the Venturi ejector is controlled to be 110 m / s. The detailed design dimensions are as follows: the ratio of the inlet section opening inner diameter D1: the nozzle inner diameter D2: the air chamber closing inner diameter D3: the mixing section length L1: the diffusion section length L2 is 38:2.5:3.5:65:1250, and the diffusion section opening angle α is 28°. Figure 2 Analysis of the reaction products showed a glycerol conversion of 63.1%, a selectivity of 57.4% for 1,3-propylene glycol, and a selectivity of 34.9% for 1,2-propylene glycol, with a ratio of 1,3 / 1,2 = 1.6. The catalyst utilization, i.e., the amount of glycerol processed per unit catalyst and per unit time, was 15.8 g / (g·h).

[0092] Example 14

[0093] To a 5L loop reactor (5L reactor volume), 3000g of 20wt% glycerol methanol solution was added, along with 24g of Pt / WO3-ZrO2 powder, a catalyst pre-reduced at 200°C for 2h, i.e., a 4wt% relative ratio of catalyst to reactant glycerol. The catalyst preparation raw material, zirconium hydroxide powder, and ammonium tungstate solution were measured in a mass ratio of WO3 to ZrO2 of 9:100, and the amount of H2PtCl6 was measured in an amount where the mass of elemental Pt accounted for 1.5% of the mass of the WO3-ZrO2 composite oxide sample. Hydrogen was introduced into the reactor through the air inlet to a system pressure of 1MPa. A circulating pump was turned on to allow the liquid in the reactor to flow slowly, followed by emptying. This process was repeated six times, with the air in the replacement loop reactor heated to a preset reaction temperature of 160°C (heating time of approximately 15min). The reactor was immediately filled with hydrogen to a reaction pressure of 2MPa. The circulating pump 4 was adjusted to a flow rate of 115m / s, which was recorded as the reaction start time. During the reaction, the hydrogen pressure in the connected reactor was maintained at a constant 2 MPa and the temperature at 160 ± 1°C. After 1 h of reaction, the flow rate of circulating pump 4 was immediately reduced and the temperature was rapidly cooled to room temperature (cooling time was approximately 15 min). After venting, the liquid product was collected and analyzed to calculate the conversion and selectivity.

[0094] During the reaction process, the linear velocity of the fluid at the nozzle of the Venturi ejector is controlled to be 115 m / s. The detailed design dimensions are as follows: the ratio of the inlet section opening inner diameter D1: the nozzle inner diameter D2: the air chamber closing inner diameter D3: the mixing section length L1: the diffusion section length L2 is 38:3:4.5:40:850, and the diffusion section opening angle α is 31°. Figure 2 Analysis of the reaction products showed a glycerol conversion of 71.6%, a selectivity of 65.7% for 1,3-propylene glycol, and a selectivity of 20.7% for 1,2-propylene glycol, with a ratio of 1,3 / 1,2 = 3.2. The catalyst utilization, i.e., the amount of glycerol processed per unit catalyst and per unit time, was 17.9 g / (g·h).

[0095] Comparative Example 1 (Reactor Hydrogenation)

[0096] 1000 g of 20% glycerol methanol solution was added to a 2L reactor, 10 g of catalyst Pt / WO3-ZrO2 powder pre-reduced at 200°C for 2 h was added (the same catalyst Pt / WO3-ZrO2 as in Example 3 of the present invention was used, with a mass of 5 wt% of the reactant glycerol) and hydrogen was introduced at 1 MPa for replacement 6 times. The reaction temperature was 160°C and the hydrogen pressure was 5 MPa (hydrogen withstood the pressure, i.e., the hydrogen gas valve was not closed). The reaction time was 5 h. The reactor was cooled, the pressure was released, and sampling was performed for analysis. The glycerol conversion rate was less than 0.9%.

[0097] Comparative Example 2 (Fixed Bed Hydrogenation)

[0098] The catalyst Pt / WO3-ZrO2 (the same catalyst Pt / WO3-ZrO2 powder as in Example 3 of the present invention) was pressed into 20-40 mesh particles (2 g) and sieved in a fixed bed. The mixture was reduced with hydrogen at atmospheric pressure (200°C, 5°C / min, for 2 h). The temperature was then lowered to 160°C, the pressure was increased to 4 MPa, and a 20% glycerol-methanol solution was fed. The mass space velocity of glycerol was 0.25 h / min. -1 , hydrogen flow rate 150ml / min, after 10h of reaction, the stable glycerol conversion rate is 61.6%, 1,3-propylene glycol selectivity is 34.3%, 1,2-propylene glycol selectivity is 14.1%, 1,3 / 1,2=2.4, and the catalyst utilization rate, that is, the processing capacity per unit catalyst per unit time is 0.195g glycerol / (g·h).

Claims

1. A method for preparing 1,3-propylene glycol, characterized in that: The 1,3-propylene glycol is prepared by hydrogenation reaction in a loop reactor using glycerol as raw material and Pt / WO3-ZrO2 as catalyst; the ratio of the opening inner diameter of the inlet section of the Venturi injector in the loop reactor: the inner diameter of the nozzle: the inner diameter of the air chamber closing: the length of the mixing section: the length of the diffusion section is 38:3:4:45:1100, and the opening angle of the diffusion section is 17°; the catalyst is powdered Pt / WO3-ZrO2, which is prepared by the following method: taking WO3-ZrO2 composite oxide powder and adding it to a glass container, adding H2PtCl6 solution under vacuum conditions, stirring and evaporating to dryness in a water bath, drying and grinding, and then placing it in a tube furnace for dechlorination treatment to obtain the catalyst Pt / WO3-ZrO2; the element Pt in the chloroplatinic acid is WO3- The WO3-ZrO2 composite oxide is 1.5% by mass of the ZrO2 composite oxide. The WO3-ZrO2 composite oxide is prepared with zirconium hydroxide powder and ammonium tungstate as main raw materials. The mass ratio of element W and element Zr in the raw materials ammonium tungstate and zirconium hydroxide is measured according to the mass ratio of WO3:ZrO2 of 9:

100. The WO3-ZrO2 composite oxide is prepared by the following method: taking zirconium hydroxide powder and placing it in a reaction container, adding a mixed aqueous solution of ammonium tungstate and oxalic acid under vacuum conditions, stirring and evaporating to dryness in a water bath, drying and grinding, placing it in a tube furnace, heating to 480℃~520℃, keeping the temperature constant for 1.5h~2.5h, and cooling to room temperature to obtain WO3-ZrO2 composite oxide; the zirconium hydroxide powder is prepared by the following method: using an ammonia precipitation method, adding concentrated ammonia dropwise to the zirconium nitrate aqueous solution, adjusting the pH value to 9~10, continuing stirring for 0.5h, aging at room temperature for 4h, filtering and washing until the pH value of the filtrate is 7, and the obtained filter cake is dried at 110℃ for 5 h is ground into zirconium hydroxide powder; the preparation method of the 1,3-propylene glycol is as follows: analytical pure glycerol is dissolved in methanol to prepare a glycerol methanol solution, which is added to the reactor of a loop reactor, and a Pt / WO3-ZrO2 powder catalyst pre-reduced by hydrogen at 200°C for 2h is quickly added to the reactor to carry out a hydrogenation reaction; the reaction pressure during the hydrogenation reaction is 2MPa, the reaction temperature is 160±1°C, and the reaction time is 1h; during the hydrogenation reaction, the fluid linear velocity at the nozzle of the Venturi injector is 105m / s; the mass concentration of the glycerol methanol solution is 20%, and the amount of the added catalyst Pt / WO3-ZrO2 accounts for 4% of the mass of the glycerol.

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