A process for the preparation of p-phenylene diethyl ether

Abstract

This invention discloses a method for preparing diethyl phenylene ether (DPE). The method utilizes hydroquinone and diethyl carbonate in the presence of a catalyst, specifically a Zr / Ho supported SAPO molecular sieve catalyst, to achieve high selectivity for DPE. This process is environmentally friendly, produces minimal waste, and features a highly active and stable catalyst with simple separation capabilities, resulting in a high product yield and promising prospects for industrial application.

Description

Technical Field

[0001] This invention belongs to the field of chemical synthesis, and specifically relates to a method for preparing p-phenylenediethyl ether. Background Technology

[0002] p-Phenylene diethyl ether, also known as 1,4-diethoxybenzene, p-diethoxybenzene, hydroquinone diethyl ether, or hydroquinone diethyl ether, has a melting point of 69-72℃ and a boiling point of 246℃. It is a white crystalline solid with a strong anise flavor and can be used in the formulation of fragrances or as a flavor enhancer. It is also an important organic synthesis intermediate used in the synthesis of pesticides, pharmaceuticals, fuels, and reagents.

[0003] Currently, the synthesis methods for terephthalic diethyl ether include the bromoethane method and the diethyl sulfate method. The bromoethane method involves a substitution reaction between hydroquinone and bromoethane under alkaline conditions to remove two molecules of hydrogen bromide, yielding terephthalic diethyl ether. This method has a low yield, and halogens cause severe corrosion to equipment, resulting in large equipment investment and significant challenges for industrial production. The diethyl sulfate method involves a direct reaction between hydroquinone and diethyl sulfate to obtain terephthalic diethyl ether; however, the raw material, diethyl sulfate, is a highly toxic chemical, posing high risks during transportation and storage, and also suffers from drawbacks such as low product purity and difficulty in treating waste.

[0004] Therefore, it is of great significance to develop a new process for the preparation of p-phenylenediethyl ether that is green and environmentally friendly, has high product selectivity, and good catalyst stability. Summary of the Invention

[0005] One objective of this invention is to provide a method for preparing diethyl phenylene ether, which uses hydroquinone and diethyl carbonate to catalyze the formation of diethyl phenylene ether under the action of a catalyst. In this method, the raw material diethyl carbonate has low toxicity, and its transportation and storage safety is far superior to that of bromoethane and diethyl sulfate. Furthermore, the product has high selectivity, with only CO2 and ethanol as byproducts, making it environmentally friendly. Moreover, the catalyst exhibits strong reactivity, good stability, and simple separation, showing promising prospects for industrial application.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing p-phenylenediethyl ether, wherein the preparation method involves the catalytic reaction of hydroquinone and diethyl carbonate to produce p-phenylenediethyl ether under the action of a catalyst; wherein the catalyst is a Zr / Ho supported SAPO molecular sieve catalyst.

[0008] The SAPO molecular sieve catalyst of this invention is a supported catalyst obtained by rationally modifying the acid-base sites on the SAPO molecular sieve with Zr / Ho elements, which can improve the selectivity of the product p-phenylenediethyl ether. Furthermore, the Zr / Ho elements are supported in the unique pore structure of the molecular sieve, optimizing the distribution of acid-base sites and resulting in a significant enhancement of the catalytic activity of the supported molecular sieve catalyst.

[0009] In one embodiment of the present invention, the molar ratio of hydroquinone and diethyl carbonate is 1:(2-2.2).

[0010] In one embodiment of the present invention, the mass ratio of hydroquinone to solvent is 1:(1-3).

[0011] In one embodiment of the present invention, the catalyst mass is 5-20% of the mass of hydroquinone.

[0012] In one embodiment of the present invention, the reaction pressure is 0.2-1 MPaG, the temperature is 70-150°C, and the reaction time is 4-10 h.

[0013] In one embodiment of the present invention, in the Zr / Ho supported SAPO molecular sieve catalyst, the total mass of the zirconium source and the holmium source is 0.1-0.3 times the mass of the SAPO molecular sieve; preferably, the molar ratio of Zr and Ho is Zr:Ho = 1:(0.2-1).

[0014] In one embodiment of the present invention, the SAPO molecules are screened from one or more of SAPO-5, SAPO-11, SAPO-18, SAPO-34, and SAPO-44.

[0015] In one embodiment of the present invention, the Zr / Ho supported SAPO molecular sieve catalyst is prepared by the following steps:

[0016] S1: Zirconium source and holmium source are dissolved in water to obtain an aqueous solution;

[0017] S2: Impregnate SAPO molecular sieves in an aqueous solution;

[0018] S3: The dried molecular sieve is calcined to obtain Zr / Ho supported SAPO molecular sieve catalyst.

[0019] In one embodiment of the present invention, the zirconium source in S1 is an organic salt and / or inorganic salt containing zirconium, preferably one or more of zirconium nitrate, zirconium sulfate, zirconium chloride, and zirconium acetate.

[0020] In one embodiment of the present invention, the holmium source in S1 is an organic salt and / or inorganic salt containing holmium, preferably one or more of holmium nitrate pentahydrate, holmium sulfate hydrate, holmium chloride, holmium bromide, holmium iodide, holmium acetate, holmium nitrate, and holmium sulfate octahydrate.

[0021] In one embodiment of the invention, the drying method in S3 is preferably freeze drying.

[0022] In one embodiment of the present invention, the calcination temperature in S3 is 400-600℃ and the calcination time is 12-24h.

[0023] Another object of the present invention is to provide a Zr / Ho supported SAPO molecular sieve catalyst.

[0024] A Zr / Ho supported SAPO molecular sieve catalyst, the catalyst being prepared by the above method, wherein the total mass of the zirconium source and the holmium source in the catalyst is 0.1-0.3 times the mass of the SAPO molecular sieve; preferably, the molar ratio of Zr to Ho is Zr:Ho = 1:(0.2-1).

[0025] In one embodiment of the present invention, the SAPO molecules in the catalyst are selected from one or more of SAPO-5, SAPO-11, SAPO-18, SAPO-34, and SAPO-44.

[0026] Another object of the present invention is to provide a p-phenylenediethyl ether, which is prepared by the above method.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] (1) Using the Zr / Ho supported SAPO molecular sieve catalyst, the hydroquinone conversion rate can reach up to 90%, and the selectivity for diethyl ether can reach up to about 94%.

[0029] (2) The Zr / Ho supported SAPO molecular sieve catalyst is easy to separate and has strong catalyst activity, good stability and multiple reuse times. The catalyst that has been reused 15 times can still achieve a hydroquinone conversion rate of over 80% when used in the reaction. Moreover, the catalyst can be calcined and regenerated, which has the potential for industrial application. Detailed Implementation

[0030] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0031] In the following examples, the conversion rate of hydroquinone and the selectivity of diethyl ether can be calculated based on the composition of the reaction solution. The analytical method used is gas chromatography, and the instrument is a Shimadzu GC-2030 gas chromatograph.

[0032] Sources of some of the raw materials used:

[0033] Hydroquinone, Diethyl Carbonate, Zirconium Nitrate, Zirconium Sulfate, Zirconium Chloride, Holmium Nitrate Pentahydrate, Holmium Sulfate Hydrate, Holmium Chloride: Aladdin Technology Co., Ltd.

[0034] SAPO-5, SAPO-11, SAPO-34 molecular sieves: Tianjin Nanhua Catalyst Co., Ltd.

[0035] Ethanol, Acetonitrile: Beijing Innocare Technology Co., Ltd.

[0036] Example 1

[0037] Catalyst preparation:

[0038] (1) Dissolve 3.39g of zirconium nitrate and 2.21g of holmium nitrate pentahydrate in 500g of pure water and stir until dissolved and mixed evenly; ensure that the molar ratio of Zr to Ho is Zr:Ho = 1:0.5.

[0039] (2) Immerse 37.33g of SAPO-5 molecular sieve in the aqueous solution of step (1) and stir at room temperature for 5h; ensure that the total mass of zirconium source and holmium source is 0.15 times the mass of SAPO-5 molecular sieve.

[0040] (3) The above solution was freeze-dried at a pressure of 50 PaA and a temperature of -25℃ for 12 hours;

[0041] (4) The dried molecular sieve was calcined in air to obtain Zr / Ho supported SAPO-5 molecular sieve catalyst. The calcination temperature was 400℃ and the calcination time was 12h.

[0042] Batch operating conditions for the hydroquinone and diethyl carbonate reactor:

[0043] First, 110g of hydroquinone, 165g of ethanol and 5.5g of Zr / Ho supported SAPO-5 molecular sieve catalyst were added to the reactor and stirred at 50℃ for half an hour to dissolve. Then, 236g of diethyl carbonate was added. The system was pressurized to 0.4MPaG, heated to 80℃, and stirred at 400r / min for 6 hours.

[0044] After the reaction was completed under the above conditions, samples were taken for analysis. The samples were diluted 10 times with acetonitrile and the composition of the reaction solution was analyzed by gas chromatography. The conversion rate of hydroquinone was calculated to be 85%, and the selectivity of diethyl ether was 88%.

[0045] Example 2

[0046] Catalyst preparation:

[0047] (1) Dissolve 2.83g of zirconium sulfate and 5.09g of holmium sulfate hydrate in 500g of pure water and stir until dissolved and mixed evenly; ensure that the molar ratio of Zr to Ho is Zr:Ho = 1:0.8.

[0048] (2) Immerse 39.6g of SAPO-11 molecular sieve in the aqueous solution of step (1) and stir at room temperature for 8h; ensure that the total mass of zirconium source and holmium source is 0.2 times the mass of SAPO-11 molecular sieve.

[0049] (3) The above solution was freeze-dried at a pressure of 100 PaA and a temperature of -15℃ for 18 hours;

[0050] (4) The dried molecular sieve was calcined in air to obtain Zr / Ho supported SAPO-11 molecular sieve catalyst. The calcination temperature was 500℃ and the calcination time was 18h.

[0051] Batch operating conditions for the hydroquinone and diethyl carbonate reactor:

[0052] First, 110g of hydroquinone, 220g of ethanol and 11g of Zr / Ho supported SAPO-11 molecular sieve catalyst were added to the reactor and stirred at 50℃ for half an hour to dissolve. Then, 247.8g of diethyl carbonate was added. The system was pressurized to 0.8MPaG, heated to 120℃, and stirred at 400r / min for 8 hours.

[0053] After the reaction was completed under the above conditions, samples were taken for analysis. The samples were diluted 10 times with acetonitrile and the composition of the reaction solution was analyzed by gas chromatography. The conversion rate of hydroquinone was calculated to be 90%, and the selectivity of diethyl ether was 94%.

[0054] Example 3

[0055] Catalyst preparation:

[0056] (1) Dissolve 2.33g of zirconium chloride and 2.71g of holmium chloride in 500g of pure water and stir until dissolved and mixed evenly; ensure that the molar ratio of Zr to Ho is Zr:Ho = 1:1.

[0057] (2) Immerse 20.16g of SAPO-34 molecular sieve in the aqueous solution of step (1) and stir at room temperature for 10h; ensure that the total mass of zirconium source and holmium source is 0.25 times the mass of SAPO-34 molecular sieve.

[0058] (3) The above solution was freeze-dried at a pressure of 200 PaA and a temperature of -10℃ for 24 hours;

[0059] (4) The dried molecular sieve was calcined in air to obtain Zr / Ho supported SAPO-34 molecular sieve catalyst. The calcination temperature was 600℃ and the calcination time was 24h.

[0060] Batch operating conditions for the hydroquinone and diethyl carbonate reactor:

[0061] First, 110g of hydroquinone, 330g of ethanol and 16.5g of Zr / Ho supported SAPO-34 molecular sieve catalyst were added to the reactor and stirred at 50℃ for half an hour to dissolve. Then, 259.6g of diethyl carbonate was added. The system was pressurized to 1MPaG, heated to 150℃, and stirred at 400r / min for 10 hours.

[0062] After the reaction was completed under the above conditions, samples were taken for analysis. The samples were diluted 10 times with acetonitrile and the composition of the reaction solution was analyzed by gas chromatography. The conversion rate of hydroquinone was calculated to be 88%, and the selectivity of diethyl ether was 90%.

[0063] Example 4

[0064] The catalyst was obtained by repeating the reaction under the conditions of Example 2 15 times. The initial catalyst preparation method, reaction conditions and raw material ratio were the same as those in Example 2. Under the above conditions, the conversion rate of hydroquinone was 80% and the selectivity of diethyl ether was 83.7%.

[0065] Comparative Example 1

[0066] The catalyst was prepared in the same manner as in Example 2, the main difference being that a holmium source was not added; all other preparation and reaction conditions were the same as in Example 2. Under the above conditions, sample analysis showed a hydroquinone conversion rate of 43% and a selectivity of 65.3% for diethyl phenyl ether.

[0067] Comparative Example 2

[0068] The catalyst was prepared in the same manner as in Example 2, the main difference being that no zirconium source was added; all other preparation and reaction conditions were the same as in Example 2. Under the above conditions, sample analysis showed a hydroquinone conversion rate of 51% and a selectivity of 69.7% for diethyl phenyl ether.

[0069] Although the present invention has been described in detail through the preferred embodiments described above, it should be understood that the above description should not be considered as a limitation of the present invention. Those skilled in the art will understand that modifications or adjustments can be made to the present invention based on the teachings of this specification. These modifications or adjustments should also be within the scope defined by the claims of the present invention.

Claims

1. A method for preparing p-phenylenediethyl ether, characterized in that, The preparation method involves the catalytic reaction of hydroquinone and diethyl carbonate to produce diethyl terephthalate under the action of a catalyst. The catalyst is a Zr / Ho supported SAPO molecular sieve catalyst.

2. The preparation method according to claim 1, characterized in that, The molar ratio of hydroquinone to diethyl carbonate is 1:(2-2.2); And / or, the mass of the catalyst is 5-20% of the mass of hydroquinone.

3. The preparation method according to claim 1 or 2, characterized in that, The reaction pressure is 0.2-1 MPaG, the temperature is 70-150℃, and the reaction time is 4-10 h.

4. The preparation method according to claim 1, characterized in that, In the Zr / Ho supported SAPO molecular sieve catalyst, the total mass of the zirconium source and the holmium source is 0.1-0.3 times the mass of the SAPO molecular sieve; And / or, the SAPO molecules are selected from one or more of SAPO-5, SAPO-11, SAPO-18, SAPO-34, and SAPO-44.

5. The preparation method according to claim 4, characterized in that, The molar ratio of Zr to Ho is Zr:Ho = 1:(0.2-1).

6. The preparation method according to claim 1, characterized in that, The Zr / Ho supported SAPO molecular sieve catalyst was prepared by the following steps: S1: Zirconium source and holmium source are dissolved in water to obtain an aqueous solution; S2: Impregnate SAPO molecular sieves in an aqueous solution; S3: The dried molecular sieve is calcined to obtain Zr / Ho supported SAPO molecular sieve catalyst.

7. The preparation method according to claim 6, characterized in that, The zirconium source in S1 is an organic salt and / or inorganic salt containing zirconium. And / or, the holmium source in S1 is an organic salt and / or inorganic salt containing holmium.

8. The preparation method according to claim 6, characterized in that, The zirconium source in S1 is one or more of zirconium nitrate, zirconium sulfate, zirconium chloride, and zirconium acetate; And / or, the holmium source in S1 is one or more of holmium nitrate pentahydrate, holmium sulfate hydrate, holmium chloride, holmium bromide, holmium iodide, holmium acetate, and holmium nitrate.

9. The preparation method according to claim 6, characterized in that, The drying method in S3 is freeze drying; And / or, the calcination temperature in S3 is 400-600℃, and the calcination time is 12-24h.

10. A Zr / Ho supported SAPO molecular sieve catalyst, characterized in that, The catalyst is prepared by the following steps: S1: Zirconium source and holmium source are dissolved in water to obtain an aqueous solution; S2: Impregnate SAPO molecular sieves in an aqueous solution; S3: The dried molecular sieve was calcined to obtain a Zr / Ho supported SAPO molecular sieve catalyst; The total mass of the zirconium source and holmium source in the catalyst is 0.1-0.3 times the mass of the SAPO molecular sieve; And / or, the SAPO molecules are selected from one or more of SAPO-5, SAPO-11, SAPO-18, SAPO-34, and SAPO-44.

11. The catalyst according to claim 10, characterized in that, The molar ratio of Zr to Ho is Zr:Ho = 1:(0.2-1).