Method for removing hydrogen peroxide in epichlorohydrin wastewater

Abstract

The invention relates to a method for removing hydrogen peroxide in epichlorohydrin wastewater, which comprises the following steps: in a hydrogen atmosphere, carrying out catalytic hydrogenation reaction on the epichlorohydrin wastewater and a hydrogenation catalyst to convert the hydrogen peroxide in the epichlorohydrin wastewater into water, wherein the hydrogenation catalyst comprises an activated carbon carrier and an active metal component; the active metal component comprises Pd. According to the invention, a small amount of residual hydrogen peroxide in the epichlorohydrin wastewater can be converted into water, so that the generation of oxygen is avoided, the nitrogen consumption is greatly reduced, and the technical economy and safety of the reaction process are improved.

Description

A method for removing hydrogen peroxide from epichlorohydrin wastewater Technical Field

[0001] This application relates to the field of catalytic chemistry technology, and more specifically, to a method for removing hydrogen peroxide from epichlorohydrin wastewater. Background Technology

[0002] Epichlorohydrin is a widely used basic organic chemical raw material, and a major raw material for the synthesis of epoxy resins, chlorohydrin rubbers, and other products. Hydrogen peroxide is a green oxidant; in a mixed solution of methanol and water, using titanium silicate molecular sieves as a catalyst, 3-chloropropene can be directly epoxidized to epichlorohydrin. This is currently a new generation of green production technology for epichlorohydrin.

[0003] CN101747296A and CN101747297A disclose a method for producing epichlorohydrin from the epoxidation reaction of 3-chloropropene and hydrogen peroxide, achieving continuous and stable synthesis of epichlorohydrin with a hydrogen peroxide conversion rate of not less than 97%. However, hydrogen peroxide is not completely converted during the reaction, and a small amount of unconverted hydrogen peroxide remains in the final epoxidation wastewater, with a mass fraction of approximately 0.05~0.5% (500-5000 ppm). This residual trace amount of hydrogen peroxide may react with methanol, affecting the safe and continuous operation of the equipment, and needs to be treated to avoid adverse effects. In existing technologies, hydrogen peroxide decomposition catalysts, such as metal oxides (CN111774064A), are typically used to catalytically decompose this portion of hydrogen peroxide. However, the generated oxygen may pose a safety risk to the reaction equipment, requiring dilution with nitrogen for discharge, consuming a large amount of nitrogen, and increasing production costs.

[0004] Therefore, in order to improve the safety and economy of the reaction process, it is necessary to develop a new generation of technologies for treating unreacted trace amounts of hydrogen peroxide in epoxidation wastewater. Summary of the Invention

[0005] The purpose of this disclosure is to provide a method for removing hydrogen peroxide from epichlorohydrin wastewater, which can convert the residual small amount of hydrogen peroxide into water, avoid the generation of oxygen, significantly reduce nitrogen consumption, and improve the technical economy and safety of the reaction process.

[0006] To achieve the above objective, this disclosure provides a method for removing hydrogen peroxide from epichlorohydrin wastewater, comprising the following steps: in a hydrogen atmosphere, epichlorohydrin wastewater is subjected to a catalytic hydrogenation reaction with a hydrogenation catalyst to convert the hydrogen peroxide in the epichlorohydrin wastewater into water; wherein the hydrogenation catalyst comprises an activated carbon support and an active metal component; the active metal component comprises Pd.

[0007] Optionally, based on the total weight of the hydrogenation catalyst, the content of the active metal component is 0.1 to 13% by weight, preferably 0.5 to 1% by weight.

[0008] Optionally, the total specific surface area of ​​the hydrogenation catalyst is 1100~2000 m². 2 / g, preferably 1500~2000 m 2 / g; the particle size is 10~180 mesh, preferably 20~110 mesh; optionally, the microporous specific surface area of ​​the hydrogenation catalyst accounts for 90~100% of the total specific surface area.

[0009] Optionally, the hydrogenation catalyst is prepared by a method comprising the following steps: (1) impregnating and drying an activated carbon support with an active metal precursor solution to obtain a catalyst precursor; optionally, the active metal precursor is selected from one or more of palladium acetate, palladium nitrate, palladium chloride and palladium oxalate, preferably palladium chloride; (2) calcining and reducing the catalyst precursor under hydrogen conditions.

[0010] Optionally, in step (1), the concentration of palladium ions in the active metal precursor solution is 0.05~7% by weight, preferably 0.25~0.50% by weight. Preferably, the impregnation treatment is equal-volume impregnation; the impregnation temperature is 20~30℃, and the impregnation time is 10~15h. Optionally, the drying treatment conditions include: a drying temperature of 100~120℃ and a drying time of 6~10h. Optionally, in step (2), the calcination reduction treatment conditions include: a reduction temperature of 300~750℃, preferably 300~620℃; a reduction time of 2~8h, preferably 3~6h; and a hydrogen flow rate of 5~100 mL / min, preferably 5~60 mL / min.

[0011] Optionally, the epichlorohydrin wastewater is derived from the reaction of 3-chloropropene and hydrogen peroxide to synthesize epichlorohydrin; optionally, based on the total weight of the epichlorohydrin wastewater, the content of hydrogen peroxide is 0.05~3% by weight, preferably 0.1~0.5% by weight.

[0012] Optionally, the epichlorohydrin wastewater further includes methanol and water; based on the total weight of the epichlorohydrin wastewater, the methanol content is 20-80% by weight, preferably 40-60% by weight.

[0013] Optionally, in the catalytic hydrogenation reaction, the weight ratio of epichlorohydrin wastewater to hydrogenation catalyst is 100:0.1~7, preferably 100:0.1~1.5.

[0014] Optionally, the conditions for the catalytic hydrogenation reaction include: a reaction temperature of 20~50℃, a reaction time of 10~60min, and a hydrogen pressure of 1~10bar.

[0015] Optionally, the conditions for the catalytic hydrogenation reaction include: a reaction temperature of 25~45℃, a reaction time of 20~60min, and a hydrogen pressure of 2~10bar.

[0016] This disclosure provides a method for removing hydrogen peroxide from epichlorohydrin wastewater. The hydrogenation catalyst used in this disclosure has metal Pd as the active center and activated carbon as the support. It has excellent catalytic activity for the hydrogenation of hydrogen peroxide to produce water, and avoids the generation of oxygen, significantly reducing nitrogen consumption and improving the technical economy and safety of the reaction process.

[0017] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Detailed Implementation

[0018] The following provides a detailed description of specific embodiments of this disclosure. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit this disclosure.

[0019] This disclosure provides a method for removing hydrogen peroxide from epichlorohydrin wastewater, comprising the following steps: in a hydrogen atmosphere, the epichlorohydrin wastewater is subjected to a catalytic hydrogenation reaction with a hydrogenation catalyst to convert the hydrogen peroxide in the epichlorohydrin wastewater into water; wherein the hydrogenation catalyst comprises an activated carbon support and an active metal component; the active metal component comprises Pd.

[0020] This disclosure provides a method for removing hydrogen peroxide from epichlorohydrin wastewater. The hydrogenation catalyst used in this disclosure has metal Pd as the active center and activated carbon as the support. It has excellent catalytic activity for the hydrogenation of hydrogen peroxide to produce water, and avoids the generation of oxygen, significantly reducing nitrogen consumption and improving the technical economy and safety of the reaction process.

[0021] In one embodiment, based on the total weight of the hydrogenation catalyst, the content of the active metal component is 0.1-13% by weight, preferably 0.5-1% by weight. The hydrogenation catalyst provided by this disclosure can achieve excellent catalytic activity even with a low loading of the active metal component, and can also improve the economic efficiency of treating epichlorohydrin wastewater. When the loading of the metal active component of the hydrogenation catalyst is within the range of this embodiment, especially within the preferred content range, the hydrogenation catalyst can achieve a more excellent hydrogen peroxide removal effect in epichlorohydrin wastewater, improving the hydrogen peroxide conversion rate.

[0022] In one specific embodiment, the total specific surface area of ​​the hydrogenation catalyst is 1100~2000 m². 2 / g, preferably 1500~2000 m 2 / g; the particle size is 10~180 mesh, preferably 20~110 mesh, and more preferably 30~80 mesh. The catalyst provided in this disclosure has a suitable specific surface area and particle size. The catalyst can be in the form of unground particles. The size of the catalyst particles has a certain influence on the catalytic activity. The larger the size, the lower the mass transfer effect and the lower the activity, requiring a higher catalyst addition amount. However, the catalyst mesh size should not be further reduced, otherwise even if an extremely excessive amount of catalyst is added, the desired effect may not be achieved. Therefore, the catalyst used in this disclosure has a particle size range that balances the addition amount and catalytic activity, and is more suitable for use in fixed-bed reactors.

[0023] In a preferred embodiment, the microporous specific surface area of ​​the hydrogenation catalyst accounts for 90-100% of the total specific surface area. In this disclosure, micropores refer to pores with a diameter of less than 2 nm. The hydrogenation catalyst provided in this disclosure has a high proportion of microporous specific surface area, which is more conducive to improving reaction activity.

[0024] In one embodiment, the hydrogenation catalyst is prepared by a method comprising the following steps: (1) impregnating an activated carbon support with an active metal precursor solution, drying and calcining the solution to obtain a catalyst precursor; optionally, the active metal precursor is selected from one or more of palladium acetate, palladium nitrate, palladium chloride and palladium oxalate; (2) reducing the catalyst precursor under hydrogen conditions.

[0025] In one specific embodiment, in step (1), the concentration of palladium ions in the active metal precursor solution is 0.05~7% by weight, preferably 0.25~0.50% by weight. Preferably, the impregnation treatment is equal volume impregnation, which is a conventional operation in the art. The impregnation temperature can be 20~30℃ and the impregnation time can be 10~15h.

[0026] In one embodiment, the drying conditions include a drying temperature of 100-120°C and a drying time of 6-10 hours. In this disclosure, the solvent is removed through drying to improve the efficiency of subsequent calcination and reduction.

[0027] In a preferred embodiment, the conditions for the calcination reduction treatment in step (2) include: a reduction temperature of 300~750℃, preferably 300~620℃; a reduction time of 2~8h, preferably 3~6h; and a hydrogen flow rate of 5~100 mL / min, preferably 5~60 mL / min. According to the process conditions in this embodiment, especially the preferred process conditions, a hydrogenation catalyst with higher catalytic performance can be prepared, thereby improving the hydrogen peroxide conversion rate.

[0028] In one specific embodiment, the epichlorohydrin wastewater originates from the reaction of 3-chloropropene with hydrogen peroxide to synthesize epichlorohydrin; specifically, the epichlorohydrin wastewater originates from the liquid after separating the unreacted substrate 3-chloropropene and the target product epichlorohydrin from the reaction solution; optionally, based on the total weight of the epichlorohydrin wastewater, the hydrogen peroxide content is 0.05~3% by weight, preferably 0.1~0.5% by weight. The method provided in this embodiment effectively removes hydrogen peroxide from epichlorohydrin wastewater within a wide range of concentrations and has a wide range of applications.

[0029] In one specific embodiment, the epichlorohydrin wastewater further includes methanol and water; based on the total weight of the epichlorohydrin wastewater, the methanol content is 20-80% by weight, preferably 40-60% by weight.

[0030] In one embodiment, in the catalytic hydrogenation reaction, the weight ratio of epichlorohydrin wastewater to hydrogenation catalyst is 100:0.1~7, preferably 100:0.1~1.5. Using the weight ratio of epichlorohydrin wastewater to hydrogenation catalyst provided in this embodiment, particularly within the preferred range, is beneficial for improving the conversion rate of hydrogen peroxide.

[0031] In one embodiment, the conditions for the catalytic hydrogenation reaction include: a reaction temperature of 20-50°C, a reaction time of 10-60 min, and a hydrogen pressure of 1-10 bar, which is beneficial for achieving efficient removal of hydrogen peroxide from epichlorohydrin wastewater.

[0032] In a preferred embodiment, the conditions for the catalytic hydrogenation reaction include: a reaction temperature of 25-45°C, a reaction time of 20-60 min, and a hydrogen pressure of 2-10 bar, which can further improve the conversion rate of hydrogen peroxide in epichlorohydrin wastewater.

[0033] According to this disclosure, the hydrogen peroxide hydrogenation reaction process is stirred, and the required reactor can be a stainless steel reactor with a polytetrafluoroethylene liner, a Hastelloy reactor, or a reactor conventionally used in the art.

[0034] The present disclosure is further described in detail below through examples. All raw materials used in the examples are commercially available.

[0035] The content of active metal components in the catalyst was obtained by inductively coupled plasma atomic emission spectrometry (ICP-AES); the total specific surface area, micropore specific surface area, and structural characteristics of the catalyst were obtained by static capacity adsorption analysis. The particle size of the catalyst was controlled by grinding and sieving. After the hydrogen peroxide hydrogenation reaction was completed, the concentration of hydrogen peroxide in the epichlorohydrin wastewater before and after the reaction was analyzed by a hydrogen peroxide titrator (Metroën, Switzerland), and the hydrogen peroxide conversion rate was calculated accordingly.

[0036] Wherein, hydrogen peroxide conversion rate (%) = (initial hydrogen peroxide concentration - hydrogen peroxide concentration after reaction) / initial hydrogen peroxide concentration × 100%.

[0037] Preparation Example 1 This preparation example is used to prepare a hydrogenation catalyst (Pd / C catalyst, denoted as Cl), an activated carbon support, and an active metal component; the active metal component includes Pd, and the content of Pd in ​​the active metal component is 0.5% by weight based on the total weight of the hydrogenation catalyst. The specific steps include: First, the water absorption of 1 gram of activated carbon is measured to be 2 grams; then, 2.0084 grams of PdCl2 aqueous solution (active metal precursor solution, palladium ion concentration of 0.25% by weight) and 1 gram of activated carbon are impregnated in equal amounts to prepare a catalyst precursor. The impregnation temperature is 25°C and the impregnation time is 12 h; after drying the catalyst precursor, it is calcined and reduced in a hydrogen atmosphere to obtain the catalyst; the drying temperature is 120°C and the drying time is 6 h; the calcination and reduction temperature is 500°C and the calcination and reduction time is 4 h, and the hydrogen flow rate is 40 mL / min.

[0038] The obtained catalyst C1 has a mesh size of 80 mesh and a total specific surface area of ​​1708 m². 2 / g, of which the microporous specific surface area accounts for 95.0%.

[0039] Preparation Example 2 This preparation example is used to prepare a hydrogenation catalyst (Pd / C catalyst, denoted as C2), an activated carbon support, and an active metal component; the active metal component includes Pd, and the content of the active metal component Pd is 1 wt% based on the total weight of the hydrogenation catalyst; this preparation example is based on the method in Preparation Example 1, except that: 2.0168 g of PdCl2 aqueous solution (active metal precursor solution, palladium ion concentration of 0.50 wt%) and 1 g of activated carbon are used to prepare the catalyst precursor by an equal volume impregnation method, and the rest of the process is the same as in Preparation Example 1.

[0040] Preparation Example 3 This preparation example is used to prepare a hydrogenation catalyst (Pd / C catalyst, denoted as C3). The difference from Preparation Example 1 is that the mesh size of the catalyst is adjusted to 100 mesh, and the rest of the process is the same as Preparation Example 1.

[0041] Preparation Example 4: This preparation example is used to prepare a hydrogenation catalyst (Pd / C catalyst, denoted as C4). The difference from Preparation Example 1 is that the mesh size of the catalyst is adjusted to 30 mesh, and the rest of the process is the same as Preparation Example 1.

[0042] Preparation Example 5: This preparation example follows the preparation method described in Preparation 1, except that the activated carbon support is replaced. The specific surface area of ​​the replaced activated carbon support is 1190 m². 2 / g, of which the microporous specific surface area accounts for 93.2%; the equivalent water absorption of 1 gram of activated carbon is 1.8 grams; then 1.8084 grams of PdCl2 aqueous solution (active metal precursor solution, palladium ion concentration of 0.28 wt%) and activated carbon (1 gram) are used to prepare catalyst precursor by equal volume impregnation method; the rest of the process is the same as in preparation example 1, and the hydrogenation catalyst C5 is prepared.

[0043] Preparation Example 6: This preparation example follows the preparation method described in Preparation 1, except that the activated carbon support is replaced. The specific surface area of ​​the replaced activated carbon support is 1852 m². 2 / g, wherein the microporous specific surface area ratio is 73.3%; the equivalent water absorption of 1 gram of activated carbon is 2.3 grams; then 2.3084 grams of PdCl2 aqueous solution (active metal precursor solution, palladium ion concentration is 0.22 wt%) and activated carbon (1 gram) are used to prepare catalyst precursor by equal volume impregnation method; the rest of the process is the same as in preparation example 1, and the hydrogenation catalyst C6 is prepared.

[0044] Preparation Example 7 This preparation example is used to prepare a hydrogenation catalyst (Pd / C catalyst, denoted as C7), an activated carbon support, and an active metal component; the active metal component includes Pd, and the content of Pd in ​​the active metal component is 0.1 wt% based on the total weight of the hydrogenation catalyst; this preparation example is based on the method in Preparation Example 1, except that: 2.0017 g of PdCl2 aqueous solution (active metal precursor solution, palladium ion concentration of 0.05 wt%) and 1 g of activated carbon are used to prepare the catalyst precursor by an equal volume impregnation method, and the rest of the process is the same as in Preparation Example 1.

[0045] Preparation Example 8 This preparation example is used to prepare a hydrogenation catalyst (Pd / C catalyst, denoted as C8), an activated carbon support, and an active metal component; the active metal component includes Pd, and the content of Pd in ​​the active metal component is 2% by weight based on the total weight of the hydrogenation catalyst. This preparation example is based on the method in Preparation Example 1, except that: 2.0340 g of PdCl2 aqueous solution (active metal precursor solution, palladium ion concentration of 1.0% by weight) and 1 g of activated carbon are impregnated in equal amounts to prepare the catalyst precursor, and the rest of the process is the same as in Preparation Example 1.

[0046] Preparation Example 9: The hydrogenation catalyst C9 was prepared according to the preparation method in Preparation Example 1. The difference between Preparation Example 9 and Preparation Example 1 is that the calcination reduction temperature was 750℃, the calcination reduction time was 2 hours, and the hydrogen flow rate was 100 mL / min.

[0047] Preparation Comparative Example 1: This preparation comparative example was used to prepare a hydrogenation catalyst (Pt / C catalyst, denoted as D1), an activated carbon support, and an active metal component. The active metal component included Pt, and based on the total weight of the hydrogenation catalyst, the content of the active metal component Pt was 0.5% by weight. This preparation comparative example followed the method in Preparation Example 1, except that 2.0106 g of H2PtCl6 aqueous solution (active metal precursor solution, platinum ion concentration of 0.25% by weight) and 1 g of activated carbon were used to prepare the catalyst precursor by an equal-volume impregnation method. The rest of the process was the same as in Preparation Example 1.

[0048] Preparation Comparative Example 2: This preparation comparative example was used to prepare a hydrogenation catalyst (Ru / C catalyst, denoted as D2), an activated carbon support, and an active metal component; the active metal component included Ru, and the content of the active metal component Ru was 0.5 wt% based on the total weight of the hydrogenation catalyst; this preparation comparative example followed the method in Preparation Example 1, except that: 2.0103 g of RuCl3 aqueous solution (active metal precursor solution, ruthenium ion concentration of 0.25 wt%) and 1 g of activated carbon were used to prepare the catalyst precursor by an equal volume impregnation method, and the rest of the process was the same as in Preparation Example 1.

[0049] The active metal content and structural characteristic parameters of the catalysts obtained from the above preparation examples and comparative examples are listed in Table 1 below.

[0050] Table 1

[0051] The catalyst mesh sizes in Table 1 are obtained by sieving the catalyst particles using 30-mesh, 80-mesh, or 100-mesh sieves.

[0052] The following examples illustrate the catalytic effect of the catalysts obtained from the above preparation examples and comparative examples in the removal of hydrogen peroxide from epichlorohydrin wastewater.

[0053] In Example 1, 50 g of epoxidized wastewater containing 50 wt% methanol and 0.5 wt% (5000 ppm) hydrogen peroxide was added to a 100 mL Hastelloy reactor. 0.05 g of catalyst C1 from Example 1 was added. The weight ratio of epichlorohydrin wastewater to hydrogenation catalyst was 100:0.1. Catalytic hydrogenation was carried out under a hydrogen atmosphere. The reaction conditions were: hydrogen pressure of 2 bar, reaction temperature of 30°C, reaction time of 60 min, and rotation speed of 500 r / min. After the reaction, the hydrogen pressure was reduced to 0.5 bar, and the catalyst was filtered. The resulting reaction solution was titrated to determine the hydrogen peroxide concentration, and the hydrogen peroxide conversion rate was calculated, as shown in Table 2.

[0054] Example 2 This example refers to the method in Example 1, except that the amount of catalyst C1 added is adjusted to 0.1g, the weight ratio of epichlorohydrin wastewater to hydrogenation catalyst is 100:0.2, the reaction time is adjusted to 40min, and the rest of the process is the same as in Example 1; the hydrogen peroxide concentration is measured after the reaction, and the hydrogen peroxide conversion rate is calculated and listed in Table 2.

[0055] Example 3 This example refers to the method in Example 1, except that the reaction temperature is adjusted to 50°C and the reaction time is adjusted to 30 min; the rest of the process is the same as in Example 1; the hydrogen peroxide concentration is measured after the reaction and the hydrogen peroxide conversion rate is calculated and listed in Table 2.

[0056] Example 4 This example follows the method in Example 1, except that catalyst C1 is replaced with catalyst C2 prepared in Preparation Example 2, and the hydrogenation catalytic reaction time is adjusted to 35 min; the rest of the process is the same as in Example 1; the hydrogen peroxide concentration is measured after the reaction, and the hydrogen peroxide conversion rate is calculated and listed in Table 2.

[0057] Example 5 This example follows the method in Example 1, except that catalyst C1 is replaced with catalyst C3 prepared in Preparation Example 3, and the rest of the process is the same as in Example 1; the hydrogen peroxide concentration is measured after the reaction and the hydrogen peroxide conversion rate is calculated and listed in Table 2.

[0058] Example 6 This example follows the method in Example 1, except that catalyst C1 is replaced with catalyst C4 prepared in Preparation Example 4, and the amount of catalyst added is adjusted to 0.5g. The weight ratio of epichlorohydrin wastewater to hydrogenation catalyst is 100:1. The rest of the process is the same as in Example 1. The hydrogen peroxide concentration is measured after the reaction, and the hydrogen peroxide conversion rate is calculated and listed in Table 2.

[0059] Example 7 This example follows the method in Example 1, except that catalyst C1 is replaced with catalyst C4 prepared in Preparation Example 4, and the hydrogen pressure is increased to 10 bar. The rest of the process is the same as in Example 1. After the reaction, the hydrogen pressure is measured to decrease to 8.5 bar. After the reaction, the hydrogen peroxide concentration is measured, and the hydrogen peroxide conversion rate is calculated and listed in Table 2.

[0060] Example 8 This example follows the method in Example 1, except that catalyst C1 is replaced with catalyst C5 prepared in Preparation Example 5, and the rest of the process is the same as in Example 1; the hydrogen pressure drops to 0.8 bar after the reaction; the hydrogen peroxide concentration is measured after the reaction, and the hydrogen peroxide conversion rate is calculated and listed in Table 2.

[0061] Example 9 This example follows the method in Example 1, except that catalyst C1 is replaced with catalyst C6 prepared in Preparation Example 6, and the rest of the process is the same as in Example 1; after the reaction, the hydrogen pressure drops to 1.3 bar, the hydrogen peroxide concentration is measured after the reaction, and the hydrogen peroxide conversion rate is calculated and listed in Table 2.

[0062] Example 10 This example follows the method in Example 1, except that catalyst C1 is replaced with catalyst C7 prepared in Preparation Example 7, and the rest of the process is the same as in Example 1; the hydrogen pressure drops to 1.1 bar after the reaction; the hydrogen peroxide concentration is measured after the reaction, and the hydrogen peroxide conversion rate is calculated and listed in Table 2.

[0063] Example 11 This example follows the method in Example 1, except that catalyst C1 is replaced with catalyst C8 prepared in Preparation Example 8, the reaction time is adjusted to 25 min, and the rest of the process is the same as in Example 1; the hydrogen peroxide concentration is measured after the reaction, and the hydrogen peroxide conversion rate is calculated and listed in Table 2.

[0064] Example 12 This example follows the method in Example 1, except that catalyst C1 is replaced with catalyst C9 prepared in Preparation Example 9, and the rest of the process is the same as in Example 1; the hydrogen pressure drops to 0.9 bar after the reaction; the hydrogen peroxide concentration is measured after the reaction, and the hydrogen peroxide conversion rate is calculated and listed in Table 2.

[0065] Example 13 This example follows the method in Example 1, except that 1g of catalyst C1 from Preparation Example 1 is added to 50g of epoxidized wastewater. The weight ratio of epichlorohydrin wastewater to hydrogenation catalyst is 100:2, and the rest of the process is the same as in Example 1. After the reaction, the hydrogen pressure drops to 0.7 bar, the hydrogen peroxide concentration is measured, and the hydrogen peroxide conversion rate is calculated and listed in Table 2.

[0066] Example 14 This example refers to the method in Example 1, except that the reaction temperature is 20°C, the reaction time is 10 min, the hydrogen pressure is 1 bar, and the rest of the process is the same as in Example 1; after the reaction, the hydrogen pressure drops to 0.8 bar, the hydrogen peroxide concentration is measured after the reaction, and the hydrogen peroxide conversion rate is calculated and listed in Table 2.

[0067] Comparative Example 1: This comparative example follows the method in Example 1, except that catalyst C1 is replaced with catalyst D1 prepared in the comparative example, and the rest of the process is the same as in Example 1; the hydrogen pressure is increased to 2.6 bar after the reaction, the hydrogen peroxide concentration is measured after the reaction, and the hydrogen peroxide conversion rate is calculated and listed in Table 2.

[0068] Comparative Example 2: This comparative example follows the method in Example 1, except that catalyst C1 is replaced with catalyst D2 prepared in the comparative example, while the rest of the process is the same as in Example 1. After the reaction, the hydrogen pressure increases to 2.7 bar, and the hydrogen peroxide concentration is measured to be 57 ppm, with a hydrogen peroxide conversion rate of 98.86%. The hydrogen peroxide concentration, conversion rate, and hydrogen consumption after the reaction obtained from the above examples and comparative examples are listed in Table 2 below.

[0069] Table 2

[0070] In Comparative Example 1, catalyst D1 used Pt as the active metal component, while in Comparative Example 2, catalyst D2 used Ru as the active metal component. After changing the active center, although hydrogen peroxide could still be converted, the pressure increased after the reaction. This indicates that Pt and Ru are the active centers for hydrogen peroxide decomposition, generating oxygen and causing the pressure increase. However, when Pd is used as the hydrogenation center for hydrogen peroxide, the pressure decreases after the reaction due to hydrogen consumption. This demonstrates that changing the type of active metal component cannot achieve the hydrogenation of hydrogen peroxide to water. Only the hydrogenation catalyst provided in this disclosure (with Pd as the active metal component) can convert hydrogen peroxide in epichlorohydrin wastewater into water.

[0071] A comparison of the results from Examples 1-4 shows that increasing the catalyst feed rate, reaction temperature, and catalyst active center loading can improve the reaction activity and shorten the time required to achieve the same hydrogen peroxide conversion rate under the same reaction conditions. This indicates that the preferred active metal loading, preferred catalyst feed rate, or preferred reaction conditions provided in this disclosure can achieve excellent catalytic hydrogenation effects.

[0072] Comparing the results of Examples 1 and 5-6, it can be seen that when the catalyst particle size is greater than 80 mesh, further reducing the catalyst particle size has virtually no effect on the reaction activity; however, in Example 6, reducing the catalyst particle size reduced the reaction activity, requiring a further increase in the catalyst feed rate to achieve the same hydrogen peroxide conversion rate. Therefore, using the preferred catalyst particle size (30-80 mesh) provided in this disclosure can achieve better catalytic activity while having a suitable particle size.

[0073] Comparing the results of Examples 1 and 7, it can be seen that the reaction activity decreases after reducing the catalyst particle size. If the catalyst dosage is not changed, the hydrogen pressure needs to be increased in Example 7 to achieve the same hydrogen peroxide conversion rate. Therefore, using the preferred catalyst mesh size (30-80 mesh) provided in this disclosure can achieve better catalytic activity while having a suitable particle size.

[0074] Comparing the results of Example 1 and Example 8, it can be seen that in Example 8, after reducing the specific surface area of ​​the catalyst support, the hydrogenation activity of the catalyst decreased, the hydrogen consumption decreased, and the hydrogen peroxide conversion rate decreased. This indicates that the hydrogenation catalyst with a preferred specific surface area used in Example 1 can obtain better hydrogen peroxide hydrogenation catalytic activity.

[0075] Comparing the results of Example 1 and Example 9, it can be seen that while keeping the specific surface area of ​​the catalyst support basically unchanged, reducing the proportion of microporous specific surface area leads to a decrease in the hydrogenation activity of the catalyst, a reduction in hydrogen consumption, and a decrease in the hydrogen peroxide conversion rate. This indicates that the hydrogenation catalyst with the preferred proportion of microporous specific surface area used in Example 1 has higher catalytic activity.

[0076] Comparing the results of Examples 1 and 10-11, it can be seen that reducing the number of active sites on the catalyst decreases the catalyst activity (the active metal component loading of catalyst C7 is 0.1 wt%), and the hydrogen peroxide conversion rate decreases in the same time period; increasing the number of active sites on the catalyst increases the catalyst activity (the active metal component loading of catalyst C8 is 2.0 wt%), and the time required to achieve the same hydrogen peroxide conversion rate is significantly shortened. However, further increasing the active site loading leads to an increase in catalyst cost. Therefore, when the active site component loading of the catalyst is within the preferred range provided in this disclosure, both catalyst activity and cost can be balanced.

[0077] Comparing the results of Examples 1 and 12, it can be seen that in Example 12, increasing the calcination and reduction temperature of catalyst C9 reduces catalyst activity and decreases hydrogen peroxide conversion. When the catalyst preparation conditions are within the preferred range provided in this disclosure, the resulting catalyst exhibits superior catalytic activity.

[0078] Comparing the results of Example 1 and Example 13, it can be seen that under the condition of further increasing the amount of catalyst added, not only does the cost of using the catalyst increase, but the external diffusion mass transfer effect of the catalyst is also affected. Under the same conditions, the hydrogen peroxide conversion rate decreases, indicating that the preferred catalyst addition weight ratio provided in this disclosure in Example 1 can have a better catalytic effect.

[0079] Comparing the results of Example 1 and Example 14, it can be seen that reducing the reaction temperature, reaction time, and reaction hydrogen pressure leads to a decrease in reaction activity and a significant decrease in hydrogen peroxide conversion rate. This indicates that the hydrogen peroxide catalytic hydrogenation reaction carried out in Example 1 according to the process conditions provided in this disclosure can achieve better catalytic effects.

[0080] The preferred embodiments of this disclosure have been described in detail above. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0081] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0082] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A method for removing hydrogen peroxide from epichlorohydrin wastewater, characterized in that, Includes the following steps: In a hydrogen atmosphere, epichlorohydrin wastewater is subjected to a catalytic hydrogenation reaction with a hydrogenation catalyst to convert hydrogen peroxide in the epichlorohydrin wastewater into water. The hydrogenation catalyst comprises an activated carbon support and an active metal component; the active metal component includes Pd.

2. The method according to claim 1, characterized in that, Based on the total weight of the hydrogenation catalyst, the content of the active metal component is 0.1 to 13% by weight, preferably 0.5 to 1% by weight.

3. The method according to claim 1, characterized in that, The total specific surface area of ​​the hydrogenation catalyst is 1100~2000 m². 2 / g, preferably 1500~2000 m 2 / g; the particle size is 10~180 mesh, preferably 20~110 mesh; optionally, the microporous specific surface area of ​​the hydrogenation catalyst accounts for 90~100% of the total specific surface area.

4. The method according to claim 1, characterized in that, The hydrogenation catalyst is prepared by a method including the following steps: (1) impregnating and drying an activated carbon support with an active metal precursor solution to obtain a catalyst precursor; optionally, the active metal precursor is selected from one or more of palladium acetate, palladium nitrate, palladium chloride and palladium oxalate, preferably palladium chloride; (2) calcining and reducing the catalyst precursor under hydrogen conditions.

5. The method according to claim 4, characterized in that, In step (1), the concentration of palladium ions in the active metal precursor solution is 0.05~7% by weight, preferably 0.25~0.50% by weight, and preferably, the impregnation treatment is equal volume impregnation; The impregnation temperature is 20~30℃ and the impregnation time is 10~15h; optionally, the drying conditions include: drying temperature of 100~120℃ and drying time of 6~10h; optionally, in step (2), the calcination reduction conditions include: reduction temperature of 300~750℃, preferably 300~620℃; reduction time of 2~8h, preferably 3~6h; hydrogen flow rate of 5~100 mL / min, preferably 5~60 mL / min.

6. The method according to claim 1, characterized in that, The epichlorohydrin wastewater is derived from the reaction of 3-chloropropene and hydrogen peroxide to synthesize epichlorohydrin; optionally, based on the total weight of the epichlorohydrin wastewater, the content of hydrogen peroxide is 0.05~3% by weight, preferably 0.1~0.5% by weight.

7. The method according to claim 6, characterized in that, The epichlorohydrin wastewater also includes methanol and water; based on the total weight of the epichlorohydrin wastewater, the methanol content is 20-80% by weight, preferably 40-60% by weight.

8. The method according to claim 1, characterized in that, In the catalytic hydrogenation reaction, the weight ratio of epichlorohydrin wastewater to hydrogenation catalyst is 100:0.1~7, preferably 100:0.1~1.

5.

9. The method according to claim 1, characterized in that, The conditions for the catalytic hydrogenation reaction include: a reaction temperature of 20-50°C, a reaction time of 10-60 min, and a hydrogen pressure of 1-10 bar.

10. The method according to claim 9, characterized in that, The conditions for the catalytic hydrogenation reaction include: a reaction temperature of 25~45℃, a reaction time of 20~60min, and a hydrogen pressure of 2~10bar.

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