Processing method for propylene epoxidation reaction raw materials and propylene epoxidation method

Abstract

The invention discloses a processing method for propylene epoxidation reaction raw materials and a propylene epoxidation method. The treatment method comprises the steps of performing calcium-based molecular sieve treatment and water washing on a reaction raw material, wherein the reaction raw material is a solution containing cumyl hydroperoxide or ethylbenzene hydroperoxide. According to the treatment method, the content of oxalic acid or oxalate in cumyl hydroperoxide or ethylbenzene hydroperoxide is reduced through calcium-based molecular sieve treatment, so that the stability of material inlet and outlet pressure of a reactor is ensured, and smooth continuous production is ensured. Alkali washing is not needed, water washing is carried out after passing through a molecular sieve bed layer, sodium ion intake can be reduced, a catalyst bed layer is protected, and bed layer pressure drop is reduced.

Description

Technical Field

[0001] The present invention relates to the field of propylene epoxidation. Specifically, it relates to a method for treating raw materials for propylene epoxidation reaction and a method for propylene epoxidation, especially a method for treating raw materials for propylene epoxidation reaction using cumene hydroperoxide or ethylbenzene hydroperoxide as an oxidant. Background Art

[0002] Cumene hydroperoxide and ethylbenzene hydroperoxide have been industrially applied to oxidize small molecule olefins such as propylene to produce corresponding epoxide products. Both are products of the air oxidation of cumene or ethylbenzene, which are convenient to prepare and have relatively good stability, and relatively high-concentration cumene hydroperoxide or ethylbenzene hydroperoxide can be obtained safely.

[0003] In the process of oxidizing cumene or ethylbenzene, some organic acids will inevitably be generated. The existing technical solution is to treat the oxidation liquid by alkali washing and water washing, wash away the organic acids, then concentrate, and finally mix with propylene as the raw material for the epoxidation reaction.

[0004] A considerable part of industrial plants use a fixed-bed form filled with heterogeneous catalysts for the epoxidation reaction. Usually, the bed pressure drop of the epoxidation reactor does not exceed 0.1 MPa. However, in practice, it is sometimes found that the bed pressure drop of the epoxidation reactor will continuously increase with the operation time, reaching 0.5 - 1.0 MPa or even higher. Once the epoxidation reactor is blocked, the peroxide remaining in the reactor is likely to decompose and cause a temperature runaway, bringing great risks to the safe operation of the plant. Therefore, when the pressure drop of the epoxidation reactor increases, it is often necessary to stop the operation in time and remove the source factors of the pressure drop resistance.

[0005] The reasons for the increase in the pressure drop of the epoxidation reactor may be diverse. The inventor found that one source of the reactor resistance is the precipitation and deposition of salts, especially oxalates, in the catalyst bed. Further analysis shows that in the raw materials for the epoxidation reaction, especially in the peroxide stream, there may sometimes be 20 - 100 mg / kg of oxalic acid or oxalate impurities, which are the source of the deposits in the catalyst bed.

[0006] In the prior art, alkali washing and water washing of the cumene or ethylbenzene oxidation liquid can remove most of the organic acids. However, due to the existence of phenomena similar to emulsification, the separation of the oil and water phases is difficult, and the oxidation liquid is likely to entrain components such as water and salts, making it very difficult to completely remove oxalates from the peroxide raw materials. When the peroxide is mixed with propylene and enters the epoxidation reactor, due to the change in physical properties and the influence of temperature, the entrained salts, especially oxalates, are likely to precipitate. Summary of the Invention

[0007] In order to improve the stability of the epoxidation reaction operation and delay the rate of increase in the reactor pressure drop, the present invention provides a method for treating the raw materials for epoxidation reaction, which avoids the deposition of oxalates on the catalyst bed by reducing the oxalic acid content in the oxidation solution.

[0008] The present invention also provides a method for propylene epoxidation, wherein the content of oxalic acid (root) in the raw materials before entering the epoxidation reactor does not exceed 10 mg / kg. The oxidant raw materials with low oxalic acid content can significantly improve the phenomenon of salt precipitation and slow down the rate of increase in the pressure drop of the oxidation reactor.

[0009] One of the objectives of the present invention is to provide a method for treating the raw materials for propylene epoxidation reaction, which includes the steps of treating the reaction raw materials with a calcium-based molecular sieve and washing with water. The reaction raw materials are solutions containing cumene hydroperoxide or ethylbenzene hydroperoxide.

[0010] According to the technical solution of the present invention, preferably, the concentration of cumene hydroperoxide or ethylbenzene hydroperoxide in the reaction raw materials is 1-60 wt%.

[0011] According to the technical solution of the present invention, more preferably, the concentration of cumene hydroperoxide or ethylbenzene hydroperoxide in the reaction raw materials is 5-25 wt%.

[0012] According to the technical solution of the present invention, the calcium-based molecular sieve includes but is not limited to at least one of 5A molecular sieve, 10X molecular sieve, calcium Y molecular sieve or other calcium ion-containing molecular sieves prepared by ion exchange.

[0013] According to the technical solution of the present invention, preferably, the calcium ion mass content of the calcium-based molecular sieve is 1-11%.

[0014] According to the technical solution of the present invention, more preferably, the calcium ion mass content of the calcium-based molecular sieve is 5-11%.

[0015] According to the technical solution of the present invention, preferably, the pore diameter of the calcium-based molecular sieve is 0.3-2 nm.

[0016] According to the technical solution of the present invention, more preferably, the pore diameter of the calcium-based molecular sieve is 0.9-1.3 nm.

[0017] According to the technical solution of the present invention, preferably, the treatment conditions are: temperature is 0-80 °C, pressure is 0-1.0 MPaG.

[0018] According to the technical solution of the present invention, more preferably, the treatment conditions are: temperature is 20-40 °C, pressure is 0.1-0.8 MpaG.

[0019] According to the technical solution of the present invention, when the reaction raw materials pass through the calcium-based molecular sieve in a continuous flow manner, preferably, the volume space velocity of the reaction raw materials is 0.1 to 10 h -1 .

[0020] According to the technical solution of the present invention, when the reaction raw materials pass through the calcium-based molecular sieve in a continuous flow manner, more preferably, the volume space velocity of the reaction raw materials is 0.1 to 0.5 h -1 .

[0021] According to the technical solution of the present invention, when the reaction raw materials contact the calcium-based molecular sieve in a batch manner, preferably, the residence time of the reaction raw materials is 0.1 to 10 h.

[0022] According to the technical solution of the present invention, when the reaction raw materials contact the calcium-based molecular sieve in a batch manner, more preferably, the residence time of the reaction raw materials is 4 to 6 h.

[0023] According to the technical solution of the present invention, the water washing includes single-stage or multi-stage water washing.

[0024] According to the technical solution of the present invention, preferably, the reaction raw materials after molecular sieve treatment are subjected to single-stage or multi-stage water washing with deionized water equivalent to 1 / 100 to 10 of their total amount.

[0025] According to the technical solution of the present invention, more preferably, the amount of water used is 1 to 3 of the weight of the reaction raw materials.

[0026] According to the technical solution of the present invention, preferably, in the reaction raw materials after molecular sieve treatment and water washing, the content of oxalic acid or oxalate ions is reduced to less than 2 mg / kg.

[0027] According to the technical solution of the present invention, more preferably, in the reaction raw materials after molecular sieve treatment and water washing, the content of oxalic acid or oxalate ions is reduced to less than 0.1 to 1.0 mg / kg, and further preferably, the content of oxalic acid or oxalate ions is reduced to less than 0.1 to 0.8 mg / kg.

[0028] The second object of the present invention is to provide a method for propylene epoxidation, comprising the following steps:

[0029] 1) Oxidizing cumene or ethylbenzene to obtain a solution containing cumene hydroperoxide or ethylbenzene hydroperoxide;

[0030] 2) Treating the solution according to the treatment method described above;

[0031] 3) Performing distillation treatment;

[0032] 4) Subjecting the material stream obtained in step 3) to an epoxidation reaction with propylene.

[0033] According to the technical solution of the present invention, in step 1), the oxidation reaction can adopt the conventional process in the art.

[0034] According to the technical solution of the present invention, in step 1), preferably, the conditions for the oxidation reaction of cumene or ethylbenzene are: reaction pressure ≤ 1.0 MPaG, and reaction temperature is 80 - 180 °C.

[0035] According to the technical solution of the present invention, in step 1), more preferably, the conditions for the oxidation reaction of cumene or ethylbenzene are: reaction pressure is 0.5 - 1 MpaG, and reaction temperature is 80 - 120 °C.

[0036] According to the technical solution of the present invention, in step 1), preferably, an alkaline compound with a content not exceeding 1000 mg / kg can be optionally added during the oxidation reaction to inhibit by-products such as phenol.

[0037] According to the technical solution of the present invention, in step 1), more preferably, the alkaline compound is at least one of calcium hydroxide or calcium carbonate.

[0038] According to the technical solution of the present invention, in step 1), preferably, the concentration of cumene hydroperoxide or ethylbenzene hydroperoxide in the reaction raw material is 1 - 60 wt%.

[0039] According to the technical solution of the present invention, in step 1), more preferably, the concentration of cumene hydroperoxide or ethylbenzene hydroperoxide in the reaction raw material is 5 - 25 wt%.

[0040] According to the technical solution of the present invention, in step 2), the step of treating the solution containing cumene hydroperoxide or ethylbenzene hydroperoxide with a calcium-based molecular sieve and washing with water is carried out.

[0041] According to the technical solution of the present invention, in step 2), preferably, the calcium-based molecular sieve is selected from at least one of 5A molecular sieve, 10X molecular sieve, calcium Y molecular sieve, or a molecular sieve containing calcium ions prepared by ion exchange.

[0042] According to the technical solution of the present invention, in step 2), preferably, the conditions for treating with the calcium-based molecular sieve include: temperature 0 - 80 °C, pressure 0 - 1.0 MpaG.

[0043] According to the technical solution of the present invention, in step 2), preferably, the reaction raw material is washed once or multiple times with water, and the amount of water used is preferably 1 / 100 - 10 times the weight of the reaction raw material.

[0044] According to the technical solution of the present invention, in step 2), preferably, the content of oxalic acid or oxalate ions in the treated reaction raw material is 2 mg / kg or less.

[0045] According to the technical solution of the present invention, in step 3), the solution containing cumene hydroperoxide or ethylbenzene hydroperoxide after removing oxalic acid (root) is distilled to remove a part of cumene or ethylbenzene solvent. The distillation can select the conventional process in the art.

[0046] According to the technical solution of the present invention, in step 3), preferably, the concentration of cumene hydroperoxide or ethylbenzene hydroperoxide in the distillate is 20-60 wt%.

[0047] According to the technical solution of the present invention, in step 3), more preferably, the concentration of cumene hydroperoxide or ethylbenzene hydroperoxide in the distillate is 50-60 wt%.

[0048] According to the technical solution of the present invention, in step 3), preferably, the content of oxalic acid or oxalate ion in the distillate does not exceed 10 mg / kg.

[0049] According to the technical solution of the present invention, in step 3), more preferably, the content of oxalic acid or oxalate ion in the distillate does not exceed 5 mg / kg.

[0050] According to the technical solution of the present invention, in step 4), the distillate is mixed with propylene and fed into an epoxidation reactor for reaction.

[0051] According to the technical solution of the present invention, in step 4), preferably, the conditions of the epoxidation reaction are: reaction pressure ≤ 10 MPaG, reaction temperature 40-130 °C, and space velocity of reaction raw materials 0.1-10 h -1 。

[0052] According to the technical solution of the present invention, in step 4), more preferably, the conditions of the epoxidation reaction are: reaction pressure 4-6 MPaG, reaction temperature 80-120 °C, and space velocity of reaction raw materials 6-8 h -1 。

[0053] According to the technical solution of the present invention, in step 4), preferably, the pressure drop of the epoxidation reactor is less than 0.5 MPa, preferably less than 0.1 Mpa.

[0054] Adopting the technical solution of the present application can reduce the content of oxalic acid or oxalate ion in the raw materials before entering the epoxidation reactor to not more than 10 mg / kg.

[0055] This method reduces the content of oxalic acid or oxalate in cumene hydroperoxide or ethylbenzene hydroperoxide by treating with calcium-based molecular sieve, so as to ensure the stability of the material inlet and outlet pressure of the reactor and guarantee the smooth progress of continuous production. This invention does not require caustic washing. After passing through the molecular sieve bed layer and then washing with water, the intake of sodium ions can be reduced, the catalyst bed layer can be protected, and the bed layer pressure drop can be reduced.

[0056] All publications, patent applications, patents and other references mentioned in this specification are hereby incorporated by reference in their entirety. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0057] When this specification uses prefixes such as "well-known to those skilled in the art", "prior art" or similar terms to introduce materials, substances, methods, steps, devices or components, etc., the objects introduced by such prefixes cover those commonly used in the art at the time when this application is filed, but also include those that are not commonly used at present but will become recognized by the art as suitable for similar purposes.

[0058] In the context of this specification, except for the content clearly stated, any matters or things not mentioned shall directly apply to those known in the art without any change. Moreover, any implementation manner described herein can be freely combined with one or more other implementation manners described herein, and the technical solutions or technical ideas formed thereby shall be regarded as part of the original disclosure or original record of this invention, and shall not be regarded as new content not disclosed or anticipated herein, unless those skilled in the art consider that such combination is obviously unreasonable.

[0059] The present invention will be further described below through examples, but not limited to these examples. Detailed Embodiments

[0060] The present invention will be specifically described below in combination with specific examples. It is necessary to point out here that the following examples are only for further illustration of the present invention and should not be construed as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention still fall within the protection scope of the present invention.

[0061] In addition, it should be noted that in the following detailed embodiments, the various specific technical features described can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0062] In addition, any combination can be made among various different embodiments of the present invention as long as it does not violate the idea of the present invention. The technical solutions thus formed are part of the original public content of this specification and also fall within the protection scope of the present invention.

[0063] According to a preferred embodiment of the present invention, the method for propylene epoxidation includes oxidizing cumene or ethylbenzene to obtain a cumene hydroperoxide or ethylbenzene hydroperoxide stream, then treating it through a calcium-based molecular sieve bed and fully washing with water to reduce the oxalic acid (root) content therein to below 2 mg / kg, and then distilling and concentrating it as the oxidant raw material for the epoxidation reaction to carry out the epoxidation reaction with propylene. The oxalic acid (root) content in the oxidant raw material before entering the epoxidation reactor does not exceed 10 mg / kg.

[0064] In the following examples, unless otherwise specified, the experimental methods used are all conventional methods, and the materials, reagents, etc. used can be purchased from domestic chemical companies.

[0065]

Example 1

[0066] 120 g of cumene was introduced into the oxidation reaction kettle, the reaction pressure was 0.5 MPaG, the reaction temperature was 80 °C, 10 g of an aqueous calcium hydroxide solution with a concentration of 100 mg / kg was added to the reaction solution, and air was slowly introduced to obtain a solution of cumene hydroperoxide with a concentration of 10 wt%.

[0067] The obtained cumene hydroperoxide was passed through a calcium-type 5A molecular sieve bed in a continuous flow manner. The calcium content in the molecular sieve was 9%, the pore diameter was 0.5 nm, the temperature was 20 °C, the pressure was 0.1 MPaG, and the volume space velocity was 0.1 h -1 , and then washed with an equal weight of deionized water. After treatment, the oxalate ion content was 0.6 mg / kg, and the content of other organic acids was 0.5 mg / kg.

[0068] Then it entered the flash tank, and the oxidant content obtained at the bottom of the tower was between 55 wt%, the oxalate ion content was 0.5 mg / kg, and the content of other organic acids was 0.3 mg / kg.

[0069] 30 g of the cumene hydroperoxide obtained by rectification was taken, the volume space velocity was 6 h -1 , the reaction temperature was 80 °C, the reaction pressure was 4 MPa, the molar ratio of propylene to cumene hydroperoxide was 8, the reaction time was 168 hours, the reaction yield was 98%, the reaction selectivity was 99%, and the reactor pressure drop was 0.01 MPa.

[0070]

Example 2

[0071] 120 g of cumene was introduced into the oxidation reactor. The reaction pressure was 1 MPaG and the reaction temperature was 100 °C. 10 g of an aqueous calcium carbonate solution with a concentration of 100 mg / kg was added to the reaction solution, and air was slowly introduced to obtain a solution of cumene hydroperoxide with a concentration of 11 wt%.

[0072] The obtained cumene hydroperoxide was passed through a calcium-type 10X molecular sieve bed in a continuous flow manner. The calcium content in the molecular sieve was 6.8%, the pore diameter was 0.9 nm, the temperature was 20 °C, the pressure was 0.1 MPaG, and the volume space velocity was 0.1 h -1 , and then it was washed with deionized water with a weight 2 times that of the raw material. After treatment, the oxalate ion content was 0.2 mg / kg, and the content of other organic acids was 0.3 mg / kg.

[0073] Then it entered the flash tank. The oxidant content obtained at the bottom of the tower was between 60 wt%, the oxalate ion content was 0.1 mg / kg, and the content of other organic acids was 0.1 mg / kg.

[0074] 30 g of the cumene hydroperoxide obtained by distillation was taken, and the volume space velocity was 8 h -1 , the reaction temperature was 100 °C, the reaction pressure was 4 MPa, the molar ratio of propylene to cumene hydroperoxide was 8, the reaction time was 168 hours, the reaction yield was 98%, the reaction selectivity was 99%, and the reactor pressure drop was 0.01 MPa.

[0075]

Example 3

[0076] 120 g of cumene was introduced into the oxidation reactor. The reaction pressure was 0.8 MPaG and the reaction temperature was 110 °C. 10 g of an aqueous calcium hydroxide solution with a concentration of 100 mg / kg was added to the reaction solution, and air was slowly introduced to obtain a solution of cumene hydroperoxide with a concentration of 10 wt%.

[0077] The obtained cumene hydroperoxide was passed through a calcium-type Y molecular sieve bed in a continuous flow manner. The calcium content in the molecular sieve was 4.8%, the pore diameter was 1.5 nm, the temperature was 20 °C, the pressure was 0.1 MPaG, and the volume space velocity was 0.1 h -1 , and then it was washed with deionized water with a weight 3 times that of the raw material. After treatment, the oxalate ion content was 1.6 mg / kg, and the content of other organic acids was 2 mg / kg.

[0078] Then it entered the flash tank. The oxidant content obtained at the bottom of the tower was between 30 wt%, the oxalate ion content was 1 mg / kg, and the content of other organic acids was 0.8 mg / kg.

[0079] 30 g of the cumene hydroperoxide obtained by distillation was taken, and the volume space velocity was 8 h -1, the reaction temperature is 110 °C, the reaction pressure is 4 MPa, the molar ratio of propylene to cumene hydroperoxide is 8, the reaction time is 168 hours, the reaction yield is 98%, the reaction selectivity is 99%, and the reactor pressure drop is 0.02 MPa.

[0080]

Example 4

[0081] 120 g of cumene was introduced into the oxidation reactor. The reaction pressure was 1 MPaG and the reaction temperature was 100 °C. 10 g of an aqueous calcium carbonate solution with a concentration of 100 mg / kg was added to the reaction solution, and air was slowly introduced to obtain a solution of cumene hydroperoxide with a concentration of 11 wt%.

[0082] The obtained cumene hydroperoxide was contacted with a calcium-type 10X molecular sieve bed in a batch manner. The calcium content in the molecular sieve was 6.8%, the pore diameter was 0.9 nm, the temperature was 20 °C, the pressure was 0.1 MPaG, and the residence time was 2 hours. Then, it was washed with deionized water with a weight 2 times that of the raw material. After treatment, the oxalate ion content was 0.7 mg / kg, and the content of other organic acids was 1 mg / kg.

[0083] Then it entered the flash tank. The oxidant content obtained at the bottom of the tower was between 58 wt%, the oxalate ion content was 0.5 mg / kg, and the content of other organic acids was 0.7 mg / kg.

[0084] 30 g of cumene hydroperoxide obtained by distillation was taken, and the volume space velocity was 8 h -1 , the reaction temperature was 100 °C, the reaction pressure was 4 MPa, the molar ratio of propylene to cumene hydroperoxide was 8, the reaction time was 168 hours, the reaction yield was 98%, the reaction selectivity was 99%, and the reactor pressure drop was 0.01 MPa.

[0085]

Example 5

[0086] 120 g of cumene was introduced into the oxidation reactor. The reaction pressure was 0.8 MPaG and the reaction temperature was 110 °C. Air was slowly introduced to obtain a solution of cumene hydroperoxide with a concentration of 9 wt%.

[0087] The obtained cumene hydroperoxide was passed through a calcium-type Y molecular sieve bed in a continuous flow form. The calcium content in the molecular sieve was 4.8%, the pore diameter was 1.5 nm, the temperature was 20 °C, the pressure was 0.1 MPaG, and the volume space velocity was 0.1 h -1 , and then it was washed with deionized water with a weight 3 times that of the raw material. After treatment, the oxalate ion content was 2 mg / kg, and the content of other organic acids was 3 mg / kg.

[0088] Then it entered the flash tank. The oxidant content obtained at the bottom of the tower was between 30 wt%, the oxalate ion content was 1.8 mg / kg, and the content of other organic acids was 1 mg / kg.

[0089] Take 30 grams of cumene hydroperoxide obtained by rectification, with a space velocity of 8 h -1 , reaction temperature 110 °C, reaction pressure 4 MPa, molar ratio of propylene to cumene hydroperoxide is 8, reaction time 168 hours, reaction yield 98%, reaction selectivity 99%, reactor pressure drop 0.03 MPa.

[0090]

Comparative Example 1

[0091] The same oxidation step as in Example 1.

[0092] Wash the obtained cumene hydroperoxide with an equal volume of calcium carbonate aqueous solution with a concentration of 1000 mg / kg, and then wash with an equal volume of deionized water. The oxalate ion content is 4.5 mg / kg, and the content of other organic acids is 3.6 mg / kg.

[0093] Then enter the flash tank, and the oxidant content obtained at the bottom of the tower is between 50 wt%, the oxalate ion content is 4 mg / kg, and the content of other organic acids is 3 mg / kg.

[0094] Take 30 grams of hydroxycumene hydroperoxide obtained by rectification, with a space velocity of 6 h -1 , reaction temperature 80 °C, reaction pressure 4 MPa, molar ratio of propylene to hydroxycumene hydroperoxide is 8, reaction time 168 hours, reaction yield 98%, reaction selectivity 99%, reactor pressure drop 0.5 MPa.

[0095]

Comparative Example 2

[0096] Introduce 120 g of cumene into the oxidation reaction kettle, reaction pressure 0.5 MPaG, reaction temperature 80 °C, add 10 grams of calcium hydroxide aqueous solution with a concentration of 100 mg / kg to the reaction solution, and slowly introduce air to obtain a solution of cumene hydroperoxide with a concentration of 10 wt%.

[0097] Pass the obtained cumene hydroperoxide through an adsorbent composed of a mixture of magnesium silicate and activated carbon in a continuous flow form, with a specific surface area of 450 m 2 / g, temperature 20 °C, pressure 0.1 MPaG, space velocity of 0.1 h -1 , and then wash with 3 times the weight of the raw material of deionized water. After treatment, the oxalate ion content is 6 mg / kg, and the content of other organic acids is 4 mg / kg.

[0098] Then enter the flash tank, and the oxidant content obtained at the bottom of the tower is between 30 wt%, the oxalate ion content is 5 mg / kg, and the content of other organic acids is 3 mg / kg.

[0099] Take 30 grams of cumene hydroperoxide obtained by rectification, with a space velocity of 6 h -1, the reaction temperature is 80 °C, the reaction pressure is 4 MPa, the molar ratio of propylene to cumene hydroperoxide is 8, the reaction time is 168 hours, the reaction yield is 95%, the reaction selectivity is 95%, and the reactor pressure drop is 0.5 MPa.

Claims

1. A method for treating raw materials for propylene epoxidation reaction, comprising the steps of subjecting the reaction raw materials to calcium-based molecular sieve treatment and water washing, wherein the reaction raw materials are solutions containing cumene hydroperoxide and / or ethylbenzene hydroperoxide.

2. The treatment method according to claim 1, characterized in that: the concentration of cumene hydroperoxide and / or ethylbenzene hydroperoxide in the reaction raw materials is 1-60 wt%, preferably 5-25 wt%.

3. The treatment method according to claim 1, characterized in that: the calcium-based molecular sieve is selected from at least one of 5A molecular sieve, 10X molecular sieve, calcium Y molecular sieve or a molecular sieve containing calcium ions prepared by ion exchange; preferably, the mass content of calcium ions in the calcium-based molecular sieve is 1-11%, more preferably 5-11%; the pore size of the calcium-based molecular sieve is 0.3-2 nm, more preferably 0.9-1.3 nm.

4. The treatment method according to claim 1, characterized in that: the conditions for the calcium-based molecular sieve treatment include: temperature 0-80 °C, preferably 20-40 °C; pressure 0-1.0 MPaG, preferably 0.1-0.8 MPaG; and / or, When the reaction raw materials pass through the calcium-based molecular sieve in a continuous flow manner, the volume space velocity of the reaction raw materials is 0.1 to 10 h -1 , preferably 0.1 to 0.5 h -1 ; and / or when the reaction raw materials are in contact with the calcium-based molecular sieve in a batch manner, the residence time of the reaction raw materials is 0.1-10 h, preferably 4-6 h.

5. The treatment method according to claim 1, characterized in that: the water washing includes one-stage or multi-stage water washing, and the amount of water used is preferably 1 / 100-10 times the weight of the reaction raw materials, more preferably 1-3 times.

6. The treatment method according to claim 1, characterized in that: the content of oxalic acid or oxalate ions in the treated reaction raw materials is 2 mg / kg or less, preferably 0.1-1.0 mg / kg.

7. A method for propylene epoxidation, comprising the following steps: 1) Oxidizing cumene or ethylbenzene to obtain a solution containing cumene hydroperoxide or ethylbenzene hydroperoxide; 2) Treating the solution according to the treatment method described in any one of claims 1-6; 3) Performing distillation treatment; 4) Subjecting the stream obtained in step 3) to an epoxidation reaction with propylene.

8. The method for propylene epoxidation according to claim 7, characterized in that in step 1): the conditions for the oxidation reaction are: reaction pressure ≤1.0 MPaG, preferably 0.5-1 MPaG; reaction temperature 80-180 °C, preferably 80-120 °C; and / or, optionally adding an alkaline compound with a content not exceeding 1000 mg / kg during the oxidation reaction, and the alkaline compound is preferably at least one of calcium hydroxide or calcium carbonate.

9. The method for propylene epoxidation according to claim 7, characterized in that: the concentration of cumene hydroperoxide or ethylbenzene hydroperoxide in the stream obtained after distillation in step 3) is 20-60 wt%, preferably 50-60 wt%; and / or, the content of oxalic acid or oxalate ions in the stream obtained after distillation in step 3) does not exceed 10 mg / kg, preferably does not exceed 5 mg / kg.

10. The method for propylene epoxidation according to claim 7, characterized in that in step 4): The conditions for the epoxidation reaction are as follows: reaction pressure ≤ 10 MPaG, preferably 4 - 6 MPaG; reaction temperature 40 - 130 °C, preferably 80 - 120 °C; space velocity of the reaction raw materials 0.1 - 10 h -1 , preferably 6 - 8 h -1 ; and / or, The pressure drop of the epoxidation reactor is less than 0.5 MPa, preferably less than 0.1 MPa.