Regeneration method of deactivated catalyst for preparing maleic anhydride through oxidation of n-butane

Abstract

The invention relates to the field of regeneration of a deactivated catalyst for preparing maleic anhydride through oxidation of n-butane, and discloses a regeneration method of a deactivated catalyst for preparing maleic anhydride through oxidation of n-butane. The method comprises the following steps: carrying out first regeneration and second regeneration on a deactivated catalyst for preparing maleic anhydride by oxidizing n-butane; wherein the first regeneration atmosphere is air and / or inert gas; wherein the second regeneration atmosphere is water vapor, inert gas and / or air. The method can greatly improve the activity of the deactivated catalyst and prolong the service life of the deactivated catalyst.

Description

Technical Field

[0001] The invention relates to the field of regeneration of deactivated catalysts for preparing maleic anhydride by oxidation of n-butane, and in particular to a regeneration method for deactivated catalysts for preparing maleic anhydride by oxidation of n-butane. Background Art

[0002] C4 hydrocarbons (1-butene, isobutylene, isobutane, n-butane, cis-2-butene, trans-2-butene, etc.) are a class of low-value products in the process of petroleum processing, with abundant output, but the utilization rate of C4 in my country is still very low. Using it as a reactant to implement deep conversion can obtain many high-value-added petrochemical products, which can be widely used in many fields of the national economy and have important strategic significance. Among them, the oxidation of n-butane to prepare maleic anhydride (abbreviated as maleic anhydride) is one of the most important industrial applications. Maleic anhydride is an important organic chemical raw material and fine chemical product. Due to the presence of olefin bonds and unsaturated carbonyl bonds in maleic anhydride molecules, maleic anhydride molecules have a high reaction diversity and can undergo addition, polymerization, esterification, hydrogenation, amidation and other reactions. Its downstream products are very rich, such as γ-butyrolactone, fumarate, unsaturated polyester resin, etc. As an important intermediate, maleic anhydride has very important applications in the fields of fine chemicals such as food, medicine, pesticides, construction, and new materials, and is an important basic material for biodegradable plastics. There is huge market demand in the future. Currently, the mainstream route for producing maleic anhydride is the n-butane oxidation method, which is a mature process with maleic anhydride catalyst as its core technology.

[0003] The catalysts for preparing maleic anhydride from n-butane mainly include VPO system, VMoO system, TiPO system and MoPO system, but decades of practice have proved that only VPO catalyst is the most effective catalyst in industry. Although VPO industrial catalyst has a long service life (usually 3-5 years), its catalyst cost is relatively expensive, and the deactivated catalyst contains heavy metals such as V. The recovery process of heavy metal catalyst is complicated and expensive, and it causes great pollution and waste. Summary of the invention

[0004] The purpose of the present invention is to overcome the problems existing in the prior art and provide a method for regenerating a deactivated catalyst for preparing maleic anhydride by oxidation of n-butane. The method can greatly improve the activity of the deactivated catalyst and extend its service life.

[0005] In order to achieve the above object, the present invention provides a method for regenerating a deactivated catalyst for preparing maleic anhydride by oxidation of n-butane, the method comprising the following steps: performing a first regeneration and a second regeneration on the deactivated catalyst for preparing maleic anhydride by oxidation of n-butane;

[0006] Wherein, the first regeneration atmosphere is air and / or inert gas;

[0007] Wherein, the second regeneration atmosphere is water vapor, inert gas and / or air.

[0008] Preferably, the first regeneration atmosphere is air and an inert gas.

[0009] Preferably, in the first regeneration atmosphere, the volume fraction of the air is 20-80%, preferably 20-50%.

[0010] Preferably, the second regeneration atmosphere is water vapor, inert gas and air.

[0011] Preferably, in the second regeneration atmosphere, the volume content of water vapor is 5-45%, preferably 10-40%; the volume content of the inert gas is 20-80%, preferably 40-80%; the volume content of the air is 10-45%, preferably 10-30%.

[0012] Through the above technical solution, the beneficial effects of the present invention include:

[0013] The regeneration method provided by the present invention can greatly improve the activity of the deactivated catalyst by adopting a safe and simple two-stage regeneration process. The regenerated catalyst is applied to the reaction of producing maleic anhydride by oxidation of n-butane, which has a higher yield of maleic anhydride, and reduces costs and increases efficiency for the stable operation of the device. Preferably, the catalyst is regenerated by an online method without disassembling the catalyst, which is simple to operate, saves time and effort, is easy to operate, does not require large-scale transformation of the industrial device, and reduces labor costs and safety risks. DETAILED DESCRIPTION

[0014] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0015] In the present invention, the "first", "second" and "third" do not limit the substances and operations, but are only used to distinguish the substances introduced in different steps and the operations performed in different stages.

[0016] In the present invention, the "room temperature" refers to 20-40°C.

[0017] A first aspect of the present invention provides a method for regenerating a deactivated catalyst for preparing maleic anhydride by oxidation of n-butane, the method comprising the following steps: performing a first regeneration and a second regeneration on the deactivated catalyst for preparing maleic anhydride by oxidation of n-butane;

[0018] Wherein, the first regeneration atmosphere is air and / or inert gas;

[0019] Wherein, the second regeneration atmosphere is water vapor, inert gas and / or air.

[0020] After a long period of operation (generally 3-5 years), the activity of the catalyst for preparing maleic anhydride by oxidation of n-butane decreases to deactivation. The inventors of the present invention have found that the regeneration of the deactivated catalyst for preparing maleic anhydride by oxidation of n-butane can be achieved by adopting the two-stage regeneration method provided by the present invention. Among them, the first regeneration is controlled to adopt a first regeneration atmosphere of air and / or an inert gas, and the second regeneration is controlled to adopt water vapor and a second regeneration atmosphere of an inert gas and / or air, which greatly improves the activity of the deactivated catalyst. The regenerated catalyst is applied to the reaction of preparing maleic anhydride by oxidation of n-butane, and the yield of maleic anhydride is higher.

[0021] In the present invention, when the n-butane oxidation to maleic anhydride is reacted at 420° C. and the maleic anhydride mass yield is lower than 80% or the molar yield is lower than 50%, it can be considered that the catalyst is deactivated and needs to be regenerated.

[0022] The present invention has a wide range of selections for the inert gas, which can be conventionally selected in the art. Preferably, the inert gas is selected from at least one of nitrogen, argon, helium and neon, preferably nitrogen.

[0023] According to the present invention, preferably, the first regeneration atmosphere is air and inert gas. This preferred embodiment is conducive to the steady improvement of catalyst activity.

[0024] According to the present invention, preferably, in the first regeneration atmosphere, the volume fraction of the air is 20-80%, preferably 20-50%. This preferred embodiment can further facilitate the steady improvement of the catalyst activity.

[0025] According to the present invention, preferably, the second regeneration atmosphere is water vapor, inert gas and air. This preferred embodiment enables the catalyst to have higher activity.

[0026] According to the present invention, preferably, in the second regeneration atmosphere, the volume content of water vapor is 5-45%, preferably 10-40%; the volume content of the inert gas is 20-80%, preferably 40-80%; the volume content of the air is 10-45%, preferably 10-30%. This preferred embodiment makes the catalyst have higher activity.

[0027] According to the present invention, preferably, the first regeneration comprises: heating the deactivated catalyst from room temperature to a first regeneration temperature in a first regeneration atmosphere, and then performing a first constant temperature maintenance.

[0028] According to the present invention, preferably, the first regeneration temperature is 380-450°C, preferably 380-430°C; the first constant temperature holding time is 0-8h, preferably 0-5h.

[0029] According to the present invention, preferably, the heating rate of heating to the first regeneration temperature is 0.1-10°C / min, preferably 0.1-5°C / min.

[0030] According to the present invention, preferably, the volume space velocity of the first regeneration atmosphere is 50-1000h -1 , preferably 50-600h -1 .

[0031] The present invention adopts the above-mentioned specific first regeneration process to steadily improve the catalyst activity.

[0032] According to the present invention, preferably, the second regeneration condition includes: in a second regeneration atmosphere, subjecting the first regeneration product to a second constant temperature maintenance at a second regeneration temperature.

[0033] According to the present invention, preferably, the second regeneration temperature is 380-450°C, preferably 380-430°C; the second constant temperature holding time is 1-20h, preferably 8-15h.

[0034] In the present invention, the second regeneration temperature may be higher than the first regeneration temperature, or may be the same as the first regeneration temperature. Preferably, the second regeneration temperature is the same as the first regeneration temperature.

[0035] When the second regeneration temperature may be higher than the first regeneration temperature, preferably, the heating rate of heating to the second regeneration temperature is 0.1-10° C. / min.

[0036] According to the present invention, preferably, the volume space velocity of the second regeneration atmosphere is 50-1000h -1 , preferably 50-600h -1 .

[0037] The present invention adopts the above-mentioned specific second regeneration process to make the catalyst have higher activity.

[0038] According to the present invention, preferably, the regeneration method further comprises: cooling the second regeneration product from the second regeneration temperature to room temperature in a third regeneration atmosphere.

[0039] According to the present invention, preferably, the cooling rate to room temperature is 1-5°C / min.

[0040] According to the present invention, preferably, the third regeneration atmosphere is an inert gas and optionally air and optionally water vapor.

[0041] According to the present invention, preferably, in the third regeneration atmosphere, the volume content of the air is 0-50%, the volume content of the inert gas is 30-100%, and the volume content of the water vapor is 0-30%.

[0042] According to the present invention, preferably, the volume space velocity of the third regeneration atmosphere is 50-1000h -1 , preferably 50-600h -1 .

[0043] The specific cooling process adopted in the present invention is beneficial to maintaining a high activity of the catalyst after regeneration.

[0044] According to the present invention, preferably, the deactivated catalyst is a vanadium phosphorus oxygen catalyst. Vanadium phosphorus oxygen catalyst is the most widely used catalyst with the best application effect in the field of n-butane oxidation to maleic anhydride. Therefore, the present invention mainly regenerates such catalyst.

[0045] The present invention has no particular limitation on the specific composition of the deactivated catalyst, which can be a deactivated catalyst after long-term operation of vanadium-phosphorus-oxygen catalysts of various compositions conventionally used in the field of n-butane oxidation to maleic anhydride. Preferably, in the deactivated catalyst, the mass ratio of vanadium to phosphorus is 0.5-2:1, calculated as the element.

[0046] The regeneration method of the present invention can be used to regenerate the catalyst by an online method without disassembling the catalyst, which is simple to operate, saves time and effort, is easy to operate, does not require large-scale transformation of industrial equipment, and reduces labor costs and safety risks. Preferably, the regeneration process of the deactivated catalyst is carried out in a reactor for producing maleic anhydride by oxidation of n-butane.

[0047] The present invention has no particular limitation on the loading amount of the deactivated catalyst in the n-butane oxidation to maleic anhydride reactor, which is generally the loading amount of the fresh catalyst in the n-butane oxidation to maleic anhydride reaction, that is, the amount loaded for the reaction is the amount regenerated later.

[0048] The present invention will be described in detail below through examples.

[0049] The deactivated catalyst used in the following examples was heated at 420°C and fed with n-butane and air, with a n-butane volume fraction of 1.8% and a volume space velocity of 2000 h / min. -1 The catalyst is used when the mass yield of maleic anhydride is 77.6wt% after reacting for a period of time under the above conditions.

[0050] Example 1

[0051] The deactivated catalyst (mass ratio of V to P was 1.6:1) was placed in a fixed bed reactor with a filling volume of 30 mL.

[0052] Step 1 - First regeneration: At room temperature, nitrogen and air are introduced, the volume fraction of nitrogen and air is 50%, and the total volume space velocity is 300h -1 The temperature was raised at a rate of 1°C / min to 380°C for the catalyst bed and maintained at this temperature for 1 h.

[0053] Step 2 - Second regeneration: The catalyst bed is maintained at 380°C and nitrogen, air and water vapor are introduced at corresponding volume fractions of 50%, 25% and 25% respectively, with a total volume space velocity of 500 h -1 , and keep at this temperature for 15h.

[0054] Step 3 - Cooling: nitrogen and air are introduced, with the volume fractions of nitrogen and air being 60% and 40% respectively, and the total volume air velocity being 500h -1 , the catalyst after the second regeneration was cooled to room temperature at a rate of 3°C / min.

[0055] The regenerated catalyst was subjected to performance evaluation. The temperature of the catalyst bed was directly raised to 420°C, and n-butane and air were introduced. The volume fraction of n-butane was 1.8%, and the volume space velocity of n-butane and air was 2000 h-1. -1 The catalytic evaluation results after 24 h of reaction are shown in Table 1.

[0056] Wherein, the volume fraction of n-butane=the volume of n-butane introduced / (the volume of n-butane introduced+the volume of air introduced)×100%.

[0057] Example 2

[0058] The deactivated catalyst (mass ratio of V to P was 1.6:1) was placed in a fixed bed reactor with a filling volume of 30 mL.

[0059] Step 1 - First regeneration: At room temperature, nitrogen was introduced with a nitrogen volume fraction of 100% and a volume space velocity of 500 h -1 The temperature of the catalyst bed was raised to 450°C at a heating rate of 5°C / min and maintained at this temperature for 1 h.

[0060] Step 2 - Second regeneration: The catalyst bed is maintained at 450°C and nitrogen, air and water vapor are introduced at volume fractions of 80%, 10% and 10% respectively, with a total volume space velocity of 100 h -1 , and keep at this temperature for 10h.

[0061] Step 3 - Cooling: nitrogen is introduced at a volumetric space velocity of 500 h -1 , the catalyst after the second regeneration was cooled to room temperature at a rate of 1°C / min.

[0062] The regenerated catalyst was subjected to performance evaluation. The temperature of the catalyst bed was directly raised to 420°C, and n-butane and air were introduced. The volume fraction of n-butane was 1.8%, and the volume space velocity of n-butane and air was 2000 h-1. -1 The catalytic evaluation results after 24 h of reaction are shown in Table 1.

[0063] Example 3

[0064] The deactivated catalyst (mass ratio of V to P was 1.6:1) was placed in a fixed bed reactor with a filling volume of 30 mL.

[0065] Step 1 - First regeneration: At room temperature, nitrogen and air are introduced, where the volume fraction of nitrogen and air is 50% and the total volume space velocity is 100h -1 The temperature was raised at a rate of 0.5°C / min to 410°C for the catalyst bed and maintained at this temperature for 5 h.

[0066] Step 2 - Second regeneration: The catalyst bed is maintained at 410°C and regenerated by introducing nitrogen, air and water vapor, with corresponding volume fractions of 50%, 25% and 25% respectively, and the total volume space velocity is 100h -1 , and keep at this temperature for 10h.

[0067] Step 3 - Cooling: nitrogen and air are introduced, with the volume fractions of nitrogen and air being 50% and 50% respectively, and the total volume air velocity being 100h -1 , the catalyst after the second regeneration was cooled to room temperature at a rate of 1°C / min.

[0068] The regenerated catalyst was subjected to performance evaluation. The temperature of the catalyst bed was directly raised to 420°C, and n-butane and air were introduced. The volume fraction of n-butane was 1.8%, and the volume space velocity of n-butane and air was 2000 h-1. -1 The catalytic evaluation results after 24 h of reaction are shown in Table 1.

[0069] Example 4

[0070] The deactivated catalyst (mass ratio of V to P was 1.6:1) was placed in a fixed bed reactor with a filling volume of 30 mL.

[0071] Step 1 - First regeneration: At room temperature, nitrogen and air were introduced, with the volume fractions of nitrogen and air being 70% and 30% respectively, and the total volume space velocity being 300h -1 The temperature of the catalyst bed was raised to 380°C at a heating rate of 1°C / min and maintained at this temperature for 5 h.

[0072] Step 2 - Second regeneration: The catalyst bed is maintained at 380°C and nitrogen, air and water vapor are introduced at corresponding volume fractions of 50%, 10% and 40% respectively, with a total volume space velocity of 300 h -1 , and keep at this temperature for 10h.

[0073] Step 3 - Cooling: nitrogen is introduced at a volumetric air velocity of 300 h -1 , the catalyst after the second regeneration was cooled to room temperature at a rate of 2°C / min.

[0074] The regenerated catalyst was subjected to performance evaluation. The temperature of the catalyst bed was directly raised to 420°C, and n-butane and air were introduced. The volume fraction of n-butane was 1.8%, and the volume space velocity of n-butane and air was 2000 h-1. -1 The catalytic evaluation results after 24 h of reaction are shown in Table 1.

[0075] Example 5

[0076] The deactivated catalyst (mass ratio of V to P was 1.6:1) was placed in a fixed bed reactor with a filling volume of 30 mL.

[0077] Step 1 - First regeneration: At room temperature, nitrogen and air are introduced, the volume fraction of nitrogen and air is 50%, and the total volume space velocity is 300h -1 The temperature was raised at a rate of 0.1°C / min to 410°C for 0 h.

[0078] Step 2 - Second regeneration: The catalyst bed is maintained at 410°C and nitrogen, air and water vapor are introduced at corresponding volume fractions of 50%, 25% and 25% respectively, with a total volume space velocity of 300h -1 , and keep at this temperature for 10h.

[0079] Step 3 - Cooling: nitrogen, air and water vapor are introduced with corresponding volume fractions of 50%, 45% and 5% respectively, and the volume space velocity is 300h -1 , the catalyst after the second regeneration was cooled to room temperature at a rate of 2°C / min.

[0080] The regenerated catalyst was subjected to performance evaluation. The temperature of the catalyst bed was directly raised to 420°C, and n-butane and air were introduced. The volume fraction of n-butane was 1.8%, and the volume space velocity of n-butane and air was 2000 h-1. -1 The catalytic evaluation results after 24 h of reaction are shown in Table 1.

[0081] Example 6

[0082] The method of Example 1 was followed, except that the regeneration temperature of the first regeneration process and the second regeneration process were both 445°C.

[0083] The regenerated catalyst was subjected to performance evaluation. The temperature of the catalyst bed was directly raised to 420°C, and n-butane and air were introduced. The volume fraction of n-butane was 1.8%, and the volume space velocity of n-butane and air was 2000 h-1. -1 The catalytic evaluation results after 24 h of reaction are shown in Table 1.

[0084] Comparative Example 1

[0085] The method of Example 1 is followed, except that the second regeneration atmosphere of the second regeneration process is nitrogen and air, with corresponding volume fractions of 50% and 50% respectively.

[0086] The regenerated catalyst was subjected to performance evaluation. The temperature of the catalyst bed was directly raised to 420°C, and n-butane and air were introduced. The volume fraction of n-butane was 1.8%, and the volume space velocity of n-butane and air was 2000 h-1. -1 The catalytic evaluation results after 24 h of reaction are shown in Table 1.

[0087] Table 1

[0088] Example No. n-Butane conversion rate / % Maleic anhydride mass yield / wt% Fresh Catalyst 90.09 110.77 Deactivated catalyst 58.21 77.6 Example 1 87.23 105.68 Example 2 83.34 99.96 Example 3 88.43 107.55 Example 4 84.34 101.15 Example 5 88.65 104.28 Example 6 82.56 98.04 Comparative Example 1 73.17 88.93

[0089] Note: The evaluation results of fresh catalyst were obtained under the same conditions as in the example.

[0090] It can be seen from the results in Table 1 that the regenerated catalyst obtained by the regeneration method of the present invention still has a high n-butane conversion rate and a high maleic anhydride yield when applied to the n-butane oxidation to maleic anhydride reaction. This shows that the catalyst obtained by the regeneration method of the present invention has a significantly higher activity.

[0091] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for regenerating a deactivated catalyst for producing maleic anhydride by oxidation of n-butane, the method comprising: The following steps are involved: The deactivated catalyst for preparing maleic anhydride by oxidation of n-butane is subjected to a first regeneration and a second regeneration; Wherein, the first regeneration atmosphere is air and / or inert gas; Wherein, the second regeneration atmosphere is water vapor, inert gas and / or air.

2. The method according to claim 1, in, The first regeneration atmosphere is air and inert gas; Preferably, in the first regeneration atmosphere, the volume fraction of the air is 20-80%, preferably 20-50%.

3. The method according to claim 1, in, The second regeneration atmosphere is water vapor, inert gas and air; Preferably, in the second regeneration atmosphere, the volume content of water vapor is 5-45%, preferably 10-40%; the volume content of the inert gas is 20-80%, preferably 40-80%; the volume content of the air is 10-45%, preferably 10-30%.

4. The method according to any one of claims 1 to 3, in, The first regeneration comprises: heating the deactivated catalyst from room temperature to a first regeneration temperature in a first regeneration atmosphere, and then maintaining the temperature at a first constant temperature; Preferably, the first regeneration temperature is 380-450°C, preferably 380-430°C; the first constant temperature holding time is 0-8h, preferably 0-5h; Preferably, the heating rate of heating to the first regeneration temperature is 0.1-10°C / min, preferably 0.1-5°C / min; Preferably, the volume space velocity of the first regeneration atmosphere is 50-1000h -1 , preferably 50-600h -1 .

5. The method according to any one of claims 1 to 4, in, The second regeneration conditions include: maintaining the first regeneration product at a second constant temperature at a second regeneration temperature in a second regeneration atmosphere; Preferably, the second regeneration temperature is 380-450°C, preferably 380-430°C; the second constant temperature holding time is 1-20h, preferably 8-15h; Preferably, the volume space velocity of the second regeneration atmosphere is 50-1000h -1 , preferably 50-600h -1 .

6. The method according to any one of claims 1 to 5, in, The regeneration method further comprises: cooling the second regeneration product from a second regeneration temperature to room temperature in a third regeneration atmosphere; Preferably, the cooling rate to room temperature is 1-5°C / min.

7. The method according to claim 6, in, The third regeneration atmosphere is an inert gas and optionally air and optionally water vapor; Preferably, in the third regeneration atmosphere, the volume content of the air is 0-50%, the volume content of the inert gas is 30-100%, and the volume content of the water vapor is 0-30%.

8. The method according to claim 6, in, The volume space velocity of the third regeneration atmosphere is 50-1000h -1 , preferably 50-600h -1 .

9. The method according to any one of claims 1 to 8, in, The deactivated catalyst is a vanadium phosphorus oxygen catalyst; Preferably, in the deactivated catalyst, the mass ratio of vanadium to phosphorus, calculated as elements, is 0.5-2:

1.

10. The method according to any one of claims 1 to 9, in, The regeneration process of the deactivated catalyst is carried out in a reactor for producing maleic anhydride by oxidation of n-butane.