Process for the preparation of phenol by oxidation of benzene with n2o in a moving bed reactor

Abstract

The application provides a method for preparing phenol by oxidizing benzene with N2O in a mobile bed reactor, which comprises: the mobile bed reactor comprises a movable part and at least three catalyst fixed beds which are fixed on the movable part and can switch positions with the movement of the movable part; the at least three catalyst fixed beds are divided into a reaction zone, a regeneration zone and a standby zone; the conveying pipeline of N2O and benzene is communicated with the catalyst fixed bed of the reaction zone, and N2O and benzene are introduced into the catalyst fixed bed of the reaction zone to carry out an oxidation reaction to prepare phenol; after the oxidation reaction is completed, the movable part is moved to disconnect the conveying pipeline of N2O and benzene from the reacted reaction zone and to communicate the conveying pipeline of N2O and benzene with the catalyst fixed bed of the standby zone, and the oxidation reaction is continuously carried out; meanwhile, the regeneration pipeline is communicated with the reacted reaction zone to carry out catalyst regeneration. The catalyst has a long service life, the reaction can be continuously carried out, the process flow is simple, and the method has a good application prospect.

Description

Technical Field

[0001] This invention relates to the field of phenol preparation technology, and in particular to a method for preparing phenol by N2O oxidation of benzene using a moving bed reactor. Background Technology

[0002] Phenol, as an important raw material and intermediate in the chemical industry, has a wide range of applications in plastics, dyes, pharmaceuticals, and pesticides. The traditional synthesis of phenol is the cumene process, which involves three steps: propylene and benzene alkylation, cumene peroxidation, and cumene peroxyacidolysis. This process suffers from poor atom economy, safety risks associated with intermediates, and low phenol yield and selectivity. Furthermore, this process produces a large amount of acetone as a byproduct, and with the acetone market becoming saturated in recent years, the excess acetone capacity negatively impacts the economic viability of this process route.

[0003] Given the numerous shortcomings of the cumene process, the one-step benzene oxidation method for phenol production has become a research hotspot in recent years, attracting increasing attention. Compared to the cumene process, the benzene oxidation method boasts advantages such as shorter synthesis steps, fewer reaction byproducts, higher atom economy, lower waste volume, and environmental friendliness, making it a promising new process for industrial-scale substitution.

[0004] The core reaction mechanism of the one-step benzene oxidation process to produce phenol involves the generation of hydroxyl radicals in the reaction system, which then substitute the benzene ring to generate phenol. Currently reported benzene oxidation processes mainly use oxygen, hydrogen peroxide, and nitrous oxide as oxidants to synthesize phenol. Compared to oxygen and hydrogen peroxide, nitrous oxide exhibits better thermal and chemical stability, effectively reducing the safety risks of the oxidation reaction. Furthermore, the resource utilization of nitrous oxide, a greenhouse gas, has significant economic implications.

[0005] Nitrous oxide, with the chemical formula N₂O, commonly known as laughing gas, has a greenhouse effect approximately 300 times that of carbon dioxide, and nitrogen oxides can severely damage the ozone layer. Therefore, the efficient utilization of nitrous oxide is of great significance for environmental protection. With the booming development of the polyester fiber industry, the production capacity of adipic acid organic monomers is gradually expanding. The industrial preparation method for adipic acid is the KA oil-nitric acid oxidation method, which generates a large amount of nitrous oxide as an oxidation byproduct. Currently, the main industrial method for treating nitrous oxide is high-temperature catalytic decomposition. This method is not only energy-intensive, but also produces nitrogen and oxygen as low-value-added decomposition products, wasting the resources of the nitrous oxide oxidant.

[0006] Therefore, developing a process for preparing phenol by oxidizing benzene with nitrous oxide solves the problem of greenhouse gas treatment costs and can also produce high-value phenol products, which is of great research significance.

[0007] In recent years, research has been conducted both domestically and internationally on the process of preparing phenol from benzene by nitrous oxide oxidation. Solutia in the United States and Boreskov in Russia jointly developed the AlphOx process, which effectively utilizes the tail gas generated by the adipic acid process and integrates the oxidation unit with the adipic acid unit. This process uses an atmospheric pressure fixed-bed adiabatic reactor and achieves a product yield of >98% based on benzene feedstock. However, this process was terminated after one year of pilot-scale operation due to high operating costs and poor stability of the catalyst during continuous operation.

[0008] US5672777 and US5110995 use modified zeolite catalysts and fixed-bed reactors to achieve a phenol selectivity of 93-97%, but the phenol yield is only 20-30%, and the exothermic reaction reduces the catalyst sintering activity.

[0009] WO9527691 uses a fixed-bed reactor, which improves the reaction space velocity and product selectivity at a higher benzene / nitrous oxide molar ratio. However, the single-pass yield of phenol in this process is less than 30%, and the large excess of benzene increases the energy consumption for product separation. CN102020535B optimizes the reactor by changing the fixed-bed reaction system to a fluidized bed, which enhances the desorption capacity of oxidation products on the catalyst and slows down the rate of carbon deposition. After 275 minutes of operation, the phenol yield is >50%, but the catalyst lifetime is still not sufficient for long-term continuous operation. Furthermore, the fluidized bed has high requirements for the catalyst's pressure and wear resistance, and it is prone to pulverization during suspension.

[0010] Therefore, it is necessary to develop a new one-step process for the oxidation of benzene to produce phenol. Summary of the Invention

[0011] In view of the problems existing in the prior art, the present invention provides a method for preparing phenol by oxidizing benzene with N2O in a moving bed reactor, which can realize continuous production of the process. Compared with the previously reported fixed bed reaction catalyst, it can be frequently regenerated and is less affected by catalyst coking and deactivation. Compared with fluidized bed reaction, the process flow is simple, the catalyst is in a relatively static state in the bed, and the requirements for catalyst mechanical strength are lower.

[0012] To achieve this objective, the present invention adopts the following technical solution:

[0013] This invention provides a method for preparing phenol by N2O oxidation of benzene using a moving bed reactor, the method comprising:

[0014] The moving bed reactor includes a movable part and at least three fixed catalyst beds fixed on the movable part and capable of changing positions as the movable part moves; the at least three fixed catalyst beds are divided into a reaction zone, a regeneration zone and a standby zone;

[0015] The N2O and benzene delivery pipelines are connected to the catalyst fixed bed in the reaction zone, and N2O and benzene are introduced into the catalyst fixed bed in the reaction zone to carry out an oxidation reaction to produce phenol; after the oxidation reaction is completed, the movable part is moved to disconnect the N2O and benzene delivery pipelines from the reaction zone after the reaction and connect them to the catalyst fixed bed in the standby zone to continue the oxidation reaction; at the same time, the regeneration pipeline is connected to the reaction zone after the reaction to regenerate the catalyst.

[0016] This invention enables continuous oxidation of N2O and benzene by employing a moving bed reactor. On the one hand, the reaction is carried out in a fixed bed, which avoids catalyst pulverization and extends the overall service life of the catalyst. On the other hand, the fixed bed can be switched for regeneration without affecting the N2O and benzene delivery pipelines and the catalyst regeneration pipelines, allowing for efficient regeneration and thus extending the overall service life of the catalyst.

[0017] Preferably, the ratio of the number of catalyst fixed beds in the reaction zone to the number of catalyst fixed beds in the regeneration zone is x, and the ratio of the oxidation reaction duration to the regeneration duration is y. The ratio of x to y is 0.8 to 1:1, for example, it can be 0.8:1, 0.83:1, 0.85:1, 0.87:1, 0.89:1, 0.92:1, 0.94:1, 0.96:1, 0.98:1 or 1:1, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0018] It is worth noting that the key to this invention lies in how to improve the overall service life of the catalyst while improving the catalytic efficiency. Therefore, the ratio of x / y is controlled to be 0.8 to 1:1. Within this range, it can be ensured that both the regeneration zone and the reaction zone are basically in operation, thereby avoiding the situation of the regeneration zone running idle and improving the catalytic efficiency of the catalyst. At the same time, it avoids the situation where there is no qualified catalyst bed in the reaction zone, which makes it difficult for the reaction to operate continuously and stably.

[0019] Preferably, the oxidation reaction time is 1.8 to 3.0 times the regeneration time, for example, it can be 1.8 times, 2.0 times, 2.2 times, 2.3 times, 2.5 times, 2.8 times or 3.0 times, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0020] Preferably, the oxidation reaction time is 4 to 35 hours, for example, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 10 hours, 12 hours, 13 hours, 15 hours, 18 hours, 20 hours, 22 hours, 25 hours, 30 hours or 35 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0021] It is worth noting that controlling the oxidation reaction time and regeneration duration is crucial. First, a longer oxidation reaction time leads to more coking in the catalyst, and the selectivity and conversion rate of the catalyst gradually decrease later. Therefore, it is necessary to effectively control the duration of a single reaction to ensure the selectivity of phenol and the conversion rate of nitrous oxide. Second, it is necessary to find a suitable regeneration time that matches the reaction time to improve the overall operating efficiency of the catalyst in the catalyst bed. This allows for the production of more phenol in a shorter time with the same amount of catalyst, significantly improving economic efficiency in actual plant operation. Based on the above considerations, this invention preferably controls the oxidation reaction time to be 1.8 to 3 times the regeneration time, generally 2 or 3 times, but also 1.8 to 2.0 times or 2.8 to 3.0 times. Correspondingly, the number of catalyst fixed beds in the reaction zone is 2.0 to 3.0 times the number of catalyst fixed beds in the regeneration zone. When the time ratio is set to less than 2.0 or 3.0 times, some leeway time is allowed for operation, which can significantly improve the operating efficiency of the catalyst bed.

[0022] Preferably, the number of catalyst fixed beds in the spare zone is at least one and at most the same as the number of catalyst fixed beds in the reaction zone.

[0023] The present invention can set one or more backup catalyst fixed beds according to different situations, which can ensure that the N2O and benzene delivery pipelines can operate continuously without stopping.

[0024] Preferably, the movable part is a movable turntable, and the catalyst fixed bed is distributed at equal angles on the movable turntable.

[0025] Preferably, the regeneration temperature is 400-800℃, for example, it can be 400℃, 445℃, 485℃, 535℃, 575℃, 620℃, 660℃, 715℃, 755℃ or 800℃, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably 550-650℃.

[0026] Preferably, the regeneration medium includes any one or a combination of at least two of oxygen, air, or N2O, with N2O being the most preferred.

[0027] It is worth noting that the regeneration process of this invention is a process in which the regeneration medium reacts with the coking on the catalyst to convert the coking into CO and CO2. This invention preferably uses N2O as the regeneration medium. On the one hand, it can save gas delivery pipelines, and regeneration can be carried out by directly connecting a branch pipeline from the reaction pipeline. On the other hand, N2O is converted into N2 and O2 at high temperature, and reacts with the coking to convert into CO2. However, some N2O still remains in the pores of the catalyst, forming a catalyst bed with adsorbed N2O in advance. After switching to the reaction zone, it can directly react with benzene to generate phenol, which improves the reaction efficiency and conversion rate.

[0028] Preferably, the flow rate of the regenerated medium is 200 to 1000 ml / min, for example, it can be 200 ml / min, 300 ml / min, 400 ml / min, 500 ml / min, 600 ml / min, 700 ml / min, 800 ml / min, 900 ml / min or 1000 ml / min, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0029] Preferably, the temperature of the oxidation reaction is 350 to 500°C, for example, 350°C, 365°C, 380°C, 400°C, 415°C, 435°C, 450°C, 465°C, 485°C or 500°C, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, with 400 to 450°C being the preferred temperature.

[0030] Preferably, the total space velocity of N2O and benzene is 3000–5000 h⁻¹. -1 For example, it could be 3000h -1 3223h -1 3445h -1 3667h -1 3889h -1 4112h -1 4334h -1 4556h -1 4778h -1 or 5000h -1 The values ​​may include, but are not limited to, the listed values; other unlisted values ​​within this range also apply, with 3500–4500 h being preferred. -1 .

[0031] Preferably, the molar ratio of benzene to N2O is 2 to 10:1, for example, it can be 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1 or 10:1, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably 4 to 6:1.

[0032] Since this invention requires matching the oxidation reaction time with the regeneration time, it is necessary to minimize the amount of coking accumulated during the reaction time. However, the molar ratio of reactants, reaction temperature, and gas hourly space velocity affect the conversion rate of nitrous oxide, the selectivity of phenol, and the carbon deposition rate. Specifically, as the molar ratio of benzene to nitrous oxide increases, the yield of phenol increases, but the rate of increase decreases after reaching a certain threshold. However, increasing the amount of benzene used leads to an excessively low concentration of the reaction product, significantly increasing separation energy consumption. Therefore, the benzene / nitrous oxide ratio is preferably 2–10, more preferably 4–6. Increasing the temperature helps promote the oxidation reaction and improves the vaporization ability of phenol, allowing it to desorb rapidly from the catalyst. However, in a solid acid catalyst system, increasing the temperature also makes the catalyst more prone to coking and deactivation. Furthermore, the thermal decomposition of nitrous oxide at high temperatures reduces the utilization rate of the raw materials. Therefore, the reaction temperature must be controlled within a suitable range, preferably 350–500°C, more preferably 400–450°C. Increasing the gas hourly space velocity (GHSV) is beneficial for improving the selectivity of phenol. Reducing the residence time of the substrate in the catalyst bed can inhibit catalyst coking to some extent and reduce the deep oxidation of phenol. However, reducing the residence time also reduces the conversion rate of nitrous oxide gas. Therefore, the gas hourly space velocity (GHSV) of the reaction (benzene vapor + nitrous oxide) needs to be controlled within a suitable range, preferably 3000–5000 h⁻¹. -1 More preferably 3500-4500h -1 .

[0033] Preferably, the catalyst for the oxidation reaction comprises a support and a transition metal oxide supported on the support.

[0034] Preferably, the transition metal oxide includes any one or a combination of at least two of iron oxide, zinc oxide, copper oxide or zirconium oxide, wherein typical but non-limiting combinations are combinations of iron oxide and zinc oxide, combinations of zirconium oxide and zinc oxide, and combinations of iron oxide and zirconium oxide.

[0035] Preferably, the carrier comprises any one or a combination of at least two of MFI molecular sieves, FAU molecular sieves, CHA molecular sieves, or Beta molecular sieves, wherein typical but non-limiting combinations are combinations of MFI molecular sieves and FAU molecular sieves, combinations of CHA molecular sieves and FAU molecular sieves, combinations of MFI molecular sieves and CHA molecular sieves, and combinations of Beta molecular sieves and FAU molecular sieves.

[0036] Preferably, the content of transition metal oxide in the catalyst is 0.05 to 0.5 wt%, for example, it can be 0.05 wt%, 0.1 wt%, 0.15 wt%, 0.2 wt%, 0.25 wt%, 0.3 wt%, 0.35 wt%, 0.4 wt%, 0.45 wt%, or 0.5 wt%, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0037] Preferably, the molar ratio of Si / Al in the catalyst is 80 to 120:1, for example, it can be 80:1, 85:1, 89:1, 94:1, 98:1, 103:1, 107:1, 112:1, 116:1 or 120:1, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0038] The catalyst used in this invention is not specifically selected; any catalyst disclosed in the prior art suitable for the preparation of phenol by nitrous oxide oxidation of benzene can be used, or adjustments can be made according to the actual situation.

[0039] Preferably, the catalyst in the catalyst fixed bed is first activated before undergoing the oxidation reaction.

[0040] Preferably, the activation treatment includes: introducing an activation medium into the catalyst fixed bed to perform activation.

[0041] Preferably, the activation medium includes any one or a combination of at least two of water vapor, nitrogen, or helium, wherein typical but non-limiting combinations are combinations of water vapor and nitrogen, combinations of helium and nitrogen, and combinations of water vapor and helium.

[0042] Preferably, the activation treatment temperature is 400-800℃, for example, 400℃, 445℃, 489℃, 534℃, 578℃, 623℃, 667℃, 712℃, 756℃ or 800℃, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably 500-600℃.

[0043] Preferably, the activation treatment time is 4 to 10 hours, for example, it can be 4 hours, 4.7 hours, 5.4 hours, 6 hours, 6.7 hours, 7.4 hours, 8 hours, 8.7 hours, 9.4 hours or 10 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably 6 to 8 hours.

[0044] Preferably, the aspect ratio of the catalyst fixed bed is 40 to 100:1, for example, it can be 40:1, 47:1, 54:1, 60:1, 67:1, 74:1, 80:1, 87:1, 94:1 or 100:1, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably 50 to 70.

[0045] Compared with the prior art, the present invention has at least the following beneficial effects:

[0046] (1) The method for preparing phenol by oxidizing benzene with N2O using a moving bed reactor provided by the present invention can realize continuous production of the process. Compared with the previously reported fixed bed reaction catalyst, it can be frequently regenerated and is less affected by catalyst coking and deactivation. Compared with fluidized bed reaction, the process is simple, the catalyst is in a relatively static state in the bed, and the requirements for catalyst mechanical strength are low.

[0047] (2) The method of preparing phenol by N2O oxidation of benzene using a moving bed reactor provided by the present invention is less affected by catalyst coking. The reaction can be carried out at a low benzene / nitrous oxide ratio. The entire process can achieve a nitrous oxide conversion rate of >70% and a phenol selectivity of >98%. The reaction effect does not decay even after continuous operation for more than 120 hours. This process is superior to the existing reports. The product separation process is simple and the product quality indicators are better than those of the cumene method. It has good industrial application prospects.

[0048] (3) The method for preparing phenol by N2O oxidation of benzene using a moving bed reactor provided by the present invention significantly improves the operating efficiency of the catalyst. The space-time yield of the catalyst is above 0.35 g / gcat / h, preferably above 0.45 g / gcat / h, and the total operating time of the catalyst can reach more than 1300 h. Attached Figure Description

[0049] Figure 1 This is the moving bed reactor used in the method for preparing phenol by oxidizing benzene with N2O using a moving bed reactor provided in Embodiment 1 of the present invention.

[0050] In the diagram: 1-Moveable section; 2-Catalyst fixed bed; 21-Reaction zone; 22-Regeneration zone; 23-Spare zone. Detailed Implementation

[0051] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0052] The present invention will now be described in further detail. However, the examples described below are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0053] Example 1

[0054] This embodiment provides a method for preparing phenol by N2O oxidation of benzene using a moving bed reactor. The moving bed reactor used in this method is as follows: Figure 1 As shown: The moving bed reactor includes a movable part 1 and three fixed catalyst beds 2 fixed to the movable part 1 and capable of changing positions as the movable part 1 moves; the three fixed catalyst beds 2 are divided into a reaction zone 21, a regeneration zone 22, and a standby zone 23, wherein the reaction zone 21 is provided with one fixed catalyst bed 2. The movable part 1 is a movable turntable, and the fixed catalyst beds 2 are distributed at equal angles on the movable turntable, where the black arrows indicate the rotation switching direction.

[0055] The method includes: loading 30g of catalyst (MFI molecular sieve supported iron oxide, iron oxide content of 0.1wt%, Si / Al elemental molar ratio of 100:1, prepared by conventional impregnation method) into four fixed catalyst beds (length-to-diameter ratio of 70:1) of a moving bed reactor, heating to 550℃, water feed rate of 50mL / h, and catalyst activation for 6h.

[0056] Then, the N2O and benzene delivery pipelines are connected to a catalyst fixed bed in the reaction zone, and N2O and benzene (the molar ratio of benzene to N2O is 5:1, and the total space velocity is 4500 h⁻¹) that have been mixed and preheated to 350°C are introduced into the catalyst fixed bed in the reaction zone. -1 The oxidation reaction was carried out at a temperature of 400℃ for 12 hours to obtain phenol.

[0057] After the oxidation reaction is completed, the movable part is moved to disconnect the N2O and benzene delivery pipelines from the reaction zone after the reaction and connect them to the catalyst fixed bed in the standby zone to continue the oxidation reaction.

[0058] Simultaneously, the regeneration pipeline is connected to the catalyst fixed bed in the reaction zone after the reaction to regenerate the catalyst. The regeneration medium is nitrous oxide, the flow rate is 400 mL / h, the regeneration temperature is 600℃, and the regeneration time for a single catalyst fixed bed is 12 h.

[0059] In this embodiment, the conversion rate and selectivity of the reaction remained essentially unchanged after 10 rounds of continuous switching of the movable part.

[0060] Example 2

[0061] This embodiment provides a method for preparing phenol by oxidizing benzene with N2O using a moving bed reactor. The moving bed reactor used in the method includes a movable part and four catalyst fixed beds fixed on the movable part, whose positions can be changed as the movable part moves. The four catalyst fixed beds are divided into a reaction zone, a regeneration zone, and a standby zone, wherein the reaction zone is provided with two catalyst fixed beds. The movable part is a movable turntable, and the catalyst fixed beds are distributed at equal angles on the movable turntable.

[0062] The method includes: loading 40g of catalyst (BEA molecular sieve supported iron oxide, iron oxide content of 0.05wt%, Si / Al elemental molar ratio of 80:1, prepared by conventional impregnation method) into four fixed catalyst beds (length-to-diameter ratio of 80:1) of a moving bed reactor, heating to 800℃, nitrogen feed rate of 150mL / h, and catalyst activation for 8h.

[0063] Then, the N2O and benzene delivery pipelines are connected to the two catalyst fixed beds in the reaction zone, and N2O and benzene (the molar ratio of benzene to N2O is 2:1, and the total space velocity is 3500 h⁻¹) that have been mixed and preheated to 450°C are introduced into the catalyst fixed beds in the reaction zone. -1 The oxidation reaction was carried out at a temperature of 450℃ for 10 hours to obtain phenol.

[0064] After the oxidation reaction is completed, the movable part is moved to disconnect the N2O and benzene delivery pipelines from the reaction zone after the reaction and connect them to the catalyst fixed bed in the standby zone to continue the oxidation reaction.

[0065] Simultaneously, the regeneration pipeline is connected to one of the catalyst fixed beds in the reaction zone after the reaction to regenerate the catalyst. The regeneration medium used is nitrous oxide, the flow rate is 450 mL / h, the regeneration temperature is 750℃, and the regeneration time for a single catalyst fixed bed is 4.9 h. After the first catalyst fixed bed is regenerated, the regeneration pipeline is switched to connect it to another catalyst fixed bed for catalyst regeneration.

[0066] Example 3

[0067] This embodiment provides a method for preparing phenol by oxidizing benzene with N2O using a moving bed reactor. The moving bed reactor used in the method includes a movable part and four catalyst fixed beds fixed on the movable part, whose positions can be changed as the movable part moves. The four catalyst fixed beds are divided into a reaction zone, a regeneration zone, and a standby zone, wherein the reaction zone is provided with two catalyst fixed beds. The movable part is a movable turntable, and the catalyst fixed beds are distributed at equal angles on the movable turntable.

[0068] The method includes: loading 35g of catalyst (FAU molecular sieve supported iron oxide, iron oxide content of 0.5wt%, Si / Al elemental molar ratio of 120:1, prepared by conventional impregnation method) into four fixed catalyst beds (length-to-diameter ratio of 60:1) of a moving bed reactor, heating to 500℃, helium feed rate of 350mL / h, and catalyst activation for 7h.

[0069] Then, the N2O and benzene delivery pipelines are connected to the two catalyst fixed beds in the reaction zone, and N2O and benzene (the molar ratio of benzene to N2O is 10:1, and the total space velocity is 4000 h⁻¹) that have been mixed and preheated to 400°C are introduced into the catalyst fixed beds in the reaction zone. -1 The oxidation reaction was carried out at a temperature of 420℃ for 12 hours to obtain phenol.

[0070] After the oxidation reaction is completed, the movable part is moved to disconnect the N2O and benzene delivery pipelines from the reaction zone after the reaction and connect them to the catalyst fixed bed in the standby zone to continue the oxidation reaction.

[0071] Simultaneously, the regeneration pipeline is connected to a catalyst fixed bed in the reaction zone after the reaction to regenerate the catalyst. The regeneration medium is nitrous oxide, the flow rate is 500 mL / h, the regeneration temperature is 750℃, and the regeneration time for a single catalyst fixed bed is 5.8 h. After the first catalyst fixed bed is regenerated, the regeneration pipeline is switched to connect it to another catalyst fixed bed for catalyst regeneration.

[0072] Example 4

[0073] This embodiment provides a method for preparing phenol by oxidizing benzene with N2O using a moving bed reactor. The method is the same as in Example 1 except that the regeneration medium is replaced with oxygen, and will not be described again here.

[0074] Example 5

[0075] This embodiment provides a method for preparing phenol by oxidizing benzene with N2O using a moving bed reactor. The method is the same as in Example 1 except that the regeneration medium is replaced with air, and will not be described again here.

[0076] Example 6

[0077] This embodiment provides a method for preparing phenol by N2O oxidation of benzene using a moving bed reactor, wherein the method has a total space velocity of 2800 h⁻¹. -1 Except for the above, everything else is the same as in Example 1, and will not be repeated here.

[0078] Example 7

[0079] This embodiment provides a method for preparing phenol by N2O oxidation of benzene using a moving bed reactor, wherein the method has a total space velocity of 6000 h⁻¹. -1 Except for the above, everything else is the same as in Example 1, and will not be repeated here.

[0080] Example 8

[0081] This embodiment provides a method for preparing phenol by oxidizing benzene with N2O using a moving bed reactor. Except for increasing the regeneration temperature to 800°C, thereby reducing the regeneration time to 8 hours, the method is the same as in Example 1 and will not be repeated here.

[0082] Test methods: Gas chromatography was used to test and calculate the average selectivity of phenol and the conversion rate of nitrous oxide during operation. Long-term operation was also conducted to test the total service life and efficiency of the catalyst after a single loading. The test results of the above examples and comparative examples are shown in Table 1.

[0083] Table 1

[0084]

[0085]

[0086] The following points can be observed from Table 1:

[0087] (1) As can be seen from the comprehensive examples 1 to 3, the method of preparing phenol by oxidizing benzene with N2O using a moving bed reactor provided by the present invention has the advantage of significantly improving the operating efficiency of the catalyst. Moreover, the entire process can achieve a nitrous oxide conversion rate of >70%, a phenol selectivity of >98%, and a catalyst space-time yield of over 0.35 g / gcat / h. The total operating time of the catalyst can reach over 1300 h.

[0088] (2) It can be seen from the combined examples 1 and 4-5 that in example 1, nitrous oxide was used as the regeneration gas. Compared with the use of oxygen and air in examples 4-5, the conversion rate of raw materials in example 1 was 72.7% and the selectivity of phenol was 98.4%. In example 4-5, the selectivity and conversion rate were significantly reduced, and the efficiency of the catalyst was also reduced. This shows that by using nitrous oxide as the regeneration gas, the present invention can further improve the operating efficiency of the catalyst.

[0089] (3) It can be seen from the combined examples 1 and 6-7 that in example 1, nitrous oxide was used as the regeneration gas. Compared with oxygen and air used in examples 6-7, the conversion rate of raw materials in example 1 was 72.7% and the selectivity of phenol was 98.4%. In example 7, the selectivity and conversion rate both decreased significantly. In example 6, the efficiency of the catalyst decreased. This shows that by preferably controlling the total space velocity of the material within a specific range, the present invention can further improve the operating efficiency of the catalyst and effectively ensure the conversion rate and selectivity of the reaction.

[0090] (4) It can be seen from the combined examples 1 and 8 that, in Example 1, the regeneration time was controlled. Compared with the increase in temperature and the shortening of regeneration time in Example 8, not only did the conversion rate of the reaction in Example 8 decrease, but the efficiency of the catalyst was also significantly lower than that in Example 1. This shows that by controlling the regeneration and reaction time within a specific range, the present invention can further improve the operating efficiency of the catalyst and effectively ensure the conversion rate and selectivity of the reaction.

[0091] The present invention has been illustrated with the above embodiments to illustrate its detailed structural features. However, the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the components used in the present invention, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing phenol by N2O oxidation of benzene using a moving bed reactor, characterized in that, The method includes: The moving bed reactor includes a movable part and at least three fixed catalyst beds fixed on the movable part and capable of changing positions as the movable part moves; the at least three fixed catalyst beds are divided into a reaction zone, a regeneration zone and a standby zone; The N2O and benzene delivery pipelines are connected to the catalyst fixed bed in the reaction zone, and N2O and benzene are introduced into the catalyst fixed bed in the reaction zone to carry out an oxidation reaction to produce phenol; after the oxidation reaction is completed, the movable part is moved to disconnect the N2O and benzene delivery pipelines from the reaction zone after the reaction and connect them to the catalyst fixed bed in the standby zone to continue the oxidation reaction; at the same time, the regeneration pipeline is connected to the reaction zone after the reaction to regenerate the catalyst. The ratio of the number of catalyst fixed beds in the reaction zone to the number of catalyst fixed beds in the regeneration zone is x, the ratio of the oxidation reaction duration to the regeneration duration is y, and the ratio of the values ​​of x to y is 0.8 to 1:

1.

2. The method according to claim 1, characterized in that, The oxidation reaction takes 1.8 to 3.0 times the regeneration time.

3. The method according to claim 1, characterized in that, The oxidation reaction takes 4 to 30 hours.

4. The method according to claim 1, characterized in that, The number of catalyst fixed beds in the standby zone is at least one and at most the same as the number of catalyst fixed beds in the reaction zone.

5. The method according to claim 1, characterized in that, The movable part is a movable turntable, and the catalyst fixed bed is distributed at equal angles on the movable turntable.

6. The method according to claim 1, characterized in that, The regeneration temperature is 400~800℃.

7. The method according to claim 6, characterized in that, The regeneration temperature is 550~650℃.

8. The method according to claim 1, characterized in that, The regeneration medium includes any one or a combination of at least two of oxygen, air, or N2O.

9. The method according to claim 8, characterized in that, The regenerated medium includes N2O.

10. The method according to claim 1, characterized in that, The flow rate of the regenerated medium is 200~1000 ml / min.

11. The method according to claim 1, characterized in that, The oxidation reaction is carried out at a temperature of 350~500℃.

12. The method according to claim 11, characterized in that, The oxidation reaction is carried out at a temperature of 400~450℃.

13. The method according to claim 1, characterized in that, The total space velocity of N2O and benzene is 3000~5000 h⁻¹. -1 .

14. The method according to claim 13, characterized in that, The total space velocity of N2O and benzene is 3500~4500 h⁻¹. -1 .

15. The method according to claim 1, characterized in that, The molar ratio of benzene to N2O is 2~10:

1.

16. The method according to claim 15, characterized in that, The molar ratio of benzene to N2O is 4~6:

1.

17. The method according to claim 1, characterized in that, The catalyst for the oxidation reaction includes a support and a transition metal oxide supported on the support.

18. The method according to claim 17, characterized in that, The transition metal oxide includes any one or a combination of at least two of iron oxide, zinc oxide, copper oxide, or zirconium oxide.

19. The method according to claim 17, characterized in that, The carrier includes any one or a combination of at least two of MFI molecular sieves, FAU molecular sieves, CHA molecular sieves, or Beta molecular sieves.

20. The method according to claim 1, characterized in that, The catalyst contains 0.05 to 0.5 wt% transition metal oxides.

21. The method according to claim 1, characterized in that, The elemental molar ratio of Si / Al in the catalyst is 80~120:

1.

22. The method according to claim 1, characterized in that, In the catalyst fixed bed, the catalyst is first activated before undergoing oxidation.

23. The method according to claim 22, characterized in that, The activation process includes: introducing an activation medium into the catalyst fixed bed to perform activation.

24. The method according to claim 23, characterized in that, The activation medium includes any one or a combination of at least two of water vapor, nitrogen, or helium.

25. The method according to claim 22, characterized in that, The activation treatment temperature is 400~800℃.

26. The method according to claim 25, characterized in that, The activation treatment temperature is 500~600℃.

27. The method according to claim 22, characterized in that, The activation treatment time is 4~10 hours.

28. The method according to claim 27, characterized in that, The activation treatment time is 6-8 hours.

29. The method according to claim 1, characterized in that, The aspect ratio of the catalyst fixed bed is 40~100:

1.

30. The method according to claim 29, characterized in that, The aspect ratio of the catalyst fixed bed is 50 to 70.

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