Preparation system and method for an epoxyalkane compound

Abstract

The present invention provides a preparation system and method for epoxyalkane compounds. The system includes at least four reactors connected in series through pipelines. Each reactor is provided with a raw material inlet. The order of the series connection between the reactors refers to the order in which the reaction materials pass through after entering the system from the raw material inlet. Equal amounts of catalysts are independently loaded in each of the reactors. Along the order of the series connection, the activities of the catalysts loaded in the reactors decrease in sequence, and the operating temperatures of the constant temperature sections in the reactors increase in sequence along the order of the series connection. The system of the present invention realizes high reaction selectivity in a high-temperature and low-concentration raw material environment corresponding to a low-activity catalyst, while also realizing high reaction selectivity in a low-temperature and high-concentration raw material environment corresponding to a high-activity catalyst. It realizes the rational utilization of the aged and deactivated catalyst, enabling the total conversion rate of the reaction to reach more than 98% while maintaining a selectivity of more than 97%.

Description

Technical Field

[0001] The present invention relates to the technical field of fine chemicals, and particularly to a preparation system and method for epoxyalkane compounds. Background Art

[0002] Currently, the industrial production methods of propylene oxide (PO) mainly include the chlorohydrin method, the co-oxidation method, and the direct oxidation method. Among them, the co-oxidation method includes the ethylbenzene co-oxidation method (PO / SM), the isobutane co-oxidation method (PO / MTBE), and the cumene hydroperoxide oxidation method (CHP). The cumene hydroperoxide oxidation method was developed by Sumitomo Chemical Company of Japan, and this technology has been industrialized at Sumitomo Chemical's Chiba Steel Plant in Japan and the Rabigh Petrochemical Plant in Saudi Arabia. The cumene oxidation method uses cumene as a carrier, and through an air oxidation reaction, it becomes cumene hydroperoxide (CHP). After CHP is concentrated, in a fixed-bed reactor, using a proprietary titanium silicalite molecular sieve catalyst, it reacts with propylene in the liquid phase to generate PO and benzyl alcohol, and then benzyl alcohol is hydrogenated to generate cumene for recycling.

[0003] In the process of CHP oxidizing propylene to generate PO, high temperature is beneficial to both the conversion rates of CHP and propylene, but it will also cause part of CHP to decompose into by-products such as phenol and acetone. How to find the optimal point between conversion rate and selectivity is the key. Since the reaction of CHP and propylene is an exothermic reaction, in the initial stage of the reaction, due to the high activity of the catalyst, it is easy to cause local overheating of the catalyst bed, resulting in a decrease in catalyst selectivity and a reduction in reaction efficiency. In CN104557783A, a packed catalyst loading method is adopted. Even by changing the catalyst loading amount in each reactor, a satisfactory propylene oxide selectivity cannot be obtained. In CN1418200A, a strategy of adding the raw material cumene hydroperoxide in segments is used to control the reaction heat, but it increases the overall complexity of the process and the implementation difficulty of the technical solution is large.

[0004] In addition, in the process of preparing PO by oxidizing propylene with CHP in the prior art, as the reaction catalyst is used for a longer time, it will inevitably be deactivated to varying degrees (refer to the relevant research on catalyst deactivation and activation in US5916835A). Based on the data of the existing PO production process by the CHP method, the catalyst activity will decrease by about 5% after continuous use for 1 month and by about 12% after continuous use for 3 months. In this regard, in the prior art, the feed components and reaction conditions of the process are often adjusted to achieve a relatively high CHP conversion rate even when using a catalyst with a relatively severe deactivation degree. However, frequent changes in process parameters during production will reduce production efficiency and increase technical risks. To avoid frequent changes in production parameters caused by changes in catalyst activity, the prior art US5849937A and CN116020353A disclose a relatively primitive design idea: through a segmented and layered reaction device, by continuously replacing the catalyst with a higher deactivation degree, the process can maintain a stable and efficient production for a long time, but it does not solve the negative impact on production caused by the performance changes of the catalyst in mass transfer and heat transfer due to the decrease in catalyst activity. Summary of the Invention

[0005] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a system and method for preparing epoxyalkane compounds, which are used to solve the problem of the negative impact on production caused by the frequent change of production parameters due to the decrease in catalyst activity in the prior art.

[0006] To achieve the above object and other related objects, the present invention provides a system for preparing epoxyalkane compounds, the system includes at least 4 reactors connected in series through pipelines in sequence, each reactor is provided with a raw material port, and the order of the series connection between the reactors refers to the order in which the reaction material passes through after entering the system from the raw material port. Each reactor is independently filled with an equal amount of catalyst, and the activity of the catalyst filled in each reactor decreases in sequence along the order of the series connection. Each reactor includes a constant temperature section at the lower part and an adiabatic section at the upper part. After the reaction material enters each reactor, it first passes through the constant temperature section and then through the adiabatic section. The operating temperature of the constant temperature section in each reactor increases in sequence along the order of the series connection.

[0007] The present invention also provides a method for preparing epoxyalkane compounds, which is carried out by using the above-mentioned system for preparing epoxyalkane compounds. The method includes:

[0008] According to the order of the series connection of the reactors, the reaction material is input from the raw material port of the initial reactor and passes through each reactor in series in sequence. The activity of the catalyst filled in each reactor decreases in sequence, and the operating temperature in each reactor increases in sequence, to obtain a propylene oxide product with a cumene hydroperoxide conversion rate ≥ 99%.

[0009] As described above, the preparation system and method of the alkylene oxide compound of the present invention have the following beneficial effects:

[0010] In the preparation system of the alkylene oxide compound of the present invention, catalysts with different activities (different service lives) are distributed at appropriate positions in the reaction process, so that the highly active catalyst preferentially contacts and reacts with the raw material stream, and the low-active catalyst contacts and reacts with the low-concentration raw material stream later; since the concentration of CHP has decreased after the reaction in the front stage of the system, a higher reaction temperature can be designed in the part of the low-active catalyst in the later stage, so that the low-active catalyst can also have a higher catalytic ability while avoiding the selective destruction of the oxidant by high temperature to the greatest extent; thus, by matching catalysts with different activities to different reactions, the severely deactivated catalyst can also play a role in the device, achieving the "maximum utilization of materials at the squeezing level" of the catalyst and extending the average service life of the catalyst by more than 3 times.

[0011] The preparation system of the alkylene oxide compound of the present invention solves the problem in the prior art that as the activity of the reaction catalyst decreases, it is necessary to frequently change process parameters (increase temperature) to maintain the selectivity of the reaction by setting a series of reactors; after the catalyst in the present invention ages, only the catalyst in the terminal reactor needs to be eliminated and replaced with a new catalyst, and at the same time, the on-off state of the valves on the pipeline is changed to change the feeding order (such as R1→R2→R3→R4, after the catalyst in R4 is replaced with a new one, it becomes R4→R1→R2→R3), so as to maintain the selectivity of the reaction.

[0012] The preparation system of the alkylene oxide compound of the present invention realizes high reaction selectivity of the highly active catalyst in a low-temperature and high-concentration raw material environment, and at the same time realizes high reaction selectivity of the low-active catalyst in a high-temperature and low-concentration raw material environment, realizes the reasonable utilization of the aged and deactivated catalyst, and enables the total conversion rate of the reaction to reach more than 98% while maintaining a selectivity of more than 97%. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the series order of the preparation system of the alkylene oxide compound according to the embodiment of the present invention.

[0014] In the drawings: R1 to R4 are all reactors; 101, 201, 301, 401 are all first valves; 102, 202, 302, 402 are second valves; 103, 203, 303, 403 are third valves; 10 is the raw material inlet; 20 is the product outlet; 11, 21, 31, 41 are all raw material ports; 12, 22, 32, 42 are all product ports. DETAILED DESCRIPTION OF THE INVENTION

[0015] The following describes the implementation manners of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0016] In addition, it should be understood that one or more method steps mentioned in the present invention do not exclude the existence of other method steps before and after the combined steps or the insertion of other method steps between the clearly mentioned steps, unless otherwise specified; it should also be understood that the combined connection relationship between one or more devices / apparatuses mentioned in the present invention does not exclude the existence of other devices / apparatuses before and after the combined devices / apparatuses or the insertion of other devices / apparatuses between the two clearly mentioned devices / apparatuses, unless otherwise specified. Moreover, unless otherwise specified, the numbers of the method steps are only convenient tools for identifying the method steps, rather than limiting the arrangement order of the method steps or the scope in which the present invention can be implemented. The change or adjustment of their relative relationships, without substantial change in the technical content, should also be regarded as the scope in which the present invention can be implemented.

[0017] Please refer to the attached drawings. It should be noted that the diagrams provided in this embodiment only illustrate the basic concept of the present invention in a schematic manner. Therefore, only the components related to the present invention are shown in the diagrams, rather than being drawn according to the number, shape, and size of the components in actual implementation. The types, numbers, and ratios of the components in actual implementation can be arbitrarily changed, and the layout type of the components may also be more complex.

[0018] In a first aspect of the present invention, a preparation system for an epoxyalkane compound is provided. The system includes at least 4 reactors connected in series through pipelines in sequence. Each reactor is provided with a raw material port. The order of the series connection between the reactors refers to the order in which the reaction materials pass through after entering the system from the raw material inlet. Equal amounts of catalysts are independently loaded in each of the reactors. The activities of the catalysts loaded in the reactors decrease in sequence along the order of the series connection. Each reactor includes a constant temperature section at the lower part and an adiabatic section at the upper part. After the reaction materials enter each reactor, they first pass through the constant temperature section and then through the adiabatic section. The operating temperatures of the constant temperature sections in the reactors increase in sequence along the order of the series connection.

[0019] In the present invention, the reactors are connected in order of the newness of the catalyst loaded in the reactor. The newer catalyst has higher activity and the operating temperature is set lower, so the selectivity of the produced epoxide product is higher. The older catalyst has lower activity, but at this time, due to its rear position, the operating temperature is higher and the concentration of the reactant CHP is lower, it can still play a catalytic role and maintain a higher selectivity.

[0020] In the preparation system of the present invention, the reactors are connected in series to form a ring and the materials flow in a carousel-like manner between the reactors. The first reactor into which the materials enter the system is the first reactor, and the reactors connected in series thereafter are the second reactor, the third reactor, the fourth reactor, ..., the nth reactor, where n is an Arabic numeral not greater than 6; for the reactor with deactivated catalyst, the original series sequence is cut out, and the cut reactor is cut in from the beginning of the original series sequence after replacing or regenerating the catalyst to become the new first reactor, and each of the reactors is cut out in sequence from the last position in the order of series connection. Among them, the first reactor into which the materials flow into the system is the first reactor; the feed of the second reactor comes from the first reactor, and the discharge goes to the third reactor; the feed of the third reactor comes from the second reactor, and the discharge goes to the fourth reactor; the feed of the fourth reactor comes from the third reactor, and the discharge goes to the next section (or is the product).

[0021] In a preferred embodiment of the present invention, the system comprises 4 to 5 reactors connected in series, for example, the system comprises 4 reactors or 5 reactors.

[0022] When the system includes 4 reactors, when the conversion rate of cumene hydroperoxide in the material output from the first reactor is lower than 35%, or when the conversion rate of cumene hydroperoxide in the material output from the second reactor is lower than 70%, or when the conversion rate of cumene hydroperoxide in the material output from the third reactor is lower than 90%, or when the conversion rate of cumene hydroperoxide in the material output from the fourth reactor is lower than 98%, it is determined that the catalyst of the fourth reactor is deactivated, the fourth reactor is cut out, the catalyst is replaced or regenerated, and then cut in from the beginning of the original series sequence as the first reactor, and sequentially, the original first reactor is changed to the second reactor, the original second reactor is changed to the third reactor, and the original third reactor is changed to the fourth reactor. That is, when a reactor cannot obtain the designed cumene hydroperoxide CHP conversion rate in the designed temperature range, its series sequence in the reactor system is automatically shifted back one position. For example, if Figure 1, in the initial reaction system, the four reactors R1, R2, R3, and R4 operate in the order of the first to the fourth, that is, R1 is the first reactor, R2 is the second reactor, R3 is the third reactor, and R4 is the fourth reactor. When the detector of the reaction monitors that the conversion rate of CHP in the material output from the first reactor is lower than 35%, or the conversion rate of CHP is lower than 70% after the second reactor discharges, or the conversion rate of CHP at the output end of the third reactor is lower than 90%, or the conversion rate of CHP in the material output from the fourth reactor is lower than 98%, it is determined that the catalyst in the corresponding reactor is severely aged and has too low activity to continue meeting the usage requirements. At this time, the catalyst of the fourth reactor R4 with the worst catalytic effect in the system is replaced with a brand-new one, and at the same time, the pipeline of the reaction device is switched so that the conveying order of the material in the reactor is changed to R4→R1→R2→R3.

[0023] When the system includes 4 reactors, in the order of series connection, the activity of the catalyst in the first reactor is such that the conversion rate of cumene hydroperoxide in the material is not less than 40%. The material then passes through the second reactor, and the activity of the catalyst in the second reactor is such that the conversion rate of cumene hydroperoxide in the material is not less than 70%. The material then passes through the third reactor, and the activity of the catalyst in the third reactor is such that the conversion rate of cumene hydroperoxide in the material is not less than 90%. The material then passes through the fourth reactor, and the activity of the catalyst in the fourth reactor is such that the conversion rate of cumene hydroperoxide in the material is not less than 98%. In the system of the present invention, since the catalyst in the front stage of the system is used frequently, and the reaction temperature in the latter stage of the catalyst is high, the catalyst ages to varying degrees during use for different reasons. For example, after the catalyst in the first reactor is used for 1 month, the first reactor is switched to the second reactor, and the catalyst is used for another 1 month. At this time, the inactivation degree of the catalyst is equivalent to that of the catalyst after being used conventionally for 3 months. When the catalyst is used in the first to fourth reactors in sequence for 1 month, the inactivation of the catalyst is very serious at this time, equivalent to the catalyst after being used normally for one year, and it has far exceeded the process requirements.

[0024] In the preparation system of the present invention, each of the reactors is also provided with a product outlet (such as Figure 1 : 12, 22, 32, 42). Each of the product outlets is connected to two material pipelines. The two material pipelines are respectively a product discharge pipeline and a continuous reaction pipeline. In the order of series connection, the continuous reaction pipeline is connected to the raw material inlet of the next reactor. The raw material inlet of each reactor is also connected to a raw material feeding pipeline. A first valve (such as Figure 1 : 101, 201, 301, 401) is provided on each of the raw material feeding pipelines. A second valve (such as Figure 1 : 102, 202, 302, 402) is provided on each of the continuous reaction pipelines. A third valve (such asFigure 1 : 103, 203, 303, 403), the first valve, the second valve and the third valve are suitable for regulating the connection sequence of the reactors connected in series in the system. The reactors are connected in series to form a loop, and by switching the valves, the material flows among the reactors in the form of a "carousel", which prolongs the average service time of the catalyst and at the same time can conveniently replace the inactivated part of the catalyst.

[0025] In a preferred embodiment of the present invention, the system is further provided with a raw material inlet 10 and a product outlet 20. The raw material ports 11, 21, 31, 41 on each reactor are all communicated with the raw material inlet 10, and the product ports 12, 22, 32, 42 on each reactor are all communicated with the product outlet 20.

[0026] In the preparation system of the present invention, each of the reactors includes a lower constant temperature section and an upper adiabatic section. After the material enters each reactor, it first passes through the constant temperature section and then through the adiabatic section.

[0027] Among them, the catalyst filling method in the constant temperature section is to be filled in the tubes; the length-diameter ratio of the tubes is 100 - 250:1. For example, it is 100 - 110:1, 110 - 120:1, 120 - 130:1, 130 - 140:1, 140 - 150:1, 150 - 160:1, 160 - 170:1, 170 - 180:1, 180 - 190:1, 190 - 200:1, 200 - 210:1, 210 - 220:1, 220 - 230:1, 230 - 240:1 or 240 - 250:1. In a preferred embodiment of the present invention, the number of the tubes is 20 - 100. For example, it is 20 - 30, 30 - 40, 40 - 50, 50 - 60, 60 - 70, 70 - 80 or 80 - 90.

[0028] The catalyst filling method in the adiabatic section is bulk filling. By adopting a special catalyst filling form (i.e., the combination of tube filling and bulk filling) in the present invention, the reaction heat is reasonably utilized to heat the material, so that the material slowly and controllably rises to and maintains at the required reaction temperature among the reactors. That is, through a stable and safe temperature control scheme in the present invention, a catalyst with lower activity is made to correspond to a higher temperature.

[0029] The height ratio of the constant temperature section to the adiabatic section is 4 - 8:1. For example, it is 4 - 5:1, 5 - 6:1, 6 - 7:1 or 7 - 8:1.

[0030] The mass ratio of the catalyst filled in the constant temperature section to the mass of the catalyst filled in the adiabatic section is 2 - 5:1. For example, it is 2 - 3:1, 3 - 4:1 or 4 - 5:1.

[0031] The length-diameter ratio of each of the reactors is 1.5 to 8:1. For example, it is 1.5 to 2:1, 2 to 2.5:1, 2.5 to 3:1, 3 to 3.5:1, 3.5 to 4:1, 4 to 4.5:1, 4.5 to 5:1, 5 to 5.5:1, 5.5 to 6:1, 6 to 6.5:1, 6.5 to 7:1, 7 to 7.5:1 or 7.5 to 8:1.

[0032] The catalyst is titanium silicalite molecular sieve.

[0033] The bulk density of the catalyst in the reactor is 0.4 to 0.6 g / mL. For example, it is 0.4 to 0.45 g / mL, 0.45 to 0.5 g / mL, 0.5 to 0.55 g / mL or 0.55 to 0.6 g / mL.

[0034] The operating temperature range of each reactor in the system is 50 to 140 °C. For example, it is 50 to 60 °C, 60 to 70 °C, 70 to 80 °C, 80 to 90 °C, 90 to 100 °C, 100 to 110 °C, 110 to 120 °C, 120 to 130 °C or 130 to 140 °C.

[0035] In the order of series connection, the operating temperature of the first reactor is 50 to 90 °C, 50 to 55 °C, 55 to 60 °C, 60 to 65 °C, 65 to 70 °C, 70 to 75 °C, 75 to 80 °C, 80 to 85 °C or 85 to 90 °C, and the temperature difference between adjacent reactors is 10 to 30 °C, 10 to 15 °C, 15 to 20 °C, 20 to 25 °C or 25 to 30 °C.

[0036] In each of the reactors, the temperature of the adiabatic section is 0 to 10 °C, 0 to 2 °C, 2 to 4 °C, 4 to 6 °C, 6 to 7 °C, 7 to 8 °C or 8 to 10 °C higher than the temperature of the constant temperature section. According to the study of reaction heat release, the temperature rise value of the material in the adiabatic section in each reactor is 2 to 10 °C higher than that in the constant temperature section. Based on this, the temperature difference between several adjacent reactors is designed to be 0 to 10 °C, and the heat is compensated or dissipated through the constant temperature section of each reactor.

[0037] The second aspect of the present invention provides a method for preparing an alkylene oxide compound, which is carried out by using the above-mentioned preparation system for alkylene oxide compounds. The method includes:

[0038] In the order of series connection of the reactors, the reaction material is input from the raw material inlet of the first reactor, and successively passes through each series-connected reactor. The activity of the catalyst loaded in each reactor decreases in turn, and the operating temperature in each reactor increases in turn, and a propylene oxide product with a conversion rate of ≥99% of cumene hydroperoxide is obtained.

[0039] In the preparation method of the present invention, the reaction materials include a double bond compound and cumene hydroperoxide.

[0040] Among them, the double bond compound is selected from one of propylene, butene, and cyclohexene oxide.

[0041] The cumene hydroperoxide material is obtained by oxidizing cumene, and it is a mixture of cumene hydroperoxide and cumene. The mass concentration of cumene hydroperoxide is 20 - 65%. For example, it is 20 - 25%, 25 - 30%, 30 - 35%, 35 - 40%, 40 - 45%, 45 - 50%, 50 - 55%, 55 - 60% or 60 - 65%.

[0042] The molar ratio of the double bond compound to cumene hydroperoxide is 2 - 8:1. For example, it is 2 - 3:1, 3 - 4:1, 4 - 5:1, 5 - 6:1, 6 - 7:1 or 7 - 8:1.

[0043] The total liquid hourly space velocity of the reaction materials is 1 - 4 h -1 ; for example, it is 1 - 2 h -1 、2 - 3 h -1 or 3 - 4 h -1 .

[0044] The pressure of the reaction materials at the raw material inlet of the reactor at the starting position is 10 - 60 bar. For example, it is 10 - 20 bar, 20 - 30 bar, 30 - 40 bar, 40 - 50 bar or 10 - 60 bar.

[0045] Example 1

[0046] Assemble the preparation system of the epoxy alkane compound

[0047] The reactor part in the system consists of four reactors. As Figure 1 shown, there are pipelines connecting between the reactors, and valves are provided on each pipeline (the four reactors are reactor R1, reactor R2, reactor R3, and reactor R4 in sequence. The valves provided on the raw material feed pipelines of the raw material inlets of the four reactors are first valve 101, first valve 201, first valve 301, and first valve 401 in sequence. The valves provided on the product discharge pipelines of the four reactors are third valve 103, third valve 203, third valve 303, and third valve 403 in sequence. The valve on the continuous reaction pipeline between reactor R1 and reactor R2 is second valve 102, the valve on the continuous reaction pipeline between reactor R2 and reactor R3 is second valve 202, the valve on the continuous reaction pipeline between reactor R3 and reactor R4 is second valve 302, and the valve on the continuous reaction pipeline between reactor R4 and reactor R1 is second valve 402), and the conveying path of the materials in the reaction device can be changed by changing the opening and closing states of each valve.

[0048] The sizes of each reactor and the catalyst loading amount are the same. The inner diameter of the tubes in the isothermal section of the reactor is 50 mm, the length is 6000 mm, and the number of tubes is 74. The catalyst in the isothermal section of the reactor is filled in the tubes, and the catalyst in the adiabatic section is randomly packed. 3 / 4 of the total amount of the catalyst is filled in the isothermal section, and 1 / 4 of the total amount of the catalyst is filled in the adiabatic section. The catalysts filled in the 1st to 4th reactors are the catalysts used after 0, 1, 2, and 3 months respectively.

[0049] As Figure 1 shown, the connection status of each valve is as shown in Table 1 below. The conveying path of the material in the device is: raw material inlet 10 → R1 → R2 → R3 → R4 → product outlet 20.

[0050] Table 1

[0051]

[0052] Note: "√" indicates that the valve is in the open state; "×" indicates that the valve is in the closed state.

[0053] Example 2

[0054] Preparation of propylene oxide

[0055] Propylene oxide is prepared using the reaction system of Example 1. At this time, the conveying path of the material in the device is: raw material inlet 10 → R1 → R2 → R3 → R4 → product outlet 20.

[0056] The reaction feed contains 504 kg / h of cumene hydroperoxide, 833 kg / h of propylene, 4 kg / h of propane, and 484 kg / h of cumene. The molar ratio of cumene hydroperoxide to propylene is 1:6. The total liquid hourly space velocity is 2.5 h -1 . The pressure at the inlet of the reactor is 50 bar (gauge pressure).

[0057] In the 1st reactor / reactor R1, the temperature in the isothermal section of the reactor is 80 °C, and it rises to 87 °C in the adiabatic section. The conversion rate of CHP is 42.8%, and the selectivity of propylene oxide is 99.5%;

[0058] In the 2nd reactor / reactor R2, the temperature in the isothermal section of the reactor is 90 °C, and it rises to 98 °C in the adiabatic section. The conversion rate of CHP is 75.1%, and the selectivity of propylene oxide is 99.1%;

[0059] In the 3rd reactor / reactor R3, the temperature in the isothermal section of the reactor is 100 °C, and it rises to 106 °C in the adiabatic section. The conversion rate of CHP is 94.2%, and the selectivity of propylene oxide is 98.5%;

[0060] In the fourth reactor / reactor R4, the temperature in the constant temperature section of the reactor is 110 °C, and it rises to 114 °C in the adiabatic section. The conversion rate of CHP is 99.5%, and the selectivity of propylene oxide is 97.8%.

[0061] Example 3

[0062] Replacement of the catalyst in the alkylene oxide compound preparation system

[0063] After the reaction system with the structure of Example 2 has been continuously used for more than 1 month, the conversion rate of CHP in the output materials of each reactor has decreased to varying degrees. When the monitoring shows that the conversion rates of CHP in the materials output from the first to the fourth reactors are respectively lower than 35%, 70%, 90%, and 98%, it is considered that the catalyst deactivation is relatively serious. At this time, the catalyst in the fourth reactor is taken out and replaced with a new catalyst. Close the valves: the first valve 101, the second valve 102, the third valve 403, and open the valves: the first valve 201, the second valve 402, the third valve 103. The states of each valve are shown in Table 2 below.

[0064] Table 2

[0065]

[0066] Note: "√" indicates the valve open state; "×" indicates the valve closed state.

[0067] At this time, the conveying path of the material in the device changes from the raw material inlet 10 → R1 → R2 → R3 → R4 → the product outlet 20 to the raw material inlet 10 → R4 → R1 → R2 → R3 → the product outlet 20.

[0068] Example 4

[0069] Preparation of butylene oxide

[0070] Use the reaction system of Example 3 to prepare butylene oxide. At this time, the conveying path of the material in the device is the raw material inlet 10 → R4 → R1 → R2 → R3 → the product outlet 20.

[0071] The reaction feed contains 304.8 kg / h of cumene hydroperoxide, 671.6 kg / h of butene, 3.2 kg / h of butane, and 707.5 kg / h of cumene. The molar ratio of cumene hydroperoxide to butene is 1:6, and the concentration of cumene hydroperoxide is 30%. The total liquid hourly space velocity is 2.0 h -1 . The pressure at the reactor inlet is 20 bar (gauge pressure).

[0072] In the first reactor / reactor R4, the temperature in the constant temperature section of the reactor is 50 °C, and it rises to 56 °C in the adiabatic section. The conversion rate of CHP is 45.8%, and the selectivity of propylene oxide is 99.5%;

[0073] In the second reactor / reactor R1, the temperature in the constant temperature section of the reactor is 70 °C, and it rises to 77 °C in the adiabatic section. The conversion rate of CHP is 76.9%, and the selectivity of propylene oxide is 99.2%.

[0074] In the third reactor / reactor R2, the temperature in the constant temperature section of the reactor is 90 °C, and it rises to 96 °C in the adiabatic section. The conversion rate of CHP is 95.3%, and the selectivity of propylene oxide is 98.7%.

[0075] In the fourth reactor / reactor R3, the temperature in the constant temperature section of the reactor is 110 °C, and it rises to 112 °C in the adiabatic section. The conversion rate of CHP is 99.7%, and the selectivity of propylene oxide is 97.9%.

[0076] Example 5

[0077] Replacement of the catalyst in the epoxyalkane compound preparation system

[0078] After the reaction system with the structure of Example 3 continued to be used for more than 1 month after replacing the catalyst, the conversion rate of CHP in the output materials of each reactor decreased to varying degrees. When the monitoring shows that the conversion rates of CHP in the materials output from the first to the fourth reactors are lower than 35%, 70%, 90%, and 98% respectively, it is considered that the catalyst deactivation is relatively serious. At this time, the catalyst in the fourth reactor is taken out and replaced with a new catalyst. Close the valves: the first valve 201, the second valve 202, the third valve 103, and open the valves: the first valve 301, the second valve 102, the third valve 203. The states of each valve are shown in Table 3 below.

[0079] Table 3

[0080]

[0081] Note: "√" indicates the valve open state; "×" indicates the valve closed state.

[0082] At this time, the conveying path of the material in the device changes from the raw material inlet 10 → R4 → R1 → R2 → R3 → product outlet 20 to the raw material inlet 10 → R3 → R4 → R1 → R2 → product outlet 20.

[0083] Example 6

[0084] Preparation of cyclohexene oxide

[0085] Use the reaction system of Example 5 to prepare cyclohexene oxide. At this time, the conveying path of the material in the device is the raw material inlet 10 → R3 → R4 → R1 → R2 → product outlet 20.

[0086] The reaction feed contains 164.2 kg / h of cumene hydroperoxide, 542.9 kg / h of cyclohexene, 2.6 kg / h of cyclohexane, and 492.7 kg / h of cumene. The molar ratio of cumene hydroperoxide to cyclohexene is 1:2, and the concentration of cumene hydroperoxide is 25%. The total liquid hourly space velocity is 1.3 h -1 . The pressure at the reactor inlet is 10 bar (gauge).

[0087] In the 1st reactor / reactor R3, the temperature in the isothermal section of the reactor is 80 °C, and it rises to 88 °C in the adiabatic section. The conversion rate of CHP is 46.2%, and the selectivity of propylene oxide is 99.7%;

[0088] In the 2nd reactor / reactor R4, the temperature in the isothermal section of the reactor is 90 °C, and it rises to 97 °C in the adiabatic section. The conversion rate of CHP is 76.4%, and the selectivity of propylene oxide is 99.5%;

[0089] In the 3rd reactor / reactor R1, the temperature in the isothermal section of the reactor is 100 °C, and it rises to 106 °C in the adiabatic section. The conversion rate of CHP is 95.8%, and the selectivity of propylene oxide is 98.9%;

[0090] In the 4th reactor / reactor R2, the temperature in the isothermal section of the reactor is 110 °C, and it rises to 112 °C in the adiabatic section. The conversion rate of CHP is 99.7%, and the selectivity of propylene oxide is 98.1%.

[0091] Example 7

[0092] Propylene oxide was prepared using the reaction system of Example 1.

[0093] The reaction feed contains 1186.9 kg / h of cumene hydroperoxide, 978.7 kg / h of propylene, 4.9 kg / h of propane, and 1139.8 kg / h of cumene. The molar ratio of cumene hydroperoxide to propylene is 1:2. The total liquid hourly space velocity is 4.0 h -1 . The pressure at the reactor inlet is 50 bar (gauge).

[0094] Example 8

[0095] Propylene oxide was prepared using the reaction system of Example 1.

[0096] The reaction feed contains 167.2 kg / h of cumene hydroperoxide, 367.7 kg / h of propylene, 1.9 kg / h of propane, and 160.6 kg / h of cumene. The molar ratio of cumene hydroperoxide to propylene is 1:8. The total liquid hourly space velocity is 1.0 h -1 . The pressure at the reactor inlet is 50 bar (gauge).

[0097] Example 9

[0098] Propylene oxide was prepared using the reaction system of Example 1.

[0099] The reaction feed contained 687.3 kg / h of cumene hydroperoxide, 566.8 kg / h of propylene, 2.9 kg / h of propane, and 456.9 kg / h of cumene. The molar ratio of cumene hydroperoxide to propylene was 1:3, and the concentration of cumene hydroperoxide was 60%. The total liquid hourly space velocity was 4 h -1 . The pressure at the reactor inlet was 10 bar (gauge pressure).

[0100] Example 10

[0101] Propylene oxide was prepared using the reaction system of Example 1.

[0102] The reaction feed contained 541.1 kg / h of cumene hydroperoxide, 446.2 kg / h of propylene, 2.3 kg / h of propane, and 1623.4 kg / h of cumene. The molar ratio of cumene hydroperoxide to propylene was 1:3, and the concentration of cumene hydroperoxide was 25%. The total liquid hourly space velocity was 4 h -1 . The pressure at the reactor inlet was 60 bar (gauge pressure).

[0103] Comparative Examples 1 - 5

[0104] Compared with Example 2, using the same material composition, the constant temperature section temperature of each reactor was changed to the conditions in Table 4 below, and at the same time, the feed rate was slightly adjusted to maintain the total liquid hourly space velocity at 2.5 h -1 The reaction was carried out.

[0105] Table 4

[0106]

[0107] Comparative Example 6

[0108] Compared with Example 2, the number of reactors was reduced to 3, and at the same time, the length of a single reactor was increased to 1.33 times. Other parameters of the equipment remained unchanged. The catalysts loaded in each reactor were those with 0, 1.5, and 3 months of used time respectively. The reaction was carried out using the same material composition, constant temperature, and total liquid hourly space velocity as in Example 2.

[0109] Comparative Example 7

[0110] Compared with Example 2, the number of reactors was reduced to 2, and at the same time, the reactor specifications were increased to 2 times. Other parameters of the equipment remained unchanged. The catalysts loaded in each reactor were those with 0 and 3 months of used time respectively. The reaction was carried out using the same material composition, constant temperature, and total liquid hourly space velocity as in Example 2.

[0111] Comparative Example 8

[0112] Compared with Example 2, a single reactor was used, the specifications of the reactor were lengthened by 4 times, a brand-new catalyst was used, and the catalyst filling method was changed to full-tube filling. The reactor was kept at a constant temperature of 80 °C during the reaction. The reaction was carried out using the same material composition and total liquid hourly space velocity as in Example 2.

[0113] Comparative Example 9

[0114] Compared with Comparative Example 8, the catalyst was an old catalyst that had been used for 2 months under conventional conditions. The reaction was carried out using the same material composition, constant temperature, and total liquid hourly space velocity as in Comparative Example 8.

[0115] Comparative Example 10

[0116] Compared with Comparative Example 8, the catalyst was an old catalyst that had been used for 4 months under conventional conditions. The reaction was carried out using the same material composition, constant temperature, and total liquid hourly space velocity as in Comparative Example 8.

[0117] Comparative Example 11

[0118] Compared with Comparative Example 8, the catalyst used was the deactivated catalyst discarded from the terminal reactor in Example 2. The reaction was carried out using the same material composition, constant temperature, and total liquid hourly space velocity as in Comparative Example 8.

[0119] Comparative Example 12

[0120] Compared with Example 2, the temperature of each constant temperature section was changed to the same temperature of 80 °C, that is, after the material in the adiabatic section of the reactor was heated up, it was cooled down to 80 °C in the constant temperature section after entering the next reactor to maintain the material temperature stable. The reaction was carried out using the same material composition and total liquid hourly space velocity as in Example 2.

[0121] Comparative Example 13

[0122] Compared with Example 2, the stacking method of the catalyst in each reactor was changed to all loose stacking, and at the same time, the whole reactor was an adiabatic reactor. The outlet temperatures of each section were monitored, which were 92, 101, 108, and 116 °C respectively. The reaction was carried out using the same material composition and total liquid hourly space velocity as in Example 2.

[0123] The experimental data and results of the above examples and comparative examples are shown in Table 5 below:

[0124] Table 5

[0125]

[0126] Note: The "starting reaction temperature" is the constant temperature of the first reactor; the "conversion rate" is the conversion rate of the reaction material after passing through the fourth reactor.

[0127] As can be seen from Table 5 above, in Comparative Example 5, the reaction temperature was too high, resulting in a decrease in selectivity. This is because a large amount of cumene hydroperoxide would decompose into phenolic substances. In Comparative Example 11, the deactivated catalyst that had been phased out was used. Although the CHP conversion rate was not high, the reaction temperature was low and not many by-products would be generated, so the selectivity was relatively high.

[0128] In summary, in the preparation system of the alkylene oxide compound of the present invention, the highly active catalyst is arranged in the front so that it can preferentially contact and react with the raw material stream, and the system operates at a high temperature. The low-active catalyst is arranged in the back to contact and react with the low-concentration raw material stream, and the system operates at a low temperature. It realizes high reaction selectivity of the highly active catalyst corresponding to a low-temperature and high-concentration raw material environment. At the same time, it also realizes that the low-active catalyst can also obtain high reaction selectivity in a high-temperature and low-concentration raw material environment, realizes the rational utilization of the aged and deactivated catalyst, and enables the total conversion rate of the reaction to reach more than 98% while maintaining a selectivity of more than 97%. Therefore, the present invention effectively overcomes various drawbacks in the prior art and has high industrial utilization value.

[0129] The above embodiments merely illustrate the principles and effects of the present invention and are not intended to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A preparation system for epoxyalkane compounds, characterized in that, The system includes at least 4 reactors connected in series in sequence through pipelines. Each of the reactors is provided with a raw material inlet. The sequential order of the series connection between the reactors refers to the order in which the reaction materials pass through successively after entering the system from the raw material inlet. Each of the reactors is independently filled with an equal amount of catalyst. Along the sequential order of the series connection, the activity of the catalyst filled in each reactor decreases successively. Each of the reactors includes an isothermal section at the lower part and an adiabatic section at the upper part. After the reaction materials enter each of the reactors, they first pass through the isothermal section and then through the adiabatic section. Along the sequential order of the series connection, the operating temperature of the isothermal section in each reactor increases successively. According to the sequential order of the series connection, the operating temperature of the first reactor at the beginning is 50 - 90 °C, and the temperature difference between adjacent reactors is 10 - 30 °C; the reactors are connected in series to form a loop and the materials flow in a carousel-like manner between the reactors. Taking the first reactor into which the reaction materials enter the system as the 1st reactor, the reactors connected in series subsequently are the 2nd reactor, the 3rd reactor, the 4th reactor, ……, the nth reactor in sequence, where n is an Arabic numeral not greater than 6; for the reactor with deactivated catalyst, it is cut out from the original series order, and after the catalyst in the cut-out reactor is replaced or regenerated, it is cut into the system from the beginning of the original series order as the new 1st reactor; each of the reactors is cut out in sequence from the last one. When the conversion rate of cumene hydroperoxide in the material output from the 1st reactor is lower than 35%, or when the conversion rate of cumene hydroperoxide in the material output from the 2nd reactor is lower than 70%, or when the conversion rate of cumene hydroperoxide in the material output from the 3rd reactor is lower than 90%, or when the conversion rate of cumene hydroperoxide in the material output from the 4th reactor is lower than 98%, it is determined that the catalyst in the corresponding reactor is severely aged and has too low activity to continue meeting the usage requirements. The 4th reactor is cut out, and after the catalyst is replaced or regenerated, it is cut into the system from the beginning of the series order as the 1st reactor. Successively, the original 1st reactor is changed to the 2nd reactor, the original 2nd reactor is changed to the 3rd reactor, and the original 3rd reactor is changed to the 4th reactor; The catalyst is titanium silicalite molecular sieve.

2. The preparation system of the alkylene oxide compound according to claim 1, characterized in that, The system includes 4 - 5 reactors connected in series in sequence.

3. The preparation system of the alkylene oxide compound according to claim 1, characterized in that, Each of the reactors is further provided with a product outlet. Each of the product outlets is connected with two material pipelines, which are respectively a product discharge pipeline and a pipeline for continuous reaction. In the sequential order of the series connection, the pipeline for continuous reaction is connected to the raw material inlet of the next reactor. The raw material inlet of each of the reactors is also connected with a raw material feed pipeline. A first valve is provided on each of the raw material feed pipelines, a second valve is provided on each of the pipelines for continuous reaction, and a third valve is provided on each of the product discharge pipelines. The first valve, the second valve, and the third valve are applicable to regulating the sequential order of the series connection of the reactors in the system.

4. The preparation system of the epoxyalkane compound according to claim 1, characterized in that, The filling method of the catalyst in the isothermal section is to be filled in the tubes; the length-diameter ratio of the tubes is 100 - 250:1; And / or, the filling method of the catalyst in the adiabatic section is bulk filling; And / or, the height ratio of the isothermal section to the adiabatic section is 4 - 8:1; And / or, the mass ratio of the catalyst filled in the isothermal section to the mass of the catalyst filled in the adiabatic section is 2 - 5:1; And / or, the aspect ratio of each of the reactors is 1.5 - 8:1; And / or, the bulk density of the catalyst in the reactor is 0.4 - 0.6 g / mL; And / or, the operating temperature range of each reactor in the system is 50 - 140 °C; And / or, in each of the reactors, the temperature of the adiabatic section is 0 - 10 °C higher than the temperature of the isothermal section.

5. A method for preparing an epoxyalkane compound, characterized in that, The method is carried out using the preparation system for epoxyalkane compounds according to any one of claims 1 - 4, and the method includes: In the order of the series connection of the reactors, the reaction material is input from the raw material inlet of the reactor at the starting position, and successively passes through each of the reactors connected in series. The activity of the catalyst filled in each of the reactors decreases in sequence, and the operating temperature in each of the reactors increases in sequence, to obtain a propylene oxide product with a conversion rate of cumene hydroperoxide ≥ 99%.

6. The preparation method of the alkylene oxide compound according to claim 5, wherein, The reaction material includes a double bond compound and cumene hydroperoxide.

7. The method for preparing an alkylene oxide compound according to claim 6, wherein The double bond compound is selected from one of propylene, butene, and cyclohexene oxide; And / or, the cumene hydroperoxide material is obtained by oxidizing cumene, and is a mixture of cumene hydroperoxide and cumene, and the mass concentration of cumene hydroperoxide is 20 - 65%; And / or, the molar ratio of the double bond compound to cumene hydroperoxide is 2 - 8:

1.

8. The method for preparing an alkylene oxide compound according to claim 5, wherein The total liquid hourly space velocity of the reaction materials is 1 to 4 h -1 ; And / or, the pressure of the reaction material at the raw material inlet of the reactor at the starting position is 10 - 60 bar.

Images