A kind of preparation method of butylene oxide

Abstract

The present invention discloses a method for preparing butylene oxide. Butene and an oxidant containing a peroxide are sequentially subjected to a first epoxidation stage and a second epoxidation stage under the action of a heterogeneous catalyst, cyclohexene is added after the first epoxidation stage, and a mixture S containing butylene oxide is obtained after the reaction is completed; the reaction temperature T1 of the first epoxidation stage is 30 to 100° C., and the reaction temperature T2 of the second epoxidation stage is 40 to 105° C.; the molar ratio of the butene, peroxide and cyclohexene is (0.5 to 0.9):1:(0.2 to 2.2). The preparation method of the present invention solves the problem of butene recovery and improves the continuous production efficiency of butylene oxide.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical synthesis, and particularly relates to a method for preparing butylene oxide. Background Art

[0002] The preparation of epoxy compounds by cumene hydroperoxide (CHP) method has the characteristics of high safety, environmental protection, and high product quality. It is one of the main preparation methods of epoxy compounds. However, cumene hydroperoxide is a heat-sensitive substance with high reaction activity. It is easily decomposed by heat or undergoes side reactions to generate impurities such as phenol. In order to ensure the efficient conversion of CHP, a higher olefin-oil ratio (such as 6:1 to 10:1) is usually used, that is, the molar amount of the raw olefin is greater than the molar amount of CHP, but this method will cause excess olefin, so the olefin needs to be separated and recycled.

[0003] Especially for butene, due to its low boiling point and the presence of alkane impurities, there are many problems in the recycling process. On the one hand, recycling and reuse requires compressing butene into a liquid state, which consumes a lot of energy; on the other hand, inert impurities such as butane in butene do not participate in the reaction during the epoxidation process, and are easy to form azeotropes with butene, making them difficult to separate. Therefore, as the number of butene cycles increases, the cumulative proportion of butane increases, reducing the recycling efficiency of butene; in addition, during the recycling process, butane and water will also form crystalline hydrates, bringing risks such as pipeline blockage.

[0004] In order to solve the above-mentioned problems in the butene recovery process, the process method of butene recovery is usually optimized. For example, CN109748769A discloses a butene recovery method in the production of butylene oxide, which adopts condensation phase separation to extract the water phase, and at the same time adopts the method of regularly discharging part of the butane impurity-containing logistics to reduce the accumulation of impurities. However, this method will still cause the condenser to be blocked, and steam purge is required for unblocking. The operation process is complicated and the energy consumption is high. In addition, the method of regularly discharging the butene logistics reduces the comprehensive utilization efficiency of butene.

[0005] It can be seen that the current optimization effect of butene recovery is not ideal, and the optimization of butene recovery process will further increase energy consumption. Therefore, it is necessary to develop a convenient method to solve the negative problems of butene recovery and thus improve the efficiency of butylene oxide production process. Summary of the invention

[0006] Purpose of the invention: The purpose of the present invention is to provide a method for preparing butylene oxide in view of the shortcomings of the prior art. The preparation method of the present invention solves the problem of butene recovery and improves the continuous production efficiency of butylene oxide.

[0007] Technical solution: The purpose of the present invention is achieved through the following technical solution:

[0008] The present invention provides a method for preparing butylene oxide, wherein butene and a peroxide-containing oxidant are subjected to a first epoxidation stage and a second epoxidation stage in sequence under the action of a heterogeneous catalyst, cyclohexene is added after the first epoxidation stage, and a mixture S containing butylene oxide is obtained after the reaction is completed;

[0009] The reaction temperature T1 of the first epoxidation stage is 30-100°C, and the reaction temperature T2 of the second epoxidation stage is 40-105°C;

[0010] The molar ratio of butene, peroxide and cyclohexene is (0.5-0.9):1:(0.2-2.2).

[0011] The present invention adopts a lower olefin-to-oil ratio and staged epoxidation, so that butene is not excessive, that is, the epoxidation reaction is carried out when the molar ratio of butene to peroxide is less than 1. Under the suitable reaction conditions of the present invention, most of the butene can be converted, and then the butene surplus can be avoided, and the butene circulation is not required. At the same time, the addition of cyclohexene after the first epoxidation stage can not only further consume the peroxide, but also promote the conversion of the remaining butene in the first epoxidation stage in the second epoxidation stage, and can take into account the high conversion rate of butene and peroxide, as well as the high selectivity of epoxy compounds. In particular, when the molar ratio of butene, peroxide and cyclohexene is controlled to (0.5-0.9):1:(0.2-2.2), the low content of phenol byproducts can also be taken into account.

[0012] The butene described in the present invention may be at least one of 1-butene, 2-butene or isobutylene.

[0013] The first epoxidation stage of the present invention, i.e., the process of epoxidation of butene with an oxidant, can be carried out in one reactor or in N reactors connected in series or in parallel, where N is a natural number ≥ 2, and more preferably N is 2 to 6. The series connection can be a linear series connection, i.e., the material enters from the first reactor and flows out from the Nth reactor; or a cyclic series connection, i.e., the material circulates in the N reactors.

[0014] The reaction temperature T1 of the first epoxidation stage can be a fixed value, or can be adjusted in real time within the range of 30 to 100° C. along with the reaction time and the activity of the heterogeneous catalyst, as long as the epoxidation reaction can proceed smoothly.

[0015] The second epoxidation stage of the present invention is a process in which the remaining butene in the first epoxidation stage, the remaining oxidant in the first epoxidation stage and the newly added cyclohexene undergo epoxidation reaction. Similarly, the second epoxidation stage can be carried out in one reactor or in M ​​reactors connected in series or in parallel, where M is a natural number ≥ 1. In particular, when the molar ratio of cyclohexene to the remaining CHP when added is low, it is further preferred that the number of M in series is 2 to 3 to further improve the conversion efficiency of CHP.

[0016] The reaction temperature T2 of the second epoxidation stage can be a fixed value, or can be adjusted in real time within the range of 40 to 105° C. along with the reaction time and the activity of the heterogeneous catalyst, as long as the epoxidation reaction can proceed smoothly.

[0017] The reactors for the first epoxidation stage and the second epoxidation stage of the present invention can be any conventional reactors in the art, such as a fluidized bed, a fixed bed, a reaction kettle, etc.

[0018] The oxidant of the present invention is a mixed solution containing a peroxide and an inert solvent. The peroxide can be selected from cumene hydroperoxide, ethylbenzene hydroperoxide, etc. Preferably, the oxidant is a cumene solution of cumene hydroperoxide. Based on the total mass of the oxidant, the mass proportion of the cumene hydroperoxide is ≤35wt%, and more preferably, the mass proportion is 5-35wt%, so as to take into account the conversion rate of olefins and reduce the risk of peroxide decomposition.

[0019] In order to further take into account the efficient conversion of peroxide and improve the conversion efficiency of unreacted butene in the first epoxidation stage in the second epoxidation stage, it is preferred that the molar amount of cyclohexene is ≥ the molar amount of peroxide remaining when it is added; it is further preferred that the ratio of the molar amount of cyclohexene to the molar amount of peroxide remaining when it is added is (2 to 4):1.

[0020] In order to take into account the olefin conversion rate and reduce the risk of peroxide decomposition, the volume space velocity of the oxidant is preferably ≥ 2h -1 , and the preferred volume space velocity is 2 to 10 h -1 The space velocity of butene and cyclohexene is the same as that of the oxidant, that is, the volume space velocity of the reaction raw materials is ≥2h -1 .

[0021] Preferably, the pressure of the first epoxidation stage and the second epoxidation stage is 0.3-4.0 MPa, so that the olefin is in the liquid phase, which can further improve the mass transfer effect between materials.

[0022] In order to take into account both low energy consumption and high conversion rate, it is further preferred that the pressure is 0.4 to 3.5 MPa.

[0023] The present invention adds cyclohexene after the first epoxidation stage, and the timing of adding cyclohexene will also affect the output ratio of butylene oxide and cyclohexene oxide. In the actual production process, real-time adjustments can be made according to the demand of the target product to achieve flexible control of the production process. In order to take into account the efficient conversion of butene under low olefin-to-oil ratio, the present invention preferably adds cyclohexene when the consumption of butene is ≥80wt%. For example, the total amount of butene added is 10g, and cyclohexene is added when the remaining amount of butene is ≤2g. Further, cyclohexene is added when the consumption of butene is 80-90wt%.

[0024] The reaction product obtained by the reaction of olefins and peroxides usually contains solvents, epoxy compounds, unreacted olefins, α,α-dimethylbenzyl alcohol, phenol, a small amount of butane and water, etc. The proportion of unreacted butene in the mixture S obtained by the preparation method of the present invention is relatively small. Based on the total mass of the mixture S, the mass proportion of butene in the mixture S is less than 0.2wt%. The mixture S can avoid the recycling problem caused by a large amount of excess butene, which is beneficial to reducing the total energy consumption of the production line. When the butene content in the mixture S is zero, the epoxy compound separation step can be directly carried out; when the mixture S still contains a small amount of butene, the mixture S is subjected to gas-liquid separation, and the light components containing butene are removed, and the light components can be directly post-processed, such as combustion treatment, and the obtained heavy components can be subjected to the epoxy compound separation step.

[0025] Furthermore, the preparation method of the present invention can also completely convert peroxides, thereby avoiding the generation of peroxide decomposition side reactions, that is, based on the total mass of the mixture S, the peroxide content in the mixture S is zero, and the phenol content is less than 50 ppm.

[0026] The preparation method of the present invention also comprises a separation step of the epoxy compound and a circulation step of cyclohexene, wherein the separation is carried out by distillation or rectification.

[0027] The step of separating the epoxy compounds of the present invention is mainly to separate butylene oxide and cyclohexene oxide to obtain the corresponding target products. The separation can be carried out by conventional methods in the art, such as distillation or rectification.

[0028] The recycling step of cyclohexene in the present invention is to separate cyclohexene from the mixture S and then circulate it to the second epoxidation stage. Since cyclohexene has a high boiling point, its recovery only needs cooling to obtain liquid cyclohexene, and the energy consumption is lower than that of butene recovery; and the molar ratio of cyclohexene to peroxide in the present invention is low, and the amount of remaining cyclohexene after the second epoxidation stage is relatively small, which can also indirectly reduce the recovery burden.

[0029] More specifically, the epoxide separation step and cyclohexene recovery step of the present invention can be carried out by the following method: the mixture S is subjected to gas-liquid separation to obtain a gas phase stream and a liquid phase stream, the gas phase stream is combusted, and the liquid phase stream is distilled to obtain a stream I-1 containing butylene oxide, a stream I-2 containing cyclohexene, a stream I-3 containing cyclohexene oxide, and a heavy component stream I-4, wherein the heavy component stream I-4 contains isopropylbenzene and α,α-dimethylbenzyl alcohol, and the stream I-2 is recycled to a position after the first epoxidation stage. The distillation can be carried out in one distillation tower or in multiple distillation towers connected in series, and the temperature and pressure of the distillation can be conventionally selected according to the characteristics of the material, such as the bottom temperature of the distillation tower is 110-130°C, the top temperature is 50-63°C, and the distillation pressure is 0.05-0.07MPa.

[0030] The heterogeneous catalyst of the present invention can be any conventional type in the art, such as titanium silicon oxide as a heterogeneous catalyst. Titanium silicon oxide can be a solid material containing mesopores, with silicon dioxide as a carrier, and loaded with active titanium. In order to take into account the efficient conversion of butene, cyclohexene, and peroxide of the present invention, the pore size of the titanium silicon oxide is preferably 2 to 40 nm, and the specific surface area is 130 to 600 m 2 / g; based on the total mass of titanium silicon oxide, the titanium content is 0.2 to 10 wt%, and the titanium content is usually calculated as titanium oxide.

[0031] Beneficial effects:

[0032] (1) The present invention has a high butene conversion rate and does not require recovery, thus avoiding the problem of butene recycling under high olefin-to-oil ratio conditions.

[0033] (2) The present invention produces cyclohexene oxide while producing butylene oxide at a high yield, and the product ratio can be flexibly adjusted, thereby increasing the added value of the production line.

[0034] (3) The present invention takes into account both high butene conversion rate and peroxide conversion rate, and the content of impurity phenol in the obtained product is low, which is beneficial to prolonging the service life of the catalyst. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is described in detail below through specific embodiments, but the protection scope of the present invention is not limited to the embodiments.

[0036] The heterogeneous catalysts used in the embodiments of the present invention are all titanium silicon oxides:

[0037] Cat1#, homemade, pore size 39.4nm, specific surface area 132m 2 / g, titanium content is 0.25wt%;

[0038] Cat2#, homemade, pore size 18.7nm, specific surface area 204.3m 2 / g, titanium content is 4.4wt%;

[0039] Cat3#, homemade, pore size 2.2nm, specific surface area 591m 2 / g, titanium content is 9.8wt%;

[0040] The homemade method of Cat1#, Cat2#, and Cat3# can adopt the conventional vapor phase titanium precipitation method in the art, such as mixing fumed silica, hydroxypropyl methylcellulose, and 25wt% silica aqueous solution evenly and extruding them into strips, drying at 110°C, and calcining at 450°C to obtain a molded body. Then put the molded body into a reaction furnace, heat it to 300°C, load titanium tetrachloride with nitrogen, keep the temperature for 25 hours, and then cool it to room temperature to obtain titanium silicon oxide.

[0041] The conversion rate and product selectivity of the raw materials of the present invention are calculated as follows:

[0042] CHP conversion rate = 100 × (consumed CHP molar amount / raw CHP molar amount) %;

[0043] Epoxide selectivity = 100 × (mol of epoxide produced / mol of CHP consumed) %;

[0044] Olefin conversion rate = 100 × (consumed olefin mole / raw olefin mole) %;

[0045] Epoxide yield = CHP conversion × epoxide selectivity.

[0046] The oxidants used in the embodiments of the present invention are all cumene solutions of cumene hydroperoxide, and the phenol content is all less than 1 ppm.

[0047] Example 1

[0048] The first epoxidation stage uses 4 fixed beds connected in series as a reactor, and the second epoxidation stage uses 3 fixed beds connected in series in a straight line as a reactor. All fixed beds have the same size and dimensions and are loaded with the same catalyst Cat2#.

[0049] The raw materials were prepared in a molar ratio of 1-butene, cumene hydroperoxide and cyclohexene of 0.7:1:0.76, and all 1-butene and an oxidant were added to the first fixed bed of the first epoxidation stage, wherein the oxidant was a 5 wt% cumene hydroperoxide solution in cumene. The volumetric space velocity of the raw materials was 10 h -1, the pressure of the reaction system is 4 MPa, the temperatures of the four fixed beds in the first epoxidation stage are set to 30°C, 50°C, 70°C, and 100°C in sequence, so that the material flow containing the raw materials and the reaction products is circulated through the four fixed beds of the first epoxidation stage in sequence, and the concentration of 1-butene is monitored. When the consumption of 1-butene is 88wt%, the connection between the first fixed bed and the fourth fixed bed is cut off, the connection between the fourth fixed bed and the second epoxidation stage is connected, and all the cyclohexene is added to the second epoxidation stage to make the material flow enter the second epoxidation stage. When adding, the molar ratio of cyclohexene to the remaining isopropylbenzene hydroperoxide is 2:1. The temperatures of the three fixed beds in the second epoxidation stage are all 40°C. After the reaction is completed, a mixture S-1# containing butylene oxide and cyclohexene oxide is obtained. It has been calculated that the conversion rate of cumene hydroperoxide is 100%, the conversion rate of 1-butene is 94.0%, the selectivity of butylene oxide is 99.3%, the selectivity of cyclohexene oxide is 99.5%, the content of cumene hydroperoxide in the mixture S-1# is zero, the content of 1-butene is 0.065%, the content of phenol is 41 ppm, and the initial yield of epoxy compounds is 99.4%.

[0050] The mixture S-1# is subjected to gas-liquid separation to obtain a gas phase stream containing 1-butene and a liquid phase stream containing epoxy compounds. The gas phase stream is combusted and the liquid phase stream is distilled. The top temperature of the distillation tower is 63°C, the bottom temperature is 130°C, and the distillation pressure is 0.05MPa. After distillation, a stream I-1 containing butylene oxide, a stream I-2 containing cyclohexene, a stream I-3 containing cyclohexene oxide, and a heavy component stream I-4 are obtained. The heavy component stream I-4 contains isopropylbenzene and α,α-dimethylbenzyl alcohol. The stream I-2 is recycled to the position after the first epoxidation stage. After continuous operation for 9 months, the yield of epoxy compounds is 95.6%, of which the yield of butylene oxide is 95.5%.

[0051] Example 2

[0052] The first epoxidation stage uses three fixed beds connected in series as a reactor, and the second epoxidation stage uses three fixed beds connected in series in a straight line as a reactor. All fixed beds have the same size and dimensions and are loaded with the same catalyst Cat2#.

[0053] The raw materials were prepared according to the molar ratio of 2-butene to cumene hydroperoxide to cyclohexene of 0.7:1:0.79, and all the 2-butene and the oxidant were added to the first fixed bed of the first epoxidation stage, wherein the oxidant was a 5 wt % cumene hydroperoxide solution in cumene, and the volumetric space velocity of the raw materials was 10 h -1, the pressure of the reaction system is 2.7 MPa, the temperatures of the three fixed beds in the first epoxidation stage are set to 30°C, 50°C, and 60°C respectively, so that the material flow containing the raw materials and the reaction products is circulated through the three fixed beds of the first epoxidation stage in turn, and the concentration of 2-butene is monitored. When the consumption of 2-butene is 86wt%, the connection between the first fixed bed and the third fixed bed is cut off, and the connection between the third fixed bed and the second epoxidation stage is connected, and all the cyclohexene is added to the second epoxidation stage to make the material flow enter the second epoxidation stage. When adding, the molar ratio of cyclohexene to the remaining isopropylbenzene hydroperoxide is 2:1. The temperatures of the three fixed beds in the second epoxidation stage are all 40°C. After the reaction, a mixture S-2# containing butylene oxide and cyclohexene oxide is obtained. It has been calculated that the conversion rate of cumene hydroperoxide is 100%, the conversion rate of 2-butene is 93.7%, the selectivity of butylene oxide is 99.5%, the selectivity of cyclohexene oxide is 99.5%, the content of cumene hydroperoxide in the mixture S-2# is zero, the content of 2-butene is 0.072%, the content of phenol is 31 ppm, and the initial yield of epoxy compounds is 99.5%.

[0054] After gas-liquid separation of the mixture S-2#, a gas phase stream containing 2-butene and a liquid phase stream containing epoxides were obtained. The gas phase stream was combusted and the liquid phase stream was distilled. The top temperature of the distillation tower was 63°C, the bottom temperature was 130°C, and the distillation pressure was 0.05MPa. After distillation, a stream I-1 containing butylene oxide, a stream I-2 containing cyclohexene, a stream I-3 containing cyclohexene oxide, and a heavy component stream I-4 were obtained. The heavy component stream I-4 contained isopropylbenzene and α,α-dimethylbenzyl alcohol. The stream I-2 was recycled to the position after the first epoxidation stage. After 9 months of continuous operation, the yield of epoxides was 95.8%, of which the yield of butylene oxide was 95.8%.

[0055] Example 3

[0056] The first epoxidation stage uses 4 fixed beds connected in series as a reactor, and the second epoxidation stage uses 3 fixed beds connected in series in a straight line as a reactor. All fixed beds have the same size and dimensions and are loaded with the same catalyst Cat2#.

[0057] The raw materials were prepared according to the molar ratio of isobutylene to cumene hydroperoxide to cyclohexene of 0.7:1:0.78, and all the isobutylene and the oxidant were added to the first fixed bed of the first epoxidation stage, wherein the oxidant was a 5 wt % cumene hydroperoxide solution in cumene, and the volumetric space velocity of the raw materials was 10 h -1, the pressure of the reaction system is 3.5 MPa, the temperatures of the four fixed beds in the first epoxidation stage are set to 30°C, 50°C, 70°C, and 100°C in sequence, so that the material flow containing the raw materials and the reaction products is circulated through the four fixed beds of the first epoxidation stage in sequence, and the concentration of isobutylene is monitored. When the consumption of isobutylene is 87wt%, the connection between the first fixed bed and the fourth fixed bed is cut off, the connection between the fourth fixed bed and the second epoxidation stage is connected, and all the cyclohexene is added to the second epoxidation stage to make the material flow enter the second epoxidation stage. When adding, the molar ratio of cyclohexene to the remaining isopropylbenzene hydroperoxide is 2:1. The temperatures of the three fixed beds in the second epoxidation stage are all 40°C. After the reaction, a mixture S-3# containing butylene oxide and cyclohexene oxide is obtained. It has been calculated that the conversion rate of cumene hydroperoxide is 100%, the conversion rate of isobutylene is 93.5%, the selectivity of butylene oxide is 99.3%, the selectivity of cyclohexene oxide is 99.5%, the content of cumene hydroperoxide in the mixture S-3# is zero, the content of isobutylene is 0.069%, the content of phenol is 40ppm, and the initial yield of epoxy compounds is 99.4%.

[0058] After the mixture S-3# is separated by gas and liquid, a gas phase stream containing isobutylene and a liquid phase stream containing epoxy compounds are obtained. The gas phase stream is combusted and the liquid phase stream is distilled. The top temperature of the distillation tower is 63°C, the bottom temperature is 130°C, and the distillation pressure is 0.05MPa. After distillation, a stream I-1 containing butylene oxide, a stream I-2 containing cyclohexene, a stream I-3 containing cyclohexene oxide and a heavy component stream I-4 are obtained. The heavy component stream I-4 contains isopropylbenzene and α,α-dimethylbenzyl alcohol. The stream I-2 is recycled to the position after the first epoxidation stage. After continuous operation for 9 months, the yield of epoxy compounds is 95.8%, of which the yield of butylene oxide is 95.7%.

[0059] Example 4

[0060] The first epoxidation stage uses 4 fixed beds connected in series as the reactor, and the second epoxidation stage uses 2 fixed beds connected in series in a straight line as the reactor. All the fixed beds have the same size and dimensions and are loaded with the same catalyst Cat3#.

[0061] The raw materials were prepared according to the molar ratio of 1-butene to cumene hydroperoxide to cyclohexene of 0.6:1:1.41, and all the 1-butene and the oxidant were added to the first fixed bed of the first epoxidation stage, wherein the oxidant was a 30 wt % cumene hydroperoxide solution in cumene, and the volumetric space velocity of the raw materials was 8 h -1, the pressure of the reaction system is 1.0 MPa, the temperatures of the four fixed beds in the first epoxidation stage are set to 30°C, 40°C, 60°C, and 80°C, respectively, so that the material flow containing the raw materials and the reaction products is circulated through the four fixed beds of the first epoxidation stage in turn, and the concentration of 1-butene is monitored. When the consumption of 1-butene is 88wt%, the connection between the first fixed bed and the fourth fixed bed is cut off, the connection between the fourth fixed bed and the second epoxidation stage is connected, and all the cyclohexene is added to the second epoxidation stage to make the material flow enter the second epoxidation stage. When adding, the molar ratio of cyclohexene to the remaining isopropylbenzene hydroperoxide is 3:1. The temperatures of the two fixed beds in the second epoxidation stage are 50°C and 70°C, respectively. After the reaction is completed, a mixture S-4# containing butylene oxide and cyclohexene oxide is obtained. It was calculated that the conversion rate of cumene hydroperoxide was 100%, the conversion rate of 1-butene was 96.4%, the selectivity of butylene oxide was 99.4%, the selectivity of cyclohexene oxide was 99.6%, the content of cumene hydroperoxide in the mixture S-4# was zero, the content of 1-butene was 0.18%, the content of phenol was 32 ppm, and the initial yield of epoxy compounds was 99.5%.

[0062] After gas-liquid separation of the mixture S-4#, a gas phase stream containing 1-butene and a liquid phase stream containing epoxides were obtained. The gas phase stream was combusted and the liquid phase stream was distilled. The top temperature of the distillation tower was 50°C, the bottom temperature was 110°C, and the distillation pressure was 0.07MPa. After distillation, a stream I-1 containing butylene oxide, a stream I-2 containing cyclohexene, a stream I-3 containing cyclohexene oxide, and a heavy component stream I-4 were obtained. The heavy component stream I-4 contained isopropylbenzene and α,α-dimethylbenzyl alcohol. The stream I-2 was recycled to the position after the first epoxidation stage. After 10 months of continuous operation, the yield of epoxides was 95.7%, of which the yield of butylene oxide was 95.6%.

[0063] Example 5

[0064] The first epoxidation stage uses two fixed beds connected in series as reactors, and the second epoxidation stage uses one fixed bed reactor. All fixed beds have the same size and dimensions and are loaded with the same catalyst Cat2#.

[0065] The raw materials were prepared according to the molar ratio of 1-butene to cumene hydroperoxide to cyclohexene of 0.5:1:2.22, and all the 1-butene and the oxidant were added to the first fixed bed of the first epoxidation stage, wherein the oxidant was a 10 wt % cumene hydroperoxide solution in cumene, and the volumetric space velocity of the raw materials was 3 h -1, the pressure of the reaction system is 0.8 MPa, the temperatures of the two fixed beds in the first epoxidation stage are set to 40° C. and 50° C. respectively, so that the material flow containing the raw materials and the reaction products is circulated through the two fixed beds of the first epoxidation stage in turn, and the concentration of 1-butene is monitored. When the consumption of 1-butene is 89wt%, the connection between the first fixed bed and the second fixed bed is cut off, the connection between the second fixed bed and the second epoxidation stage is connected, and all the cyclohexene is added to the second epoxidation stage to make the material flow enter the second epoxidation stage. When adding, the molar ratio of cyclohexene to the remaining isopropylbenzene hydroperoxide is 4:1. The temperature of the fixed bed in the second epoxidation stage is 60° C. After the reaction is completed, a mixture S-5# containing butylene oxide and cyclohexene oxide is obtained. It has been calculated that the conversion rate of cumene hydroperoxide is 100%, the conversion rate of 1-butene is 95.6%, the selectivity of butylene oxide is 99.5%, the selectivity of cyclohexene oxide is 99.7%, the content of cumene hydroperoxide in the mixture S-5# is zero, the content of 1-butene is 0.078%, the content of phenol is 35ppm, and the initial yield of epoxy compounds is 99.6%.

[0066] After gas-liquid separation of the mixture S-5#, a gas phase stream containing 1-butene and a liquid phase stream containing epoxides were obtained. The gas phase stream was combusted and the liquid phase stream was distilled. The top temperature of the distillation tower was 55°C, the bottom temperature was 120°C, and the distillation pressure was 0.06MPa. After distillation, a stream I-1 containing butylene oxide, a stream I-2 containing cyclohexene, a stream I-3 containing cyclohexene oxide, and a heavy component stream I-4 were obtained. The heavy component stream I-4 contained isopropylbenzene and α,α-dimethylbenzyl alcohol. The stream I-2 was recycled to the position after the first epoxidation stage. After 9 months of continuous operation, the yield of epoxides was 95.8%, of which the yield of butylene oxide was 95.7%.

[0067] Example 6

[0068] The first epoxidation stage uses 4 fixed beds connected in series as a reactor, and the second epoxidation stage uses 2 fixed beds connected in series in a straight line as a reactor. All fixed beds have the same size and dimensions and are loaded with the same catalyst Cat1#.

[0069] The raw materials were prepared in a molar ratio of 1-butene to cumene hydroperoxide to cyclohexene of 0.8:1:1. All 1-butene and an oxidant were added to the first fixed bed of the first epoxidation stage. The oxidant was a 15 wt % cumene hydroperoxide solution in cumene. The volumetric space velocity of the raw materials was 7 h -1, the pressure of the reaction system is 2.0 MPa, the temperature of the four fixed beds in the first epoxidation stage is 70° C., the material flow containing the raw materials and the reaction products is circulated through the four fixed beds of the first epoxidation stage in sequence, and the concentration of 1-butene is monitored. When the consumption of 1-butene is 83wt%, the connection between the first fixed bed and the fourth fixed bed is cut off, the connection between the fourth fixed bed and the second epoxidation stage is connected, and all the cyclohexene is added to the second epoxidation stage to make the material flow enter the second epoxidation stage. When adding, the molar ratio of cyclohexene to the remaining isopropylbenzene hydroperoxide is 3:1. The temperatures of the two fixed beds in the second epoxidation stage are 80° C. and 90° C. respectively. After the reaction is completed, a mixture S-6# containing butylene oxide and cyclohexene oxide is obtained. It was calculated that the conversion rate of cumene hydroperoxide was 100%, the conversion rate of 1-butene was 98.3%, the selectivity of butylene oxide was 99.4%, the selectivity of cyclohexene oxide was 99.7%, the content of cumene hydroperoxide in the mixture S-6# was zero, the content of 1-butene was 0.067%, the content of phenol was 28 ppm, and the initial yield of epoxy compounds was 99.5%.

[0070] After gas-liquid separation of the mixture S-6#, a gas phase stream containing 1-butene and a liquid phase stream containing epoxy compounds were obtained. The gas phase stream was combusted and the liquid phase stream was distilled. The top temperature of the distillation tower was 55°C, the bottom temperature was 120°C, and the distillation pressure was 0.06MPa. After distillation, a stream I-1 containing butylene oxide, a stream I-2 containing cyclohexene, a stream I-3 containing cyclohexene oxide, and a heavy component stream I-4 were obtained. The heavy component stream I-4 contained isopropylbenzene and α,α-dimethylbenzyl alcohol. The stream I-2 was recycled to the position after the first epoxidation stage. After 10 months of continuous operation, the yield of epoxy compounds was 95.6%, of which the yield of butylene oxide was 95.5%.

[0071] Example 7

[0072] The first epoxidation stage uses 6 straight-line fixed beds in series as reactors, and the second epoxidation stage uses 3 straight-line fixed beds in series as reactors. All fixed beds have the same size and dimensions and are loaded with the same catalyst Cat2#.

[0073] The raw materials were prepared according to the molar ratio of 1-butene to cumene hydroperoxide to cyclohexene of 0.9:1:0.28, and all the 1-butene and the oxidant were added to the first fixed bed of the first epoxidation stage, wherein the oxidant was a 25 wt % cumene hydroperoxide solution in cumene, and the volumetric space velocity of the raw materials was 5 h -1, the pressure of the reaction system is 1.5 MPa, and the temperatures of the six fixed beds in the first epoxidation stage are set to 30°C, 30°C, 50°C, 50°C, 70°C, and 70°C, respectively, so that the material flow containing the raw materials and the reaction products passes through the six fixed beds of the first epoxidation stage in sequence. When the material flows out of the sixth fixed bed, the consumption of 1-butene is 80wt%. At this time, cyclohexene is added to the connecting pipeline between the outlet of the sixth fixed bed of the first epoxidation stage and the inlet of the first fixed bed of the second epoxidation stage, so that the material flow directly enters the second epoxidation stage. When adding, the molar ratio of cyclohexene to the remaining isopropylbenzene hydroperoxide is 1:1. The temperatures of the three fixed beds in the second epoxidation stage are 80°C, 90°C, and 105°C, respectively. After the reaction, a mixture S-7# containing butylene oxide and cyclohexene oxide is obtained. It has been calculated that the conversion rate of isopropylbenzene hydroperoxide is 100%, the conversion rate of 1-butene is 100%, the selectivity of butylene oxide is 99.6%, the selectivity of cyclohexene oxide is 99.8%, the content of isopropylbenzene hydroperoxide in the mixture S-7# is zero, the content of 1-butene is zero, the content of phenol is 24ppm, and the initial yield of epoxy compounds is 99.6%.

[0074] After gas-liquid separation of the mixture S-7#, a gas phase stream containing light components and a liquid phase stream containing epoxides were obtained. The gas phase stream was combusted and the liquid phase stream was distilled. The top temperature of the distillation tower was 55°C, the bottom temperature was 120°C, and the distillation pressure was 0.06MPa. After distillation, a stream I-1 containing butylene oxide, a stream I-2 containing cyclohexene, a stream I-3 containing cyclohexene oxide, and a heavy component stream I-4 were obtained. The heavy component stream I-4 contained isopropylbenzene and α,α-dimethylbenzyl alcohol. The stream I-2 was recycled to the position after the first epoxidation stage. After 9 months of continuous operation, the yield of epoxides was 95.8%, of which the yield of butylene oxide was 95.8%.

[0075] Example 8

[0076] The first epoxidation stage uses one fixed bed reactor, and the second epoxidation stage uses three fixed beds connected in series in a straight line as reactors. All fixed beds have the same size and dimensions and are loaded with the same catalyst Cat2#.

[0077] The raw materials were prepared according to the molar ratio of 1-butene to cumene hydroperoxide to cyclohexene of 0.5:1:1.13, and all the 1-butene and the oxidant were added to the first fixed bed of the first epoxidation stage, wherein the oxidant was a 35 wt % cumene hydroperoxide solution in cumene, and the volumetric space velocity of the raw materials was 2 h -1The reaction system pressure is 0.4 MPa, the temperature of the fixed bed in the first epoxidation stage is 30°C, the material flow containing the raw materials and the reaction products is circulated in the fixed bed of the first epoxidation stage, and the content of 1-butene is detected. When the consumption of 1-butene is 87wt%, the circulation is cut off and cyclohexene is added in the second epoxidation stage, so that the material flow directly enters the second epoxidation stage. The molar ratio of cyclohexene to the remaining isopropylbenzene hydroperoxide is 2:1 when added. The temperatures of the three fixed beds in the second epoxidation stage are 40°C, 60°C, and 90°C, respectively. After the reaction, a mixture S-8# containing butylene oxide and cyclohexene oxide is obtained. It has been calculated that the conversion rate of cumene hydroperoxide is 100%, the conversion rate of 1-butene is 97.4%, the selectivity of butylene oxide is 99.2%, the selectivity of cyclohexene oxide is 99.4%, the content of cumene hydroperoxide in the mixture S-8# is zero, the content of 1-butene is 0.157%, the content of phenol is 48 ppm, and the initial yield of epoxy compounds is 99.3%.

[0078] After gas-liquid separation of the mixture S-8#, a gas phase stream containing 1-butene and a liquid phase stream containing epoxides were obtained. The gas phase stream was combusted and the liquid phase stream was distilled. The top temperature of the distillation tower was 55°C, the bottom temperature was 120°C, and the distillation pressure was 0.06MPa. After distillation, a stream I-1 containing butylene oxide, a stream I-2 containing cyclohexene, a stream I-3 containing cyclohexene oxide, and a heavy component stream I-4 were obtained. The heavy component stream I-4 contained isopropylbenzene and α,α-dimethylbenzyl alcohol. The stream I-2 was recycled to the position after the first epoxidation stage. After 8 months of continuous operation, the yield of epoxides was 95.4%, of which the yield of butylene oxide was 95.3%.

[0079] Comparative Example 1

[0080] Six straight-line series-connected fixed beds are used as the first reaction unit, and three straight-line series-connected fixed beds are used as the second reaction unit. All the fixed beds have the same size and dimensions and are loaded with the same catalyst Cat2#.

[0081] The raw materials were prepared according to the molar ratio of 1-butene to cumene hydroperoxide of 0.9:1, and all the 1-butene and the oxidant were added to the first fixed bed of the first reaction unit, wherein the oxidant was a 25 wt % cumene hydroperoxide solution in cumene, and the volumetric space velocity of the raw materials was 5 h -1, the pressure of the reaction system is 1.5MPa, the temperature of the 6 fixed beds in the first reaction unit is set to 30℃, 30℃, 50℃, 50℃, 70℃, 70℃ in sequence, so that the material flow containing the raw material and the reaction product passes through the 6 reactors of the first reaction unit in sequence, when the material flows out of the 6th reactor, the consumption of 1-butene is 80wt%, and then the material enters the second reaction unit, the temperature of the 3 reactors in the second reaction unit is 40℃, and after the reaction, a mixture S-D1# containing butylene oxide is obtained. It is calculated that the conversion rate of isopropylbenzene hydroperoxide is 74.8%, the conversion rate of 1-butene is 80%, the selectivity of butylene oxide is 96.3%, the content of isopropylbenzene hydroperoxide in the mixture S-D1# is 5.63%, the content of 1-butene is 1.5%, the content of phenol is 2068ppm, and the initial yield of epoxy compounds is 72.0%.

[0082] Comparative Example 2

[0083] The first epoxidation stage uses 6 straight-line fixed beds in series as reactors, and the second epoxidation stage uses 3 straight-line fixed beds in series as reactors. All fixed beds have the same size and dimensions and are loaded with the same catalyst Cat2#.

[0084] The raw materials were prepared according to the molar ratio of 1-butene to cumene hydroperoxide to cyclohexene of 0.3:1:1.5, and all the 1-butene and the oxidant were added to the first fixed bed of the first epoxidation stage, wherein the oxidant was a 35 wt % cumene hydroperoxide solution in cumene, and the volumetric space velocity of the raw materials was 5 h -1 , the pressure of the reaction system is 1.5 MPa, and the temperatures of the six fixed beds in the first epoxidation stage are set to 30°C, 30°C, 50°C, 50°C, 70°C, and 70°C, respectively, so that the material flow containing the raw materials and the reaction products passes through the six fixed beds of the first epoxidation stage in sequence. When the material flows out of the sixth fixed bed, the consumption of 1-butene is 83wt%. At this time, cyclohexene is added to the connecting pipeline between the outlet of the sixth fixed bed of the first epoxidation stage and the inlet of the first fixed bed of the second epoxidation stage, so that the material flow directly enters the second epoxidation stage. When adding, the molar ratio of cyclohexene to the remaining isopropylbenzene hydroperoxide is 2:1. The temperatures of the three fixed beds in the second epoxidation stage are 40°C, 60°C, and 90°C, respectively. After the reaction, a mixture S-D2# containing butylene oxide and cyclohexene oxide is obtained. It has been calculated that the conversion rate of cumene hydroperoxide is 100%, the conversion rate of 1-butene is 96.6%, the selectivity of butylene oxide is 98.8%, the selectivity of cyclohexene oxide is 99.4%, the content of cumene hydroperoxide in the mixture S-D2# is zero, the content of 1-butene is 0.1%, the content of phenol is 1057ppm, and the initial yield of epoxy compounds is 99.2%.

[0085] The mixture S-D2# is subjected to gas-liquid separation to obtain a gas phase stream containing 1-butene and a liquid phase stream containing epoxy compounds. The gas phase stream is combusted and the liquid phase stream is distilled. The top temperature of the distillation tower is 55°C, the bottom temperature is 120°C, and the distillation pressure is 0.06MPa. After distillation, a stream I-1 containing butylene oxide, a stream I-2 containing cyclohexene, a stream I-3 containing cyclohexene oxide, and a heavy component stream I-4 are obtained. The heavy component stream I-4 contains isopropylbenzene and α,α-dimethylbenzyl alcohol. The stream I-2 is recycled to the position after the first epoxidation stage. After 4 months of continuous operation, the yield of epoxy compounds is 94.2%, of which the yield of butylene oxide is 93.8%.

[0086] Comparative Example 3

[0087] The first epoxidation stage uses 4 fixed beds connected in series as the reactor, and the second epoxidation stage uses 2 fixed beds connected in series in a straight line as the reactor. All the fixed beds have the same size and dimensions and are loaded with the same catalyst Cat3#.

[0088] The raw materials were prepared according to the molar ratio of 1-butene to cumene hydroperoxide to cyclohexene of 0.6:1:0.19, and all the 1-butene and the oxidant were added to the first fixed bed of the first epoxidation stage, wherein the oxidant was a 30 wt % cumene hydroperoxide solution in cumene, and the volumetric space velocity of the raw materials was 8 h -1 , the pressure of the reaction system is 1.0 MPa, the temperatures of the four fixed beds in the first epoxidation stage are set to 30°C, 40°C, 60°C, and 80°C, respectively, so that the material flow containing the raw materials and the reaction products is circulated through the four fixed beds of the first epoxidation stage in turn, and the concentration of 1-butene is monitored. When the consumption of 1-butene is 88wt%, the connection between the first fixed bed and the fourth fixed bed is cut off, the connection between the fourth fixed bed and the second epoxidation stage is connected, and all the cyclohexene is added to the second epoxidation stage to make the material flow enter the second epoxidation stage. When adding, the molar ratio of cyclohexene to the remaining isopropylbenzene hydroperoxide is 0.4:1. The temperatures of the two fixed beds in the second epoxidation stage are 50°C and 70°C, respectively. After the reaction is completed, a mixture S-D3# containing butylene oxide and cyclohexene oxide is obtained. It has been calculated that the conversion rate of cumene hydroperoxide is 76.3%, the conversion rate of 1-butene is 95.8%, the selectivity of butylene oxide is 98.7%, the selectivity of cyclohexene oxide is 97.2%, the content of cumene hydroperoxide in the mixture S-D3# is 2.45%, the content of 1-butene is 0.25%, the content of phenol is 3643ppm, and the initial yield of epoxy compounds is 74.9%.

[0089] Comparative Example 4

[0090] The first epoxidation stage uses 4 fixed beds connected in series as the reactor, and the second epoxidation stage uses 2 fixed beds connected in series in a straight line as the reactor. All the fixed beds have the same size and dimensions and are loaded with the same catalyst Cat3#.

[0091] The raw materials were prepared according to the molar ratio of 1-butene to cumene hydroperoxide to cyclohexene of 0.6:1:3.3, and all the 1-butene and the oxidant were added to the first fixed bed of the first epoxidation stage, wherein the oxidant was a 30 wt % cumene hydroperoxide solution in cumene, and the volumetric space velocity of the raw materials was 8 h -1 , the pressure of the reaction system is 1.0 MPa, the temperatures of the four fixed beds in the first epoxidation stage are set to 30°C, 40°C, 60°C, and 80°C, respectively, so that the material flow containing the raw materials and the reaction products is circulated through the four fixed beds of the first epoxidation stage in turn, and the concentration of 1-butene is monitored. When the consumption of 1-butene is 88wt%, the connection between the first fixed bed and the fourth fixed bed is cut off, the connection between the fourth fixed bed and the second epoxidation stage is connected, and all the cyclohexene is added to the second epoxidation stage to make the material flow enter the second epoxidation stage. When adding, the molar ratio of cyclohexene to the remaining isopropylbenzene hydroperoxide is 7:1. The temperatures of the two fixed beds in the second epoxidation stage are 50°C and 70°C, respectively. After the reaction is completed, a mixture S-D4# containing butylene oxide and cyclohexene oxide is obtained. It has been calculated that the conversion rate of isopropylbenzene hydroperoxide is 100%, the conversion rate of 1-butene is 92.2%, the selectivity of butylene oxide is 98.3%, the selectivity of cyclohexene oxide is 99.1%, the content of isopropylbenzene hydroperoxide in the mixture S-D4# is zero, the content of 1-butene is 0.33%, the content of phenol is 38 ppm, and the initial yield of epoxy compounds is 99.1%.

[0092] The mixture S-D4# was subjected to gas-liquid separation to obtain a gas phase stream containing 1-butene and a liquid phase stream containing epoxy compounds. The gas phase stream was combusted and the liquid phase stream was distilled. The top temperature of the distillation tower was 50°C, the bottom temperature was 110°C, and the distillation pressure was 0.07MPa. After distillation, a stream I-1 containing butylene oxide, a stream I-2 containing cyclohexene, a stream I-3 containing cyclohexene oxide, and a heavy component stream I-4 were obtained. The heavy component stream I-4 contained isopropylbenzene and α,α-dimethylbenzyl alcohol. The stream I-2 was recycled to the position after the first epoxidation stage. After 9 months of continuous operation, the yield of epoxy compounds was 95.2%.

[0093] From the above results, it can be seen that the method of the present invention with low olefin-oil ratio and cyclohexene coordinated staged epoxidation can efficiently convert butene, with a total conversion rate of butene>93%, and the content of unreacted butene in the obtained mixture S is small, or even no butene remains, so the butene recycling step can be omitted, thereby avoiding the high energy consumption and impurity accumulation required for recycling. At the same time, the method of the present invention can also convert peroxide by 100%, and the content of phenol, a byproduct of peroxide decomposition, in the reaction product is small, thereby solving the problem of difficult recycling of peroxide, achieving efficient conversion of raw materials, and helping to improve the operating efficiency of the production line.

[0094] In Comparative Example 1, only butene is epoxidized. Due to the excess of peroxide, the risk of side reactions increases, the phenol content in the reaction product is high, and the comprehensive conversion rate of butene is low. Comparative Examples 2 to 4 all use cyclohexene for coordinated staged epoxidation, but the olefin-oil ratio of butene to peroxide in Comparative Example 2 is too low, which increases the risk of peroxide decomposition in the first stage and the phenol content in the product is high; the olefin-oil ratio of cyclohexene to peroxide in Comparative Example 3 is too low, resulting in a low conversion rate of peroxide and a high phenol content; the olefin-oil ratio of cyclohexene to peroxide in Comparative Example 4 is too high, resulting in a poor conversion rate of butene, less than 93%.

[0095] In addition, the present invention also examines the service life of the catalyst, that is, the change in the time that the device can operate when the yield of the epoxy compound decreases by no more than 4%. The results show that Examples 1 to 8 of the present invention can all achieve continuous operation for 8 months or more, while the yield of the epoxy compound of Comparative Example 2 decreases by ≥4% after 4 to 5 months of continuous operation. It can be seen that the present invention can extend the service life of the catalyst by more than 30%.

[0096] As described above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the present invention itself. Various changes in form and details may be made without departing from the spirit and scope of the present invention as defined in the appended claims.

Claims

1. A method for preparing butylene oxide, characterized in that: The butene and the peroxide-containing oxidant are subjected to a first epoxidation stage and a second epoxidation stage in sequence under the action of a heterogeneous catalyst, cyclohexene is added after the first epoxidation stage, and a mixture S containing butylene oxide is obtained after the reaction is completed; The reaction temperature T1 of the first epoxidation stage is 30-100°C, and the reaction temperature T2 of the second epoxidation stage is 40-105°C; The molar ratio of butene, peroxide and cyclohexene is (0.5-0.9):1:(0.2-2.2); When the consumption of butene is 80-90wt%, cyclohexene is added; The peroxide is cumene hydroperoxide.

2. The method for preparing butylene oxide according to claim 1, characterized in that: The oxidant is a cumene solution of cumene hydroperoxide; based on the total mass of the oxidant, the mass proportion of the cumene hydroperoxide is ≤35wt%.

3. The method for preparing butylene oxide according to claim 1, characterized in that: The molar amount of the cyclohexene is ≥ the molar amount of the remaining peroxide when the cyclohexene is added.

4. The method for preparing butylene oxide according to claim 3, characterized in that: The ratio of the molar amount of the cyclohexene to the molar amount of the remaining peroxide when the cyclohexene is added is (2-4):

1.

5. The method for preparing butylene oxide according to claim 1, characterized in that: The volume space velocity of the oxidant is ≥2h -1 .

6. The method for preparing butylene oxide according to claim 1, characterized in that: The pressure of the first epoxidation stage and the second epoxidation stage is 0.3-4.0 MPa.

7. The method for preparing butylene oxide according to claim 1, characterized in that: Based on the total mass of the mixture S, the mass proportion of butene in the mixture S is less than 0.2 wt %.

8. The method for preparing butylene oxide according to claim 1, characterized in that: Based on the total mass of the mixture S, the content of peroxide in the mixture S is zero, and the content of phenol is less than 50 ppm.

9. The method for preparing butylene oxide according to claim 1, characterized in that: The method also includes a step of separating the epoxy compound and a step of recycling the cyclohexene, wherein the separation is carried out in a distillation or rectification manner.

10. The method for preparing butylene oxide according to claim 1, characterized in that: The heterogeneous catalyst is titanium silicon oxide; the pore size of the titanium silicon oxide is 2-40 nm, and the specific surface area is 130-600 m 2 / g; based on the total mass of titanium silicon oxide, the titanium content is 0.2~10wt%.