Polyalkyl aromatic hydrocarbon preparation system based on fixed bed reactor

Abstract

The utility model discloses a polyalkyl aromatic hydrocarbon preparation system based on a fixed bed reactor, which is characterized in that a catalyst bed layer is divided into a plurality of sections according to the characteristics of aromatic hydrocarbon liquid phase alkylation reaction, and perforated plates and coil pipes are arranged among the sections; reaction liquid at the lower layer is uniformly distributed again after passing through a porous plate, and passes through a coil pipe heat exchange area at a certain flow speed, under the heat transfer strengthening action of fins or threads, the reaction raw materials and the reaction liquid are subjected to sufficient heat exchange, most reaction heat is removed, and the reaction raw materials are preheated, so that the temperature of a catalyst bed layer is uniformly distributed, and the probability of side reaction is reduced; and heat is fully utilized, and the effects of energy conservation and emission reduction are achieved.

Description

Technical Field

[0001] This application relates to a polyalkyl aromatic hydrocarbon preparation system based on a fixed-bed reactor, which belongs to the field of aromatic hydrocarbon preparation. Background Technology

[0002] Aromatic hydrocarbons are one of the basic products and raw materials of the petrochemical industry, mainly including benzene, toluene and xylene, ethylbenzene, and cumene. Aromatic hydrocarbons can be alkylated with olefins in a liquid phase to produce high-value-added chemicals, such as tert-butyltoluene, tert-butylethylbenzene, isopropyltoluene, and diisopropylbenzene. Among the aforementioned polyalkyl aromatic hydrocarbons, para-alkyl-substituted aromatic hydrocarbons have a wider range of applications. For example, para-alkyl-substituted tert-butyl aromatic hydrocarbons are key specialty monomer raw materials for the production of new polymer materials, with broad application prospects in high-end industries such as engineering plastics, high-speed rail, aviation, and electronic information. Alkyl-substituted tert-butyl aromatic hydrocarbons have three isomers, and ortho-position impurities significantly affect product quality; therefore, strict control of reaction selectivity is crucial.

[0003] Aromatic hydrocarbon liquid-phase alkylation reactions are typically exothermic, and both fixed-bed and tubular reactors are used. Fixed-bed reactors are suitable for reactions with low exothermic activity, have a simple reactor structure, and low manufacturing costs. When the exothermic activity is high, tubular reactors are generally chosen. Tubular reactors consume more materials and require additional heat exchange systems, resulting in higher investment costs and stricter requirements for catalyst loading.

[0004] Most of the heat-transferring fixed-bed reactors reported so far are gas-phase fixed-bed reactors, which do not consider the comprehensive utilization of heat transfer and heat removal during liquid-phase reactions. Utility Model Content

[0005] According to one aspect of this application, a polyalkyl aromatic hydrocarbon preparation system based on a fixed-bed reactor is provided, comprising a fixed-bed reactor including an outer cylinder and a catalyst bed disposed inside, the catalyst bed comprising at least two layers;

[0006] Each pair of catalyst beds is provided with a serpentine tube and a perforated plate;

[0007] The snake tube is provided in at least one layer and is located above the perforated plate;

[0008] The ratio of the heat exchange area of ​​the serpentine tube to the cross-sectional area of ​​the fixed-bed reactor is 0.05 to 0.6.

[0009] Optionally, the distance between the snake tube and the perforated plate is 100-1000 mm.

[0010] Optionally, the serpentine tube may be an annular serpentine tube or a U-shaped serpentine tube;

[0011] The outer side of the snake tube is provided with fins or threads.

[0012] Optionally, the perforated plate is provided with a plurality of cylindrical or conical sieve holes that are connected vertically;

[0013] The porosity of the upper layer of the porous plate is 2-60%;

[0014] The diameter of the upper hole of the sieve is 0.5-15mm, and when the sieve hole is conical, the cone angle is 5-120°.

[0015] Optionally, the preparation system further includes a light-light-removal tower, a recovery tower, and a product tower connected in sequence to the fixed-bed reactor;

[0016] The top of the recovery tower is also connected to the fixed-bed reactor;

[0017] The fixed-bed reactor is also connected to a heater.

[0018] The reactants, aromatic hydrocarbons and their corresponding olefins, are fed into the coil of a fixed-bed reactor. The reactants are heated after heat exchange with the catalyst bed in the coil, and then heated by a heater before entering the lower feed inlet of the fixed-bed reactor. The reactants undergo a liquid-phase alkylation reaction in the catalyst bed.

[0019] The reaction products are collected from the top outlet of the fixed-bed reactor and sent to the downstream light hydrocarbon removal tower. The light hydrocarbon removal tower is a continuous distillation tower. The small amount of low-carbon hydrocarbons entrained in the reaction products are discharged from the top of the light hydrocarbon removal tower, and the bottom product is sent to the recovery tower.

[0020] The main function of the recovery tower is to recover the aromatic hydrocarbons from the raw material. After distillation, the aromatic hydrocarbons are collected from the top of the recovery tower and returned to the reactor feed line after being pressurized by a pump. The bottom liquid containing the product and high-boiling substances enters the product tower. The product and high-boiling substances are separated in the product tower. The qualified alkylated aromatic hydrocarbon product is collected from the top of the tower, while the high-boiling substances are collected from the bottom of the tower.

[0021] Using this preparation system, the overall selectivity of the specified alkylated product can reach over 90%.

[0022] Aromatic hydrocarbon conversion rate = (moles of aromatic hydrocarbons in feed - moles of aromatic hydrocarbons in product) / moles of aromatic hydrocarbons in feed × 100%;

[0023] Selectivity of para-alkylated products = (moles of para-alkylated products in the product) / (total moles of alkylated products in the product) × 100%.

[0024] Optionally, the outlet of the serpentine coil is connected to the inlet of the heater, and the outlet of the heater is connected to the lower inlet of the fixed-bed reactor.

[0025] Optionally, when the fixed-bed reactor is used to prepare tert-butylethylbenzene from ethylbenzene and isobutylene, the catalyst bed is divided into 2 to 8 sections;

[0026] The distance between the perforated plate and the serpentine tube is 100-800 mm, the opening rate of the upper layer of the perforated plate is 10-40%, the diameter of the sieve holes is 0.5-12 mm, and the cone angle of the sieve holes is 5-90°.

[0027] A U-shaped serpentine tube with threads on the outside is selected, and the ratio of its heat exchange area to the reactor cross-sectional area is 0.05 to 0.5.

[0028] Optionally, when the fixed-bed reactor is used to prepare tert-butyltoluene from toluene and isobutylene, the catalyst bed is divided into 3 to 9 sections;

[0029] The distance between the perforated plate and the serpentine tube is 200-900 mm. The opening rate of the upper layer of the perforated plate is 5-50%. The diameter of the holes above the sieve holes is 1-15 mm. The sieve holes are cylindrical.

[0030] A U-shaped serpentine tube with threads on the outside is selected, and the ratio of its heat exchange area to the reactor cross-sectional area is 0.05 to 0.5.

[0031] Optionally, when the fixed-bed reactor is used to prepare isopropyltoluene from toluene and propylene, the catalyst bed of the reactor is divided into 3 to 10 sections;

[0032] The distance between the perforated plate and the serpentine tube is 300-1000mm, the opening rate of the upper layer of the perforated plate is 10-60%, the diameter of the sieve holes is 0.5-15mm, and the cone angle of the sieve holes is 15-120°.

[0033] An annular serpentine tube with fins on the outside is selected, and the ratio of its heat exchange area to the reactor cross-sectional area is 0.1 to 0.6.

[0034] Optionally, when the fixed-bed reactor is used to prepare diisopropylbenzene from cumene and propylene: the catalyst bed of the reactor is divided into 3 to 10 sections;

[0035] The distance between the perforated plate and the serpentine tube is 200-900 mm, the opening rate of the upper layer of the perforated plate is 15-60%, the diameter of the sieve holes is 1-12 mm, and the cone angle of the sieve holes is 10-120°.

[0036] An annular serpentine tube with fins on the outside is selected, and the ratio of its heat exchange area to the reactor cross-sectional area is 0.1 to 0.6.

[0037] The beneficial effects that this application can produce include:

[0038] The polyalkyl aromatic hydrocarbon preparation system based on a fixed-bed reactor provided in this application has the advantages of simple catalyst loading, inter-stage heat transfer, inlet feed temperature rise, reduced catalyst bed temperature rise, improved product selectivity, and reduced energy consumption.

[0039] Based on the characteristics of the liquid-phase alkylation reaction of aromatic hydrocarbons, this application divides the catalyst bed into multiple sections and sets porous plates and coils between the sections. The lower layer of reaction liquid is redistributed after passing through the porous plates and flows through the heat exchange zone of the coil at a certain flow rate. Under the heat transfer enhancement effect of the fins or threads, the reactants and the reaction liquid exchange heat fully, remove most of the reaction heat, and preheat the reactants, so as to achieve uniform temperature distribution of the catalyst bed, reduce the probability of side reactions, and realize the full utilization of heat, thereby achieving the effect of energy saving and emission reduction.

[0040] This application can achieve a total selectivity of over 90% for the specified alkylated product. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the structure of a polyalkyl aromatic hydrocarbon preparation system provided in one embodiment of this application;

[0042] Figure 2 This is a schematic diagram of the structure of a fixed-bed reactor provided in one embodiment of this application;

[0043] Figure 3 For this application Figure 2 Sectional view of AA in the middle;

[0044] Figure 4 For this application Figure 2 Cross-sectional view of the middle section (BB).

[0045] List of components and reference numerals:

[0046] 1-Catalyst bed, 2-Snake coil, 3-Perforated plate, 21-Annular snake coil, 22-U-shaped snake coil, 31-Sieve, R01-Fixed bed reactor, T01-Light weight removal tower, E01-Heater, T02-Recovery tower, T03-Product tower. Detailed Implementation

[0047] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0048] like Figure 1 As shown, according to one embodiment of this application, a polyalkyl aromatic hydrocarbon preparation system based on a fixed-bed reactor is provided, including a fixed-bed reactor R01, such as... Figure 2 As shown, the fixed-bed reactor R01 includes an outer cylinder and a catalyst bed 1 disposed inside, the catalyst bed 1 including at least two layers;

[0049] Each pair of catalyst beds 1 is provided with a serpentine tube 2 and a porous plate 3;

[0050] The snake tube 2 is provided in at least one layer and is located above the porous plate 3;

[0051] The ratio of the heat exchange area of ​​the serpentine tube 2 to the cross-sectional area of ​​the fixed-bed reactor R01 is 0.05 to 0.6.

[0052] The preparation system also includes a light-light-removal tower T01, a recovery tower T02, and a product tower T03 that are sequentially connected to the fixed-bed reactor R01.

[0053] The top of the recovery tower T02 is also connected to the fixed-bed reactor R01;

[0054] The fixed-bed reactor R01 is also connected to the heater E01. Specifically, the outlet of the serpentine tube 2 is connected to the inlet of the heater E01, and the outlet of the heater E01 is connected to the lower inlet of the fixed-bed reactor R01.

[0055] The distance between the snake tube 2 and the perforated plate 3 is 100-1000 mm.

[0056] like Figure 3 As shown, the serpentine tube 2 is selected as either an annular serpentine tube 21 or a U-shaped serpentine tube 22;

[0057] The outer side of the snake tube 2 is provided with fins or threads.

[0058] like Figure 4 As shown, the porous plate 3 is provided with a plurality of cylindrical or conical sieve holes 31 that are connected vertically.

[0059] The porosity of the upper layer of the perforated plate 3 is 2-60%;

[0060] The upper diameter of the sieve hole 31 is 0.5-15mm, and when the sieve hole 31 is conical, the cone angle is 5-120°.

[0061] Process flow:

[0062] The reactants, aromatic hydrocarbons and corresponding olefins, are fed into the coil 2 of the fixed-bed reactor R01. The reactants are heated after heat exchange with the catalyst bed 1 in the coil 2. After being heated by the heater E01, they enter the lower feed port of the fixed-bed reactor R01. The reactants undergo liquid-phase alkylation reaction in the catalyst bed 1.

[0063] The reaction products are collected from the top outlet of the fixed-bed reactor R01 and sent to the downstream light hydrocarbon removal tower T01. The light hydrocarbon removal tower T01 is a continuous distillation tower. The small amount of low-carbon hydrocarbons entrained in the reaction products are discharged from the top of the light hydrocarbon removal tower T01, and the bottom product is sent to the recovery tower.

[0064] The main function of the recovery tower is to recover the aromatic hydrocarbons from the raw material. After distillation, the aromatic hydrocarbons are collected from the top of the recovery tower and returned to the reactor feed line after being pressurized by a pump. The bottom liquid containing the product and high-boiling substances enters the product tower T03. The product and high-boiling substances are separated in the product tower T03. The qualified alkylated aromatic hydrocarbon product is collected from the top of the tower, while the high-boiling substances are collected from the bottom of the tower.

[0065] Using this preparation system, the overall selectivity of the specified alkylated product can reach over 90%.

[0066] Aromatic hydrocarbon conversion rate = (moles of aromatic hydrocarbons in feed - moles of aromatic hydrocarbons in product) / moles of aromatic hydrocarbons in feed × 100%;

[0067] Selectivity of para-alkylated products = (moles of para-alkylated products in the product) / (total moles of alkylated products in the product) × 100%.

[0068] Example 1

[0069] The fixed-bed reactor R01 of this application is used to prepare tert-butylethylbenzene from ethylbenzene and isobutylene. The structure of the fixed-bed reactor R01 is as follows: Figure 2 As shown, the catalyst bed 1 of the reactor is divided into 4 sections, with a porous plate 3 and a serpentine tube 2 set between the sections. The distance between the porous plate 3 and the serpentine tube 2 is 400 mm. The opening rate of the upper layer of the porous plate 3 is 35%, the aperture of the sieve hole 31 is 3 mm, and the cone angle of the sieve hole 31 is 60°.

[0070] A U-shaped serpentine tube 22 with threads on the outside is selected, and its heat exchange area to reactor cross-sectional area ratio is 0.4.

[0071] Using the Beta@ZSM-12 core-shell molecular sieve catalyst developed by the Dalian Institute of Chemical Physics, Figure 1 The equipment connection shown is configured such that the reaction temperature is 200℃, the reaction pressure is 2.5 MPaG, the molar ratio of ethylbenzene to isobutylene is 4.0, and the isobutylene mass hourly space velocity (HHSV) is 1.0 h⁻¹. -1 .

[0072] Calculations show that the single-pass conversion rate of ethylbenzene in this embodiment is 23.5%, and the selectivity of tert-butylethylbenzene in tert-butylethylbenzene is 96.5%.

[0073] Comparative Example 1

[0074] The conventional fixed-bed reactor R01 was used to prepare tert-butylethylbenzene from ethylbenzene and isobutylene, with the catalyst bed 1 divided into 4 sections.

[0075] Using the Beta@ZSM-12 core-shell molecular sieve catalyst developed by the Dalian Institute of Chemical Physics, Figure 1The equipment connection shown is configured such that the reaction temperature is 200℃, the reaction pressure is 2.5 MPaG, the molar ratio of ethylbenzene to isobutylene is 4.0, and the isobutylene mass hourly space velocity (HHSV) is 1.0 h⁻¹. -1 .

[0076] According to calculations, the single-pass conversion rate of ethylbenzene in this embodiment is 22.6%, and the selectivity of tert-butylethylbenzene in tert-butylethylbenzene is 93.8%.

[0077] By comparing Example 1 and Comparative Example 1, it can be seen that using the fixed-bed reactor R01 of this application significantly improves the selectivity of p-tert-butylethylbenzene in the product.

[0078] Example 2

[0079] The fixed-bed reactor R01 of this application is used to prepare tert-butyltoluene from toluene and isobutylene. The structure of the fixed-bed reactor R01 is as follows: Figure 2 As shown, the catalyst bed 1 of the reactor is divided into 4 sections, with a porous plate 3 and a serpentine tube 2 set between the sections. The distance between the porous plate 3 and the serpentine tube 2 is 400 mm. The opening rate of the upper layer of the porous plate 3 is 40%. The aperture of the sieve hole 31 is 3 mm and the cone angle of the sieve hole 31 is 45°.

[0080] A U-shaped serpentine tube 22 with threads on the outside is selected, and its heat exchange area to reactor cross-sectional area ratio is 0.35.

[0081] Using the Beta / MOR co-crystallized molecular sieve catalyst developed by the Dalian Institute of Chemical Physics, Figure 1 The equipment connection shown is configured such that the reaction temperature is 200℃, the reaction pressure is 2.5 MPaG, the molar ratio of toluene to isobutylene is 4.0, and the isobutylene mass hourly space velocity (HHSV) is 1.0 h⁻¹. -1 .

[0082] According to calculations, the single-pass conversion rate of toluene in this embodiment is 23.7%, and the selectivity of tert-butyltoluene in tert-butyltoluene is 96.5%.

[0083] Example 3

[0084] The fixed-bed reactor R01 of this application is used to prepare isopropyltoluene from toluene and propylene. The structure of the fixed-bed reactor R01 is as follows: Figure 2 As shown, the catalyst bed 1 of the reactor is divided into 5 sections, with perforated plates 3 and serpentine tubes 2 set between the sections. The distance between the perforated plates 3 and the serpentine tubes 2 is 500 mm. The opening rate of the upper layer of the perforated plates 3 is 30%, the aperture of the sieve holes 31 is 4 mm, and the cone angle of the sieve holes 31 is 30°.

[0085] An annular serpentine tube 21 is selected, with fins on the outside, and the ratio of its heat exchange area to the reactor cross-sectional area is 0.35.

[0086] Using the Beta@ZSM-12 core-shell molecular sieve catalyst developed by the Dalian Institute of Chemical Physics, Figure 1 The equipment connection shown is configured such that the reaction temperature is 200℃, the reaction pressure is 2.5 MPaG, the toluene to propylene molar ratio is 4.0, and the propylene mass hourly space velocity is 1.0 h⁻¹. -1 .

[0087] According to calculations, the single-pass conversion rate of toluene in this embodiment is 23.3%, and the selectivity of m- and p-isopropyltoluene in isopropyltoluene is 96.5%.

[0088] Example 4

[0089] The fixed-bed reactor R01 of this application is used to prepare diisopropylbenzene from cumene and propylene. The structure of the fixed-bed reactor R01 is as follows: Figure 2 As shown, the catalyst bed 1 of the reactor is divided into 6 sections, with perforated plates 3 and serpentine tubes 2 set between the sections. The distance between the perforated plates 3 and the serpentine tubes 2 is 450 mm. The opening rate of the upper layer of the perforated plates 3 is 35%, the aperture of the sieve holes 31 is 3 mm, and the cone angle of the sieve holes 31 is 30°.

[0090] An annular serpentine tube 21 is selected, with fins on the outside, and the ratio of its heat exchange area to the reactor cross-sectional area is 0.35.

[0091] Using the Beta molecular sieve catalyst developed by the Dalian Institute of Chemical Physics, Figure 1 The equipment connection shown is configured such that the reaction temperature is 140℃, the reaction pressure is 3.0 MPaG, the molar ratio of cumene to propylene is 4.0, and the mass hourly space velocity (WHSV) of cumene is 1.5 h⁻¹. -1 .

[0092] According to calculations, the single-pass conversion rate of cumene in this embodiment is 22.9%, and the selectivity of m- and p-diisopropylbenzene in diisopropylbenzene is 99.6%.

[0093] The above description is only a part of the embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

Claims

1. A polyalkyl aromatic hydrocarbon preparation system based on a fixed-bed reactor, characterized in that, The reactor includes a fixed-bed reactor, which comprises an outer cylinder and a catalyst bed disposed inside the cylinder, the catalyst bed comprising at least two layers. Each pair of catalyst beds is provided with a serpentine tube and a perforated plate; The snake tube is provided in at least one layer and is located above the perforated plate; The ratio of the heat exchange area of ​​the serpentine tube to the cross-sectional area of ​​the fixed-bed reactor is 0.05 to 0.

6.

2. The polyalkyl aromatic hydrocarbon preparation system based on a fixed-bed reactor according to claim 1, characterized in that, The distance between the snake tube and the perforated plate is 100-1000 mm.

3. The polyalkyl aromatic hydrocarbon preparation system based on a fixed-bed reactor according to claim 2, characterized in that, The snake tube is either a ring-shaped snake tube or a U-shaped snake tube; The outer side of the snake tube is provided with fins or threads.

4. The polyalkyl aromatic hydrocarbon preparation system based on a fixed-bed reactor according to claim 3, characterized in that, The perforated plate is provided with multiple cylindrical or conical sieve holes that are connected vertically. The porosity of the upper layer of the porous plate is 2-60%; The diameter of the upper hole of the sieve is 0.5-15mm, and when the sieve hole is conical, the cone angle is 5-120°.

5. The polyalkyl aromatic hydrocarbon preparation system based on a fixed-bed reactor according to claim 1, characterized in that, The preparation system also includes a light-light residue removal tower, a recovery tower, and a product tower that are sequentially connected to the fixed-bed reactor; The top of the recovery tower is also connected to the fixed-bed reactor; The fixed-bed reactor is also connected to a heater.

6. The polyalkyl aromatic hydrocarbon preparation system based on a fixed-bed reactor according to claim 5, characterized in that, The outlet of the serpentine coil is connected to the inlet of the heater, and the outlet of the heater is connected to the lower inlet of the fixed-bed reactor.

7. The polyalkyl aromatic hydrocarbon preparation system based on a fixed-bed reactor according to claim 4, characterized in that, When the fixed-bed reactor is used to prepare tert-butylethylbenzene from ethylbenzene and isobutylene, the catalyst bed is divided into 2 to 8 sections. The distance between the perforated plate and the serpentine tube is 100-800 mm, the opening rate of the upper layer of the perforated plate is 10-40%, the diameter of the sieve holes is 0.5-12 mm, and the cone angle of the sieve holes is 5-90°. A U-shaped serpentine tube with threads on the outside is selected, and the ratio of its heat exchange area to the reactor cross-sectional area is 0.05 to 0.

5.

8. The polyalkyl aromatic hydrocarbon preparation system based on a fixed-bed reactor according to claim 4, characterized in that, When the fixed-bed reactor is used to prepare tert-butyltoluene from toluene and isobutylene, the catalyst bed is divided into 3 to 9 sections. The distance between the perforated plate and the serpentine tube is 200-900 mm. The opening rate of the upper layer of the perforated plate is 5-50%. The diameter of the holes above the sieve holes is 1-15 mm. The sieve holes are cylindrical. A U-shaped serpentine tube with threads on the outside is selected, and the ratio of its heat exchange area to the reactor cross-sectional area is 0.05 to 0.

5.

9. The polyalkyl aromatic hydrocarbon preparation system based on a fixed-bed reactor according to claim 4, characterized in that, When the fixed-bed reactor is used to prepare isopropyltoluene from toluene and propylene, the catalyst bed of the reactor is divided into 3 to 10 sections. The distance between the perforated plate and the serpentine tube is 300-1000mm, the opening rate of the upper layer of the perforated plate is 10-60%, the diameter of the sieve holes is 0.5-15mm, and the cone angle of the sieve holes is 15-120°. An annular serpentine tube with fins on the outside is selected, and the ratio of its heat exchange area to the reactor cross-sectional area is 0.1 to 0.

6.

10. The polyalkyl aromatic hydrocarbon preparation system based on a fixed-bed reactor according to claim 4, characterized in that, When the fixed-bed reactor is used to prepare diisopropylbenzene from cumene and propylene, the catalyst bed of the reactor is divided into 3 to 10 sections. The distance between the perforated plate and the serpentine tube is 200-900 mm, the opening rate of the upper layer of the perforated plate is 15-60%, the diameter of the sieve holes is 1-12 mm, and the cone angle of the sieve holes is 10-120°. An annular serpentine tube with fins on the outside is selected, and the ratio of its heat exchange area to the reactor cross-sectional area is 0.1 to 0.6.

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