Catalytic rectification method for removing isooctane reaction raw material impurities

Abstract

The invention relates to the field of chemical engineering, in particular to a catalytic distillation method for removing impurities in isooctane reaction raw materials, which comprises the following steps: S1, separating a C4 raw material and butadiene: treating the C4 raw material with desalted water to obtain a washed C4 raw material; carrying out coalescence dehydration treatment on the washed C4 raw material to obtain a dehydrated C4 raw material; the dehydrated C4 raw material is subjected to catalytic rectification treatment, a rectified C4 raw material is obtained, a catalyst for catalytic rectification treatment is a La-Ce / ZSM-5 catalyst, and the rectified C4 raw material is subjected to membrane separation, so that the C4 raw material and butadiene are obtained; and S2, pumping the C4 raw material into an alkylation reactor, and carrying out an alkylation reaction on the C4 raw material and isobutane under the action of a solid superacid catalyst to prepare isooctane. Compared with the prior art, the method has the advantages that impurities in the C4 raw material are removed, the byproduct butadiene and the C4 raw material are extracted, the service life of a catalyst in the isooctane preparation process can be prolonged by using the C4 raw material, the solid superacid catalyst is improved at the same time, and the C4 conversion rate and the isooctane yield are improved.

Description

Technical Field

[0001] This invention relates to the field of chemical technology, and specifically to a catalytic distillation method for removing impurities from isooctane reaction feedstock. Background Technology

[0002] Isooctane plays a vital role in the fuel, chemical, and aerospace industries, primarily as an additive in gasoline and aviation gasoline to adjust their octane number, and as a non-polar inert solvent in organic synthesis. Isooctane is mainly produced by using C4 as a raw material to prepare isooctene, which is then subjected to hydrogenation catalysis to obtain isooctane.

[0003] ZL01112660.4 discloses a method for producing isooctane and automotive liquefied petroleum gas through the oligomerization and hydrogenation of mixed C4 compounds. Specifically, it discloses a reaction process using mixed C4 compounds as raw materials at a reaction temperature of 160℃-230℃, a pressure of 3.0-5.0 MPa, and a space velocity of 0.5-6.0 h⁻¹. -1 Under certain conditions, the raw materials are sequentially fed into a series fixed-bed reactor, where they react with a solid acid catalyst. The catalyst is a solid phosphoric acid catalyst, a hydrogen-form ZSM-5 zeolite catalyst, or a silica-alumina microsphere catalyst. The weight concentration of C4 olefins in the gaseous effluent from the first reactor is controlled at 20-40%, and the weight concentration of C4 olefins in the effluent from the second reactor is less than or equal to 4%. The liquid effluents from both reactors enter a separation zone. The liquid effluents are separated to obtain isooctene with a purity of ≥96% by weight. The isooctene is then contacted with the catalyst, and the reaction is carried out at a reaction temperature of 200-300℃ and a space velocity of 1.0-5.0 h⁻¹. -1 Isooctane is produced by hydrogenation under conditions of 2.5-6.0 MPa pressure and a hydrogen:isooctene volume ratio of 100-800. The catalyst is a nickel-supported hydrogenation catalyst with a nickel oxide content of 20-30% by weight on an alumina or zeolite support. The invention obtains isooctane and automotive liquefied petroleum gas (LPG) through a two-stage oligomerization process and by controlling the conversion rate of each stage. However, the C4 feedstock contains impurities such as butadiene, which easily aggregates, cokes, and poisons the catalyst, leading to a decrease in catalyst lifespan and catalytic efficiency.

[0004] Furthermore, butadiene is the main raw material for synthetic rubber, and currently 80% of synthetic rubber is produced from butadiene. From the perspective of raw material energy, if butadiene can be separated from C4 raw materials, it can both obtain butadiene products and extend the catalyst life, achieving a win-win situation. Secondly, the existing catalytic distillation catalysts are not effective in removing total sulfur and butadiene.

[0005] To overcome the above problems, this invention first employs pretreatment of the C4 feedstock to separate the C4 feedstock and butadiene, obtaining butadiene product and extending the catalyst lifespan during isooctane preparation, thereby reducing production costs and improving economic efficiency. Simultaneously, during isooctane preparation, a solid superacid catalyst is prepared and alkylation is used to prepare isooctane, improving the C4 feedstock conversion rate and isooctane yield. Summary of the Invention

[0006] The purpose of this invention is to provide a catalytic distillation method for removing impurities from isooctane reaction feedstocks, aiming to solve the problems of impurities in C4 feedstocks poisoning the catalyst, leading to a decrease in catalyst lifespan, and the poor removal effect of catalytic distillation catalysts on total sulfur and butadiene.

[0007] To achieve the above objectives, the present invention provides a catalytic distillation method for removing impurities from isooctane reaction feedstock, comprising: S1, Separating C4 feedstock and butadiene: The C4 feedstock is treated with demineralized water to obtain washed C4 feedstock; the washed C4 feedstock is then subjected to coalescence dehydration treatment to obtain dehydrated C4 feedstock; the dehydrated C4 feedstock is then subjected to catalytic distillation treatment to obtain distilled C4 feedstock, wherein the catalyst for the catalytic distillation treatment is a La-Ce / ZSM-5 catalyst; the distilled C4 feedstock is then subjected to membrane separation to obtain C4 feedstock and butadiene; S2, Preparation of isooctene from C4 feedstock: The above-mentioned C4 feedstock is pumped into an alkylation reactor, and under the action of a solid superacid catalyst, the C4 feedstock undergoes an alkylation reaction with isobutane to prepare isooctane.

[0008] According to the above technical solution, the step of separating C4 feedstock and butadiene is carried out in a separation device for continuous separation of C4 feedstock and butadiene. The separation device consists of a water washing tower, a coalescer, a catalytic distillation tower, a top condenser of the catalytic distillation tower, a bottom reboiler of the catalytic distillation tower, and a membrane separation device. The water washing tower is equipped with a two-stage demineralized water treatment to avoid uneven distribution of demineralized water and insufficient gas-liquid mixing, which would lead to methanol and nitrogen compound residues.

[0009] Preferably, in the above technical solution, the preparation method of the La-Ce / ZSM-5 catalyst is as follows: S11. Roast ZSM-5 molecular sieve powder at 500-600℃ for 4-5 hours, then cool and set aside. Weigh lanthanum nitrate and cerium nitrate separately, add them to deionized water to dissolve, adjust the pH of the solution to 5.0-6.0, stir evenly and let stand to obtain an ion exchange solution with a total metal ion concentration of 0.1-0.3 mol / L. S12, the ZSM-5 molecular sieve is added to the ion exchange solution according to a preset solid-liquid ratio, and after multiple ion exchange reactions, the mixture is filtered to obtain a solid product. The solid product is washed with deionized water until no La is found in the filtrate.3+ With Ce 3 + The sample was detected, washed with anhydrous ethanol, and the washed solid was dried to obtain the precursor. S13, the precursor is placed in a muffle furnace and heated to 200-250°C at a rate of 2-5°C / min, and held for 2-3 hours; then heated to 500-550°C at a rate of 5-8°C / min, and held for 4-6 hours; then cooled to 100-200°C and held for 2-3 hours; and finally cooled to obtain the La-Ce / ZSM-5 catalyst.

[0010] Preferably, in the above technical solution, the preset solid-liquid ratio is 1:10.

[0011] Preferably, in the above technical solution, the conditions for the ion exchange reaction are a reaction temperature of 60-80℃, a stirring rate of 200-300 r / min, and a reaction time of 6-8 hours.

[0012] Preferably, in the above technical solution, the La in the ion exchange solution 3+ With Ce 3+ The molar ratio is 1.5-2.0:1.

[0013] Preferably, in the above technical solution, the drying refers to drying at a drying temperature of 80-100℃ for 12-16 hours.

[0014] Preferably, in the above technical solution, the preparation method of the solid superacid catalyst is as follows: Solid superacid S2O8 / ZrO2 powder is calcined in a muffle furnace and cooled for later use; lanthanum nitrate and cerium nitrate are weighed into a beaker, deionized water is added, and the mixture is stirred to dissolve, preparing an impregnation solution; the pH of the impregnation solution is adjusted to 5.0-5.5 with an alkaline solution; then, the S2O8 / ZrO2 powder is weighed into the beaker, magnetically stirred for 5-6 hours, filtered, and washed with deionized water until no NO3 is detected. - The precursor was obtained by drying; the precursor was placed in a muffle furnace for calcination and cooled to obtain a solid superacid catalyst.

[0015] Preferably, in the above technical solution, the calcination is carried out by controlling the heating rate to rise to 500-550℃ at a rate of 3-5℃ / min, and then holding the temperature for 3-4 hours.

[0016] Preferably, in the above technical solution, the La of the solid superacid catalyst 3+ With Ce 3+ The total load is 6-9 wt%.

[0017] Preferably, in the above technical solution, the process of placing the precursor in a muffle furnace for calcination and cooling to obtain a solid superacid catalyst involves introducing N2 and heating the temperature to 500-550°C at a rate of 3-5°C / min, and holding the temperature for 3-4 hours.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) Remove impurities from the C4 raw material, extract the by-product butadiene and the C4 raw material. Using the C4 raw material can extend the service life of the catalyst in the preparation of isooctane, and at the same time prepare a solid superacid catalyst with uniform loading and stable acid sites, thereby improving the C4 conversion rate and isooctane yield. (2) The La-Ce / ZSM-5 catalyst used in catalytic distillation has high efficiency in desulfurization and can effectively remove butadiene, which can significantly reduce the total sulfur content and butadiene content in C4 feedstock; (3) Prepare solid superacid catalysts and optimize reaction conditions to improve the conversion rate of C4 feedstock and the yield of isooctane. Attached Figure Description

[0019] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings.

[0020] Figure 1 This is a schematic diagram of a separation device for continuously separating C4 feedstock and butadiene according to the present invention; Figure 2 This is a graph showing the surface area of ​​S2O8 / ZrO2 in solid superacid S2O8 / ZrO2 powder calcined at different calcination temperatures. Detailed Implementation

[0021] The technical solutions in the embodiments of this invention are clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0022] A separation device for continuously separating C4 feedstock and butadiene, the device as follows: Figure 1 The device shown includes a water washing tower 100, a coalescer 200, a catalytic distillation tower 300, a catalytic distillation tower top condenser 400, a catalytic distillation tower bottom reboiler 500, and several membrane separators 601. The water washing tower 100 is connected to the bottom of the coalescer 200 at the top. The coalescer 200 is connected to the catalytic distillation tower 300. The catalytic distillation tower 300 is connected to the catalytic distillation tower top condenser 400 at the top. The catalytic distillation tower 300 is connected to the catalytic distillation tower bottom reboiler 500 at the bottom. The catalytic distillation tower 300 is connected to the membrane separation device.

[0023] The specific structure of the separation equipment for continuously separating C4 feedstock and butadiene is as follows: The washing tower 100 is configured from top to bottom as follows: a first washing cavity 101, a wire mesh demister 102, a first demineralized water ejector 103, a first packing container 104, a second demineralized water ejector 105, a second packing container 106, a third packing container 107, a second washing cavity 108, and a wastewater outlet. The first packing container 104 and the second packing container 106 are filled with structured packing. During washing, demineralized water is first introduced into the washing tower 100 through the first demineralized water ejector 103 and the second demineralized water ejector 105. Then, C4 feed gas is introduced into the washing tower 100 through the inlet. The C4 feed gas passes through the structured packing of the third packing container 107 and the second packing container 106, and is washed away by the demineralized water to remove methanol and nitrogen compounds. The structured packing of the first packing container 103 and the demineralized water further remove residual methanol and nitrogen compounds, preventing uneven distribution of demineralized water and ensuring that methanol and nitrogen compounds remain in the C4 element. Methanol and nitrogen compounds in the C4 feedstock are fully discharged. The methanol and nitrogen compound wastewater is discharged from the wastewater outlet at the bottom of the water washing tower. The coalescer 200 is equipped with a coalescing packing device 201, a first coalescing cavity 202, and a second coalescing cavity 203. The coalescing packing device 201 is filled with coalescing packing and is located between the first coalescing cavity 202 and the second coalescing cavity 203. The first coalescing cavity 202 is connected to the water washing tower 100 via a connecting pipe, and the second coalescing cavity 203 is connected to the catalytic distillation unit 300 via a connecting pipe. After being treated by the wire mesh demister 101, the washed C4 feedstock enters the first coalescing cavity 202 of the coalescer 200 through the connecting pipe between the water washing tower 100 and the coalescer 200, and then enters the second coalescing cavity 203 through the coalescing packing device 201. The catalytic distillation column 300, from top to bottom, comprises a first distillation cavity 301, a first tray structure 302, a second distillation cavity 303, a catalyst 304, a third distillation cavity 305, a second tray structure 306, and a fourth distillation cavity 307. The C4 feedstock enters the third distillation cavity 305 through the connecting pipe between the second coalescence cavity 203 and the catalytic distillation column 300, passes through the catalyst 304, and then enters the second distillation cavity 303. A membrane separation device consisting of several external membrane separators 601 is used. The sulfur-containing heavy components washed from the catalytic converter enter the fourth rectification cavity 307 through the second tray structure 306. From the outlet of the fourth rectification cavity 307, they enter the bottom reboiler 500 of the catalytic distillation column. After reboiling in the bottom reboiler 500, the sulfur-containing heavy components return to the fourth rectification cavity 307 in gaseous form as C4 feedstock, while the sulfur-containing heavy components are discharged from the bottom reboiler 500. The overhead vapor enters the first rectification cavity 301 through the first tray structure 302, and then enters the top condenser 400 of the catalytic distillation column through the outlet of the first rectification cavity 301. The vapor is condensed into liquid, with part of it flowing back to the first rectification cavity 301 and part of the liquid being discharged.The C4 feedstock enters a membrane separation device consisting of several membrane separators 601 through the second distillation cavity 303. The membrane material on the membrane separator is a polyZIF membrane, which has excellent C4H6 permeation selectivity. Using it as the separator membrane avoids poor separation effect. Multiple membrane separators are connected in parallel to avoid the need to shut down the entire line when replacing the membranes of some membrane separators. At the same time, the parallel connection of multiple separators increases the separation rate and accelerates the separation speed of C4 feedstock and butadiene. Example 1

[0024] The specific preparation method of the catalytic distillation catalyst is as follows: S11, ZSM-5 molecular sieve powder was placed in a muffle furnace, and the temperature was raised to 550℃ at a rate of 5℃ / min. It was then calcined at 550℃ for 4 hours and allowed to cool naturally to room temperature before use. Certain amounts of lanthanum nitrate and cerium nitrate were weighed and dissolved in deionized water to prepare an ion exchange solution with a total metal ion concentration of 0.3 mol / L. Among these, La... 3+ With Ce 3+ The molar ratio is 1.5:1. The pH of the solution is adjusted to 5.5 with ammonia water, stirred evenly, and then left to stand for 30 minutes. S12, the pretreated ZSM-5 molecular sieve was added to the above ion exchange solution at a solid-liquid ratio of 1:10 (g / mL), and placed in a constant temperature water bath at a controlled reaction temperature of 80℃, a stirring rate of 250 r / min, and a reaction time of 6 hours. The solid was then separated by filtration. The solid was added to the above ion exchange solution at a solid-liquid ratio of 1:10 (g / mL), and placed in a constant temperature water bath at a controlled reaction temperature of 55℃, a stirring rate of 100 r / min, and a reaction time of 8 hours. The solid was then separated by filtration, and the solid product was repeatedly washed with deionized water until no La was found in the filtrate. 3+ With Ce 3+ The sample was detected, and then washed with anhydrous ethanol. The washed solid was placed in a vacuum drying oven and dried at 80°C for 12 hours to obtain the precursor. S13, the precursor is placed in a muffle furnace and heated to 200°C at a rate of 2°C / min, and held for 2 hours; then heated to 500°C at a rate of 8°C / min, and held for 4 hours; cooled to 200°C and held for 2 hours; and naturally cooled to room temperature to obtain La-Ce / ZSM-5 catalyst 1.

[0025] Comparative Example 1 The specific preparation method of the catalytic distillation catalyst is as follows: S11, ZSM-5 molecular sieve powder was placed in a muffle furnace, and the temperature was raised to 550℃ at a rate of 5℃ / min. It was then calcined at 550℃ for 4 hours and allowed to cool naturally to room temperature before use. Certain amounts of lanthanum nitrate and cerium nitrate were weighed and dissolved in deionized water to prepare an ion exchange solution with a total metal ion concentration of 0.3 mol / L. Among these, La... 3+ With Ce 3+ The molar ratio is 1.5:1. The pH of the solution is adjusted to 5.0-6.0 with ammonia water, stirred evenly, and then allowed to stand for 30 minutes. S12, the pretreated ZSM-5 molecular sieve was added to the above ion exchange solution at a solid-liquid ratio of 1:20 (g / mL), and the mixture was placed in a constant temperature water bath with the reaction temperature controlled at 65℃, the stirring rate at 250 r / min, and the reaction time at 6 hours. The solid was separated by filtration, and the solid product was repeatedly washed with deionized water until no La was found in the filtrate. 3+ With Ce 3+ The sample was detected, and then washed with anhydrous ethanol. The washed solid was placed in a vacuum drying oven and dried at 80°C for 12 hours to obtain the precursor. S13, the precursor is placed in a muffle furnace and heated to 200°C at a rate of 6°C / min, and held for 2 hours; then heated to 500°C at a rate of 15°C / min, and held for 4 hours; cooled to 200°C and held for 2 hours; and naturally cooled to room temperature to obtain La-Ce / ZSM-5 catalyst 2.

[0026] Comparative Example 2 The specific preparation method of the catalytic distillation catalyst is as follows: S11, ZSM-5 molecular sieve powder was placed in a muffle furnace, and the temperature was raised to 550℃ at a rate of 5℃ / min. It was then calcined at 550℃ for 4 hours and allowed to cool naturally to room temperature before use. Certain amounts of copper nitrate and cerium nitrate were weighed and dissolved in deionized water to prepare an ion exchange solution with a total metal ion concentration of 0.3 mol / L. Among these, Cu... 2+ With Ce 3+ The molar ratio is 1:1. The pH of the solution is adjusted to 5.5 with ammonia. After stirring evenly, the solution is allowed to stand for 30 minutes. S12, the pretreated ZSM-5 molecular sieve was added to the above ion exchange solution at a solid-liquid ratio of 1:20 (g / mL), and the mixture was placed in a constant temperature water bath with the reaction temperature controlled at 65℃, the stirring rate at 300 r / min, and the reaction time at 8 hours. The solid was separated by filtration, and the solid product was repeatedly washed with deionized water until no Cu was found in the filtrate. 2+ With Ce 3+ The sample was detected, and then washed with anhydrous ethanol. The washed solid was placed in a vacuum drying oven and dried at 100°C for 16 hours to obtain the precursor. S13, the precursor is placed in a muffle furnace and heated to 200°C at a rate of 2°C / min, and held for 2 hours; then heated to 500°C at a rate of 8°C / min, and held for 4 hours; and then naturally cooled to room temperature to obtain Cu-Ce / ZSM-5 catalyst 3.

[0027] Comparative Example 3 The specific preparation method of the catalytic distillation catalyst is as follows: S11, ZSM-5 molecular sieve powder was placed in a muffle furnace, and the temperature was raised to 550℃ at a rate of 5℃ / min. It was then calcined at 550℃ for 4 hours and allowed to cool naturally to room temperature before use. Certain amounts of copper nitrate and nickel nitrate were weighed and dissolved in deionized water to prepare an ion exchange solution with a total metal ion concentration of 0.3 mol / L. Among these, Cu... 2+ with Ni 2+ The molar ratio is 1:1. The pH of the solution is adjusted to 5.0-6.0 with ammonia water. After stirring evenly, it is allowed to stand for 30 minutes. S12, the pretreated ZSM-5 molecular sieve was added to the above ion exchange solution at a solid-liquid ratio of 1:10 (g / mL), and placed in a constant temperature water bath at a controlled temperature of 65℃, a stirring rate of 250 r / min, and a reaction time of 6 hours. The solid was then separated by filtration. The solid was added back to the above ion exchange solution at a solid-liquid ratio of 1:10 (g / mL), and placed in a constant temperature water bath at a controlled temperature of 50℃, a stirring rate of 100 r / min, and a reaction time of 8 hours. The solid was then separated by filtration, and the solid product was repeatedly washed with deionized water until no Cu was found in the filtrate. 2+ with Ni 2+ The sample was detected, and then washed with anhydrous ethanol. The washed solid was placed in a vacuum drying oven and dried at 100°C for 16 hours to obtain the precursor. S13, the precursor is placed in a muffle furnace and heated to 200°C at a rate of 2°C / min, and held for 2 hours; then heated to 500°C at a rate of 8°C / min, and held for 4 hours; cooled to 200°C and held for 2 hours; and naturally cooled to room temperature to obtain Cu-Ni / ZSM-5 catalyst 4.

[0028] The catalysts prepared in Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3 and the ZSM-5 catalyst were used as catalysts in the catalyst of the catalytic distillation column. The same catalytic distillation parameters as the catalytic distillation column were set, and the contents of sulfur and butadiene in the C4 feedstock after distillation were detected.

[0029] Table 1. Total sulfur content and butadiene content of different catalysts packed into the catalytic distillation column. Total sulfur content / ppm Butadiene content / ppm C4 feedstock before distillation 73 5073 ZSM-5 catalyst 26 4134 La-Ce / ZSM-5 catalyst 1 0.1 2651 La-Ce / ZSM-5 catalyst 2 0.8 2977 Cu-Ce / ZSM-5 catalyst 3 0.6 3482 Cu-Ni / ZSM-5 catalyst 4 3.4 3908 As can be seen from Table 1, the type of catalyst in the catalytic distillation column catalyst affects the removal of sulfur-containing substances and butadiene content in the C4 feedstock, while the modification and preparation method of the catalyst also affect the catalytic distillation of the C4 feedstock to a certain extent.

[0030] Figure 2 The calcination method is as follows: solid superacid S2O8 / ZrO2 powder is placed in a muffle furnace, and the heating rate is controlled at 3℃ / min. After heating to 350℃, 400℃, 450℃, 500℃, 550℃, 600℃, 650℃ and 700℃, the temperature is held for calcination for 4 hours.

[0031] from Figure 2 It can be seen that before the calcination temperature is 500℃, the surface area of ​​S2O8 / ZrO2 increases with the increase of calcination temperature. Between 500-550℃, the surface area of ​​S2O8 / ZrO2 tends to be in equilibrium. After 550℃, the surface area of ​​S2O8 / ZrO2 shows a decreasing trend. Example 2

[0032] A catalytic distillation method for removing impurities from isooctane reaction feedstock, the method comprising: S1, Separating C4 feedstock and butadiene: The C4 feedstock is pumped into the second washing cavity 108 of the washing tower 100 at a rate of 100 L / h. After passing through the first packer 104, the second packer 106, the third packer 107, and the wire mesh demister 102, it enters the second washing cavity 108 to obtain washed C4 feedstock. The washed C4 feedstock enters the coalescing tank 200 and is then packed with coalescing materials to obtain dehydrated C4 feedstock. The dehydrated C4 feedstock is then fed into the catalytic distillation tower 300. The catalyst filled in the catalytic tower 304 is the La-Ce / ZSM-5 catalyst prepared in Example 1. After catalytic distillation, the distilled C4 feedstock is obtained. The distilled C4 feedstock enters the membrane separator to obtain C4 feedstock and butadiene. S2, Preparation of Isooctene from C4 Raw Materials: The above-mentioned C4 raw materials are pumped into an alkylation reactor. Under the action of a solid superacid catalyst, the C4 raw materials and isobutane undergo an alkylation reaction to prepare isooctane. The preparation method of the solid superacid catalyst is as follows: Solid superacid S2O8 / ZrO2 powder is placed in a muffle furnace, and the heating rate is controlled at 3℃ / min to 500℃. After holding at this temperature for 4 hours, it is naturally cooled to room temperature for later use. 20g of lanthanum nitrate and 20g of cerium nitrate are weighed into a beaker and 1000mL of deionized water is added. The mixture is stirred and dissolved to prepare an impregnation solution. The pH of the impregnation solution is adjusted to 5.5 with dilute ammonia water. Then, 100g of S2O8 / ZrO2 is weighed into the beaker, magnetically stirred for 6 hours, filtered, and washed with deionized water until no NO3 is found. -The precursor was dried overnight at 110°C in a vacuum drying oven to obtain a precursor. The precursor was then placed in a muffle furnace, and N2 was introduced to raise the temperature to 500°C at a rate of 5°C / min. The temperature was maintained for 3.5 hours, and then cooled to obtain a solid superacid catalyst. The La content of the solid superacid catalyst was... 3+ With Ce 3+ The total load is 7.8 wt%. Example 3

[0033] A catalytic distillation method for removing impurities from isooctane reaction feedstock, the method comprising: S1, Separating C4 feedstock and butadiene: The C4 feedstock is pumped into the second washing cavity 108 of the washing tower 100 at a rate of 100 L / h. After passing through the first packer 104, the second packer 106, the third packer 107, and the wire mesh demister 102, it enters the second washing cavity 108 to obtain washed C4 feedstock. The washed C4 feedstock enters the coalescing tank 200 and is then packed with coalescing materials to obtain dehydrated C4 feedstock. The dehydrated C4 feedstock is then fed into the catalytic distillation tower 300. The catalyst filled in the catalytic tower 304 is the La-Ce / ZSM-5 catalyst prepared in Example 1. After catalytic distillation, the distilled C4 feedstock is obtained. The distilled C4 feedstock enters the membrane separator to obtain C4 feedstock and butadiene. S2, Preparation of Isooctene from C4 Raw Materials: The above-mentioned C4 raw materials are pumped into a reactor, and then into an alkylation reactor. Under the action of a solid superacid catalyst, the C4 raw materials react with isobutane to produce isooctane. The preparation method of the solid superacid catalyst is as follows: Solid superacid S2O8 / ZrO2 powder is placed in a muffle furnace, and the heating rate is controlled at 3℃ / min to 500℃. It is then calcined at this temperature for 4 hours and allowed to cool naturally to room temperature for later use. 22.5g of lanthanum nitrate and 22.5g of cerium nitrate are weighed into a beaker and 1000mL of deionized water is added. The mixture is stirred and dissolved to prepare an impregnation solution. The pH of the impregnation solution is adjusted to 5.5 with dilute ammonia. Then, 100g of S2O8 / ZrO2 is weighed into the beaker, magnetically stirred for 6 hours, filtered, and washed with deionized water until no NO3 is found. - The precursor was dried overnight in a vacuum drying oven at 110°C to obtain a precursor. The precursor was then placed in a muffle furnace, and N2 was introduced to raise the temperature to 500°C at a rate of 3°C / min. The temperature was maintained for 4 hours, and the precursor was cooled to obtain a solid superacid catalyst. The La content of the solid superacid catalyst was... 3+ With Ce 3+ The total load is 8.2 wt%.

[0034] Comparative Example 4 A catalytic distillation method for removing impurities from isooctane reaction feedstock, the method comprising: S1, Preparation of Isooctene from C4 Raw Materials: C4 raw materials are directly pumped into an alkylation reactor. Under the action of a solid superacid catalyst, the C4 raw materials react with isobutane to produce isooctene. The preparation method of the solid superacid catalyst is as follows: Solid superacid S2O8 / ZrO2 powder is placed in a muffle furnace, and the heating rate is controlled at 3℃ / min to 500℃. After holding at this temperature for 4 hours, it is naturally cooled to room temperature for later use. 20g of lanthanum nitrate and 20g of cerium nitrate are weighed into a beaker and 1000mL of deionized water is added. The mixture is stirred and dissolved to prepare an impregnation solution. The pH of the impregnation solution is adjusted to 5.5 with dilute ammonia. Then, 100g of S2O8 / ZrO2 is weighed into the beaker, magnetically stirred for 6 hours, filtered, and washed with deionized water until no NO3 is found. - The precursor was dried overnight in a vacuum drying oven at 110°C to obtain a precursor. The precursor was then placed in a muffle furnace, and N2 was introduced to raise the temperature to 500°C at a rate of 5°C / min. The temperature was maintained for 4 hours, and the precursor was cooled to obtain a solid superacid catalyst. The La content of the solid superacid catalyst was... 3+ With Ce 3+ The total load is 7.8 wt%.

[0035] Comparative Example 5 A catalytic distillation method for removing impurities from isooctane reaction feedstock, the method comprising: S1, Separating C4 feedstock and butadiene: The C4 feedstock is pumped into the bottom of a water washing tower. The water washing tower has a traditional structure, consisting of a first water washing cavity, a wire mesh demister, a demineralized water ejector, a first packing device, a second packing device, a third packing device, a second water washing cavity, and a wastewater outlet from top to bottom. The first, second, and third packing devices are arranged longitudinally along the water washing tower to obtain washed C4 feedstock. The washed C4 feedstock enters a coalescing tank 200 and is then coalesced to obtain dehydrated C4 feedstock. The dehydrated C4 feedstock is then fed into a catalytic distillation tower 300. The catalysts filled in the catalytic tank 304 are ZnO and Al2O3. After catalytic distillation, distilled C4 feedstock is obtained. The distilled C4 feedstock enters a membrane separator to obtain C4 feedstock and butadiene. S2, Preparation of Isooctene from C4 Raw Materials: The above-mentioned C4 raw materials are pumped into an alkylation reactor. Under the action of a solid superacid catalyst, the C4 raw materials and isobutane undergo an alkylation reaction to prepare isooctane. The preparation method of the solid superacid catalyst is as follows: Solid superacid S2O8 / ZrO2 powder is placed in a muffle furnace, and the heating rate is controlled at 3℃ / min to 500℃. After holding at this temperature for 4 hours, it is naturally cooled to room temperature for later use. 20g of lanthanum nitrate and 20g of cerium nitrate are weighed into a beaker and 1000mL of deionized water is added. The mixture is stirred and dissolved to prepare an impregnation solution. The pH of the impregnation solution is adjusted to 5.5 with dilute ammonia water. Then, 100g of S2O8 / ZrO2 is weighed into the beaker, magnetically stirred for 6 hours, filtered, and washed with deionized water until no NO3 is found.- The precursor was dried overnight in a vacuum drying oven at 110°C to obtain a precursor. The precursor was then placed in a muffle furnace, and N2 was introduced to raise the temperature to 500°C at a rate of 5°C / min. The temperature was maintained for 4 hours, and the precursor was cooled to obtain a solid superacid catalyst. The La content of the solid superacid catalyst was... 3+ With Ce 3+ The total load is 7.6 wt%.

[0036] The service life of the solid superacid catalysts of Examples 2, 3, 4 and 5 are shown in Table 1.

[0037] Table 2 Service life of solid superacid catalysts solid superacid catalyst lifespan / d Example 2 117 Example 3 115 Comparative Example 4 11 Comparative Example 5 58 As can be seen from Table 2 above, the service life of the catalyst in Comparative Example 5 is much longer than that of the catalyst in Comparative Example 4, while the catalysts in Examples 2 and 3 have the longest service life. This indicates that the degree of removal of impurities such as butadiene, sulfur, moisture, and methanol in the C4 feedstock significantly affects the service life of the catalyst.

[0038] Table 3. Impurities in C4 feedstock butadiene / ppm Total sulfur / ppm Moisture / ppm Methanol / ppm Example 2 1.3 0.1 0.05 0.3 Example 3 1.5 0.2 0.08 0.6 Comparative Example 4 5073 73 3.81 123 Comparative Example 5 63 41 0.07 29 As can be seen from Table 3 above, the structure of the water washing tower affects the methanol removal. The catalysts used in the catalytic distillation tower, ZnO and Al2O3, are relatively less effective at removing impurities from C4 feedstock. The C4 feedstock in Comparative Example 5 still contains a lot of methanol, butadiene and total sulfur residue.

[0039] Comparative Example 6 It is basically the same as Example 2, except that step 2 is different.

[0040] S2, Preparation of isooctene from C4 feedstock: The C4 feedstock treated as in step S1 of Example 2 is pumped into an alkylation reactor. Under the action of a solid superacid catalyst, the C4 feedstock and isobutane undergo an alkylation reaction to prepare isooctane. The solid superacid catalyst is a single-component S2O8 / ZrO2 catalyst.

[0041] Comparative Example 7 It is basically the same as Example 2, except that step 2 is different.

[0042] S2, Preparation of Isooctene from C4 Raw Material: The C4 raw material treated as in step S1 of Example 2 is pumped into an alkylation reactor. Under the action of a solid superacid catalyst, the C4 raw material reacts with isobutane to produce isooctane. The preparation method of the solid superacid catalyst is as follows: Solid superacid S2O8 / ZrO2 powder is placed in a muffle furnace, and the heating rate is controlled at 3℃ / min to 500℃. After holding at this temperature for 4 hours, it is naturally cooled to room temperature for later use. 40g of nickel hexanitrate is weighed into a beaker and 1000mL of deionized water is added. The mixture is stirred and dissolved to prepare an impregnation solution. The pH of the impregnation solution is adjusted to 5.5 with dilute ammonia. Then, 100g of S2O8 / ZrO2 is weighed into the beaker, magnetically stirred for 6 hours, filtered, and washed with deionized water until no NO3 is found. - The precursor was dried overnight at 110°C in a vacuum drying oven to obtain a precursor. The precursor was then placed in a muffle furnace and heated to 500°C at a rate of 5°C / min, held at that temperature for 4 hours, and cooled to obtain a solid superacid catalyst. The Ni content of the solid superacid catalyst... 2+ The total load is 8.1 wt%.

[0043] The conversion rate of C4 feedstock and the yield of isooctane were tested after the reaction, and the results are shown in Table 4 below.

[0044] Table 4. Conversion rates of C4 feedstock and isooctene. C4 feed conversion rate (%) Isooctane yield (%) Example 2 98.1 94.2 Example 3 98.7 94.5 Comparative Example 4 90.4 88.6 Comparative Example 5 95.3 92.8 Comparative Example 6 89.1 86.7 Comparative Example 7 92.8 90.9 This invention can be implemented in various ways and is not limited to the embodiments described. Those skilled in the art will understand that the invention can be implemented in other specific ways without changing the technical concept or essential features. Therefore, it should be understood that the embodiments described above are exemplary and not intended to limit the invention.

Claims

1. A catalytic distillation method for removing impurities from isooctane reaction feedstock, characterized in that, include: S1, Separating C4 feedstock and butadiene: The C4 feedstock is treated with demineralized water to obtain washed C4 feedstock; The washed C4 feedstock is subjected to coalescence and dehydration treatment to obtain dehydrated C4 feedstock; the dehydrated C4 feedstock is subjected to catalytic distillation treatment to obtain distilled C4 feedstock, wherein the catalyst for the catalytic distillation treatment is a La-Ce / ZSM-5 catalyst; the distilled C4 feedstock is subjected to membrane separation to obtain C4 feedstock and butadiene. S2, Preparation of isooctene from C4 feedstock: The above-mentioned C4 feedstock is pumped into an alkylation reactor, and under the action of a solid superacid catalyst, the C4 feedstock undergoes an alkylation reaction with isobutane to prepare isooctane.

2. The catalytic distillation method for removing impurities from isooctane reaction feedstock as described in claim 1, characterized in that, The La-Ce / ZSM-5 catalyst is prepared as follows: S11. Roast ZSM-5 molecular sieve powder at 500-600℃ for 4-5 hours, then cool and set aside. Weigh lanthanum nitrate and cerium nitrate separately, add them to deionized water to dissolve, adjust the pH of the solution to 5.0-6.0, stir evenly and let stand to obtain an ion exchange solution with a total metal ion concentration of 0.1-0.3 mol / L. S12, the ZSM-5 molecular sieve is added to the ion exchange solution according to a preset solid-liquid ratio, and after multiple ion exchange reactions, the mixture is filtered to obtain a solid product. The solid product is washed with deionized water until no La is found in the filtrate. 3+ With Ce 3+ The sample was detected, washed with anhydrous ethanol, and the washed solid was dried to obtain the precursor. S13, the precursor is placed in a muffle furnace and heated to 200-250°C at a rate of 2-5°C / min, and held for 2-3 hours; then heated to 500-550°C at a rate of 5-8°C / min, and held for 4-6 hours; then cooled to 100-200°C and held for 2-3 hours; and finally cooled to obtain the La-Ce / ZSM-5 catalyst.

3. The catalytic distillation method for removing impurities from isooctane reaction feedstock as described in claim 2, characterized in that, The preset solid-liquid ratio is 1:

10.

4. The catalytic distillation method for removing impurities from isooctane reaction feedstock as described in claim 2, characterized in that, The conditions for the ion exchange reaction are a reaction temperature of 60-80℃, a stirring rate of 200-300 r / min, and a reaction time of 6-8 hours.

5. The catalytic distillation method for removing impurities from isooctane reaction feedstock as described in claim 2, characterized in that, La in ion exchange solution 3+ With Ce 3+ The molar ratio is 1.5-2.0:

1.

6. The catalytic distillation method for removing impurities from isooctane reaction feedstock as described in claim 2, characterized in that, The drying process refers to drying at a temperature of 80-100℃ for 12-16 hours.

7. The catalytic distillation method for removing impurities from isooctane reaction feedstock as described in claim 1, characterized in that, The preparation method of the solid superacid catalyst is as follows: Solid superacid S2O8 / ZrO2 powder is calcined in a muffle furnace and cooled for later use; lanthanum nitrate and cerium nitrate are weighed into a beaker, deionized water is added, and the mixture is stirred to dissolve, thus preparing an impregnation solution. The pH of the impregnation solution is adjusted to 5.0-5.5 with an alkaline solution. Then, the S2O8 / ZrO2 powder is weighed into the beaker, magnetically stirred for 5-6 hours, filtered, and washed with deionized water until no NO3 is detected. - The precursor was obtained by drying; the precursor was placed in a muffle furnace for calcination and cooled to obtain a solid superacid catalyst.

8. The catalytic distillation method for removing impurities from isooctane reaction feedstock as described in claim 7, characterized in that, The roasting process involves heating at a rate of 3-5℃ / min to 500-550℃, followed by holding at that temperature for 3-4 hours.

9. The catalytic distillation method for removing impurities from isooctane reaction feedstock as described in claim 7, characterized in that, The La in the solid superacid catalyst 3+ With Ce 3+ The total load is 6-9 wt%.

10. The catalytic distillation method for removing impurities from isooctane reaction feedstock as described in claim 7, characterized in that, The precursor is placed in a muffle furnace for calcination and then cooled to obtain a solid superacid catalyst. The calcination is carried out by introducing N2 and heating at a rate of 3-5℃ / min to 500-550℃, and holding at that temperature for 3-4 hours.

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