A method for preparing surfactants by gas-liquid two-phase membrane reaction based on tail gas recirculation

Abstract

The present invention provides a method for preparing surfactants by gas-liquid two-phase membrane reaction based on tail gas recycling, belonging to the technical field of fine chemical engineering. By increasing the dosage of sulfur and reducing the dosage of dry air, the present invention reduces the waste gas emissions at the source and also reduces the power consumption required for treating dry air. The present invention uses the initially formed dry tail gas for dilution, which can dilute the mixed gas with a high gas concentration to meet the gas concentration requirements for the sulfonation reaction with liquid-phase organic substances. Therefore, dry tail gas can be continuously generated through gas-liquid separation, and a part of the generated dry tail gas is used as the recycled tail gas to dilute the mixed gas, so that the concentration of the mixed gas reaches the gas concentration required for the sulfonation reaction, and the emissions of waste gas and waste liquid can also be reduced. In addition, the method provided by the present invention can be used for the transformation of old equipment, and only a tail gas recycling device needs to be added in the existing process, greatly reducing the cost of equipment transformation.

Description

Technical Field

[0001] The present invention relates to the field of fine chemical technology, and particularly relates to a method for preparing a gas-liquid two-phase membrane reaction surfactant based on tail gas recycling. Background Art

[0002] Surfactants are classified into anionic surfactants, cationic surfactants, nonionic surfactants and amphoteric surfactants, and are used as the main components of washing liquids.

[0003] Currently, the SO3 film sulfonation method is usually used to prepare surfactants. Using gaseous substances (such as SO3) and organic substances forming a liquid film (such as LAB, AEO2, etc.), a chemical reaction occurs at the gas-liquid two-phase interface to generate organic sulfonic acid or organic sulfate ester. Specifically: air is compressed, cooled and dehumidified by freezing, and dried by silica gel adsorption to generate dry air; sulfur is burned in dry air to generate SO2, and SO2 is converted into SO3 under the action of a catalyst, and after cooling, SO3 gas is defogged to remove fuming sulfuric acid to obtain SO3 gas with a certain gas concentration; the SO3 gas is subjected to a sulfonation reaction with the liquid-phase organic substance, the obtained product is separated into gas and liquid, the obtained liquid-phase product is post-treated to obtain a surfactant product, the obtained gas-phase product is defogged by static electricity to obtain dry tail gas, and the dry tail gas is discharged after alkali washing treatment. In this method, since the SO3 gas concentration required for producing different surfactants is different. For example, a 5mol% SO3 gas concentration is only suitable for the gas-liquid two-phase membrane reaction of alkylbenzenes, such as the commonly used linear alkylbenzene (LAB, molecular weight 240); while the gas-liquid two-phase membrane reaction of fatty alcohol polyoxyethylene ethers requires a 3mol% SO3 gas concentration, such as the commonly used AEO2 (molecular weight 285). Therefore, it is necessary to adjust the amounts of sulfur and dry air according to different products to obtain a suitable SO3 gas concentration. To obtain a lower SO3 gas concentration, the commonly used methods at present include: one is to increase the air feed amount, and the other is to reduce the sulfur feed amount. Both of these methods will increase the amount of air required per unit product. Since dry air is used for sulfur burning and conversion, air needs to be dehumidified by compression refrigeration and silica gel adsorption drying to obtain dry air, which requires the consumption of electric energy to complete. Therefore, when increasing the amount of air required per unit product, it is bound to result in a higher power consumption. And when increasing the amount of air required per unit product, it will also lead to a larger tail gas emission, and thus lead to a larger amount of liquid caustic used for treating the tail gas and a high wastewater emission.

[0004] To solve the above problems, researchers in this field can change the equipment or process route, etc., to solve the problems of high wastewater and waste gas emissions and high power consumption caused by a large amount of air used, but the improvement of equipment and process will require a large amount of capital investment and increase the production cost. Summary of the Invention

[0005] The object of the present invention is to provide a method for preparing surfactants by gas-liquid two-phase membrane reaction based on tail gas recycling, which has less wastewater and waste gas emissions, low power consumption, and can reduce the equipment transformation cost.

[0006] In order to achieve the above object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing surfactants by gas-liquid two-phase membrane reaction based on tail gas recycling, comprising the following steps:

[0008] (1) Sulfur is successively subjected to sulfur combustion and conversion in dry air to obtain a product gas with a SO3 gas concentration of 2-7 mol%; after the product gas is subjected to a sulfonation reaction with a liquid-phase organic substance, gas-liquid separation is carried out to obtain an initial dry tail gas;

[0009] (2) Sulfur is successively subjected to sulfur combustion and conversion in dry air to obtain a mixed gas; the mass ratio of the sulfur to the dry air is 1:(8-16), and the SO3 gas concentration in the mixed gas is 4-14 mol%;

[0010] (3) The mixed gas obtained in step (2) is diluted with a dilution gas to obtain a diluted mixed gas, and the SO3 gas concentration in the diluted mixed gas is 2-7 mol%; the dilution gas is the initial dry tail gas and / or recycled dry tail gas obtained in step (1);

[0011] (4) The diluted mixed gas obtained in step (3) is mixed with a liquid-phase organic substance in a gas-liquid two-phase membrane reactor for a sulfonation reaction to obtain a liquid-phase reaction product and a tail gas;

[0012] (5) The liquid-phase reaction product obtained in step (4) is post-treated to obtain a surfactant product;

[0013] (6) The tail gas obtained in step (4) is subjected to electrostatic demisting to obtain a dry tail gas; part of

[0014] the dry tail gas is used as the recycled dry tail gas to dilute the mixed gas in step (2); the remaining part of the dry tail gas is treated by alkali washing to obtain a qualified waste gas and a qualified waste liquid;

[0015] There is no time sequence between step (5) and step (6).

[0016] Preferably, the mass ratio of sulfur to dry air in step (1) is 1:(16-32).

[0017] Preferably, the humidity of the dry air in steps (1) and (2) is independently 2-11 g / m 3 .

[0018] Preferably, the method for preparing the dry air includes: sequentially compressing, freezing, and adsorbing and drying the air with silica gel to obtain dry air.

[0019] Preferably, the SO3 gas concentration of the initial dry tail gas in the step (1) and the recycled dry tail gas in the step (3) is independently 0.03-0.07 mol%.

[0020] Preferably, the SO3 gas concentration in the diluted mixed gas in the step (3) is 2.5-3 mol% or 5-6 mol%.

[0021] Preferably, the liquid-phase organic matter in the step (4) is selected from sulfonatable substances of alkylbenzenes, fatty alcohol polyoxyethylene ethers, α-olefins, fatty alcohols, fatty acid methyl esters, or animal and vegetable oils.

[0022] Preferably, the solvent used for the alkali washing treatment in the step (6) is a sodium hydroxide solution.

[0023] Preferably, the mass concentration of the sodium hydroxide solution is 32-40%.

[0024] Preferably, the pH value of the solution after the alkali washing treatment in the step (6) is 7.5-8.5 to obtain qualified waste liquid.

[0025] The present invention provides a method for preparing a surfactant by a gas-liquid two-phase membrane reaction based on tail gas recycling. First, sulfur and dry air are used to obtain a product gas with an SO3 gas concentration of 2-7 mol% through sulfur combustion and conversion. This gas concentration can meet the gas concentration required for the sulfonation reaction of the product gas and the liquid-phase organic matter, and thus dry tail gas can be obtained through sulfonation reaction and gas-liquid separation, providing the original dilution gas for the diluted mixed gas; after obtaining the dry tail gas, by limiting the mass ratio of sulfur to dry air, a mixed gas with an SO3 gas concentration of 4-14 mol% is obtained. This step can significantly increase the amount of sulfur used and reduce the amount of dry air used, which can reduce the waste gas emissions at the source on the one hand and reduce the power consumption required for treating dry air on the other hand; the present invention uses the initially formed dry tail gas for dilution, enabling the higher gas concentration mixed gas to meet the requirements for the sulfonation reaction with the liquid-phase organic matter. Therefore, dry tail gas can be continuously generated through gas-liquid separation, and part of the generated dry tail gas is used as recycled tail gas to dilute the mixed gas. This can make the concentration of the mixed gas reach the concentration required for the sulfonation reaction on the one hand and reduce the generation of waste gas and the emissions of waste gas and waste liquid on the other hand.

[0026] In addition, the method provided by the present invention only adds the process of tail gas recycling. Therefore, when it is used for the transformation of old equipment, only a tail gas recycling device needs to be added, which greatly reduces the cost of equipment transformation. The results of the examples show that when producing LABSA with a SO3 gas concentration of 5 mol%, the ratio of dry air to production decreases from 20 times to about 10 times, and the ratio of dry tail gas treatment to production decreases from 18.5 times to 9.25 times; when producing AE2S with a SO3 gas concentration of 3 mol%, the ratio of dry air to production decreases from 33 times to 16.5 times; the ratio of dry tail gas treatment to production decreases from 30.6 times to 15.3 times. Therefore, the method provided by the present invention halves the amount of dry air and dry tail gas treatment per unit output, and has the advantages of reducing the power consumption of the device, reducing emissions, doubling the output, halving the unit consumption of liquid caustic soda, and halving the emissions of fuming sulfuric acid and black acid. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a process flow diagram of the preparation of surfactants by gas-liquid two-phase membrane reaction based on tail gas recycling according to the present invention;

[0028] Figure 2 is a process flow diagram of the preparation of surfactants by gas-liquid two-phase membrane reaction in the prior art. DETAILED DESCRIPTION OF THE INVENTION

[0029] The present invention provides a method for preparing surfactants by gas-liquid two-phase membrane reaction based on tail gas recycling, comprising the following steps:

[0030] (1) Sulfur is successively subjected to sulfur combustion and conversion in dry air to obtain a product gas with a SO3 gas concentration of 2-7 mol%; after the product gas is subjected to sulfonation reaction with a liquid-phase organic substance, gas-liquid separation is carried out to obtain an initial dry tail gas;

[0031] (2) Sulfur is successively subjected to sulfur combustion and conversion in dry air to obtain a mixed gas; the mass ratio of the sulfur to the dry air is 1:(8-16), and the SO3 gas concentration in the mixed gas is 4-14 mol%;

[0032] (3) The mixed gas obtained in step (2) is diluted with a dilution gas to obtain a diluted mixed gas, and the SO3 gas concentration in the diluted mixed gas is 2-7 mol%; the dilution gas is the initial dry tail gas and / or recycled dry tail gas obtained in step (1);

[0033] (4) The diluted mixed gas obtained in step (3) is mixed with a liquid-phase organic substance in a gas-liquid two-phase membrane reactor for sulfonation reaction to obtain a liquid-phase reaction product and a tail gas;

[0034] (5) The liquid-phase reaction product obtained in step (4) is post-treated to obtain a surfactant product;

[0035] (6) After subjecting the tail gas obtained in the step (4) to electrostatic demisting, dry tail gas is obtained; part of the dry tail gas is used as recycled dry tail gas to dilute the mixed gas in the step (2); the remaining part of the dry tail gas is treated by alkali washing to obtain up-to-standard waste gas and up-to-standard waste liquid.

[0036] In the present invention, sulfur is successively subjected to sulfur combustion and conversion in dry air to obtain a product gas with a SO3 gas concentration of 2-7 mol%; after the product gas is subjected to a sulfonation reaction with a liquid-phase organic substance and then gas-liquid separation, initial dry tail gas is obtained.

[0037] In the present invention, the humidity of the dry air is preferably 2-11 g / m 3 (20 °C), more preferably 2.585-10.68 g / m 3 (20 °C). When the humidity of the dry air is controlled within the above range in the present invention, it is more beneficial to sulfur combustion and conversion, and there are fewer side reactions.

[0038] In the present invention, the preparation method of the dry air preferably includes: successively compressing, freezing and drying the air with silica gel adsorption to obtain dry air. The present invention has no special limitation on the devices for compression, freezing and drying, and conventional devices for compression, freezing and silica gel adsorption drying can be used. In the present invention, the device for compression and freezing is preferably a lithium bromide unit or an electric ice machine cooling unit, and the silica gel adsorption drying is preferably renewable silica gel adsorption drying; the temperature of the compression and freezing is preferably 0-10 °C, more preferably 0-5 °C. In the present invention, most of the moisture in the air is condensed by compressing and freezing the air, and then the moisture is adsorbed by renewable silica gel adsorption drying to achieve the purpose of air drying.

[0039] In the present invention, the mass ratio of the sulfur to the dry air is preferably 1:(16-32). By controlling the mass ratio of the sulfur to the dry tail gas within the above range in the present invention, the SO3 gas concentration of the obtained product gas can be 2-7 mol%. In the present invention, when the mass ratio of the sulfur to the dry air is preferably 1:(16-20), the SO3 gas concentration of the product gas is preferably 5-6 mol%; when the mass ratio of the sulfur to the dry air is preferably 1:(28-32), the SO3 gas concentration of the product gas is preferably 2.5-3 mol%.

[0040] In the present invention, SO2 is generated by burning sulfur, and the SO2 is converted to SO3. There are no special limitations on the devices for sulfur burning and conversion in the present invention, and conventional devices for sulfur burning and conversion can be used. In the present invention, the device for sulfur burning is preferably a sulfur burner; the device for conversion is preferably a conversion tower. There are no special limitations on the parameters for sulfur burning and conversion in the present invention, and conventional parameters for sulfur burning and conversion can be used. In the present invention, the temperature for conversion is preferably 440 - 450 °C, and the catalyst for conversion is preferably vanadium pentoxide.

[0041] Preferably, the gas obtained from sulfur burning and conversion in the present invention is demisted to obtain the product gas. In the present invention, the SO3 gas concentration in the product gas is 2 - 7 mol%, preferably 2.5 - 3 mol% or 5 - 6 mol%. Using the above product gas in the present invention can meet the gas concentration required for the sulfonation reaction between the product gas and the liquid-phase organic matter, and then through the sulfonation reaction and gas-liquid separation, the initial dry tail gas can be obtained.

[0042] In the present invention, the liquid-phase organic matter is preferably selected from alkylbenzene sulfonic acid or fatty alcohol polyoxyethylene ether sulfonic acid. By selecting different liquid-phase organic matters to react with the product gas in the present invention, different surfactant products can be generated. In the present invention, the molecular weight of the alkylbenzene sulfonic acid is preferably 210 - 500, more preferably 240; the molecular weight of the fatty alcohol polyoxyethylene ether sulfonic acid is preferably 200 - 430, more preferably 285.

[0043] There are no special limitations on the mass ratio of the product gas to the liquid-phase organic matter in the present invention, and it can be adjusted according to conventional experiments to ensure full reaction between the two. In the present invention, when the liquid-phase organic matter is preferably selected from alkylbenzene sulfonic acid, the SO3 gas concentration in the product gas is 5 - 6 mol%, and the mass ratio of the product gas to the liquid-phase organic matter is preferably 2.63 - 2.245:1, more preferably 2.248:1; when the liquid-phase organic matter is preferably selected from fatty alcohol polyoxyethylene ether sulfonic acid, the SO3 gas concentration in the product gas is 2.5 - 3 mol%, and the mass ratio of the product gas to the liquid-phase organic matter is preferably 3.265 - 3.845:1.

[0044] There are no special limitations on the device and parameters for the sulfonation reaction in the present invention, and conventional devices and parameters for the sulfonation reaction can be used. In the present invention, the device for the sulfonation reaction is preferably a gas-liquid two-phase membrane reactor; the temperature for the sulfonation reaction is preferably 30 - 31 °C.

[0045] There are no special limitations on the device for gas-liquid separation in the present invention, and a conventional device for gas-liquid separation can be used to separate the gas phase and the liquid phase in the reaction product. In the present invention, the device for gas-liquid separation is preferably a gas-liquid separator.

[0046] In the present invention, the liquid-phase reaction product obtained by gas-liquid separation is post-treated to obtain a surfactant product. The present invention has no special limitation on the post-treatment method, and it can be adjusted according to the types of conventional surfactants. In the present invention, when the liquid-phase organic matter is selected from alkylbenzene sulfonic acid, the post-treatment includes aging and hydrolysis to obtain LABSA; the present invention has no special limitation on the aging and hydrolysis methods, and conventional aging and hydrolysis can be used. When the liquid-phase organic matter is selected from fatty alcohol polyoxyethylene ether sulfonic acid, the post-treatment includes neutralization, degassing, and adjustment carried out in sequence to obtain AE2S. The present invention has no special limitation on the methods of neutralization, degassing, and adjustment, and conventional neutralization, degassing, and adjustment can be used.

[0047] In the present invention, the tail gas obtained by gas-liquid separation is subjected to electrostatic demisting to obtain electrostatic demisting dry tail gas. The present invention removes organic acid mist in the tail gas through electrostatic demisting to obtain initial dry tail gas, which can be used as initial dilution gas. The present invention has no special limitation on the output of the initial dry tail gas, and it can be adjusted according to needs, so that after increasing the sulfur consumption subsequently, the SO3 gas concentration in the diluted mixed gas can reach 2-7 mol% for adjustment.

[0048] After obtaining the initial dry tail gas, the present invention burns sulfur and converts it in dry air in sequence to obtain a mixed gas.

[0049] In the present invention, the preparation method of the dry air is the same as that of the dry air described in the above technical solution, and will not be elaborated here.

[0050] In the present invention, the mass ratio of the sulfur to the dry air is 1:(8-16), preferably 1:(9-10). By controlling the amounts of sulfur and dry air within the above ranges, the present invention can make the SO3 gas concentration in the mixed gas obtained by sulfur burning and conversion be 4-14 mol%, increase the sulfur consumption, reduce the air consumption, reduce the generation amount of waste gas from the source, and can also prevent the SO3 concentration in the subsequent tail gas from being too high after backmixing and entering the reactor, resulting in more side reactions. In the present invention, when the mass ratio of the sulfur to the dry air is 1:(8-9), the SO3 gas concentration in the mixed gas obtained by sulfur burning and conversion is preferably 8-12 mol%; when the mass ratio of the sulfur to the dry air is 1:(15-16), the SO3 gas concentration in the mixed gas obtained by sulfur burning and conversion is preferably 5-6 mol%.

[0051] The present invention preferably demists the gas obtained by sulfur burning and conversion to obtain a mixed gas. In the present invention, the demisting device is preferably an electrostatic demister. The present invention removes fuming sulfuric acid through demisting.

[0052] After obtaining the mixed gas, the present invention dilutes the mixed gas with a dilution gas to obtain a diluted mixed gas.

[0053] In the present invention, the SO3 gas concentration in the diluted mixed gas is 2-7 mol%, preferably 2.5-3 mol% or 5-6 mol%. By setting the SO3 gas concentration in the diluted mixed gas within the above range, the present invention can be applied to the preparation of different surfactants.

[0054] In the present invention, the dilution gas is the initial dry tail gas and / or the recycled dry tail gas. In the present invention, the initial dry tail gas and / or the recycled dry tail gas include SO3 and air, etc., and the SO3 gas concentration is 0.9-1 mol%. On the one hand, the present invention can reduce the amount of waste gas treatment and the discharge of waste water through the initial dry tail gas and / or the recycled dry tail gas, and on the other hand, it can also reduce the concentration of the mixed gas.

[0055] The present invention has no special limitation on the dosage of the dilution gas, and it is only necessary to adjust the SO3 gas concentration in the diluted mixed gas to 2-7 mol%. In the present invention, a flow meter and a regulating valve are provided at the diluted mixed gas, and when the device indicates 70%-87% of the intake air flow during the recycling of the dry tail gas, the SO3 gas concentration in the diluted mixed gas is 2-7 mol%.

[0056] After obtaining the diluted mixed gas, the present invention mixes the diluted mixed gas with a liquid-phase organic matter in a gas-liquid two-phase membrane reactor to carry out a sulfonation reaction, obtaining a liquid-phase reaction product and a tail gas.

[0057] In the present invention, the method and parameters of mixing the diluted mixed gas with the liquid-phase organic matter in the gas-liquid two-phase membrane reactor to carry out the sulfonation reaction are the same as those of the above technical solution for the sulfonation reaction of the generated gas and the liquid-phase organic matter, and will not be elaborated here.

[0058] The present invention preferably performs gas-liquid separation on the product obtained from the sulfonation reaction to obtain a tail gas and a liquid-phase reaction product. The present invention has no special limitation on the device for gas-liquid separation, and a conventional gas-liquid separation device can be used to separate the gas phase and the liquid phase in the reaction product. In the present invention, the device for gas-liquid separation is preferably a gas-liquid separator.

[0059] After obtaining the tail gas and the liquid-phase product, the present invention performs post-treatment on the liquid-phase reaction product to obtain a surfactant product. In the present invention, the post-treatment is the same as the post-treatment in the above technical solution for preparing the initial dry tail gas, and will not be elaborated here.

[0060] In the present invention, after the tail gas passes through electrostatic demisting, dry tail gas is obtained. In the present invention, the electrostatic demisting can remove the organic acid mist in the tail gas to obtain dry tail gas.

[0061] In the present invention, the partial dry tail gas is used as the recycled dry tail gas. The present invention does not particularly limit the amount of the recycled dry tail gas, which is adjusted according to the SO3 gas concentration in the diluted mixed gas so that the SO3 gas concentration is 2-7 mol%.

[0062] In the present invention, it is preferred to set a gas transmission pipeline at the outlet of the electrostatic demisting to transport the recycled dry tail gas to the mixed gas. By adding a gas transmission pipeline in the existing process flow in the present invention and using all or part of the dry tail gas as the recycled dry tail gas to dilute the mixed gas, the amount of air used can be greatly reduced, the energy consumption can be reduced, and the cost of modifying the equipment is relatively low.

[0063] In the present invention, the solvent used in the caustic washing treatment is preferably a sodium hydroxide solution, and the mass concentration of the sodium hydroxide solution is preferably 32-40%, more preferably 32%. Through the caustic washing treatment in the present invention, SO3 in the remaining dry tail gas after absorbing the recycled dry tail gas can be absorbed, the content of SO3 in the tail gas can be reduced, and the waste gas can meet the emission standards.

[0064] The present invention does not particularly limit the amount of the sodium hydroxide solution, which is adjusted according to the amount of the remaining dry tail gas so that the waste gas after treating the remaining dry tail gas can meet the emission standards. In the present invention, the pH value of the solution after the caustic washing treatment is 7.5-8.5, and the qualified waste liquid is obtained. The present invention does not particularly limit the device for the caustic washing treatment, and a conventional caustic washing treatment device can be used. In the present invention, the device for the caustic washing treatment is preferably a caustic washing tower.

[0065] The process flow chart of the method provided by the present invention is preferably as Figure 1 shown: Compress, freeze, dehumidify and adsorb dry the air with silica gel to obtain dry air. Burn sulfur and convert it in the dry air in sequence, and remove the mist of SO3 gas to obtain a mixed gas with an SO3 gas concentration of 10 mol% (i.e., Figure 1 the 10% SO3 gas phase in); After diluting the mixed gas with a diluent gas, enter a gas-liquid two-phase membrane reactor with a liquid-phase organic matter for sulfonation reaction, and separate the obtained product into a liquid-phase product and a tail gas; The liquid-phase product is post-treated with organic sulfonic acid / ester to obtain a product; After the tail gas is electrostatically demisted, part of the dry tail gas is recycled as a diluent gas to the mixed gas; The remaining part of the dry tail gas is subjected to caustic washing treatment through a tail gas caustic washing tower to obtain qualified waste gas and qualified waste liquid.

[0066] The method provided by the present invention first controls sulfur combustion and conversion to obtain a product gas with an SO3 gas concentration of 2-7 mol%, and obtains dry tail gas through sulfonation reaction, gas-liquid separation, etc., providing the original dilution gas for the dilution mixture gas; after obtaining the dry tail gas, the present invention obtains a mixture gas with an SO3 gas concentration of about 10 mol% by defining the mass ratio of sulfur to dry air, and uses the initially formed dry tail gas for dilution, enabling the mixture gas with a higher gas concentration to meet the requirements for the sulfonation reaction with liquid-phase organic substances. Therefore, dry tail gas can be continuously generated through gas-liquid separation, and a part of the generated dry tail gas is used as the recycled tail gas for diluting the mixture gas. On the one hand, this can make the concentration of the mixture gas reach the concentration required for the sulfonation reaction, and on the other hand, it can also reduce the generation of waste gas and the emissions of waste gas and waste liquid. In addition, the method provided by the present invention only adds the tail gas recycling process, so when it is used for the transformation of old equipment, only a tail gas recycling device needs to be added, greatly reducing the cost of equipment transformation.

[0067] The technical solutions in the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0068] Example 1

[0069] A method for preparing a surfactant by gas-liquid two-phase membrane reaction based on tail gas recycling, the steps are as follows:

[0070] (1) Use an electric ice machine refrigeration unit device to compress, freeze and dehumidify air, and dry it with a renewable silica gel adsorption drying device to obtain dry air with a humidity of 2.585 g / m 3 (at 20 °C); Feed sulfur into a sulfur combustion furnace, conduct sulfur combustion in dry air to obtain a gas containing SO2, then cool the obtained gas to 425 °C and enter a conversion tower, use vanadium pentoxide as a catalyst for conversion, and then use SO3 gas to demist the converted gas to obtain a product gas with an SO3 gas concentration of 5 mol%, and recover fuming sulfuric acid (waste acid); In a gas-liquid two-phase membrane reactor, control the reaction temperature to be 30-31 °C for the sulfonation reaction of the product gas and liquid-phase organic substances (LAB with a molecular weight of 240), and after the product is subjected to gas-liquid separation, obtain tail gas and a liquid-phase product; After the tail gas is subjected to electrostatic demisting, obtain the initial dry tail gas; Taking 1T of product as an example, the feed rate of sulfur is 100 kg / h, the feed rate of dry air is 1800 kg / h, the mass ratio of sulfur to dry air is 1:18, and the feed rate of liquid-phase organic substances is 774 kg / h; The feed rate of the product gas is 1740 kg / h, that is, the mass ratio of the product gas to the liquid-phase organic substances is 2.248:1;

[0071] (2) Feed sulfur into the sulfur burner, burn sulfur in dry air to obtain a gas containing SO2, then cool the obtained gas to 425 °C and enter the conversion tower, carry out conversion using vanadium pentoxide as a catalyst, and then remove the mist of the converted gas with SO3 gas to obtain a mixed gas with a SO3 gas concentration of 10 mol%. The feed rate of the sulfur is 200 kg / h, the feed rate of the dry air is 1800 kg / h, and the mass ratio of sulfur to dry air is 1:9;

[0072] (3) Dilute the mixed gas obtained in step (2) with a dilution gas to obtain a diluted mixed gas, and the SO3 gas concentration in the diluted mixed gas is 5.39 mol%. The dilution gas is the initial dry tail gas and the recycled dry tail gas obtained in step (1). The usage method of the initial dry tail gas and the recycled dry tail gas is as follows: First, dilute the mixed gas with the initial dry tail gas to make the dry tail gas flowmeter indicate 1680 kg / h. After the subsequent diluted mixed gas reacts with the liquid-phase organic matter to generate dry tail gas, recycle the dry tail gas and continuously dilute the mixed gas to make the dry tail gas flowmeter indicate 1320 kg / h. That is, when the dry tail gas is recycled, the device indicates 73.33% of the inlet gas flow rate;

[0073] (4) Mix the diluted mixed gas obtained in step (3) with a liquid-phase organic matter (LAB with a molecular weight of 240) in a gas-liquid two-phase membrane reactor, control the reaction temperature at 30 - 31 °C to carry out the sulfonation reaction, and then separate the product into gas and liquid phases to obtain tail gas and a liquid-phase product. The feed rate of the liquid-phase organic matter is 1548 kg / h; the feed rate of the diluted mixed gas is 3480 kg / h, that is, the mass ratio of the diluted mixed gas to the liquid-phase organic matter is 2.248:1;

[0074] (5) Thoroughly mix the liquid-phase reaction product obtained in step (4) in an aging tank for 30 min, and then add 9.685 kg / h of water for hydrolysis to obtain a surfactant product alkyl benzene sulfonic acid (LABSA);

[0075] (6) After electrostatic demisting of the tail gas obtained in step (4), obtain dry tail gas. Use part of the dry tail gas as recycled dry tail gas and transport it through a pipeline to the mixed gas in step (2) for dilution; the remaining part of the dry tail gas is introduced into an alkali scrubbing tower for alkali scrubbing treatment, control the pH value of the alkali scrubbing tower at 7.5 - 8.5 to obtain up-to-standard waste gas and up-to-standard waste liquid. The alkali scrubbing treatment uses a sodium hydroxide solution with a mass concentration of 32%.

[0076] Example 2

[0077] A method for preparing a surfactant by gas-liquid two-phase membrane reaction based on tail gas recycling, the steps are as follows:

[0078] (1) Compress and freeze-dry the air using a Roots blower and a potassium bromide refrigeration unit, and dry it using a renewable silica gel adsorption drying device to obtain dry air with a humidity of 2.585 g / m 3 (20 °C); Feed sulfur into a sulfur burner, burn sulfur in the dry air to obtain a gas containing SO2, then cool the obtained gas to 425 °C and enter a conversion tower, carry out conversion using vanadium pentoxide as a catalyst, and then remove the mist of the converted gas using SO3 gas to obtain a product gas with a SO3 gas concentration of 2.49 mol%, and recover fuming sulfuric acid (waste acid); React the obtained product gas with a liquid-phase organic matter (AEO2 with a molecular weight of 285) in a gas-liquid two-phase membrane reactor, control the reaction temperature at 30 - 31 °C for sulfonation reaction, and after the product is separated by gas-liquid separation, obtain tail gas and a liquid-phase product; After the tail gas is removed by electrostatic mist, obtain the initial dry tail gas; Taking 1.2T of product as an example, the feed rate of sulfur is 100 kg / h, the feed rate of dry air is 2900 kg / h, the mass ratio of sulfur to dry air is 1:29, and the feed rate of the liquid-phase organic matter is 870 kg / h; The feed rate of the product gas is 2844 kg / h, that is, the mass ratio of the product gas to the liquid-phase organic matter is preferably 3.269:1;

[0079] (2) Feed sulfur into a sulfur burner, burn sulfur in the dry air to obtain a gas containing SO2, then cool the obtained gas to 425 °C and enter a conversion tower, carry out conversion using vanadium pentoxide as a catalyst, and then remove the mist of the converted gas using SO3 gas to obtain a mixed gas with a SO3 gas concentration of 4.99 mol%; The feed rate of sulfur is 169 kg / h, the feed rate of dry air is 2900 kg / h, and the mass ratio of sulfur to dry air is 1:17;

[0080] (3) Dilute the mixed gas obtained in step (2) using a dilution gas to obtain a diluted mixed gas, and the SO3 gas concentration in the diluted mixed gas is 2.73 mol%; The dilution gas is the initial dry tail gas and the recycled dry tail gas obtained in step (1); The usage method of the initial dry tail gas and the recycled dry tail gas is: First, dilute the mixed gas using the initial dry tail gas to make the dry tail gas flowmeter indicate 1680 kg / h. After the subsequent diluted mixed gas reacts with the liquid-phase organic matter to generate dry tail gas, recycle the dry tail gas and continuously dilute the mixed gas to make the dry tail gas flowmeter indicate 2500 kg / h; That is, when the dry tail gas is recycled, the device indicates 86.21% of the inlet flow rate;

[0081] (4) Mix the diluted mixed gas obtained in step (3) with a liquid-phase organic matter (AEO2 with a molecular weight of 285) in a gas-liquid two-phase membrane reactor, control the reaction temperature at 30 - 31 °C for sulfonation reaction, and after the product is separated by gas-liquid separation, obtain tail gas and a liquid-phase product;

[0082] (5) Post-treat and neutralize the liquid-phase reaction product obtained in step (4) (add liquid caustic soda, a buffer solution composed of lemon water or sodium carbonate, and water, and control the pH to 9.5 - 10.5), degas (remove dioxane in the product to below 10 ppm), and adjust (stir and let stand) to obtain the surfactant product fatty alcohol polyoxyethylene ether sulfonic acid (AE2S);

[0083] (6) After electrostatic demisting the tail gas obtained in step (4), obtain dry tail gas; use part of the dry tail gas as recycled dry tail gas and transport it through a pipeline to the mixed gas in step (2) for dilution; pass the remaining part of the dry tail gas into an alkali scrubbing tower for alkali scrubbing treatment, control the pH value of the alkali scrubbing tower to 7.5 - 8.5, and obtain up-to-standard waste gas and up-to-standard waste liquid; the alkali scrubbing treatment uses a sodium hydroxide solution with a mass concentration of 32%.

[0084] Comparative Example 1

[0085] A method for preparing a surfactant by gas-liquid two-phase membrane reaction:

[0086] (1) Compress, freeze, and dehumidify air using an electric ice machine refrigeration unit, and dry it using a renewable silica gel adsorption drying device to obtain dry air with a humidity of 2.585 g / m 3 (at 20 °C); Feed sulfur into a sulfur burner, burn sulfur in the dry air to obtain a gas containing SO2, then cool the obtained gas to 425 °C and enter a conversion tower, use vanadium pentoxide as a catalyst for conversion, and then remove the mist of the converted gas using SO3 gas to obtain a product gas with a SO3 gas concentration of 5 - 6 mol%;

[0087] (2) Mix the product gas obtained in step (1) with a liquid-phase organic substance (LAB with a molecular weight of 240) in a gas-liquid two-phase membrane reactor, control the reaction temperature to 30 - 31 °C for sulfonation reaction, and after gas-liquid separation of the product, obtain tail gas and a liquid-phase product; the feed rate of the liquid-phase organic substance is 1548 kg / h; the feed rate of the product gas is 3480 kg / h;

[0088] (3) Thoroughly mix the liquid-phase reaction product obtained in step (2) in an aging tank for 30 min, and then add 9.685 kg / h of water for hydrolysis to obtain the surfactant product alkyl benzene sulfonic acid (LABSA);

[0089] (4) After electrostatic demisting the tail gas obtained in step (2), obtain dry tail gas; pass the dry tail gas into an alkali scrubbing tower for alkali scrubbing treatment, control the pH value of the alkali scrubbing tower to 7.5 - 8.5, and obtain up-to-standard waste gas and up-to-standard waste liquid; the alkali scrubbing treatment uses a sodium hydroxide solution with a mass concentration of 32%.

[0090] Comparative Example 2

[0091] A method for preparing surfactants by gas-liquid two-phase membrane reaction:

[0092] (1) Compress, freeze and dehumidify air using an electric ice machine refrigeration unit, and dry it using a renewable silica gel adsorption drying device to obtain dry air with a humidity of 2.585 g / m 3 (at 20 °C); Feed sulfur into a sulfur burner, burn sulfur in the dry air to obtain a gas containing SO2, then cool the obtained gas to 425 °C and enter a conversion tower, carry out conversion using vanadium pentoxide as a catalyst, and then remove the mist of the converted gas using SO3 gas to obtain a product gas with a SO3 gas concentration of 2.5 - 3 mol%;

[0093] (2) Mix the product gas obtained in step (1) with a liquid-phase organic matter (AEO2 with a molecular weight of 285) in a gas-liquid two-phase membrane reactor, control the reaction temperature to be 30 - 31 °C for sulfonation reaction, and then separate the gas and liquid of the product to obtain tail gas and a liquid-phase product; the feed rate of the liquid-phase organic matter is 1470 kg / h; the feed rate of the product gas is 2900 kg / h;

[0094] (3) Post-treat the liquid-phase reaction product obtained in step (2) by neutralization (add liquid alkali, a buffer solution composed of lemon water or sodium carbonate, etc., and water, control the pH to be 9.5 - 10.5), degassing (remove dioxane in the product to below 10 ppm), and adjustment (stir and stand) to obtain fatty alcohol polyoxyethylene ether sulfonic acid (AE2S);

[0095] (4) After electrostatic demisting the tail gas obtained in step (2), obtain dry tail gas; pass the dry tail gas into an alkali scrubbing tower for alkali scrubbing treatment, control the pH value of the alkali scrubbing tower to be 7.5 - 8.5 to obtain up-to-standard waste gas and up-to-standard waste liquid; the alkali scrubbing treatment uses a sodium hydroxide solution with a mass concentration of 32%.

[0096] Test Example 1

[0097] When preparing surfactants by the methods of Examples 1 - 2 and Comparative Examples 1 - 2, the consumption of dry air and the amount of tail gas treatment are shown in Table 1:

[0098] Table 1 Comparison results of energy consumption of the methods of Examples 1 - 2 and Comparative Examples 1 - 2

[0099]

[0100] As can be seen from Examples 1-2 and Comparative Examples 1-2, taking the production capacity of 1 T / h of products as an example, the method of the comparative examples requires 1800 kg / h of dry air, 100 kg / h of sulfur, and 3.1 kmol / h of organic raw materials (LAB or AEO2). According to the method provided by the present invention, it needs to be adjusted to 1800 kg / h of dry air unchanged, 200 kg / h of sulfur, and 6.2 kmol / h of organic raw materials (LAB or AEO2). The dosage of sulfur added by the method provided by the present invention is doubled.

[0101] As can be seen from Table 1, when producing LABSA with a SO3 gas concentration of 5 mol%, the ratio of dry air to production decreases from 20 times to about 10 times, and the ratio of dry tail gas treatment to production also decreases from 18.5 times to 9.25 times; when producing AE2S with a SO3 gas concentration of 3%, the ratio of dry air to production decreases from 33 times to 16.5 times. The ratio of dry tail gas treatment to production also decreases from 30.6 times to 15.3 times. It can be seen that the method provided by the present invention can halve the amount of dry air and the amount of dry tail gas treatment per unit output, reduce the power consumption of the device, reduce emissions, double the output, halve the unit consumption of liquid caustic soda, and halve the emissions of fuming sulfuric acid and black acid.

[0102] Moreover, Comparative Examples 1-2 are the existing methods for preparing surfactants by gas-liquid two-phase membrane reaction, and their process flow diagrams are as Figure 2 shown. According to Figure 1 and Figure 2 it can be seen that the method provided by the present invention can be used for new device construction and old device renovation, which will reduce the investment cost. Especially for the expansion of production of old devices, the investment cost will be greatly reduced.

[0103] Test Example 2

[0104] The surfactant was prepared by the method of Comparative Example 2, except that when the standard production capacity / T was 0.9, 1, and 1.1 respectively, the analysis results of the obtained products are shown in Table 2:

[0105] Table 2 Analysis results of surfactants prepared by the method of Comparative Example 2

[0106]

[0107] The surfactant was prepared by the method of Example 2, except that when the standard production capacity / T was 1.4, 1.6, and 1.8 respectively, the analysis results of the obtained products are shown in Table 3:

[0108] Table 3 Analysis results of surfactants prepared by the method of Example 2

[0109]

[0110] As can be seen from Table 2 and Table 3, the method provided by the present invention can not only halve the amount of dry air and the amount of dry tail gas treatment per unit output, reduce the power consumption of the device, reduce emissions, double the output, halve the unit consumption of liquid caustic soda, and halve the emissions of fuming sulfuric acid and black acid. At the same time, since the dry tail gas recycling ratio can be increased to more than 50%, it has an improving effect on product quality, especially significantly reducing the dioxane content of AE2S.

[0111] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing surfactants by gas-liquid two-phase membrane reaction based on tail gas recycling, comprising the following steps: (1) Sulfur is successively subjected to sulfur combustion and conversion in dry air to obtain a product gas with a SO3 gas concentration of 2-7 mol%; after the product gas is sulfonated with a liquid-phase organic substance, gas-liquid separation is carried out to obtain initial dry tail gas; (2) Sulfur is successively subjected to sulfur combustion and conversion in dry air to obtain a mixed gas; the mass ratio of the sulfur to the dry air is 1:(8-16), and the SO3 gas concentration in the mixed gas is 4-14 mol%; (3) The mixed gas obtained in step (2) is diluted with a dilution gas to obtain a diluted mixed gas, and the SO3 gas concentration in the diluted mixed gas is 2.5-3 mol% or 5-6 mol%; the dilution gas is the initial dry tail gas obtained in step (1) and / or recycled dry tail gas; (4) The diluted mixed gas obtained in step (3) is mixed with a liquid-phase organic substance in a gas-liquid two-phase membrane reactor for sulfonation reaction to obtain a liquid-phase reaction product and tail gas; (5) The liquid-phase reaction product obtained in step (4) is post-treated to obtain a surfactant product; (6) The tail gas obtained in step (4) is subjected to electrostatic demisting to obtain dry tail gas; part of the dry tail gas is used as recycled dry tail gas to dilute the mixed gas in step (2); the remaining part of the dry tail gas is treated by alkali washing to obtain up-to-standard waste gas and up-to-standard waste liquid; The preparation method of the dry air in steps (1) and (2) includes: successively compressing, freezing and drying the air with silica gel adsorption to obtain dry air; When the SO3 gas concentration in the diluted mixed gas in step (3) is 2.5-3 mol%, the liquid-phase organic substance is fatty alcohol polyoxyethylene ether; When the SO3 gas concentration in the diluted mixed gas in step (3) is 5-6 mol%, the liquid-phase organic substance is alkylbenzene; There is no time sequence between step (5) and step (6).

2. The method according to claim 1, characterized in that, The mass ratio of sulfur to dry air in step (1) is 1:(16-32).

3. The method according to claim 1, wherein The humidity of the dry air in the steps (1) and (2) is independently 2 to 11 g / m 3 .

4. The method according to claim 1, wherein The SO3 gas concentration of the initial dry tail gas in step (1) and the recycled dry tail gas in step (3) is independently 0.03-0.07 mol%.

5. The method according to claim 1, wherein The solvent used for alkali washing in step (6) is sodium hydroxide solution.

6. The method according to claim 5, wherein The mass concentration of the sodium hydroxide solution is 32-40%.

7. The method according to claim 1, characterized in that The pH value of the solution after alkali washing in step (6) is 7.5-8.5 to obtain up-to-standard waste liquid.

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