阅读说明：本技术 一种连续非均相管式反应合成二乙氧基甲烷的方法 (Method for synthesizing diethoxymethane by continuous heterogeneous tubular reaction ) 是由 顾正桂 费维民 汪凯军 曹晓艳 于 2020-05-19 设计创作，主要内容包括：本发明公开了一种连续非均相管式反应合成二乙氧基甲烷的方法,包括以聚苯乙烯基磺酸型树脂为催化剂,以非均相管式反应器作为反应装置,甲醛和乙醇作为反应原料,两者在反应装置中流经聚苯乙烯基磺酸型树脂催化剂,进行连续化反应制备二乙氧基甲烷。本发明方法具有反应过程连续化、反应时间短、转化率高、选择性好及易于控制产品质量等特点。相较于使用无机酸催化剂,反应产物无需中和且对设备无腐蚀。(The invention discloses a method for synthesizing diethoxymethane by continuous heterogeneous tubular reaction, which comprises the steps of taking polystyrene sulfonic acid resin as a catalyst, taking a heterogeneous tubular reactor as a reaction device, taking formaldehyde and ethanol as reaction raw materials, allowing the polystyrene sulfonic acid resin catalyst and the formaldehyde and the ethanol to flow through the reaction device, and carrying out continuous reaction to prepare diethoxymethane. The method has the characteristics of continuous reaction process, short reaction time, high conversion rate, good selectivity, easy control of product quality and the like. Compared with the use of inorganic acid catalyst, the reaction product does not need to be neutralized and does not corrode equipment.)

1. A method for synthesizing diethoxymethane by continuous heterogeneous tubular reaction is characterized in that polystyrene sulfonic acid type resin is used as a catalyst, a heterogeneous tubular reactor is used as a reaction device, formaldehyde and ethanol are used as reaction raw materials, and the polystyrene sulfonic acid type resin catalyst and the formaldehyde and the ethanol flow through the reaction device to carry out continuous reaction to prepare diethoxymethane.

2. The continuous heterogeneous tubular reaction method for synthesizing diethoxymethane according to claim 1, wherein the polystyrene sulfonic acid type resin catalyst is prepared by the following method:

adding polystyrene-divinylbenzene white balls into a container, adding concentrated sulfuric acid, carrying out programmed heating to 85-95 ℃ for swelling, continuing heating to 125-135 ℃, carrying out heat preservation for a period of time, then cooling to room temperature, adding dilute sulfuric acid for washing, then dropwise adding deionized water for repeatedly washing to neutrality, and drying to obtain the polystyrene-based sulfonic acid resin catalyst.

3. The continuous heterogeneous tubular reaction process for the synthesis of diethoxymethane according to claim 2, wherein the degree of crosslinking of the polystyrene-divinylbenzene white spheres is 7 to 9%.

4. The continuous heterogeneous tubular reaction method for synthesizing diethoxymethane according to claim 2, wherein the concentrated sulfuric acid is 98% concentrated sulfuric acid, and the dilute sulfuric acid is 30% dilute sulfuric acid.

5. The continuous heterogeneous tubular reaction process for the synthesis of diethoxymethane according to claim 2, wherein the temperature programming rate is 8-12 ℃/h; the heat preservation time at the temperature of 125-135 ℃ is 4-6 h.

6. The method for synthesizing diethoxymethane by continuous heterogeneous tubular reaction according to claim 1, wherein the molar ratio of the raw material ethanol to formaldehyde is (3-6): 1, the reaction temperature is 60-90 ℃, the feeding rate is 0.01-0.20 ml/min, and the reaction pressure is 0.101-1.000 Mpa.

7. The continuous heterogeneous tubular reaction method for synthesizing diethoxymethane according to claim 1, wherein the heterogeneous tubular reactor comprises five parts, namely a raw material input system, a preheater, a tubular reactor, a condenser and a reaction product collection system, wherein the preheater preheats the reaction raw material, the synthesis reaction occurs in the tubular reactor, and the condenser cools the reaction product to facilitate discharging.

8. The continuous heterogeneous tubular reaction method for synthesizing diethoxymethane according to claim 7, wherein the reaction raw materials are mixed according to a certain ratio, and are injected into the preheater for increasing the temperature through the raw material input system according to a certain feed rate.

9. The continuous heterogeneous tubular reaction process for the synthesis of diethoxymethane as claimed in claim 7, wherein the polystyrenesulfonic acid type resin catalyst is fixed at the upper end of the tubular reactor by a jacketed or forked fixed bed, the reaction material heated by the preheater is passed through a solid acid catalyst bed on the fixed bed to perform aldol condensation reaction, and a heating and heat-insulating device is installed outside the reactor to perform heating and maintain the temperature of the reaction within a set value range.

10. The continuous heterogeneous tubular reaction method for synthesizing diethoxymethane according to claim 7, wherein the mixed solution after the full reaction in the tubular reactor section flows to the condenser section to be cooled under the driving of the carrier gas, and the cooled mixed solution enters the reaction product collection system to be subjected to gas-liquid separation and collection.

Technical Field

The invention discloses a method for synthesizing diethoxymethane by continuous heterogeneous tubular reaction, belonging to the technical field of diethoxymethane preparation.

Background

Diethoxymethane is a chemical raw material with excellent performance and wide application, and is also called as methylal diethanol, formaldehyde ester and the like, and English is simply called as follows: and (4) DEM. The molecular structural formula is CH₃CH₂OCH₂OCH₂CH₃From the knotStructurally, diethoxymethane corresponds to a cytidine diether and thus has an ether-like odor. From the organic matter classification, diethoxymethane is an acetal, is relatively stable to alkaline solutions, but is easily hydrolyzed into formaldehyde in an acidic aqueous solution under warm conditions, and is often used for organic synthesis reactions in alkaline solutions. The diethoxymethane is colorless transparent liquid in appearance, the melting point is-66.5 ℃, the boiling point is 88 ℃, and the diethoxymethane is easily soluble in organic solvents such as ethanol, benzene, ether and the like and slightly soluble in water.

The use of diethoxymethane is mainly used in two aspects: (1) the diethoxymethane is used as a solvent for reaction, and has the characteristics of low toxicity, strong dissolving capacity, hydrophilic and oleophilic properties, low viscosity, moderate boiling point, difficult oxidation, low toxicity, high oxygen content and the like; can be used as a solvent for alkylation, acylation, organic lithium reaction and oxidation reaction, and can replace some common solvents, such as tetrahydrofuran, ethyl acetate, dichloromethane and the like. (2) Used as reagents such as formaldehyde equivalents, ethoxymethylating agents, substrates for carbonylation, and sources of ethanol, etc. And the additive can be used as an additive of diesel fuel, and can improve the combustion quality of the diesel fuel, improve the cetane number of the diesel fuel and enhance the antiknock property of the diesel fuel after being compounded with the diesel fuel.

At present, the diethoxymethane is synthesized mainly by the following five methods: (1) the dichloromethane method adopts dichloromethane and sodium ethoxide as reaction raw materials, the reaction temperature is 50 ℃, the method is an early method for synthesizing diethoxymethane, but due to the existence of sodium ethoxide, the reaction condition is required to be anhydrous operation, the reaction condition is harsh, the yield of DEM is low, and the DEM is rarely used. (2) The dimethyl sulfoxide method comprises the steps of adopting ethanol and dimethyl sulfoxide as reaction raw materials, and using polyphosphoric acid as a catalyst to synthesize diethoxymethane, wherein the dimethyl sulfoxide is decomposed under the catalysis of the polyphosphoric acid to provide formaldehyde, and the formaldehyde reacts with the ethanol to generate the diethoxymethane; the method needs more dimethyl sulfoxide and has low product yield, so that the method is difficult to be used for producing the diethoxymethane on a large scale. (3) The calcium chloride method adopts formaldehyde and ethanol as reaction raw materials, and adopts calcium chloride as a catalyst to synthesize diethoxymethane, so that the reaction yield is high, but the reaction time is long, large-scale production is not facilitated, the catalyst needs to be subjected to post-treatment after the reaction, and the process flow is complicated. (4) A chloramphenicol by-product method, wherein a methenamine solution of p-nitro-2-bromoacetophenone is generated in the production process of chloramphenicol, and a mixed solution of hydrochloric acid and ethanol is added into the solution to obtain a by-product diethoxymethane, but the yield obtained by the method is limited and is not beneficial to industrial large-scale production; (5) the acid catalysis method adopts formaldehyde and ethanol as reaction raw materials, and concentrated hydrochloric acid as a catalyst to synthesize diethoxymethane, has simple reaction operation method, short reaction time and high yield, is a relatively ideal method for synthesizing diethoxymethane, but also has some defects, such as strong corrosion to equipment, need of neutralizing products and the like.

Disclosure of Invention

The purpose of the invention is as follows: in order to solve the technical problems, the invention provides a method for synthesizing diethoxymethane by continuous heterogeneous tubular reaction, which has the characteristics of continuous reaction, short reaction time, high conversion rate, easy quality control and the like.

The technical scheme is as follows: in order to achieve the purpose, the invention adopts the following technical scheme:

a method for synthesizing diethoxymethane by continuous heterogeneous tubular reaction comprises the steps of taking polystyrene sulfonic resin as a catalyst, taking a heterogeneous tubular reactor as a reaction device, taking formaldehyde and ethanol as reaction raw materials, enabling the polystyrene sulfonic resin catalyst and the formaldehyde and the ethanol to flow through the reaction device, and carrying out continuous reaction to prepare diethoxymethane.

Preferably, the method comprises the following steps:

the preparation method of the polystyrene sulfonic resin catalyst comprises the following steps:

adding polystyrene-divinylbenzene white balls into a container, adding concentrated sulfuric acid, carrying out programmed heating to 85-95 ℃ for swelling, continuing heating to 125-135 ℃, carrying out heat preservation for a period of time, then cooling to room temperature, adding dilute sulfuric acid for washing, then dropwise adding deionized water for repeatedly washing to neutrality, and drying to obtain the polystyrene-based sulfonic acid resin catalyst.

More preferably, the polystyrene-divinylbenzene white spheres have a degree of crosslinking of 7 to 9%.

More preferably, the concentrated sulfuric acid is 98% concentrated sulfuric acid, and the dilute sulfuric acid is 30% dilute sulfuric acid.

Further preferably, the rate of the temperature programming is 8-12 ℃/h; the heat preservation time at the temperature of 125-;

the molar ratio (3-6) of the raw material ethanol to the formaldehyde is as follows: 1, more preferably 4: 1; the reaction temperature is 60-90 ℃, and more preferably 75 ℃; the feeding rate is 0.01-0.20 ml/min, and more preferably 0.10 ml/min; the reaction pressure is 0.101 to 1.000MPa, more preferably 0.101MPa, i.e., normal pressure.

Heterogeneous tubular reactor includes five parts of raw materials input system, pre-heater, tubular reactor, condenser and reaction product collecting system, and wherein the pre-heater preheats reaction raw materials, and synthetic reaction takes place in tubular reactor, and the condenser cools down the ejection of compact of being convenient for to the product after the reaction.

The reaction process using the heterogeneous tubular reactor is specifically as follows:

(1) the formaldehyde solution and the ethanol are used as reaction raw materials, and the formaldehyde solution and the ethanol have good intersolubility, so that the two raw materials are firstly mixed according to a certain proportion and are injected into a preheater for heating through a raw material input system according to a certain feeding rate.

(2) The reactor section is filled with a solid acid catalyst in advance, the catalyst is fixed at the upper end part of the tubular reactor by a jacketed or forked fixed bed, the reaction raw material heated by the preheater flows through a solid acid catalyst bed layer on the fixed bed to carry out aldol condensation reaction, and meanwhile, a heating and heat-preserving device is arranged outside the reactor to heat and maintain the temperature of the reaction within a set value range, and the error is +/-1 ℃.

(3) Mixed liquid after the full reaction of the tubular reactor section flows to the condenser section to be cooled under the driving of carrier gas, the cooled mixed liquid enters the reaction product collecting system to be subjected to gas-liquid separation and collected, and the continuous feeding and continuous discharging are realized in the whole reaction process.

Has the advantages that: the method takes formaldehyde and ethanol as reaction raw materials, selects a solid acid catalyst to be filled in a reactor, and continuously synthesizes diethoxymethane in a continuous heterogeneous tubular reactor. Compared with the use of inorganic acid catalyst, the reaction product does not need to be neutralized and does not corrode equipment.

Drawings

FIG. 1 is a schematic diagram of a heterogeneous tubular reactor apparatus used in an embodiment of the present invention, wherein: the system comprises a v-stop valve, an S-three-way conversion valve, a TCI temperature control device, a TI temperature measurement device, a PI pressure measurement device, a 1-gas steel cylinder, a 2-filter, a 3-pressure maintaining valve, a 4-dryer, a 5-mass flow device, a 6-check valve, a 7-buffer, an 8-preheater, a 9-preheater heating furnace, a 10-reactor heating furnace, an 11-reactor, a 12-condenser, a 13-gas-liquid separator, a 14-back pressure valve, a 15-manual sampler, a 16-wet flow device, a 17-high-pressure liquid sampler and an 18-peristaltic pump.

FIG. 2 is SEM morphology before and after sulfonation of polystyrene-divinylbenzene white spheres.

FIG. 3 is a Fourier infrared spectrum of polystyrene-divinylbenzene white spheres before and after sulfonation, wherein: a-polystyrene white ball and B-sulfonated polystyrene resin.

FIG. 4 shows NH before and after sulfonation of polystyrene-divinylbenzene white spheres₃-TPD profile.

Detailed Description

The technical solution of the present invention is further described in detail with reference to the accompanying drawings and embodiments.

The heterogeneous tubular reactor used in the following examples, the structure of which is shown in FIG. 1, clearly shows the preheater, the reactor, the condenser and the continuous inlet and outlet of the reaction raw materials and the carrier gas, and the method for synthesizing diethoxymethane by using the same to perform the continuous heterogeneous tubular reaction is as follows:

(1) the formaldehyde solution (37 wt%) and ethanol (95 wt%) are used as reaction raw materials, and because the formaldehyde solution and the ethanol have good intersolubility, the two raw materials are firstly mixed according to a certain proportion, and the mixed raw material liquid is injected into a preheater 8 for heating through a peristaltic pump 18 according to a certain feeding rate.

(2) The tubular reactor 11 section is filled with a solid acid catalyst in advance, the catalyst is fixed at the upper end part of the reactor by a jacketed or forked fixed bed, the reaction raw material heated by the preheater 8 flows through a catalyst bed layer for reaction, and meanwhile, a heating and heat-preserving device is arranged outside the reactor 11 for heating and maintaining the temperature measurement of the reaction within a set value range, and the error is +/-1 ℃.

(3) The mixed liquid after the full reaction in the reactor 11 section flows to the condenser 12 section under the drive of the carrier gas for cooling, the cooled mixed liquid enters the gas-liquid separator 13 for gas-liquid separation, and the separated product mixed liquid is sampled and analyzed by the high-pressure liquid sampler 17; the whole reaction process realizes continuous feeding and continuous discharging. The temperature range of the freezing liquid in the condenser is-15 ℃ to 10 ℃, and all components of the product mixed liquid can be effectively changed into liquid phase in the temperature range.

The length of a preheater section pipe of the tubular reactor is 300mm, the diameter of the preheater section pipe is 10mm, and the heating power of the preheating furnace is 1 Kw; the length of the reactor section pipe is 720mm, the inner diameter is 20mm, a three-section heating furnace is adopted, and the heating power of each section is 1.5 Kw; the length of the condenser section pipe is 330mm, and the inner diameter of the condenser section pipe is 5 mm; the length of the gas-liquid separator is 200mm, and the outer diameter is 45 mm.

The self-made polystyrene sulfonic acid resin catalyst adopted in the following examples has the following preparation method:

1g of polystyrene-divinylbenzene white balls with the crosslinking degree of 8 percent are added into a 100ml single-neck flask with a reflux device, and then 20ml of 98 percent concentrated sulfuric acid is added; heating up the mixture at a heating rate of 10 ℃/h for a program heating up the mixture from room temperature to 90 ℃, and swelling the mixture for 2 h; then raising the temperature from 90 ℃ to 130 ℃, and preserving the heat for 5.0 h; naturally cooling to room temperature, adding 30% dilute sulfuric acid for washing to ensure sufficient sulfonation, slowly dropwise adding deionized water under stirring, repeatedly washing to neutrality, and drying in a 60 ℃ oven for 24h to obtain the polystyrene sulfonic acid type resin catalyst.