Chlorination grading reaction process in ethyl maltol production

Abstract

The invention provides a chlorination grading reaction process in ethyl maltol production, and relates to the technical field of ethyl maltol production, the chlorination grading reaction process comprises the following steps: primary chlorination reaction: conveying a methanol solution into a primary chlorination kettle for cooling, and adding furfuryl alcohol and chlorine for reaction; second-stage chlorination reaction: after the first-stage chlorination reaction is finished, conveying materials in the first-stage chlorination kettle to a second-stage chlorination kettle, cooling the second-stage chlorination kettle, and adding furfuryl alcohol and chlorine for reaction; and a third-stage chlorination reaction: after the second-stage chlorination reaction is finished, conveying the material in the second-stage chlorination kettle to a third-stage chlorination kettle, adding furfuryl alcohol and chlorine for reaction, and finishing the third-stage chlorination reaction. The furfuryl alcohol and chlorine can fully react, the chlorination yield is improved, chlorine supplement operation is not needed after the reaction is finished, chlorine consumption is low, and pollution is small.

Description

Technical Field

[0001] The invention relates to the technical field of ethyl maltol production, and in particular to a chlorination graded reaction process in ethyl maltol production. Background Art

[0002] The production process of ethyl maltol is divided into Grignard section, chlorination section, sublimation section, crystallization section and drying section. Among them, the chlorination section is divided into chlorination reaction process, hydrolysis reaction process and neutralization reaction process, which plays a key role in the production of ethyl maltol.

[0003] Prior art, such as patent CN106366062A, discloses a chlorination reaction method in maltol production, which specifically includes the following steps: a. Put a methanol aqueous solution with a content of 55% into a chlorination kettle for circulation cooling, b. Prepare a mixed solution of furfuryl alcohol and methanol in a volume ratio of 1:1, c. When the temperature of the chlorination kettle drops to -15°C, start dripping the mixed solution of furfuryl alcohol and methanol, and at the same time drip hydrochloric acid and hydrogen peroxide into the kettle continuously for reaction, and drip the mixed solution of furfuryl alcohol and methanol: hydrochloric acid: hydrogen peroxide = 24:24:12. The invention uses hydrochloric acid and hydrogen peroxide to replace chlorine to participate in the chlorination reaction, which reduces environmental pollution and improves the conversion rate and economic benefits of the chlorination section.

[0004] For example, patent CN102060821A discloses a chlorination reaction method and device in the production of ethyl maltol. The reaction device is composed of a reactor, a circulating pump, and a plate heat exchanger. The reaction method is to first pump a methanol solution into a chlorination reactor and freeze it to below -18°C, then drop furfuryl alcohol, and pass the chlorine gas in the liquid chlorine cylinder into the chlorination reactor through a buffer tank. The material is circulated and cooled through a plate heat exchanger to control the reaction temperature to ≤-8°C. The invention is safe and convenient to operate, the reaction device has a simple structure, and improves the utilization rate of raw materials and the yield of products.

[0005] For example, patent CN102391229A discloses a continuous production method and device for ethyl maltol chlorination, which includes the following steps: a. Continuously injecting the recovered methanol solution into the chlorination reactor, and continuously dripping furfuryl alcohol into the chlorination reactor when the temperature of the methanol solution drops below -10°C, and introducing chlorine gas for reaction, the liquid level in the chlorination reactor rises to the overflow port, and automatically overflows to the hydrolysis reactor; b. After the reactants enter the hydrolysis reactor, steam is introduced to start steaming, the by-products of chloromethane and methanol in the chlorination reaction are evaporated, and the crude ethyl maltol is released from the bottom of the hydrolysis reactor; after condensation by the condenser, the chloromethane gas is recovered as the finished chloromethane; the methanol solution is sent to the methanol recovery tank, and then the methanol solution is sent to the freezing kettle, and returned to the chlorination reactor after cooling. The method and device of the invention can be produced continuously, which increases the production capacity of a single set of equipment. Due to the continuous production of chloromethane recovery, the impact on the environment is eliminated and added value is generated.

[0006] However, the technology in the above invention has problems such as incomplete chlorination reaction, need for chlorine replenishment operation, large chlorine consumption or easy pollution.

[0007] In view of the problems existing in the prior art, it is necessary to find a chlorination graded reaction process in the production of ethyl maltol with low chlorine consumption and low pollution. Summary of the invention

[0008] The invention aims at the problems existing in the prior art and provides a chlorination graded reaction process in the production of ethyl maltol. The furfuryl alcohol and chlorine can fully react with each other, thereby improving the chlorination yield. After the reaction is completed, there is no need to perform chlorine supplementation operation, the chlorine consumption is small, and the pollution is small.

[0009] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0010] The present invention provides a chlorination graded reaction process, comprising the following steps:

[0011] Primary chlorination reaction: transport the methanol solution to the primary chlorination kettle for cooling, add furfuryl alcohol and chlorine gas for reaction;

[0012] Secondary chlorination reaction: After the primary chlorination reaction is completed, the materials in the primary chlorination kettle are transported to the secondary chlorination kettle. After the secondary chlorination kettle is cooled down, furfuryl alcohol and chlorine are added to react;

[0013] Tertiary chlorination reaction: After the secondary chlorination reaction is completed, the materials in the secondary chlorination kettle are transported to the tertiary chlorination kettle, and after cooling, furfuryl alcohol and chlorine are added to react to end the tertiary chlorination reaction;

[0014] Among them, the primary chlorination kettle, the secondary chlorination kettle, and the tertiary chlorination kettle are connected in series, the primary chlorination kettle is correspondingly provided with a primary furfuryl alcohol batching tank, the secondary chlorination kettle is correspondingly provided with a secondary furfuryl alcohol batching tank, and the tertiary chlorination kettle is correspondingly provided with a tertiary furfuryl alcohol batching tank;

[0015] Taking the methanol solution in the primary chlorination reactor as a reference, the mass ratio of the furfuryl alcohol to the methanol solution in the primary furfuryl alcohol batching tank is 1:0.5-0.7, the mass ratio of the furfuryl alcohol to the methanol solution in the secondary furfuryl alcohol batching tank is 1:0.8-0.9, and the mass ratio of the furfuryl alcohol to the methanol solution in the tertiary furfuryl alcohol batching tank is 1:0.95-1.0.

[0016] Furthermore, the mass ratio of furfuryl alcohol to methanol solution in the primary furfuryl alcohol batching tank is 1:0.6.

[0017] Furthermore, the mass ratio of furfuryl alcohol to methanol solution in the secondary furfuryl alcohol batching tank is 1:0.85.

[0018] Furthermore, the mass ratio of furfuryl alcohol to methanol solution in the tertiary furfuryl alcohol batching tank is 1:0.95.

[0019] Furthermore, the mass fraction of the methanol solution is 50-60%.

[0020] Furthermore, the mass ratio of the flow rate of chlorine gas to the flow rate of furfuryl alcohol in the primary chlorination reaction, the secondary chlorination reaction and the tertiary chlorination reaction is 1:1.58-1.59.

[0021] Furthermore, the primary chlorination reaction, the secondary chlorination reaction, and the tertiary chlorination reaction are all terminated when the mass volume ratio of the added amount of furfuryl alcohol to the chlorination kettle is 2-4Kg:50L.

[0022] Preferably, the primary chlorination reaction, the secondary chlorination reaction, and the tertiary chlorination reaction are all terminated when the mass volume ratio of the added amount of furfuryl alcohol to the chlorination kettle is 3Kg:50L.

[0023] Furthermore, the cooling in the primary chlorination reaction, the secondary chlorination reaction and the tertiary chlorination reaction is all to below -10°C.

[0024] Preferably, the cooling in the primary chlorination reaction, the secondary chlorination reaction and the tertiary chlorination reaction is all to -10°C.

[0025] Furthermore, the reaction product after the three-stage chlorination reaction is transferred into a hydrolysis kettle, steam is introduced to start steaming, so that the by-products of the chlorination reaction, methyl chloride and methanol, are evaporated and recovered, and the crude ethyl maltol is released from the bottom of the hydrolysis kettle.

[0026] The technical effects achieved by the present invention are:

[0027] 1. The chlorination reaction mainly uses 50%-60% methanol solution as a solvent and is pumped into the chlorination kettle for freezing and cooling, and a mixed solution of furfuryl alcohol and methanol (content ≥ 99%) is prepared. When the temperature of the solvent in the chlorination kettle drops below -10°C, chlorine gas is introduced into the chlorination kettle at the same time and a mixed solution of furfuryl alcohol and methanol is added dropwise. During the chlorination reaction, the chlorine gas first contacts the methanol solution to react and produce a part of hydrochloric acid, and then contacts the furfuryl alcohol for reaction. Theoretically, the weight of chlorine gas required for the chlorination reaction is between 1.126-1.127 times the weight of furfuryl alcohol. In fact, the amount of chlorine gas used is 1.16-1.19 times that of furfuryl alcohol. The main reason is that chlorine gas reacts with water in the methanol solution to form a part of hydrochloric acid and a small part of chlorine gas is vented and escaped. After the original process chlorination reaction is completed, chlorine gas needs to be supplemented to continue to react with the unreacted furfuryl alcohol in the kettle. The amount of chlorine gas supplemented is completely determined by experience. The present invention does not require chlorine supplementation operation, uses chlorination graded reaction, adjusts the proportion of furfuryl alcohol according to different stages of the chlorination reaction, allows chlorine to fully react with furfuryl alcohol, thereby avoiding side reactions and improving the chlorination yield;

[0028] 2. The process of the present invention can reduce chlorine consumption and the amount of wastewater generated by tail gas treatment;

[0029] 3. The process of the present invention is conducive to the chlorination reaction. Furfuryl alcohol can fully react with chlorine, which avoids the situation that chlorine fails to react with furfuryl alcohol in time and reacts with methanol and water to affect the chlorination yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0031] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0032] Before further describing the specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below; it should also be understood that the terms used in the examples of the present invention are for describing specific embodiments rather than for limiting the scope of protection of the present invention.

[0033] When the embodiment gives a numerical range, it should be understood that, unless otherwise specified in the present invention, the two endpoints of each numerical range and any numerical value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used herein have the same meanings as those of ordinary skill in the art to which the present invention belongs.

[0034] It is worth noting that the raw materials used in the present invention are all common commercially available products, so their sources are not specifically limited.

[0035] As attached Figure 1 As shown: the first-level chlorination kettle, the second-level chlorination kettle, and the third-level chlorination kettle are connected in series with each other, the first-level chlorination kettle is correspondingly provided with a first-level furfuryl alcohol batching tank, the second-level chlorination kettle is correspondingly provided with a second-level furfuryl alcohol batching tank, and the third-level chlorination kettle is correspondingly provided with a third-level furfuryl alcohol batching tank.

[0036] Example 1 A chlorination graded reaction process

[0037] The following steps are involved:

[0038] Primary chlorination reaction: 50% of the methanol solution is transported to a primary chlorination kettle and cooled to -10°C, and furfuryl alcohol (the ratio of furfuryl alcohol to methanol is 1:0.5) and chlorine (the mass ratio of the flow rate of chlorine to the flow rate of furfuryl alcohol is 1:1.58) are added for reaction;

[0039] Secondary chlorination reaction: After the primary chlorination reaction is completed, the materials in the primary chlorination kettle are transported to the secondary chlorination kettle. After the secondary chlorination kettle is cooled to -10°C, furfuryl alcohol (the ratio of furfuryl alcohol to methanol is 1:0.8) and chlorine (the mass ratio of the flow rate of chlorine to the flow rate of furfuryl alcohol is 1:1.59) are added to react;

[0040] Three-stage chlorination reaction: After the two-stage chlorination reaction is completed, the material in the two-stage chlorination kettle is transported to the three-stage chlorination kettle, cooled to -10°C, and then furfuryl alcohol (the ratio of furfuryl alcohol to methanol is 1:0.95) and chlorine (the mass ratio of the flow rate of chlorine and the flow rate of furfuryl alcohol is 1:1.59) are added to react to terminate the three-stage chlorination reaction and obtain a chlorinated product.

[0041] Example 2 A chlorination graded reaction process

[0042] The following steps are involved:

[0043] Primary chlorination reaction: 60% methanol solution is transported to a primary chlorination kettle and cooled to -10°C, and furfuryl alcohol (the ratio of furfuryl alcohol to methanol is 1:0.7) and chlorine (the mass ratio of the flow rate of chlorine to the flow rate of furfuryl alcohol is 1:1.59) are added for reaction;

[0044] Secondary chlorination reaction: After the primary chlorination reaction is completed, the materials in the primary chlorination kettle are transported to the secondary chlorination kettle. After the secondary chlorination kettle is cooled to -10°C, furfuryl alcohol (the ratio of furfuryl alcohol to methanol is 1:0.9) and chlorine (the mass ratio of the flow rate of chlorine to the flow rate of furfuryl alcohol is 1:1.58) are added to react;

[0045] Three-stage chlorination reaction: After the two-stage chlorination reaction is completed, the material in the two-stage chlorination kettle is transported to the three-stage chlorination kettle, cooled to -10°C, and then furfuryl alcohol (the ratio of furfuryl alcohol to methanol is 1:1.0) and chlorine (the mass ratio of the flow rate of chlorine and the flow rate of furfuryl alcohol is 1:1.59) are added to react to terminate the three-stage chlorination reaction and obtain a chlorinated product.

[0046] Example 3 A chlorination graded reaction process

[0047] The following steps are involved:

[0048] Primary chlorination reaction: 55% methanol solution is transported to a primary chlorination reactor and cooled to -10°C, and furfuryl alcohol (the ratio of furfuryl alcohol to methanol is 1:0.6) and chlorine (the mass ratio of the flow rate of chlorine to the flow rate of furfuryl alcohol is 1:1.59) are added for reaction;

[0049] Secondary chlorination reaction: After the primary chlorination reaction is completed, the materials in the primary chlorination kettle are transported to the secondary chlorination kettle. After the secondary chlorination kettle is cooled to -10°C, furfuryl alcohol (the ratio of furfuryl alcohol to methanol is 1:0.85) and chlorine (the mass ratio of the flow rate of chlorine to the flow rate of furfuryl alcohol is 1:1.58) are added to react;

[0050] Three-stage chlorination reaction: After the two-stage chlorination reaction is completed, the material in the two-stage chlorination kettle is transported to the three-stage chlorination kettle, cooled to -10°C, and then furfuryl alcohol (the ratio of furfuryl alcohol to methanol is 1:0.95) and chlorine (the mass ratio of the flow rate of chlorine and the flow rate of furfuryl alcohol is 1:1.59) are added to react to terminate the three-stage chlorination reaction and obtain a chlorinated product.

[0051] Comparative Example 1

[0052] The chlorination step disclosed in Chinese patent CN102391229B is adopted, that is, 55% methanol solution is continuously injected into the chlorination reaction kettle at a speed of 100 L / h, and the chlorination reaction kettle is turned on for external circulation refrigeration. When the temperature of the methanol solution drops to -10°C, furfuryl alcohol is continuously added to the chlorination reaction kettle at a rate of 60 L / h, and chlorine gas is continuously introduced at a rate of 30 kg / h until the reaction is completed to obtain a chlorinated product.

[0053] Comparative Example 2

[0054] The difference from Example 3 is that the volume fraction of the methanol solution is 85%, and the other steps are the same as Example 3.

[0055] Performance data:

[0056] 1. Chlorination product yield:

[0057] Detection method: After the chlorination reaction is completed, the methanol solution is recovered by distillation through the next process of chlorination hydrolysis. The chlorination hydrolysis temperature is between 85 and 95°C for molecular rearrangement reaction to generate ethyl maltol, and then ethyl maltol is separated by sublimation through physical reaction. The sublimation is condensed in a condenser and is in liquid state. It is transferred to a low-temperature freezing kettle for freezing and crystallization of ethyl maltol, and then dried by a centrifuge and weighed. Then the yield of the chlorinated product is further calculated by weighing and measuring. The detection results are shown in Table 1 below.

[0058] Table 1

[0059] Chlorination product yield% Example 1 74.5 Example 2 74.6 Example 3 74.9 Comparative Example 1 68.3 Comparative Example 2 71.6

[0060] According to the test results in Table 1, the yields of the chlorinated products finally obtained by the methods of Examples 1-3 of the present invention, i.e., the chlorination classification method, are all above 74%, while the yield of the chlorinated product in Comparative Example 1 using the method disclosed in the prior art is significantly reduced to about 68%. In Comparative Example 2, changing the volume fraction of methanol will also affect the yield of the chlorinated product, making the yield lower than that of the embodiment.

[0061] 2. Chlorine consumption

[0062] The chlorine consumption is the amount of chlorine used in the chlorination reaction, and what is detected is the weight of chlorine consumed by 500 kg of furfuryl alcohol.

[0063] Testing method: Weighing and measuring by weighing scale, the test results are shown in Table 2 below

[0064] Table 2

[0065] Chlorine consumption Example 1 563Kg Example 2 564Kg Example 3 563.5Kg Comparative Example 1 582Kg Comparative Example 2 572Kg

[0066] According to the test results in Table 2, the chlorine consumption detected by the method of Examples 1-3 of the present invention, i.e., the chlorination classification method, is significantly lower than that of Comparative Example 1 (the method disclosed in the prior art) and Comparative Example 2, indicating that the method provided by the present invention can reduce chlorine consumption and the amount of sewage generated by tail gas treatment.

[0067] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A chlorination graded reaction process, characterized in that: The following steps are involved: Primary chlorination reaction: transport the methanol solution to the primary chlorination kettle for cooling, add furfuryl alcohol and chlorine gas for reaction; Secondary chlorination reaction: After the primary chlorination reaction is completed, the materials in the primary chlorination kettle are transported to the secondary chlorination kettle. After the secondary chlorination kettle is cooled down, furfuryl alcohol and chlorine are added to react; Tertiary chlorination reaction: After the secondary chlorination reaction is completed, the materials in the secondary chlorination kettle are transported to the tertiary chlorination kettle, and after cooling, furfuryl alcohol and chlorine are added to react to end the tertiary chlorination reaction; Among them, the primary chlorination kettle, the secondary chlorination kettle, and the tertiary chlorination kettle are connected in series, the primary chlorination kettle is correspondingly provided with a primary furfuryl alcohol batching tank, the secondary chlorination kettle is correspondingly provided with a secondary furfuryl alcohol batching tank, and the tertiary chlorination kettle is correspondingly provided with a tertiary furfuryl alcohol batching tank; Taking the methanol solution in the primary chlorination reactor as a reference, the mass ratio of the furfuryl alcohol to the methanol solution in the primary furfuryl alcohol batching tank is 1:0.5-0.7, the mass ratio of the furfuryl alcohol to the methanol solution in the secondary furfuryl alcohol batching tank is 1:0.8-0.9, and the mass ratio of the furfuryl alcohol to the methanol solution in the tertiary furfuryl alcohol batching tank is 1:0.95-1.

0.

2. The chlorination graded reaction process according to claim 1, characterized in that: The mass ratio of furfuryl alcohol to methanol solution in the primary furfuryl alcohol batching tank is 1:0.

6.

3. The chlorination graded reaction process according to claim 1, characterized in that: The mass ratio of furfuryl alcohol to methanol solution in the secondary furfuryl alcohol batching tank is 1:0.

85.

4. The chlorination graded reaction process according to claim 1, characterized in that: The mass ratio of furfuryl alcohol to methanol solution in the tertiary furfuryl alcohol batching tank is 1:0.

95.

5. The chlorination graded reaction process according to claim 1, characterized in that: The mass fraction of the methanol solution is 50-60%.

6. The chlorination graded reaction process according to claim 1, characterized in that: The mass ratio of the flow rate of chlorine gas to the flow rate of furfuryl alcohol in the primary chlorination reaction, the secondary chlorination reaction and the tertiary chlorination reaction is 1:1.58-1.

59.

7. The chlorination graded reaction process according to claim 1, characterized in that: The primary chlorination reaction, the secondary chlorination reaction and the tertiary chlorination reaction are all completed when the mass volume ratio of the added amount of furfuryl alcohol to the chlorination kettle is 2-4Kg:50L.

8. The chlorination graded reaction process according to claim 7, characterized in that: The primary chlorination reaction, the secondary chlorination reaction and the tertiary chlorination reaction are all completed when the mass volume ratio of the added amount of furfuryl alcohol to the chlorination kettle is 3Kg:50L.

9. The chlorination graded reaction process according to claim 1, characterized in that: The temperature reduction in the primary chlorination reaction, the secondary chlorination reaction and the tertiary chlorination reaction is all to below -10°C.

10. The chlorination graded reaction process according to claim 9, characterized in that: The temperature reduction in the primary chlorination reaction, the secondary chlorination reaction and the tertiary chlorination reaction is all to -10°C.

Images