阅读说明：本技术 硝酸异辛酯联产硫镁肥的工艺方法 (Process method for co-producing sulfur magnesium fertilizer by isooctyl nitrate ) 是由 黄占凯 董广前 张晓行 张春丽 王会 赵洪 赵迎秋 李庚� 吴巍 于 2020-12-30 设计创作，主要内容包括：本发明属于硝酸异辛酯联产硫镁肥的工艺方法。该工艺方法包括：将异辛醇与硝酸和硫酸的混合酸按比例在一定温度下于微通道反应器中进行化学反应,然后将反应产物进行静置,分出上层轻相经净化干燥得到硝酸异辛酯产品,分出下层重相废硫酸并采用镁氧中和剂中和到中性,经陈化筛分得到硫镁肥。本发明方法采用镁氧中和剂中和硝酸异辛酯生产过程产生的废硫酸生产硫镁肥,即可解决硝酸异辛酯生产废酸的环保问题,同时也可降低硫镁肥的生产成本,解决了现有硝酸异辛酯规模化生产的制约瓶颈和环保问题。(The invention belongs to a process method for co-producing a sulfur magnesium fertilizer by isooctyl nitrate. The process method comprises the following steps: carrying out chemical reaction on isooctyl alcohol and mixed acid of nitric acid and sulfuric acid in a microchannel reactor at a certain temperature according to a certain proportion, standing a reaction product, separating out an upper layer light phase, purifying and drying to obtain an isooctyl nitrate product, separating out a lower layer heavy phase waste sulfuric acid, neutralizing to neutrality by adopting a magnesium-oxygen neutralizer, and aging and screening to obtain the magnesium sulfate fertilizer. The method of the invention adopts the magnesia neutralizer to neutralize the waste sulfuric acid generated in the production process of the isooctyl nitrate to produce the sulfur-magnesium fertilizer, thereby solving the environmental protection problem of the waste acid generated in the production process of the isooctyl nitrate, reducing the production cost of the sulfur-magnesium fertilizer, and solving the restriction bottleneck and environmental protection problems of the existing large-scale production of the isooctyl nitrate.)

1. A process method for co-producing a sulfur magnesium fertilizer by isooctyl nitrate is characterized by comprising the following steps: and (2) carrying out chemical reaction on isooctyl alcohol, mixed acid of nitric acid and sulfuric acid in a microchannel reactor at the temperature of 10-40 ℃ for 10-50 seconds, standing the reaction product, separating out an upper layer light phase, purifying and drying to obtain an isooctyl nitrate product, separating out a lower layer heavy phase waste sulfuric acid, diluting with water, slowly adding a magnesium oxide neutralizer under stirring, fully stirring to be neutral, aging, and screening to obtain the magnesium sulfate fertilizer.

2. The method according to claim 1, wherein the mass ratio of the nitric acid to the sulfuric acid is 1: 3.

3. the method according to claim 1, wherein the mass ratio of isooctyl alcohol to mixed acid is 1: 2.

4. the process of claim 1 wherein the magnesium oxide neutralizing agent is magnesium hydroxide, basic magnesium carbonate, magnesium oxide or a mixture thereof.

5. The method according to claim 1, wherein the aging time is 20 to 28 hours.

Technical Field

The invention relates to production of isooctyl nitrate as diesel cetane number improver, in particular to a process method for co-producing a sulfur magnesium fertilizer by isooctyl nitrate.

Background

Isooctyl nitrate has been widely used for improving the cetane number of diesel oil as an excellent diesel oil cetane number improver. Isooctyl nitrate is generally produced by an isooctanol nitration method, nitric acid and isooctanol are subjected to nitration reaction in a reactor in the presence of a concentrated sulfuric acid catalyst, and then catalyst sulfuric acid is separated to obtain isooctyl nitrate, wherein the sulfuric acid is used as the catalyst and is not consumed theoretically. The reaction is a rapid heterogeneous exothermic reaction with a heat of reaction of about 91 kJ/moL. In the reaction process, raw material isooctanol and product isooctyl nitrate with lighter density are in an upper organic phase, and nitric acid, sulfuric acid and water with heavier density are in a lower acid phase, so that potential safety hazards are easily caused due to the non-uniformity of a reaction system, and the method is also a key influence factor for improving the production efficiency. The traditional production process of isooctyl nitrate adopts a stirring reaction kettle to carry out intermittent production, because the reaction is violent and simultaneously releases a large amount of reaction heat, if the reaction heat can not be removed out of the reaction system in time, the reaction system will increase the temperature instantly, the materials will overflow from the reaction kettle and the nitric acid is decomposed along with the continuous addition of reactants to generate toxic nitrogen oxide gas diffusion, and simultaneously the occurrence of side reaction causes the increase of impurities which are difficult to be separated in the products and even the accumulation of high heat to cause the combustion or explosion of the materials. Because the stirring reaction kettle has inherent difficulties of concentrated feeding, difficult instant diffusion and the like, and causes the local occurrence of reaction at high temperature, the isooctyl nitrate product produced by adopting the method has lower purity and difficult quality guarantee.

In recent years, due to the application of a microchannel reaction process, the reaction safety of isooctyl nitrate is greatly improved. However, concentrated sulfuric acid is used as a catalyst in the production of isooctyl nitrate, waste sulfuric acid separated after the reaction contains a small amount of nitric acid, isooctanol and other organic impurities, the material is extremely unstable due to the existence of the small amount of nitric acid and isooctanol, the material can continuously react and release toxic nitrogen oxide gas along with environmental change, and meanwhile, the temperature rises at any time due to the continuous reaction of residual nitric acid and isooctanol and the heat release, so that a plurality of safety and environmental protection problems and uncertainty of the production process are brought to temporary storage and recycling. Meanwhile, because the raw materials bring the accumulation of impurities, the product quality is influenced by direct recycling, so that the waste sulfuric acid is difficult to directly return to the synthesis process for recycling. Therefore, the reaction by-product waste sulfuric acid generally needs high-temperature distillation and purification for recycling, the high-temperature distillation and purification cannot accept the cost and the production equipment requirements are very strict. Therefore, the failure of proper treatment of a large amount of waste sulfuric acid is also an important restriction factor influencing the large-scale production of isooctyl nitrate.

Chinese patent 200910218792.9 discloses a continuous production process of isooctyl nitrate. Sending mixed acid and alcohol mixed by industrial fuming nitric acid and concentrated sulfuric acid into a micro-tube type reactor for reaction, wherein the retention time of the mixed acid and the alcohol in the reactor is less than 1000 milliseconds, the reaction temperature is 40-70 ℃, the reaction pressure is 0.1-5 MPa, and the flow ratio of the mixed acid to the alcohol is 0.5-2: 1; the product continuously flows into an alcohol acid separating tank from the outlet of the micro-tube reactor, and enters a crude product tank after an acid layer is removed; (3) and (3) washing the crude product with water, washing with alkali, washing with water again to be neutral, and removing trace moisture through a drying unit to obtain a final product. The patent does not specify the treatment of the spent sulfuric acid.

Chinese patent 201410082963.0 discloses a method for synthesizing isooctyl nitrate in a continuous flow reactor. Which comprises reacting H₂SO₄-HNO₃The mixture flows in a flow reactor and isooctyl alcohol flows into the flow reactor,thereby reacting said isooctanol with said H₂SO₄-HNO₃Mixing the mixed acid, generating a reaction mixture flow flowing in the reactor, and simultaneously maintaining the reaction mixture flow flowing in the reactor at-10 ℃ to 35 ℃ for reaction, wherein the residence time of the reaction mixture flow in the flow reactor is 5-40 seconds, H₂SO₄-HNO₃H in the mixture₂SO₄The concentration is 85-95%. Characterized in that the flow of reactants/reaction products in a glass, glass-ceramic or ceramic flow reactor causes the flow of said reaction/reaction products in a channel having a variable shape along its entire length, causing mixing throughout the residence time, with a conversion of 100% and a yield greater than or equal to 99.5%. Collecting reacted H₂SO₄And in H₂SO₄-HNO₃Reusing the collected H in the mixed acid₂SO₄. This patent suggests the reuse of the recovered sulfuric acid, but does not describe in detail the specific method of reuse of the waste sulfuric acid or mixed acid after the reaction.

Chinese patent application No. 201711305777.9 discloses a method for producing isooctyl nitrate. The method mainly comprises the following steps: metering and conveying nitric-sulfuric mixed acid and isooctyl alcohol raw materials through reliable and stable feeding equipment, mixing and reacting two raw materials in a micro mixer, carrying out heat exchange on the mixed materials in a micro heat exchanger, further reacting in a single-tube reactor, separating acidic isooctyl nitrate and waste acid from reaction products in an automatic separator, quickly carrying out water washing, alkali washing and water washing processes in a series of micro mixers, and finally drying or standing to remove water in the acidic isooctyl nitrate to obtain the product isooctyl nitrate. The patent does not describe a method for treating waste acid.

In conclusion, the large-scale manufacturing process of the isooctyl nitrate is not perfect, particularly, the waste sulfuric acid which is a byproduct influencing the environment is not reasonably solved all the time, and the large-scale production of the isooctyl nitrate is severely restricted.

Disclosure of Invention

Aiming at the problems in the prior art, the invention not only carries out full experimental research on the microchannel reaction process, but also carries out targeted comprehensive utilization experimental research on waste sulfuric acid generated in the reaction process in the process of preparing the isooctyl nitrate product by the reaction of isooctyl alcohol and nitric acid, and creatively provides a process method for the isooctyl nitrate co-production of the magnesium sulfate fertilizer, which has low cost, simple process, safety and environmental protection.

The invention is realized by the following technical scheme:

a process method for co-producing a sulfur magnesium fertilizer by isooctyl nitrate comprises the following steps: carrying out nitration and esterification reaction on isooctyl alcohol, mixed acid of nitric acid and sulfuric acid in a microchannel reactor at the temperature of 10-40 ℃ for 10-50 seconds, standing the reaction product, separating an upper layer light phase, purifying and drying to obtain an isooctyl nitrate product, separating a lower layer heavy phase waste sulfuric acid, slowly adding a magnesium oxide neutralizer under stirring, fully stirring to be neutral, aging for at least 24 hours, and screening to obtain the magnesium sulfate fertilizer.

In the above technical solution, the mass ratio of the nitric acid to the sulfuric acid is preferably 1: 3.

the mass ratio of the isooctyl alcohol to the mixed acid is preferably 1: 2.

the magnesium oxide neutralizer is preferably magnesium hydroxide, magnesium carbonate, magnesium oxide or a mixture thereof.

In the above technical scheme, the magnesium oxide neutralizer is preferably magnesium hydroxide, magnesium carbonate, magnesium oxide or a mixture thereof.

Adding magnesium oxide neutralizer into the waste sulfuric acid, and fully stirring the mixture to be neutral, wherein the aging time needs to reach 24 hours. Too short an aging time may result in incomplete reaction of weakly basic substances in the magnesia neutralizer, and a longer aging time has no influence on the product quality and stability, but affects the production efficiency, and preferably aging is carried out for 24-26 hours.

Carrying out nitration and esterification reaction on isooctyl alcohol and mixed acid of nitric acid and sulfuric acid in a microchannel reactor, wherein the nitric acid at least reaches the theoretical amount in order to ensure that the isooctyl alcohol is consumed as much as possible.

The reaction temperature and residence time should be as close to complete as possible. The reaction temperature is increased, the residence time is shortened, but the requirement of overhigh reaction temperature on the heat dissipation efficiency is overhigh, and the reaction is easy to lose control to cause danger. If the reaction temperature is too low or the retention time is too short, incomplete reaction is caused, and unreacted substances in the separated product and the waste sulfuric acid are increased, so that the product purity is poor and the stability of the waste sulfuric acid is poor. The reaction temperature is preferably 25 ℃ and maintained for 30 seconds.

The addition amount of the catalyst sulfuric acid also has a great influence on the reaction speed, and adding too little sulfuric acid will slow the reaction, and although the reaction speed can be increased by increasing the reaction temperature, the safety risk is increased. Too much sulfuric acid addition will increase the amount of sulfuric acid used and produce more waste sulfuric acid.

The sulfur-magnesium fertilizer belongs to one of the main fertilizer varieties except nitrogen-phosphorus-potassium fertilizer, and is widely applied at home and abroad. The magnesium sulfate fertilizer is usually prepared by directly reacting magnesium oxide with sulfuric acid. According to the technical scheme, the magnesium oxide neutralizer is adopted to neutralize waste sulfuric acid generated in the production process of isooctyl nitrate to produce the magnesium sulfate fertilizer, so that the environmental protection problem of waste acid generated in the production of isooctyl nitrate can be solved, the production cost of the magnesium sulfate fertilizer can be reduced, and the restriction bottleneck and environmental protection problems of the existing large-scale production of isooctyl nitrate are solved.

Drawings

FIG. 1 is a process flow chart of the process method for co-producing the magnesium sulfate fertilizer by isooctyl nitrate.

Detailed Description

The technical scheme and the technical effect of the invention are further explained by combining the specific embodiments.

Example 1

Mixing nitric acid and sulfuric acid according to the weight ratio of 1:3 to prepare mixed acid, respectively metering the mixed acid and isooctanol (the weight ratio of the isooctanol to the mixed acid is 1:2), simultaneously pumping the mixed acid and the isooctanol into a microchannel reactor, keeping the total speed of reactants pumped into the microchannel reactor to be 5L/h, and adjusting the flow speed of cooling water to ensure that the temperature of the mixed materials in the reactor is 25 ℃. Collecting reaction finished liquid at the outlet of the reactor, guiding the reaction finished liquid into a knockout, standing, separating out an upper layer light phase, purifying and drying to obtain an isooctyl nitrate product, and measuring the main content to be 99.6% by using a gas chromatography.

Diluting the lower layer heavy phase waste sulfuric acid with water, slowly adding industrial-grade magnesium hydroxide under stirring, fully stirring until the pH is neutral 7, aging for 24 hours, then screening to obtain the magnesium sulfate fertilizer, detecting according to a method specified by HG/T2680-2017, wherein the Mg content is 17.28%, and the magnesium sulfate fertilizer meets the standard of the magnesium sulfate fertilizer for II-class fertilizers.

Example 2

Mixing nitric acid and sulfuric acid according to the weight ratio of 1:3 to prepare mixed acid, respectively metering the mixed acid and isooctanol (the weight ratio of the isooctanol to the mixed acid is 1:2), simultaneously pumping the mixed acid and the isooctanol into a microchannel reactor, keeping the total speed of reactants pumped into the microchannel reactor to be 1L/h, and adjusting the flow speed of cooling water to ensure that the temperature of the mixed materials in the reactor is 10 ℃. Collecting reaction finished liquid at the outlet of the reactor, guiding the reaction finished liquid into a knockout, standing, separating out an upper layer light phase, purifying and drying to obtain an isooctyl nitrate product, and measuring the main content to be 99.5% by using a gas chromatography.

Diluting the lower layer heavy phase waste sulfuric acid with water, slowly adding light magnesium oxide under stirring, fully stirring until the pH is neutral (7), aging for 24 hours, then screening to obtain the magnesium sulfate fertilizer, detecting according to a method specified by HG/T2680-2017, wherein the Mg content is 17.15%, and the standard of the magnesium sulfate fertilizer for the II-type fertilizer is met.

Example 3

Mixing nitric acid and sulfuric acid according to the weight ratio of 1:3 to prepare mixed acid, respectively metering the mixed acid and isooctanol (the weight ratio of the isooctanol to the mixed acid is 1:2), simultaneously pumping the mixed acid and the isooctanol into a microchannel reactor, keeping the total speed of reactants pumped into the microchannel reactor to be 10L/h, and adjusting the flow speed of cooling water to ensure that the temperature of the mixed materials in the reactor is 40 ℃. Collecting reaction finished liquid at the outlet of the reactor, guiding the reaction finished liquid into a knockout, standing, separating out an upper layer light phase, purifying and drying to obtain an isooctyl nitrate product, and measuring the main content to be 99.7% by using a gas chromatography.

Diluting the lower layer heavy phase waste sulfuric acid with water, slowly adding basic magnesium carbonate under stirring, fully stirring until the pH is neutral (7), aging for 24 hours, then screening to obtain the magnesium sulfate fertilizer, detecting according to a method specified by HG/T2680-2017, wherein the Mg content is 16.91 percent and accords with the standard of the magnesium sulfate fertilizer for II-class fertilizers.

Example 4

Mixing nitric acid and sulfuric acid according to the weight ratio of 1:3 to prepare mixed acid, respectively metering the mixed acid and isooctanol (the weight ratio of the isooctanol to the mixed acid is 1:2), simultaneously pumping the mixed acid and the isooctanol into a microchannel reactor, keeping the total speed of reactants pumped into the microchannel reactor to be 5L/h, and adjusting the flow speed of cooling water to ensure that the temperature of the mixed materials in the reactor is 25 ℃. Collecting reaction finished liquid at the outlet of the reactor, guiding the reaction finished liquid into a knockout, standing, separating out an upper layer light phase, purifying and drying to obtain an isooctyl nitrate product, and measuring the main content to be 99.7% by using a gas chromatography.

Diluting the lower layer heavy phase waste sulfuric acid with water, slowly adding a mixture of industrial magnesium hydroxide, basic magnesium carbonate and magnesium oxide (MgOH/MgCO3/MgO is 1:1:1 in weight ratio) under stirring, fully stirring until the pH is neutral 7, aging for 24 hours, screening to obtain the magnesium sulfate fertilizer, detecting according to a method specified by HG/T2680-2017, wherein the Mg is 16.82 percent and meets the standard of the magnesium sulfate fertilizer for II fertilizers.

Comparative example 1

Mixing nitric acid and sulfuric acid according to the weight ratio of 1:3 to prepare mixed acid, respectively metering the mixed acid and isooctanol (the weight ratio of the isooctanol to the mixed acid is 1:2), simultaneously pumping the mixed acid and the isooctanol into a microchannel reactor, keeping the total speed of reactants pumped into the microchannel reactor to be 5L/h, and adjusting the flow speed of cooling water to ensure that the temperature of the mixed materials in the reactor is 25 ℃. Collecting reaction finished liquid at the outlet of the reactor, guiding the reaction finished liquid into a knockout, standing, separating out an upper layer light phase, purifying and drying to obtain an isooctyl nitrate product, and measuring the main content to be 99.7% by using a gas chromatography. Separating and recovering the lower heavy phase waste sulfuric acid for one-time circulating reaction.

And recycling the lower heavy phase waste sulfuric acid and supplementing a small amount of fresh sulfuric acid and nitric acid to prepare mixed acid (the weight ratio of the nitric acid to the sulfuric acid is 1:3), respectively metering the mixed acid and isooctanol (the weight ratio of the isooctanol to the mixed acid is 1:2), simultaneously pumping the mixed acid and the isooctanol into a microchannel reactor, keeping the total speed of reactants pumped into the microchannel reactor to be 5L/h, and adjusting the flow speed of cooling water to ensure that the temperature of the mixed materials in the reactor is 25 ℃. Collecting reaction finished liquid at the outlet of the reactor, introducing the reaction finished liquid into a knockout, standing, separating out an upper layer light phase, purifying and drying to obtain an isooctyl nitrate product, and measuring the main content to be 99.1% by using a gas chromatography. And (3) standing the primary circulation reaction completion liquid by the same method, separating lower heavy phase waste sulfuric acid for secondary circulation reaction, purifying and drying upper light phase to obtain an isooctyl nitrate product, and measuring the main content to be 98.8% by using a gas chromatography. Recycling the recovered sulfuric acid for use in the synthesis of isooctyl nitrate results in a reduction in product quality.