CN117903857A - Sulfur-free odorizing agent ingredient preparation process - Google Patents

Abstract

The invention discloses a sulfur-free odorizing agent ingredient preparation process, which belongs to the technical field of odorizing agents and comprises the following steps: the following raw materials in percentage by mass are prepared: 38% of methyl acrylate, 2% of 2-ethyl-3-methyl pyrazine, 1.7-1.9% of amide compounds, 1% of synergistic agent, 0.1-0.3% of composite stabilizer and the balance of ethyl acrylate, wherein the sum of the mass percentages of the raw materials is 100%; adding an amide compound and a synergist into a mixer, and stirring and mixing to obtain a first component; adding methyl acrylate, 2-ethyl-3-methyl pyrazine and ethyl acrylate into a mixer, and stirring and mixing to obtain a component II; the component one is added into the component two, and the composite stabilizer is added after stirring and mixing for 3-5min, and the sulfur-free odorizing agent is obtained after continuous stirring.

Description

Preparation process of sulfur-free odorant ingredients

Technical Field

The invention belongs to the technical field of odorants, and in particular relates to a process for preparing ingredients for a sulfur-free odorant.

Background technique

Gas odorization is one of the active safety measures of gas companies and has received great attention. At present, the commonly used odorants are tetrahydrothiophene (THT) and mercaptan mixture (TBM). Both odorants contain sulfur (S) elements. When burned, they will produce _SO2 gas, which affects the quality of gas combustion and the product quality of some industrial users, while polluting the environment. As people's requirements for clean energy continue to increase, the control of sulfur content in natural gas continues to strengthen, and the use of sulfur-free odorants has become a future development trend. Sulfur-free odorants have the same function as conventional odorants. They are a substance that can play a warning role, have a strong ability to mix with natural gas, are in a gaseous state in the gas pipeline, are non-corrosive, and will not harm the human body and the environment when burned.

Currently, the most widely used sulfur-free odorant is a colorless transparent liquid with a pungent odor. Its main raw materials are methyl acrylate and ethyl acrylate, with a content of more than 95%. However, methyl acrylate and ethyl acrylate are sensitive to light and heat, which leads to more stringent storage conditions for sulfur-free odorants. When exposed to heat or light, the stability of the sulfur-free odorant deteriorates, resulting in a decrease in the content of effective components and product deterioration.

Summary of the invention

The purpose of the present invention is to provide a process for preparing sulfur-free odorant ingredients, so as to solve the problem of harsh storage conditions of existing sulfur-free odorants.

The purpose of the present invention can be achieved through the following technical solutions:

The process for preparing the sulfur-free odorant ingredients comprises the following steps:

S1. Prepare the following raw materials in percentage by mass: 38% methyl acrylate, 2-ethyl-3-methylpyrazine, 1.7-1.9% amide compound, 1% synergist, 0.1-0.3% composite stabilizer, and the balance is ethyl acrylate. The total percentage by mass of the above raw materials is 100%;

S2, adding the amide compound and the synergist into a mixer, stirring at a speed of 300-360 r/min for 10-15 min to obtain component 1;

S3, adding methyl acrylate, 2-ethyl-3-methylpyrazine and ethyl acrylate into a mixer, stirring and mixing at a speed of 200-300 r/min for 15-20 min to obtain component 2;

S4. Add component 1 to component 2, stir and mix at a speed of 200-300 r/min for 3-5 minutes, then add the composite stabilizer, and continue stirring for 5-10 minutes to obtain a sulfur-free odorizer.

Furthermore, during the stirring process in step S3, the temperature is controlled to be less than or equal to 10°C.

Among them, the composite stabilizer is compounded by 4,6-dinitro-2-sec-butylphenol and piperidine free radical type dual inhibitor.

Furthermore, the composite stabilizer is prepared by mixing 4,6-dinitro-2-sec-butylphenol and piperidine free radical type dual inhibitor in a mass ratio of 1:1-5.

Further, the piperidine free radical type dual polymerization inhibitor is obtained by the following steps:

Add the hydroxylamine aqueous solution into the reactor, then add the ethanol solution of TEMPO methyl methacrylate, stir and react at room temperature for 24 hours, and remove water by rotary evaporation to obtain a piperidine free radical type dual polymerization inhibitor, the molar ratio of hydroxylamine to TEMPO methyl methacrylate is 1:2, the mass fraction of the hydroxylamine aqueous solution is 50%, and the ethanol solution of TEMPO methyl methacrylate is composed of TEMPO methyl methacrylate and anhydrous ethanol in a dosage ratio of 1g:5-10mL. Hydroxylamine and TEMPO methyl methacrylate are used as raw materials, and the amino group is reacted with the methyl acrylate group to obtain the piperidine free radical type dual polymerization inhibitor.

Furthermore, the synergist is 3-methylindole.

Furthermore, the amide compound is one of N,N-dimethylformamide and N,N-dimethylacetamide.

Beneficial effects of the present invention:

1. The present invention provides a process for preparing sulfur-free odorant ingredients. The odorant obtained by the process does not contain sulfur element, will not corrode equipment pipelines, meets environmental protection standards, and has a high odor level and good stability. It has very good application value as a combustible gas leak warning additive.

2. The present invention introduces a specific composition of 3-methylindole into the traditional sulfur-free odorizer composed of methyl acrylate and ethyl acrylate. The 3-methylindole not only has good compatibility with the components of the sulfur-free odorizer, but also has a foul odor itself, which can greatly improve the odor level of the sulfur-free odorizer. In addition, the presence of conjugated double bonds in 3-methylindole has a certain absorption effect on ultraviolet rays and can work together with the composite stabilizer to improve the light stability of the odorizer.

3. The present invention introduces a composite stabilizer into the sulfur-free odorant composed of traditional methyl acrylate and ethyl acrylate, which is specifically compounded by 4,6-dinitro-2-sec-butylphenol and a piperidine free radical type dual polymerization inhibitor, wherein 4,6-dinitro-2-sec-butylphenol is a phenolic polymerization inhibitor, and the piperidine free radical type dual polymerization inhibitor has the advantages of both hydroxylamine polymerization inhibitor and piperidine free radical polymerization inhibitor, and contains hydroxylamine and tetramethylpiperidine-1-oxyl free radical in its molecular structure. The composite stabilizer has a good polymerization inhibition effect on methyl acrylate and ethyl acrylate, especially 4,6-dinitro-2-sec-butylphenol has a high electrophilicity, which can attract the 0-H electrons on the hydroxylamine group of the piperidine free radical type dual polymerization inhibitor to approach hydrogen atoms, thereby reducing the electron density of oxygen atoms, weakening the 0-H bond, and easily releasing protons, so that the rate of generating nitroxide free radicals is accelerated, so that the composite stabilizer can play a good synergistic role in inhibiting polymerization reactions, which is beneficial to improving the light and heat stability of the odorant.

Detailed ways

The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Embodiment 1:

The process for preparing the sulfur-free odorant ingredients comprises the following steps:

S1. Prepare the following raw materials in percentage by mass: 38 kg methyl acrylate, 2 kg 2-ethyl-3-methylpyrazine, 1.7 kg N,N-dimethylformamide, 1 kg 3-methylindole, 0.1 kg composite stabilizer, and 57.2 kg ethyl acrylate;

S2, adding N,N-dimethylformamide and 3-methylindole into a mixer, stirring at a speed of 300 r/min for 10 min to obtain component 1;

S3, adding methyl acrylate, 2-ethyl-3-methylpyrazine and ethyl acrylate into a mixer, stirring and mixing at a speed of 200 r/min for 15 min, controlling the temperature to be less than or equal to 10° C. during the stirring process, to obtain component 2;

S4. Add component 1 to component 2, stir and mix at a speed of 200 r/min for 3 minutes, then add the composite stabilizer, and continue stirring for 5 minutes to obtain a sulfur-free odorizer.

The composite stabilizer is prepared by mixing 4,6-dinitro-2-sec-butylphenol and piperidine free radical type dual inhibitor in a ratio of 1:1 by mass.

The piperidine free radical type dual polymerization inhibitor is obtained by the following steps:

3.3 kg of 50 wt% hydroxylamine aqueous solution was added to the reactor, and then a mixed solution consisting of 24.2 kg of TEMPO methyl methacrylate and 242 L of anhydrous ethanol was added, and the mixture was stirred and reacted at room temperature for 24 hours. The water was removed by rotary evaporation to obtain a piperidine free radical type dual inhibitor.

Embodiment 2:

The process for preparing the sulfur-free odorant ingredients comprises the following steps:

S1. Prepare the following raw materials in percentage by mass: 38 kg methyl acrylate, 2 kg 2-ethyl-3-methylpyrazine, 1.8 kg N,N-dimethylacetamide, 1 kg 3-methylindole, 0.2 kg composite stabilizer, and 57 kg ethyl acrylate;

S2, adding N,N-dimethylacetamide and 3-methylindole into a mixer, stirring at a speed of 320 r/min for 13 min, to obtain component 1;

S3, adding methyl acrylate, 2-ethyl-3-methylpyrazine and ethyl acrylate into a mixer, stirring and mixing at a speed of 250 r/min for 18 min, controlling the temperature to be less than or equal to 10° C. during the stirring process, to obtain component 2;

S4. Add component 1 to component 2, stir and mix at a speed of 260 r/min for 4 minutes, then add the composite stabilizer, and continue stirring for 8 minutes to obtain a sulfur-free odorizer.

The composite stabilizer is prepared by mixing 4,6-dinitro-2-sec-butylphenol and piperidine free radical type dual inhibitor in a ratio of 1:3 by mass.

The piperidine free radical type dual polymerization inhibitor is obtained by the following steps:

3.3 kg of 50 wt% hydroxylamine aqueous solution was added to the reactor, and then a mixed solution consisting of 24.2 kg of TEMPO methyl methacrylate and 121 L of anhydrous ethanol was added, and the mixture was stirred and reacted at room temperature for 24 hours. The water was removed by rotary evaporation to obtain a piperidine free radical type dual inhibitor.

Embodiment 3:

The process for preparing the sulfur-free odorant ingredients comprises the following steps:

S1. Prepare the following raw materials in percentage by mass: 38 kg methyl acrylate, 2 kg 2-ethyl-3-methylpyrazine, 1.9 kg N,N-dimethylformamide, 1 kg 3-methylindole, 0.3 kg composite stabilizer, and 56.8 kg ethyl acrylate;

S2, adding N,N-dimethylformamide and 3-methylindole into a mixer, stirring at a speed of 360 r/min for 15 min to obtain component 1;

S3, adding methyl acrylate, 2-ethyl-3-methylpyrazine and ethyl acrylate into a mixer, stirring and mixing at a speed of 300 r/min for 20 min, controlling the temperature to be less than or equal to 10° C. during the stirring process, to obtain component 2;

S4. Add component 1 to component 2, stir and mix at a speed of 300 r/min for 5 minutes, then add the composite stabilizer, and continue stirring for 10 minutes to obtain a sulfur-free odorizer.

The composite stabilizer is prepared by mixing 4,6-dinitro-2-sec-butylphenol and piperidine free radical type dual inhibitor in a mass ratio of 1:5.

The piperidine free radical type dual polymerization inhibitor is obtained by the following steps:

3.3 kg of 50 wt% hydroxylamine aqueous solution was added to the reactor, followed by addition of 24.2 kg of TEMPO methyl methacrylate and 186 L of anhydrous ethanol as a solution ester, and the mixture was stirred and reacted at room temperature for 24 h. Water was removed by rotary evaporation to obtain a piperidine free radical type dual inhibitor.

Comparative Example 1:

The sulfur-free odorant ingredient production process is compared with Example 1, wherein the "prepare the following raw materials in mass percentage: 38 kg of methyl acrylate, 2 kg of 2-ethyl-3-methylpyrazine, 1.7 kg of N,N-dimethylformamide, 1 kg of 3-methylindole, 0.1 kg of composite stabilizer, and 57.2 kg of ethyl acrylate" in step S1 of Example 1 is replaced by "prepare the following raw materials in mass percentage: 38 kg of methyl acrylate, 2 kg of 2-ethyl-3-methylpyrazine, 1.7 kg of N,N-dimethylformamide, 0.1 kg of composite stabilizer, and 58.2 kg of ethyl acrylate", and the rest of the preparation process is the same as Example 1.

Comparative Example 2:

The sulfur-free odorant ingredient production process is compared with Example 1, wherein "the composite stabilizer is formed by mixing 4,6-dinitro-2-sec-butylphenol and piperidine free radical type dual inhibitor in a mass ratio of 1:2" is replaced by "the composite stabilizer is 4,6-dinitro-2-sec-butylphenol", and the rest of the preparation process is the same as Example 1.

Comparative Example 3:

The sulfur-free odorant ingredient production process is compared with Example 1, wherein "the composite stabilizer is formed by mixing 4,6-dinitro-2-sec-butylphenol and piperidine free radical type dual polymerization inhibitor in a ratio of 1:2 by mass" is replaced by "the composite stabilizer is a piperidine free radical type dual polymerization inhibitor", the preparation process of the piperidine free radical type dual polymerization inhibitor is the same as that of Example 1, and the rest of the preparation process is the same as that of Example 1.

The sulfur-free odorants obtained in Examples 1-3 and Comparative Examples 1-3 were tested, including the olfactory grade and stability. The odor intensity was determined according to the Sales grade adopted in the Guidelines for Natural Gas-Gas Odorization ISO/TS 16922, which is divided into 0-5 grades, 1 for no odor, 0.5 for very weak odor (lower limit of odor perception), 1 for weak odor, 2 for moderate odor (warning odor grade), 3 for strong odor, 4 for very strong odor, and 5 for maximum odor (upper limit of odor perception). The test process is as follows:

Olfactory grade: Anhydrous ethanol was selected as the diluent solution, and the sulfur-free odorant prepared in the above Examples 1-3 and Comparative Examples 1-3 was diluted to a sulfur-free odorant solution with a concentration of 10 mg/ ^m3 . The above sulfur-free odorant solution with a concentration of 10 mg/ ^m3 was evenly sprayed on filter paper, and 40 independent test subjects were selected to smell, and the olfactory grade of each test subject was recorded, and finally the average value was calculated;

Stability: The sulfur-free odorants obtained in Examples 1-3 and Comparative Examples 1-3 were placed at 60° C. for 6 months, and samples were taken to detect the methyl acrylate content. The sulfur-free odorants obtained in Examples 1-3 and Comparative Examples 1-3 were placed in glass bottles and exposed to natural light outdoors for 30 days, and samples were taken to detect the methyl acrylate content.

The test results are shown in Table 1:

;

It can be seen from the data recorded in Table 1 that, compared with Comparative Examples 1-3, the sulfur-free odorants obtained in Examples 1-3 not only have a high olfactory grade, but also have good photothermal stability. Specifically, it can be seen from the test results of Example 1 and Comparative Example 1 that by removing 3-methylindole in the present invention, the sulfur-free odorant obtained not only has a lower olfactory grade, but also has poor photothermal stability. It can be seen from the test results of Example 1, Comparative Example 2 and Comparative Example 3 that when the stabilizer is all 4,6-dinitro-2-sec-butylphenol or piperidine free radical type dual inhibitor, the photothermal stability of the sulfur-free odorant is worse than the combination of the two. Therefore, the sulfur-free odorant prepared by the present invention has high stability and high olfactory grade, and has very good application value as a combustible gas leak warning additive.

It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims (6)

1. The sulfur-free odorizing agent ingredient preparation process is characterized by comprising the following steps of:

S1, preparing the following raw materials in percentage by mass: 38% of methyl acrylate, 2% of 2-ethyl-3-methyl pyrazine, 1.7-1.9% of amide compounds, 1% of synergistic agent, 0.1-0.3% of composite stabilizer and the balance of ethyl acrylate, wherein the sum of the mass percentages of the raw materials is 100%;

S2, adding the amide compound and the synergist into a mixer, and stirring and mixing for 10-15min at the rotating speed of 300-360r/min to obtain a component I;

S3, adding methyl acrylate, 2-ethyl-3-methyl pyrazine and ethyl acrylate into a mixer, stirring and mixing for 15-20min at the rotating speed of 200-300r/min, and controlling the temperature to be less than or equal to 10 ℃ to obtain a component II;

s4, adding the first component into the second component, stirring and mixing for 3-5min at the rotating speed of 200-300r/min, adding the compound stabilizer, and continuing stirring for 5-10min to obtain the sulfur-free odorizing agent.

2. The process for preparing the sulfur-free odorizing agent ingredient according to claim 1, wherein the compound stabilizer comprises 4, 6-binitro-2-sec-butylphenol and piperidine radical double polymerization inhibitor according to the mass of 1: 1-5.

3. The process for preparing a sulfur-free odorizing agent formulation of claim 2, characterized in that the piperidine radical type double polymerization inhibitor is obtained by:

adding hydroxylamine water solution into a reaction kettle, adding ethanol solution of TEMPO methyl methacrylate, stirring at room temperature for reaction for 24 hours, and spin-evaporating water to obtain the piperidine free radical type double polymerization inhibitor.

4. The process for preparing a sulfur-free odorizing agent formulation of claim 3, wherein the molar ratio of hydroxylamine to TEMPO methyl methacrylate is 1:2, the mass fraction of the hydroxylamine aqueous solution is 50%, and the ethanol solution of TEMPO methyl methacrylate is prepared from TEMPO methyl methacrylate and absolute ethanol according to the dosage ratio of 1g:5-10 mL.

5. The process for preparing a sulfur-free odorizing agent formulation of claim 1, wherein the synergist is 3-methylindole.

6. The process for preparing a sulfur-free odorizing agent formulation of claim 1, wherein the amide compound is one of N, N-dimethylformamide and N, N-dimethylacetamide.