WO2023103113A1

WO2023103113A1 - Method for desulfurization of waste tire by using supercritical carbon dioxide

Info

Publication number: WO2023103113A1
Application number: PCT/CN2021/141609
Authority: WO
Inventors: 刘宁; 王星丽; 于刚强; 代成娜; 陈标华; 徐瑞年; 王宁
Original assignee: 北京工业大学
Priority date: 2021-12-07
Filing date: 2021-12-27
Publication date: 2023-06-15
Also published as: CN114031811A

Abstract

The present invention relates to the technical field of desulfurization of waste tires, and provides a method for desulfurization of a waste tire by using supercritical carbon dioxide. According to the method, under specific temperature and pressure conditions, supercritical carbon dioxide is used as a reaction medium, and has excellent solubility and permeability, so that the tire can be swelled in the reaction process, and a desulfurizing agent is introduced into the tire and reacts with a main chain or a cross-linking bond in a cross-linked network structure to remove the sulfur element from the interior of the tire. The method is simple in technology process, high in process controllability, and easy to operate.

Description

A kind of supercritical carbon dioxide is used for the method of waste tire desulfurization

technical field

The invention relates to the technical field of waste tire desulfurization, in particular to a method for removing sulfur from waste tires by using supercritical carbon dioxide.

Background technique

With the development of the economy and the prosperity of the automobile industry, automobiles have entered thousands of households, and at the same time, the output of waste tires is also increasing. Scrap tires are high-molecular polymers, and after vulcanization treatment to produce a cross-linked structure, the stability is extremely strong, and its disposal is larger than that of general solid waste, and it is difficult to degrade in the natural state for decades. Therefore, the disposal of waste tires has always been an important and difficult problem faced by the automobile industry.

At present, there are three main ways to recycle waste tires: Re-use of prototypes, which mainly refers to the production of old tires into recycled rubber powder or the refurbishment of tires. However, due to the rapid development of rubber industry technology, high-quality, low-priced synthetic rubber makes the market competitiveness of reclaimed rubber and old tire retreading less. At the same time, as an ingredient of road asphalt - reclaimed rubber powder cannot be used in the market because of its high cost. Incineration of waste tires and other polymer wastes is used to obtain energy such as electricity and steam. Although waste tires can be treated to a certain extent, it has a low resource utilization rate. From the perspective of polymer waste utilization, thermal cracking can not only recover energy, but also obtain products with higher added value. Therefore, it is generally believed that thermal cracking is a treatment scheme with high efficiency, mainly because it can produce hydrocarbon compounds, carbon black and gas with high calorific value.

The main products of tire pyrolysis are pyrolysis carbon black, pyrolysis gas and pyrolysis oil. Carbon black is the reinforcement and filler of rubber, accounting for about 25%-30% of the rubber mass. The main solid product after tire pyrolysis is pyrolysis carbon black, and a certain amount of carbonaceous deposits will be deposited on its surface during the pyrolysis process. At present, the application of pyrolysis carbon black is mainly in two aspects: as a rubber reinforcing filler, but pyrolysis carbon black has a high sulfur content, which limits the use of pyrolysis carbon black as a rubber reinforcing agent; Activated carbon is prepared by activation and modification of carbon dioxide or water vapor at low temperature. Cracking gas is mainly a mixture of alkanes and olefins, and its main components are: methane, ethane, ethylene, propane, acetylene, butane, butene, etc. The composition and output of cracked gas are greatly affected by cracking raw materials, cracking process and temperature. When the cracking temperature rises, hydrocarbons with larger molecular weight undergo further cracking and dehydrogenation reactions to generate small molecular gases. At present, most pyrolysis processes produce less pyrolysis gas, but have higher calorific value, and the pyrolysis gas can be used as fuel to provide energy for the pyrolysis of waste tires. Pyrolysis oil is a mixture of paraffins, olefins and aromatics, its color is brown, its composition is relatively complex, its calorific value is high, and it is mainly used as fuel. However, the sulfur content in waste tire pyrolysis oil is very high, which makes it have disadvantages such as dark color, high viscosity, and high density, which restricts its industrialization prospect. Excessive sulfur content also limits the use of pyrolysis oil as a fuel oil. The pyrolysis oil must be further refined, such as desulfurization, vacuum distillation, etc., to improve its fuel characteristics before being used as fuel oil.

Supercritical fluid technology utilizes the characteristics of high diffusivity, high permeability, and high solubility of substances in a supercritical state, and uses supercritical substances as reaction media for physical or chemical reactions. It has been used in extraction and separation, pharmaceuticals, power generation, metallurgy, Dyeing and other aspects have been widely used. Among them, there have been more researches on the use of supercritical fluids to treat high molecular polymers that are difficult to degrade, especially waste tire rubber.

Based on this, the present invention aims to remove the sulfur content in waste tires. In order to solve the problem that the subsequent pyrolysis products of tires are limited in application due to excessive sulfur content, the present invention uses supercritical carbon dioxide to remove sulfur in waste tires. Element, supercritical carbon dioxide has excellent solubility and permeability. During the reaction process, the tire can be swelled, and the desulfurizer can be brought into the tire to react with the main chain or cross-linked bond in the cross-linked network structure to release the sulfur element Remove from the inside of the tire.

Contents of the invention

The purpose of the present invention is to provide a method for removing sulfur in waste tires, which mainly uses supercritical carbon dioxide as a reaction medium, utilizes its excellent solubility and permeability to better penetrate the desulfurizer into the inside of the tire, and selectively Break the S-S bond in the waste tire and take the sulfur element out of the tire.

The present invention adopts following technical scheme to realize:

First, cut the tread rubber from waste tires, simply clean it, and cut the tread rubber into small pieces after washing off the surface dust, put it in a crusher for crushing, and sieve after crushing. The particle size of the present invention is 0.55- 1mm of tire particles;

Further, weigh 2g of waste tire samples and 0.2g of desulfurizing agent diphenyl disulfide, and mix the two evenly;

Further, take 2g waste tire sample and 0.2g desulfurizer 2,2'-dibenzamidodiphenyl disulfide, mix the two evenly;

Further, take 2g waste tire sample and 0.2g desulfurization agent tetramethylthiuram disulfide, and mix the two evenly;

Furthermore, 2g of waste tire samples and 0.2g of desulfurizer N-cyclohexyl-2-benzothiazolesulfenamide were weighed, and the two were mixed uniformly;

Furthermore, weigh 2g of waste tire samples and 0.1g of desulfurizing agent diphenyl disulfide, and mix the two evenly;

Further, take 2g waste tire sample and 0.3g desulfurizer diphenyl disulfide, mix the two evenly;

Further, take 2g waste tire sample and 0.4g desulfurizer diphenyl disulfide, mix the two evenly;

Further, the mixed material is placed in a supercritical carbon dioxide reactor, and the air in the reactor is drawn out with a vacuum pump, and the pressure relief valve is closed after exhausting;

Further, carbon dioxide is introduced into the reactor to adjust the pressure inside the reactor to 5-20MPa, and the carbon dioxide is pumped into the reactor to reach a predetermined pressure value through a booster pump, and the temperature is raised at the same time, and the set temperature is 150-350°C. The temperature and pressure in the reactor are used to make the carbon dioxide in the reactor in a supercritical state;

Furthermore, diphenyl disulfide is used as a desulfurizer to desulfurize waste tires. The reaction conditions are: reaction temperature 150-350°C, reaction pressure 10MPa, reaction time 1-5h, and the amount of desulfurizer used is 5% of the mass of waste tires. %-20%;

Furthermore, use 2,2'-dibenzamidodiphenyl disulfide as desulfurizer to desulfurize waste tires, the reaction conditions are: reaction temperature 150-350°C, reaction pressure 10MPa, reaction time 4h, desulfurizer The dosage is 10% of the mass of waste tires;

Furthermore, tetramethylthiuram disulfide is used as a desulfurizer to desulfurize waste tires. The reaction conditions are: reaction temperature 150-350°C, reaction pressure 10MPa, reaction time 4h, and the amount of desulfurizer used is 1/4 of the waste tire mass. 10%;

Furthermore, use N-cyclohexyl-2-benzothiazole sulfenamide as a desulfurizer to desulfurize waste tires. The reaction conditions are: reaction temperature 150-350°C, reaction pressure 10MPa, reaction time 4h, desulfurizer dosage 10% of the mass of waste tires;

Further, fully react for 1-5 hours after the reaction temperature and pressure reach the set value;

Further, after the reaction is finished, the gas in the reactor is sampled, and the pressure is released and the temperature is lowered after the sampling is completed.

Compared with the prior art, the present invention has the following advantages:

1. Using carbon dioxide in a supercritical state as the reaction medium, use its excellent solubility and permeability to fully swell waste tires, bring the desulfurizer into the tire, and make use of the main chain or cross-linking in the cross-linked network structure The bond reacts to remove sulfur from the interior of the tire.

2. The method of the present invention can remove about 30% of the sulfur content in waste tires, and solves the problem of limited application of subsequent waste tire pyrolysis products due to excessive sulfur content.

3. The method of the invention has simple technical process, strong process controllability and simple operation.

Description of drawings

Fig. 1 is the flow chart of supercritical carbon dioxide reactor of the present invention

Detailed ways

The technical solution of this patent will be further described in detail below in conjunction with specific embodiments, and the content of the present invention is not limited thereto at all.

The embodiments of this patent are described in detail below, and the embodiments described below are exemplary and are only used to explain this patent, and cannot be interpreted as limitations on this patent.

Example 1

A kind of supercritical carbon dioxide is used for the method for waste tire desulfurization, and concrete steps are as follows:

(1) Cut the tread rubber from waste tires, simply clean it, and cut the tread rubber into small pieces after washing off the surface dust, place it in a crusher for pulverization, and sieve after pulverization. The particle diameter of the present invention is 0.55-1mm tire particles;

(2) Take by weighing 2g waste tire sample and 0.2g desulfurizing agent diphenyl disulfide, mix the two evenly;

(3) The mixture is placed in a supercritical carbon dioxide reactor, and the air in the reactor is taken out with a vacuum pump, and the pressure relief valve is closed after draining;

(4) Introduce carbon dioxide into the reaction kettle, adjust the pressure in the kettle to 10MPa, the carbon dioxide is pumped into the reaction kettle through the booster pump to reach the predetermined pressure value, and at the same time raise the temperature, the set temperature is 250°C, under this temperature and pressure condition, the carbon dioxide in a supercritical state;

(5) Fully react for 1 hour after the reaction temperature and pressure reach the set value;

(6) After the reaction, the gas in the reactor is sampled, and the pressure is released and the temperature is lowered after sampling;

(7) Characterize the gas collected in the reaction and the waste tire samples treated with supercritical carbon dioxide. The results show that the H ₂ S content in the sampled gas is 0.36%, and the sulfur content removal rate in waste tires is 11.41%.

Example 2

(3) Mixed material is placed in the supercritical carbon dioxide reactor, with vacuum pump, the air in the reactor is taken out, and the pressure relief valve is closed after draining;

(4) Introduce carbon dioxide into the reactor, adjust the pressure in the reactor to 10MPa. in a supercritical state;

(5) Fully react for 4 hours after the reaction temperature and pressure reach the set value;

(6) After the reaction, the gas in the reactor is sampled, the pressure is released and the temperature is lowered after the sampling is completed, and the pressure is released and the temperature is lowered after sufficient reaction;

(7) Characterize the gas collected in the reaction and the waste tire samples treated with supercritical carbon dioxide. The results show that the H ₂ S content in the sampled gas is 0.48%, and the sulfur content removal rate in waste tires is 29.90%.

Example 3

(5) Fully react for 3 hours after the reaction temperature and pressure reach the set value;

(7) Characterize the gas collected in the reaction and the waste tire samples treated with supercritical carbon dioxide. The results show that the H ₂ S content in the sampled gas is 0.38%, and the sulfur content removal rate in waste tires is 16.91%.

Example 4

(7) Characterize the gas collected in the reaction and the waste tire samples treated with supercritical carbon dioxide. The results show that the H ₂ S content in the sampled gas is 0.40%, and the sulfur content removal rate in waste tires is 15.46%.

Example 5

(2) Weigh 2g of waste tire samples and 0.1g of desulfurized diphenyl disulfide, and mix the two evenly;

(7) Characterize the gas collected in the reaction and the waste tire samples treated with supercritical carbon dioxide. The results show that the H ₂ S content in the sampled gas is 0.32%, and the sulfur content removal rate in waste tires is 4.33%.

Example 6

(2) Weigh 2g waste tire sample and 0.2g desulfurizer 2,2'-dibenzamidodiphenyl disulfide, mix the two evenly;

(7) Characterize the gas collected in the reaction and the waste tire samples treated with supercritical carbon dioxide. The results show that the H ₂ S content in the sampled gas is 1.54%, and the sulfur content removal rate in waste tires is 18.21%.

Example 7

(4) Introduce carbon dioxide into the reaction kettle, adjust the pressure in the kettle to 10MPa, the carbon dioxide is pumped into the reaction kettle through the booster pump to reach the predetermined pressure value, and at the same time, the temperature is raised, and the set temperature is 300 ° C. Under this temperature and pressure condition, the carbon dioxide in a supercritical state;

(7) Characterize the gas collected in the reaction and the waste tire samples treated with supercritical carbon dioxide. The results show that the H ₂ S content in the sampled gas is 0.49%, and the sulfur content removal rate in waste tires is 19.00%.

Example 8

(4) Introduce carbon dioxide into the reactor, adjust the pressure in the reactor to 15MPa, the carbon dioxide is pumped into the reactor through the booster pump to reach the predetermined pressure value, and the temperature is raised at the same time, and the set temperature is 250 ° C. Under this temperature and pressure condition, the carbon dioxide in a supercritical state;

(7) Characterize the gas collected in the reaction and the waste tire samples treated with supercritical carbon dioxide. The results show that the H ₂ S content in the sampled gas is 1.43%, and the sulfur content removal rate in waste tires is 13.51%.

Example 9

(4) Introduce carbon dioxide into the reaction kettle, adjust the pressure in the kettle to 20MPa, the carbon dioxide is pumped into the reaction kettle through the booster pump to reach the predetermined pressure value, and at the same time raise the temperature, the set temperature is 250°C, under this temperature and pressure condition, the carbon dioxide in a supercritical state;

(7) Characterize the gas collected in the reaction and the waste tire samples treated with supercritical carbon dioxide. The results show that the H ₂ S content in the sampled gas is 1.44%, and the sulfur content removal rate in waste tires is 8.06%.

Example 10

(2) Take by weighing 2g waste tire sample and 0.3g desulfurizing agent diphenyl disulfide, mix the two evenly;

(7) Characterize the gas collected in the reaction and the waste tire samples treated with supercritical carbon dioxide. The results show that the H ₂ S content in the sampled gas is 0.33%, and the sulfur content removal rate in waste tires is 3.63%.

Example 11

(2) Take by weighing 2g waste tire sample and 0.4g desulfurizer diphenyl disulfide, mix the two evenly;

(7) Characterize the gas collected in the reaction and the waste tire samples treated with supercritical carbon dioxide. The results show that the H ₂ S content in the sampled gas is 0.38%, and the sulfur content removal rate in waste tires is 6.15%.

The desulfurization effect of tires prepared in Examples 1-11 after supercritical carbon dioxide desulfurization treatment was characterized, and the characterization results are shown in Table 1:

Table 1 Characterization of desulfurization effect

The above is only a preferred embodiment of the present invention, but the protection scope of the present invention is not limited thereto, and any modification made by those skilled in the art within the technical scope disclosed in the present invention is equivalent to Replacement and improvement, etc., should be included in the scope of protection of the invention.

Claims

A method for desulfurizing waste tires with supercritical carbon dioxide, characterized in that under specific temperature and pressure conditions, supercritical carbon dioxide is used as a reaction medium, and the tire is swelled by solubility and permeability to bring the desulfurizer into the tire. Reacts with the main chain or cross-links in the cross-linked network structure to remove sulfur from the interior of the tire.
A method for desulfurizing waste tires with supercritical carbon dioxide according to claim 1, wherein the desulfurizing agent is diphenyl disulfide, 2,2'-dibenzamidodiphenyl disulfide, Tetramethylthiuram disulfide or N-cyclohexyl-2-benzothiazole sulfenamide.
A method for desulfurizing waste tires with supercritical carbon dioxide according to claim 1, characterized in that the reaction conditions are: reaction temperature 150-350°C, reaction pressure 5-25MPa, reaction time 1-5h, desulfurizer The dosage is 5%-20% of the mass of waste tires.
A method for desulfurizing waste tires with supercritical carbon dioxide according to claim 3, characterized in that when diphenyl disulfide is used as the desulfurizing agent, the reaction conditions are: reaction temperature 150-350 ° C, reaction pressure 5-25MPa, the reaction time is 1-5h, and the amount of desulfurizer is 5%-20% of the waste tire mass.
A method for desulfurizing waste tires with supercritical carbon dioxide according to claim 3, characterized in that when using 2,2'-dibenzamidodiphenyl disulfide as a desulfurizing agent, the reaction conditions are: The temperature is 150-350° C., the reaction pressure is 10 MPa, the reaction time is 4 hours, and the amount of the desulfurizer is 10% of the waste tire mass.
A method for desulfurizing waste tires with supercritical carbon dioxide according to claim 3, characterized in that when tetramethylthiuram disulfide is used as a desulfurizing agent, the reaction conditions are: reaction temperature 150-350°C, The reaction pressure is 10MPa, the reaction time is 4h, and the amount of desulfurizer is 10% of the waste tire mass.
A method for desulfurizing waste tires with supercritical carbon dioxide according to claim 3, characterized in that, when N-cyclohexyl-2-benzothiazole sulfenamide is used as a desulfurizing agent, the reaction conditions are: reaction temperature 150-350°C, the reaction pressure is 10MPa, the reaction time is 4h, and the amount of desulfurizer is 10% of the mass of waste tires.
A method for desulfurizing waste tires according to any one of claims 2-7, wherein the specific steps are as follows:

(1) Cut the tread rubber from waste tires, wash off the surface dust, cut the tread rubber into small pieces, place them in a crusher for crushing, sieve after crushing, and select tire particles with a particle size of 0.55-1mm;

(2) Stir and mix the tire particles and the desulfurizer evenly;

(3) Mixed material is put into supercritical carbon dioxide reactor, with vacuum pump, the air in the reactor is extracted out, and the pressure relief valve is closed after draining;

(4) Afterwards, carbon dioxide is introduced into the reactor to adjust the pressure in the reactor to 5-20MPa. Carbon dioxide is pumped into the reactor to reach a predetermined pressure value through a booster pump, and the temperature is raised at the same time. The set temperature is 150-350°C. Adjust the temperature and pressure in the reactor so that the carbon dioxide in the reactor is in a supercritical state;

(5) Fully react for 1-5 hours after the reaction temperature and pressure reach the set value;

(6) After the reaction, the gas in the reactor is sampled, and the pressure is released and the temperature is lowered after the sampling is completed.