KR100357455B1 - Thermal Decomposition of the Waste-Rubber - Google Patents

Abstract

The present invention relates to a pyrolysis method of waste rubber using a catalyst for pyrolysis reaction of waste rubber. In the pyrolysis and reduction of washed and cut waste rubber, the water contained in the waste rubber is passed through a preheater through the cut waste rubber. When the catalyst was added, the catalyst was preheated to 320-340 ° C., the reaction start temperature, and then added to the first reactor, and 0.01-0.1 parts by weight based on 100 parts by weight of waste rubber in which molybdenum oxide was added as a catalyst for starting the reaction. Initiate the pyrolysis reaction, and then transfer to a second reactor that is maintained at a temperature of 200-270 ℃ to continue the pyrolysis reaction, and to thermally decompose waste rubber continuously at low temperature through the method of the present invention As a result, the processing cost problem, which has been the biggest problem in the past, has been solved, thereby polluting the global environment. We can recycle the used rubbers in bulk. In addition, the material reduced by the method of the present invention because the reaction is carried out at a low temperature can be recycled in a wider range of excellent quality.

Description

Thermal Decomposition of Waste Rubbers {Thermal Decomposition of the Waste-Rubber}

The present invention relates to a pyrolysis method of waste rubber using a catalyst for pyrolysis of waste rubber, and more particularly, to a pyrolysis method of waste rubber using molybdenum oxide as a pyrolysis catalyst.

Waste rubbers are classified as environmental pollutants that deteriorate the global environment because they do not dissolve well after being disposed of. In particular, as the number of automobiles increases due to the development of the automobile industry, the amount of waste tires, which is a kind of waste rubber, is rapidly increasing every year. The amount of waste tires produced in Korea is over 20 million in 1997. Currently, the recycling rate of waste tires in Korea is about 60%, but most of them are used for civil engineering by military units. The planned use of waste tires is likely to lead to serious environmental problems if proper treatment techniques are not developed.

Recycling of waste rubbers, represented by waste tires, can be divided into recycling and processing technologies and technologies used as energy sources. Dual regeneration and processing technology is not only difficult to mass process, but also disadvantageous in terms of cost, and the demand is gradually decreasing. Examples of the regeneration and processing technology include separating waste tire rubber, mixing it with asphalt, and using it as a packaging material, and using powder rubber as a slab mat, tennis court, and golf course passage mat.

The technology for using waste tires as an energy source is to use the high calorie value of tires as alternative energy. That is, the tire is burned to generate steam or hot water, or used as a raw material and fuel in a cement firing process. However, this technology can handle waste tires on a large scale, but the quality of cement is deteriorated in case of combustion of air pollutants such as soot and sulfurous acid gas, economic feasibility compared with coal, or applied to cement firing process. There is a possibility that the application is limited.

Another technique for recycling waste tires is pyrolysis of waste tires. Pyrolysis of waste tires has led to the development of pyrolysis processes for a long time because of the advantages of solving environmental problems and obtaining high value-added oils. However, until now, the pyrolysis technology of waste tires has not been commercialized in earnest. The reason is that the pyrolysis process is performed at a relatively high temperature (350-700 ° C.), which requires expensive equipment and high production cost. In the case of the process, it is difficult to secure economic feasibility in competition with cheap oil, and the quality of the obtained product is poor.

However, in recent years, the price of crude oil is gradually increasing, and the problem of disposal of waste tires has been highlighted as a social problem, so the pyrolysis process capable of large-scale treatment is again becoming a subject of interest.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for thermally decomposing waste rubber at low temperature. Another object of the present invention is to provide a low temperature pyrolysis process having excellent quality of the reduced product obtained after pyrolysis of waste rubber. Another object of the present invention is to continuously pyrolyze waste rubber at low temperatures.

1 is a process diagram illustrating a schematic process of the present invention.

In the present invention, in order to pyrolyze and reduce the washed and cut waste rubber, the cut waste rubber is passed through a preheater to remove moisture contained in the waste rubber, and preheated to 320-340 ° C., which is a reaction start temperature, and then put into the reactor. In addition, the molybdenum oxide is added to the reactor as a reaction initiation catalyst to initiate the pyrolysis reaction, and then continue the pyrolysis reaction at a temperature of 200-270 ℃.

Hereinafter, the present invention will be described in detail.

The onset temperature of pyrolysis of the waste tire in the non-catalyst state is 350 ° C or higher. It is also necessary to maintain this temperature even after pyrolysis has commenced in order to continue the reaction. Since the pyrolysis reaction occurs at such a high temperature, not only expensive equipment is required, but also the production cost is high and the physical properties of the obtained product are poor, as described above.

In the present invention, using molybdenum oxide as the reaction start catalyst, the reaction start temperature was lowered to about 330 ° C. However, before the waste tire pieces are introduced into the first reactor, the reaction must be preheated to a temperature of 320-340 ° C. The primary reactor is maintained at a temperature of 320-340 ° C. What is unique is that once the reaction is initiated the reaction temperature is lowered to 200-270 ° C. and the reaction continues at this temperature. Thus, the initial decomposition products in which the reaction is initiated are sent to a secondary reactor where the temperature of 200-270 ° C. is maintained. In addition, after the start of the reaction, the reaction is continued at low temperature even if a separate reaction start catalyst is not added. This temperature is significantly lower than 600-700 ° C., which is the temperature of a continuous pyrolysis process in which no catalyst is added.

Molybdenum oxide has a variety of such as MoO ₃ , MoO ₆ , Mo ₃ O ₈ , Mo ₈ O ₂₃ , Mo ₉ O ₂₆ . However, MoO ₃ is not only easy to purchase but also has a good catalytic effect. The usage-amount of a reaction start catalyst is 0.01-0..1 weight part with respect to 100 weight part of raw materials thrown in. If it is below this range, the catalyst input effect is insufficient, and even if it exceeds this range, no further synergistic effect will occur.

Figure 1 is a schematic process diagram of the present invention, the waste tire chip washed and cut in the preheating step is preheated to 320-340 ℃ the thermal decomposition start temperature of the present invention at the same time the water is evaporated. The preheated chip is introduced into a first reactor in which 320-340 ° C. is maintained, and a pyrolysis start catalyst is introduced into the first reactor. The pyrolyzed reactant is sent to a second reactor maintained at 200-270 ° C., where the decomposition products oil and gas are generated. The pressure inside the reactor is a low pressure of less than 1/2 atm. If the pressure exceeds this range, oil will adhere to the solid residue obtained after pyrolysis. Since there should be no oxygen in the reactor, the vacuum pump is operated initially to drain the air and then charged with nitrogen gas.

The gaseous hydrocarbons, which are cracked products, are collected in the gas collector and the liquid oil is condensed and sent to the oil reservoir. Carbon black, steel, fibers, residues, etc., which are solids in the decomposition products are separated and collected in a separate solid reservoir. The gas collected in the gas collector can be reused as a heat source.

An embodiment of the present invention is as follows. Although this embodiment is intended for waste tires, the method of the present invention is equally applicable to other waste rubbers.

(Example)

Molybdenum oxide powder was used as a catalyst to start the reaction while simultaneously discharging 1000 g of waste tire specimen (2 X 2 cm), which had been sufficiently washed and dried and preheated to 330 ° C., was charged with nitrogen gas and maintained at 330 ° C. 0.05 g was added. After confirming that the pyrolysis reaction was initiated, the pressure inside the reactor was maintained at 200 mmHg pressure, and the specimen from which decomposition was started was transferred to a second reactor having a temperature of 250 ° C. and a pressure of 200 mmHg. The pyrolysis reaction was completed as the second reactor residence time was about 30 minutes, and the solid residue was 493 g, oil 385 g and gas 122 g. Gas is the total amount of decomposition products that are released to the atmosphere without condensation.

The main component of the solid residue in the decomposition product was carbon black, and the component analysis showed 77.7 wt% carbon, 18.0 wt% ash, and 4.3 wt% volatiles. Ash is a solid filler that is mostly formulated in the manufacture of tires and the volatiles were undigested.

Elemental analysis of the resulting oil was C: 84.1% by weight, H: 12.5% by weight, N: 2.01% by weight, S: 0.3% by weight.

(Comparative Example)

The same procedure as in Example was carried out, but the catalyst for starting the reaction was not used. As a result, the pyrolysis reaction was started at 360 ℃, the reaction was stopped when the temperature was lowered in the second reactor and the reaction continued very slowly only by maintaining the thermal decomposition start temperature 360 ℃.

As can be seen through the above embodiments, the process of the present invention solves the problem of processing cost, which has been the biggest problem since the method of the present invention can continuously decompose waste rubber at low temperature, thereby contaminating the global environment. Waste rubber can be recycled in large quantities. In addition, the material reduced by the method of the present invention because the reaction is carried out at a low temperature can be recycled in a wider range of excellent quality.

Claims (4)

In the pyrolysis and reduction of the washed and cut waste rubber, the cut waste rubber is passed through a preheater to remove water contained in the waste rubber, and preheated to 320-340 ° C., which is a reaction start temperature when the catalyst is added, and then to the first reactor. To the first reactor to start the pyrolysis reaction by adding 0.01-0.1 parts by weight of molybdenum oxide to 100 parts by weight of the spent rubbers as a catalyst to start the reaction, and then to a second reactor where the temperature of 200-270 ° C. is maintained. Pyrolysis method of waste rubber, characterized in that the transfer to continue the pyrolysis reaction. The method for thermally decomposing waste rubber according to claim 1, wherein the molybdenum oxide is MoO ₃ . The method of claim 1, wherein the pressure inside the reactor is less than 1/2 atm. The method of claim 1, wherein the interior of the reactor is an oxygen-free environment, characterized in that the pyrolysis of waste rubber.