Mild pyrolysis method for preparing liquid hydrocarbon through waste polyolefin

A technology for waste polyolefins and liquid hydrocarbons, applied in the field of mild cracking, can solve the problems of low liquid yield, increased catalytic cracking section, and high gas yield, avoiding unfavorable secondary reactions, reducing melt viscosity, and low cracking temperature. Effect

Inactive Publication Date: 2015-11-04
INST OF PROCESS ENG CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] The above-mentioned patents all involve the technology of waste plastic cracking to produce liquid hydrocarbons and co-cracking or returning to re-cracking technology. Generally speaking, the current technology has the following shortcomings: 1) The gas yield is too high and the liquid yield is low, which is not conducive to the liquefaction and recycling of waste plastics; 2) The high viscosity of waste plastics in molten state and the low thermal conductivity of waste plastics are not conducive to the continuous operation of pyrolysis. Co-pyrolysis of waste plastics and other materials is one of the means to solve this problem, but the addition of other materials may bring side effects. Products such as aromatics are not conducive to being used as raw materials for ethylene cracking; 3) polyolefin thermal cracking products are mainly linear alkanes with a very low octane number, which is not conducive to being used as fuel oil. For the purpose of producing fuel oil, it is often necessary to increase Catalytic cracking section; 4) ignoring the impact of optimization of reaction conditions (heating rate, reaction temperature and reaction time, etc.) in the cracking reaction on product characteristics

Method used

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  • Mild pyrolysis method for preparing liquid hydrocarbon through waste polyolefin
  • Mild pyrolysis method for preparing liquid hydrocarbon through waste polyolefin
  • Mild pyrolysis method for preparing liquid hydrocarbon through waste polyolefin

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0035] The mild cracking of embodiment 1 polyolefin (HDPE, HDPE / PP)

[0036] Such as figure 1 Shown, a kind of mild cracking method that utilizes waste polyolefin to produce liquid hydrocarbon, described method comprises the following steps:

[0037] 1) Pre-treatment: After separating and removing components that are easy to release harmful gases from waste polyolefin plastics, the waste polyolefin plastics are crushed and granulated to obtain polyolefin particles with a particle size of 2-4 mm as cracking raw materials;

[0038] 2) Wax production: After adding the waste polyolefin particles prepared in step 1) to the wax production device, seal the wax production device and purge the air with an inert gas to ensure that the cracking reaction is carried out in an inert atmosphere, and set the reaction temperature range When the temperature is 300-380°C, start stirring and start heating, the stirring rate is 200-400rpm, the heating rate is 2-20°C / min, and the set reaction temp...

Embodiment 2

[0066] The mild cracking of embodiment 2 waste polyolefin (HDPE / PP=50 / 50)

[0067] Such as figure 2 Shown, a kind of mild cracking method that utilizes waste polyolefin to produce liquid hydrocarbon, described method comprises the following steps:

[0068] 1) Using mixed waste polyolefin particles with a particle size of 2 to 5 mm (50 / 50 waste HDPE / PP, black, provided by Longda Plastic Products Factory in Xiongxian County, Hebei Province) as a cracking raw material;

[0069] 2) Wax making: After adding the waste polyolefin particles in step 1) to the wax making device, seal the wax making device and blow out the air with an inert gas to ensure that the cracking reaction is carried out in an inert atmosphere. The reaction temperature range is set to 300 ~380°C, start stirring and start heating, the stirring rate is 200~400rpm, the heating rate is 2~20°C / min, and the set reaction temperature is reached. After the reaction is completed, stop heating and cool down to obtain wast...

Embodiment 3

[0080] 1) Use waste polyolefin (HDPE / PP=50 / 50) with a particle size of 0.1-200mm as the cracking raw material;

[0081] 2) Heating the waste polyolefin above at a heating rate of 4°C / min, cooling down immediately when the temperature reaches 380°C to obtain a white solid waste polyolefin wax;

[0082] 3) Heat up waste polyolefin, waste polyolefin / waste polyolefin wax = 2:1, and waste polyolefin wax to 430°C at a heating rate of 4°C / min, and maintain this temperature for 30min or 40min, collect The gaseous product at this temperature, the yield of gaseous product is shown in Table 8.

[0083] Table 8 Yield list of waste HDPE / PP mild cracking products

[0084]

[0085] It can be seen from Table 8 that when HDPE and the produced wax are mixed and cracked (mass ratio is 2:1), the yield of the obtained gaseous product is about 3% higher than the theoretical yield, indicating that after the waste polyolefin is made into wax It has a very good function of promoting the cracking ...

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Abstract

The invention discloses a mild pyrolysis method for preparing liquid hydrocarbon through waste polyolefin. The method includes the following steps of firstly, conducting pretreatment; secondly, manufacturing wax; thirdly, conducting mixing and copyrolysis; fourthly, terminating mixing and copyrolysis; fifthly, conducting product collection. According to the method, the low heating rate is adopted, cleavage reaction happens to materials in the temperature rise process, the constant-temperature process and the cooing process, the yield of the liquid hydrocarbon is increased, secondary polymerization or dehydrogenation reaction are little during reaction, and the obtained liquid hydrocarbon is mainly composed of alkane and is extremely low in arene content.

Description

technical field [0001] The invention belongs to the technical field of recycling waste plastics, in particular, the invention relates to a mild cracking method for preparing liquid hydrocarbons from waste polyolefins. Background technique [0002] Plastic is a polymer material with a wide range of uses. Statistics show that in 2011, China's plastic consumption has reached nearly 60 million tons, accounting for more than a quarter of the world's total consumption, and China has become the world's largest plastic consumer. At the same time, a large amount of waste plastics has caused increasingly serious "white pollution". [0003] Landfill, incineration, and recycling are the main methods of waste plastics treatment at present. With the increasing amount of waste plastics and the increasingly stringent environmental management, landfill and incineration have begun to be restricted or even resisted. The chemical recovery of small molecular hydrocarbons (solid wax, liquid oi...

Claims

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Application Information

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IPC IPC(8): C10G1/00
Inventor 温浩景晓东赵月红许志宏
Owner INST OF PROCESS ENG CHINESE ACAD OF SCI
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