Two-Step Pyrolysis for Crosslinked Rubber Decomposition
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Solution Overview
Problem
Existing methods for decomposing crosslinked rubbers, such as pyrolysis at high temperatures and microbial decomposition, face challenges in achieving high monomer yield due to gasification, aromatization, and low recycling efficiency of carbon black.
Innovation Solution
A two-step pyrolysis method is employed, where a crosslinked rubber containing diene-based rubber is first pyrolyzed at 150° C to 400° C, followed by further pyrolysis of the decomposition product at 600° C to 950° C in an inert gas atmosphere without a catalyst.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a crosslinked rubber is pyrolyzed at high temperature to decompose the rubber, then the decomposition speed is improved, but gasification and aromatization of the decomposition product occur, reducing monomer yield
Solution Approach 1:
The pyrolysis process is divided into two distinct stages: a first pyrolysis stage at a lower temperature (150-400°C) to break the crosslinked structure and obtain preliminary decomposition products, and a second pyrolysis stage at a higher temperature (600-950°C) to further decompose the intermediate products. This segmentation allows the decomposition to proceed efficiently while controlling gasification and aromatization, thereby improving monomer yield compared to single-stage high-temperature pyrolysis.
2Manufacturing precision
If a crosslinked rubber is pyrolyzed at high temperature to decompose the rubber, then the decomposition completeness is improved, but a carbonized layer forms on carbon black, reducing its reinforcing capability
Solution Approach 1:
The two-stage pyrolysis process enables controlled decomposition where the first stage at lower temperature breaks crosslinks without excessive carbonization, and the second stage at higher temperature completes the decomposition of organic components. This segmentation prevents the formation of a thick carbonized layer on carbon black particles, preserving their surface properties and reinforcing capability while achieving complete decomposition of the rubber matrix.
3Object-affected harmful factors
If microorganisms are used to decompose crosslinked rubber to achieve material recycling, then environmental friendliness is improved, but the decomposition time becomes excessively long and monomer yield is low
Solution Approach 1:
The invention replaces the biological decomposition mechanism (microorganisms) with a thermal decomposition mechanism (pyrolysis). By using controlled heating in two stages, the process achieves rapid breakdown of crosslinked rubber structures without the time constraints of biological systems, while still enabling material recycling through monomer recovery. This substitution dramatically reduces decomposition time from days or weeks to hours or minutes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method improves the monomer yield by inhibiting gasification and aromatization in the first step and effectively decomposing the intermediate product in the second step, while also enhancing the recycling efficiency of carbon black.
Implementation Method 1
a first decomposition step of pyrolyzing a crosslinked rubber containing a rubber component that includes a diene-based rubber at not lower than 150° C. and not higher than 400° C.
Implementation Method 2
a second decomposition step of further pyrolyzing a decomposition product obtained through the first decomposition step at not lower than 600° C. and not higher than 950° C.
Data Source
AI summary
Provided is a method of decomposing a crosslinked rubber that can improve monomer yield. The method of decomposing a crosslinked rubber includes: a first decomposition step of pyrolyzing a crosslinked rubber containing a rubber component that includes a diene-based rubber at not lower than 150° C. and not higher than 400° C.; and a second decomposition step of further pyrolyzing a decomposition product obtained through the first decomposition step at not lower than 600° C. and not higher than 950° C. in an inert gas atmosphere and in the absence of a catalyst. The first decomposition step is preferably performed in an inert gas atmosphere.