Two-Step Pyrolysis for Crosslinked Rubber Decomposition
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Solution Overview
Problem
Existing methods for decomposing crosslinked rubbers, such as pyrolysis 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 300°C to 450°C in an inert gas atmosphere without a catalyst.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high temperature pyrolysis is used to decompose crosslinked rubber, then decomposition speed is improved, but monomer yield decreases due to gasification and aromatization
Solution Approach 1:
The decomposition process is divided into two distinct stages: a first pyrolysis stage at 150-400°C to break crosslinks and generate monomers, followed by a second pyrolysis stage at 300-450°C to further decompose oligomers. This segmentation allows each stage to operate at optimized temperatures, preventing excessive gasification and aromatization while maintaining high decomposition efficiency.
Solution Approach 2:
The method employs periodic temperature control with two distinct heating periods: an initial period at lower temperature (150-400°C) to preserve monomer yield, followed by a second period at higher temperature (300-450°C) to complete decomposition. This periodic action prevents continuous high-temperature exposure that causes gasification and aromatization.
2Reliability
If high temperature pyrolysis is used to decompose crosslinked rubber, then decomposition completeness is improved, but carbon black reinforcing capability decreases due to carbonized layer formation
Solution Approach 1:
The method changes the temperature parameter through two distinct ranges: 150-400°C in the first stage to achieve decomposition without excessive carbonization, and 300-450°C in the second stage to complete the decomposition while minimizing carbonized layer formation on carbon black surfaces, thereby preserving reinforcing capability.
3Object-affected harmful factors
If microbial decomposition is used to decompose crosslinked rubber, then environmental impact is reduced, but decomposition time increases and monomer yield decreases
Solution Approach 1:
The method replaces the biological microbial decomposition system with a controlled thermal pyrolysis system. This substitution eliminates the long decomposition times and low monomer yields associated with microbial methods while maintaining environmentally friendly operation through inert gas atmosphere control that prevents harmful emissions.
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, retaining the monomer skeleton, and allowing for the efficient recycling of carbon black, thereby enhancing the recyclability of crosslinked rubber.
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.; and a second decomposition step of further pyrolyzing a decomposition product obtained through the first decomposition step
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 300° C. and not higher than 450° 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.