Plastic Depolymerization via Aromatic Solvent Catalytic Cracking
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Solution Overview
Problem
Conventional methods for disposing of plastic waste are economically inefficient and often result in wasted products and contamination due to the use of solvents in processes like delayed coking, pyrolysis, and liquefaction, which fail to effectively convert plastic polymers into valuable hydrocarbon products like light olefins, benzene, toluene, and xylenes.
Innovation Solution
A method involving the dissolution of plastic polymers in aromatic-rich solvents from an aromatic recovery complex, followed by catalytic cracking in a riser or downer FCC reactor, utilizing a catalyst to produce light products such as propene, ethene, benzene, toluene, and xylenes, while minimizing solvent contamination and maximizing the economic use of low-value hydrocarbon streams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional disposal methods like incineration or landfill are used, then plastic waste is disposed of, but economic efficiency is poor and no valuable products are obtained
Solution Approach 1:
The invention changes the chemical parameters of plastic waste by dissolving it in aromatic solvents and subjecting it to catalytic cracking at specific temperatures (500-750°C), transforming it from an indisposable solid waste into valuable liquid hydrocarbon products including light olefins and aromatic compounds
Solution Approach 2:
Aromatic solvents serve as intermediaries in the conversion process, dissolving the plastic polymer and facilitating its transformation into valuable hydrocarbon products through catalytic cracking, while the solvents themselves are recovered and reused
2Loss of substance
If plastic waste is converted into hydrocarbon products through delayed coking, pyrolysis, or gasification, then some hydrocarbon products are obtained, but product waste occurs and solvents introduce contaminants like sulfur and nitrogen
Solution Approach 1:
The invention optimizes process parameters by using catalytic cracking at controlled temperatures (500-750°C) with specific catalysts, changing the reaction pathway to produce higher quality hydrocarbon products with fewer contaminants compared to conventional thermal processes
Solution Approach 2:
The process extracts and removes harmful contaminants through the catalytic cracking mechanism and subsequent product separation, eliminating sulfur and nitrogen compounds from the final hydrocarbon products while maximizing valuable output
3Ease of operation
If solvents are used in conventional refining processes to dissolve plastic waste, then plastic can be processed, but the solvents introduce contaminants such as sulfur and nitrogen into the products
Solution Approach 1:
The invention changes the chemical composition parameters of the solvent system by using aromatic solvents with specific molecular structures that do not contain sulfur and nitrogen, fundamentally altering the contamination profile of the process
Solution Approach 2:
The aromatic solvents are used in a controlled process where they dissolve the plastic, facilitate cracking, and are then recovered and reused, avoiding the need for expensive contaminant removal treatments while maintaining product quality
4Ease of operation
If valuable hydrocarbons are used as solvents in processing, then plastic waste can be dissolved and processed, but the process becomes uneconomical due to loss of valuable solvent
Solution Approach 1:
The invention implements a solvent recovery system where aromatic solvents are separated from the reaction products and reused in subsequent processing cycles, eliminating solvent loss and making the process economically viable
Solution Approach 2:
The aromatic solvents serve multiple functions: dissolving the plastic polymer, acting as a reaction medium for catalytic cracking, and being recovered for reuse, thereby maximizing the utility of the solvent and reducing overall process costs
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 approach effectively converts waste plastic polymers into valuable petrochemicals, offering an economical and efficient alternative to conventional disposal methods by utilizing aromatic bottoms as a solvent for catalytic cracking, thereby recovering monomers and producing light aromatic products with reduced contamination.
Implementation Method 1
dissolving the plastic polymer in the aromatic bottoms to obtain a dissolved plastic polymer solution
Implementation Method 2
catalytically cracking the dissolved plastic polymer solution in the presence of a catalyst such that the dissolved plastic polymer and the C9+ aromatic compounds are cracked to obtain light products
Data Source
AI summary
Methods for depolymerization of a plastic polymer. An embodiment includes supplying a plastic polymer and aromatic bottoms from an aromatic recovery complex, the aromatic bottoms comprising C9+ aromatic compounds; dissolving the plastic polymer in the aromatic bottoms to obtain a dissolved plastic polymer solution comprising dissolved plastic polymer and C9+ aromatic compounds; and catalytically cracking the dissolved plastic polymer solution in the presence of a catalyst such that the dissolved plastic polymer and the C9+ aromatic compounds are cracked to obtain light products.