Hydrocracking Aromatic Polymers to Recover Hydrocarbons
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Solution Overview
Problem
Current plastic recycling methods face challenges such as complex product formation, low yield, and incomplete decomposition, making it difficult to effectively recycle plastics into high-value chemicals with industrial potential.
Innovation Solution
A method involving hydrocracking of polymers containing aromatic rings using a catalyst system with a carrier and active ingredients like Ru, Rh, Pt, Pd, Fe, Ni, Cu, or Co, which selectively breaks C—O and C—C bonds without hydrogenating the benzene ring, producing aromatic hydrocarbons at high yields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional catalysts with high C-O and C-C bond breaking activity are used, then the cracking efficiency is improved, but the benzene ring is also hydrogenated, reducing selectivity
Solution Approach 1:
The catalyst design applies local quality by creating distinct functional zones: the carrier provides acid sites for selective C-O and C-C bond breaking, while the metal particles provide hydrogenation activity. This spatial and functional separation allows the C-O and C-C bonds to be broken without complete hydrogenation of the benzene ring, achieving both high cracking efficiency and selectivity for aromatic hydrocarbons.
2Speed
If high temperature pyrolysis/cracking is used, then the decomposition speed is improved, but the product complexity increases and separation becomes difficult
Solution Approach 1:
The invention changes the temperature parameter from conventional high temperature (≥500°C) pyrolysis to a lower temperature range (200-400°C) hydrocracking process. This parameter change, combined with the use of hydrogen atmosphere and catalyst, achieves fast decomposition while producing simpler, more separable aromatic hydrocarbon products with fewer byproducts.
3Loss of substance
If decomposition treatment is used, then the plastic can be broken down, but the product yield is low and decomposition is incomplete
Solution Approach 1:
The invention introduces hydrogen as an intermediary substance that facilitates complete decomposition of the polymer. The hydrogen atmosphere prevents carbonaceous residue formation and promotes complete conversion to aromatic hydrocarbons, achieving both complete decomposition and high product yield that cannot be achieved by thermal decomposition alone.
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 achieves high selectivity and yields up to 85% molar yield of aromatic hydrocarbons, suitable for industrial applications as raw materials for various products, while avoiding hydrogenation of the benzene ring.
Implementation Method 1
reacting the polymer containing aromatic rings dispersed in a solvent with hydrogen under the action of a catalyst at a temperature of no more than 350° C.
Implementation Method 2
the catalyst may include a carrier and an active ingredient supported on the carrier, the active ingredient may include at least one of Ru, Rh, Pt, Pd, Fe, Ni, Cu or Co
Data Source
AI summary
Disclosed is a method for preparing aromatic hydrocarbons by hydrocracking a polymer containing aromatic rings, which includes reacting the polymer fragment with hydrogen under the action of a catalyst at a temperature of no more than 350° C.; separating a reaction product to obtain the aromatic hydrocarbons. The catalyst comprises a carrier and an active ingredient supported on the carrier, the active ingredient is at least one selected from Ru, Rh, Pt, Pd, Fe, Ni, Cu and Co, the carrier is at least one selected from metal oxide, phosphate, molecular sieve, SiO2 and sulfonated carbon, the metal oxide is at least one selected from Al2O3, Nb2O5, Nb2O5—Al2O3, Nb2O5—SiO2, TiO2, ZrO2, CeO2 and MoO3; the phosphate is at least one selected from NbOPO4 and ZrOPO4; and the molecule sieve is at least one selected from Nb-SBA-15, Nafion, H-ZSM-5, H-Beta and H-Y.