Catalytic Cracking Waste Plastic Light Hydrocarbon Recycling
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Solution Overview
Problem
Catalytic cracking of waste plastic often results in low valorization of gas products, with 'off-gases' typically used for energy recovery, and there is a need to increase the production of valuable kerosene and diesel fractions while maintaining high quality.
Innovation Solution
Introducing a gas stream comprising light weight hydrocarbons, including propylene, into the reactor during catalytic cracking of waste plastic, which surprisingly transforms these light hydrocarbons into heavier products, increasing kerosene and diesel fractions and improving diesel quality by reducing aromatic content, and allowing recycling of 'off-gases' to enhance product yields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If catalytic cracking is performed on waste plastic, then high molecular weight polymers are converted into volatile compounds, but the gas products (C1-C4) are difficult to valorize and typically used for energy recovery only
Solution Approach 1:
The patent converts the previously useless or low-value gas products (C1-C4) into valuable heavier hydrocarbons (kerosene and diesel fractions) by reintroducing them into the cracking reactor. This transforms a waste stream that was only suitable for energy recovery into a valuable feedstock that enhances liquid fuel production.
Solution Approach 2:
Instead of discarding the gas products from catalytic cracking, the patent recovers them by reintroducing into the reactor system. This closed-loop approach allows the light hydrocarbons to be converted into heavier, more valuable liquid fuel fractions, thereby recovering what would otherwise be lost or underutilized.
2Productivity
If light weight hydrocarbons are introduced into the cracking reactor, then they should undergo reactions transforming them into even lighter compounds, but surprisingly they are transformed into heavier products increasing kerosene and diesel fractions
Solution Approach 1:
The patent implements a feedback mechanism by taking the gas products from the cracking reactor and reintroducing them back into the same reactor. This feedback loop allows the light hydrocarbons to interact with the catalyst and existing reaction conditions, unexpectedly producing heavier liquid fuel fractions rather than further decomposition.
3Productivity
If off-gases are recycled into the process, then kerosene and diesel fractions are further increased, but process complexity increases
Solution Approach 1:
The patent makes the cracking reactor multi-functional by using it both for the primary catalytic cracking of waste plastic and for the conversion of recycled gas products. This single reactor performs multiple functions: initial polymer decomposition and subsequent light hydrocarbon conversion to heavier liquids, eliminating the need for separate processing units.
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 significantly increases the production of valuable kerosene and diesel fractions with improved quality, specifically by converting light hydrocarbons into heavier products and recycling 'off-gases', without affecting reaction kinetics or overall conversion efficiency.
Implementation Method 1
catalytic cracking of waste plastic so as to convert high molecular weight polymers into volatile compounds
Implementation Method 2
light weight hydrocarbons being introduced within a reactor for cracking waste plastic are transformed into heavier products
Data Source
Figure 1a
Figure 1b
Figure 1c
AI summary
The present invention relates to a process for converting waste plastic into gases, liquid fuels and waxes by catalytic cracking. The process comprises the steps of introducing waste plastic and a catalyst within a reactor; allowing at least a portion of the waste plastic to be converted to gases, liquid fuels and waxes within the reactor; and removing a product stream containing said gases, liquid fuels and waxes from the reactor.