Zeolitic Catalyst Pyrolysis Dechlorination
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Solution Overview
Problem
Current methods for converting waste plastics into hydrocarbon streams through pyrolysis produce liquid products with high chlorine content and limited olefin content, making them unsuitable as feedstock for steam crackers due to stringent feed requirements.
Innovation Solution
A process involving simultaneous pyrolysis and dechlorination of mixed plastics using a zeolitic catalyst, which includes medium and large pore zeolites, to produce a treated hydrocarbon liquid stream with reduced viscosity and chloride content, suitable for steam cracker feedstock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional pyrolysis process is used to convert waste plastics to hydrocarbon liquid, then plastic waste is converted to liquid products, but the liquid products contain high chlorine content and limited olefin content making them unsuitable for steam cracker feedstock
Solution Approach 1:
A basic compound (such as calcium oxide, calcium hydroxide, or sodium hydroxide) is introduced as an intermediary substance to react with and remove chlorine from the pyrolysis liquid products. The basic compound acts as a mediator between the chlorinated pyrolysis products and the desired clean hydrocarbon feedstock, converting harmful chlorine into removable salts while preserving the hydrocarbon components.
Solution Approach 2:
The chlorine component is selectively extracted and removed from the pyrolysis liquid products through treatment with basic compounds. This extraction process separates the harmful chlorine (converted to water-soluble salts) from the valuable hydrocarbon fraction, producing a dechlorinated liquid suitable for steam cracker feedstock while maintaining hydrocarbon production quantity.
2Quantity of substance
If conventional pyrolysis process is used, then plastic waste is converted to hydrocarbon liquid, but the liquid products have high viscosity requiring additional treatment steps
Solution Approach 1:
The dechlorination and viscosity reduction processes are merged into a single integrated treatment step using basic compounds. The basic compound simultaneously removes chlorine (through salt formation) and reduces viscosity (through chemical reaction with chlorinated components), eliminating the need for separate treatment units and reducing overall process complexity while maintaining hydrocarbon production.
3Adaptability or versatility
If pyrolysis oil with high chlorine content is used as steam cracker feedstock, then feedstock availability is improved, but operational costs increase and cracking efficiency decreases
Solution Approach 1:
The invention creates a copy or analogue of ideal steam cracker feedstock from waste plastic pyrolysis products. By treating pyrolysis liquid with basic compounds to remove chlorine and reduce viscosity, the process produces a feedstock that replicates the properties of conventional naphtha or other suitable steam cracker feeds, enabling waste plastics to serve as viable feedstock without compromising cracking efficiency or requiring specialized equipment modifications.
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
The process effectively reduces chloride content to ppm levels and lowers viscosity, making the hydrocarbon stream amenable for use in steam crackers, enhancing cracking efficiency and reducing operational costs by minimizing treatment steps.
Implementation Method 1
simultaneous pyrolysis and dechlorination of mixed plastics using a zeolitic catalyst
Implementation Method 2
dechlorination of the pyrolysis oil
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A process for processing mixed plastics comprising simultaneous pyrolysis and dechlorination of the mixed plastics, the process comprising contacting the mixed plastics with a zeolitic catalyst in a pyrolysis unit to produce a hydrocarbon product comprising a gas phase and a liquid phase; and separating the hydrocarbon product into a hydrocarbon gas stream and a hydrocarbon liquid stream, wherein the hydrocarbon gas stream comprises at least a portion of the gas phase of the hydrocarbon product, wherein the hydrocarbon liquid stream comprises at least a portion of the liquid phase of the hydrocarbon product, wherein the hydrocarbon liquid stream comprises one or more chloride compounds in an amount of less than about 100 ppmw chloride, based on the total weight of the hydrocarbon liquid stream, and wherein the hydrocarbon liquid stream is characterized by a viscosity of less than about 400 cP at a temperature of 300 °C.