Waste Plastic Sorting for C2-C8 Hydrocarbon Production
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Solution Overview
Problem
There is a demand for a more efficient method to obtain C2-C8 unsaturated hydrocarbons from waste plastics, as these compounds are diverse and crucial for producing petrochemical raw materials.
Innovation Solution
A method involving the sorting of waste plastics to isolate a polyolefin-based plastic mixture, followed by decomposition to produce a reaction product containing C2-C8 unsaturated hydrocarbons, and subsequent cleaning and purification to separate these hydrocarbons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If waste plastic is directly decomposed without sorting, then the decomposition process becomes simpler, but the production efficiency and purity of C2-C8 unsaturated hydrocarbons decrease
Solution Approach 1:
The waste plastic decomposition process is segmented into two distinct pathways: (1) sorting and decomposing polyolefin-based plastics (50 mass% or more) to produce C2-C8 unsaturated hydrocarbons, and (2) heating non-polyolefin residues to produce synthesis gas for alcohol synthesis. This segmentation allows each pathway to be optimized for its specific chemical composition, thereby improving the purity and efficiency of C2-C8 unsaturated hydrocarbon production while preventing contamination from other plastic types.
2Device complexity
If all waste plastic components are processed together, then the processing steps are reduced, but the quality and purity of the resulting C2-C8 unsaturated hydrocarbons deteriorate
Solution Approach 1:
The processing system is divided into separate handling streams for polyolefin-based plastics and non-polyolefin residues. The sorting step separates these components, allowing the polyolefin stream to undergo decomposition optimized for C2-C8 unsaturated hydrocarbon production, while the residue stream is directed to synthesis gas production. This physical and chemical segmentation ensures that each material type is processed under conditions optimal for its composition, maximizing hydrocarbon purity.
Solution Approach 2:
The invention extracts and isolates the polyolefin-based plastic component (50 mass% or more) from the mixed waste plastic stream through sorting. This extracted polyolefin fraction is then dedicated to C2-C8 unsaturated hydrocarbon production, removing it from the general waste stream. This extraction prevents contamination of the hydrocarbon product by other plastic types that would produce different decomposition products, thereby ensuring high purity.
3Quantity of substance
If polyolefin-based plastic content is increased to 50 mass% or more through sorting, then the yield of C2-C8 unsaturated hydrocarbons improves, but the preprocessing complexity increases
Solution Approach 1:
The sorting process leverages the inherent chemical and physical properties of polyolefin-based plastics (such as density, melting point, and chemical resistance) to enable their identification and separation from other plastic types. By utilizing these self-characterizing properties, the system achieves effective sorting without requiring overly complex analytical or separation equipment, thus balancing the increased yield benefit with acceptable preprocessing complexity.
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 enables the efficient production of C2-C8 unsaturated hydrocarbons from waste plastics, facilitating the regeneration of petrochemical raw materials and promoting recycling.
Implementation Method 1
step (2) of decomposing the plastic mixture (A) to obtain a reaction product containing a C2-C8 unsaturated hydrocarbon
Implementation Method 2
step (12) of heating the residue (B) to obtain a mixed gas containing carbon monoxide, carbon dioxide, and hydrogen
Implementation Method 3
step (14) of causing carbon monoxide, carbon dioxide, and hydrogen contained in the adjustment gas to react with each other to obtain an alcohol
Data Source
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AI summary
A method for producing a C2-C8 unsaturated hydrocarbon according to the present invention includes: step (1) of sorting, from a waste plastic, a plastic mixture (A) having a polyolefin-based plastic content of 50% by mass or more and a residue (B); step (2) of decomposing the plastic mixture (A) to obtain a reaction product containing a C2-C8 unsaturated hydrocarbon; and step (3) of cleaning and purifying the reaction product to separate the C2-C8 unsaturated hydrocarbon.