Waste Plastic Oil Purification With Integrated Trap Hydrotreatment
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Solution Overview
Problem
Pyrolysis plastic oil contains impurities such as olefins, dienes, silicon, metals, halogens, and other hetero-elements that prevent its direct use in processes like steam cracking, leading to catalyst poisoning, corrosion, and coke formation.
Innovation Solution
A two-step hydrotreatment process using a catalyst with both hydrotreating and trapping functions, combined with pre-treatments like solvent extraction and filtration, to remove impurities and saturate olefins and dienes, followed by a second hydrotreatment to produce a purified hydrocarbon stream suitable for steam cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If pyrolysis plastic oil is used directly in steam cracking, then process simplicity is maintained, but catalyst poisoning and coke formation occur
Solution Approach 1:
The patent applies preliminary action by implementing a trap unit before the steam cracking process to remove impurities (silicon, metals, phosphorous, halogenates) from pyrolysis plastic oil. This pre-treatment prevents catalyst poisoning and coke formation in downstream processes while maintaining overall process efficiency.
Solution Approach 2:
The trap unit acts as an intermediary between the pyrolysis plastic oil and the steam cracking process. It selectively removes harmful impurities while allowing the hydrocarbon stream to pass through, thereby protecting the catalyst without requiring complete redesign of the cracking process.
2Manufacturing precision
If multiple separate purification steps are used, then impurity removal effectiveness is improved, but process complexity increases
Solution Approach 1:
The patent merges multiple purification functions (trapping of silicon, metals, phosphorous, and halogenates) into a single integrated trap unit. This unified approach achieves comprehensive impurity removal while avoiding the complexity of multiple separate purification steps, as the trap unit operates as one cohesive system with sequential removal mechanisms.
Solution Approach 2:
The trap unit is designed with multi-functionality to simultaneously handle multiple types of impurities (silicon, metals, phosphorous, halogenates) through a single device. This universal approach eliminates the need for multiple specialized purification units while maintaining high removal effectiveness for all impurity types.
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 impurities to levels allowing the pyrolysis plastic oil to be used in steam cracking, minimizing catalyst deactivation and coke formation, thereby enhancing process efficiency and product yield.
Implementation Method 1
Putting in contact the effluent obtained at the step a) with silica gel, clays, alkaline or alkaline earth metal oxide, iron oxide, ion exchange resins, active carbon, active aluminium oxide, molecular sieves, alkaline oxide and/or porous supports containing lamellar double hydroxide modified or not and silica gel, or any mixture thereof to trap silicon and/or metals and/or phosphorous and/or halogenates
Implementation Method 2
performing a hydrotreating step at a temperature of at least 200° C.
Implementation Method 3
The catalyst presents both (i) an hydrotreating function and (ii) a trap function
Data Source
AI summary
Process for the purification of a hydrocarbon stream including: a) Providing a hydrocarbon stream having a diene value of at most 1.5 g I2/100 g and a bromine number of at least 5 g Br2/100 g, and containing at least 10 wt % of pyrolysis plastic oil; d) contacting the effluent obtained in step a) with silica gel, clays, alkaline or alkaline earth metal oxide, iron oxide, ion exchange resins, active carbon, active aluminum oxide, molecular sieves, alkaline oxide 10 and/or porous supports and silica gel, or any mixture thereof; e) performing a second hydrotreating step; and f) recovering a purified hydrocarbon stream, where the second hydrotreating step is performed over at least one catalyst that presents both (i) an hydrotreating function and (ii) a trap function.