Modified Red Mud Chlorine Adsorption in Waste Plastic Pyrolysis
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Solution Overview
Problem
Pyrolysis oil produced from waste plastics has a high content of chlorine, which makes it unsuitable for direct use as a high-value-added fuel and requires additional refinery processes to remove impurities, leading to equipment corrosion and abnormal reactions.
Innovation Solution
A method involving the use of modified red mud, which exhibits enhanced chlorine adsorption characteristics, is employed in the pyrolysis process of waste plastics. The modified red mud is characterized by specific X-ray diffraction peak intensities, allowing for effective reduction of chlorine content in the pyrolysis oil.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If waste plastic pyrolysis oil is used directly as fuel, then energy utilization is improved, but high chlorine content causes equipment corrosion and abnormal reactions
Solution Approach 1:
The patent applies preliminary action by adding red mud to the pyrolysis reactor before the pyrolysis process begins. The red mud is pre-positioned to interact with chlorine during pyrolysis, preventing its harmful effects before they can occur. This proactive approach eliminates the need for post-treatment and directly prevents equipment corrosion while enabling energy utilization.
Solution Approach 2:
Red mud serves as an intermediary substance between the waste plastic feedstock and the pyrolysis oil product. It mediates the chlorine removal process by adsorbing chlorine during pyrolysis, thereby protecting the final oil product from harmful chlorine content while enabling direct use as fuel without additional treatment.
2Manufacturing precision
If adsorbent is used to remove chlorine, nitrogen and impurities, then product purity is improved, but adsorbent must be used in high content and continuously replaced
Solution Approach 1:
The red mud performs self-service by simultaneously serving as both a pyrolysis catalyst and a chlorine adsorbent. It remains in the reactor after pyrolysis and continues to adsorb chlorine from the produced oil, eliminating the need for separate adsorbent materials and their continuous replacement. The system uses the same material for multiple functions throughout the process.
Solution Approach 2:
The patent changes the operational parameters by using red mud in small quantities (0.1-5 wt% of feedstock) rather than the high adsorbent content (2-50 times oil content) required by conventional methods. This parameter change is achieved by modifying how the material is used - as a pyrolysis additive with continuous in-situ adsorption rather than as a separate bulk adsorbent.
3Manufacturing precision
If hydrotreating is performed to adsorb chlorine, then chlorine removal is improved, but excessive hydrogen chloride production causes equipment corrosion and abnormal reactions
Solution Approach 1:
The patent converts the harmful chlorine in waste plastics into a beneficial process feature. By adding red mud to the pyrolysis reactor, the chlorine that would normally cause corrosion is transformed into an adsorbate that binds to red mud particles. This converts a harmful byproduct into a controlled intermediate that facilitates chlorine removal without generating excessive hydrogen chloride.
4Ease of manufacture
If red mud is utilized as is, then processing cost is reduced, but strong alkalinity and high water content limit its utilization
Solution Approach 1:
The patent changes the operational parameters by using red mud in its raw, unprocessed state directly in the pyrolysis reactor. The high water content and strong alkalinity that normally limit red mud utilization are converted into beneficial features - the water provides steam for the pyrolysis atmosphere and the alkalinity enhances chlorine adsorption capacity, eliminating the need for expensive drying and grinding processes.
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 method effectively reduces the chlorine content in pyrolysis oil to levels suitable for direct introduction into a refinery process, avoiding the need for additional post-treatment and reducing process costs and environmental impact.
Implementation Method 1
a technique using an adsorbent such as CaO or a waste fluid catalytic cracking (FCC) catalyst (E-cat) has been performed
Implementation Method 2
a method of converting waste plastics into oil by performing a pyrolysis process
Implementation Method 3
when the modified red mud is subjected to X-ray diffraction (XRD) analysis, an intensity of a first peak at a 2θ diffraction angle of 14±0.1° is higher than an intensity of a second peak at a 2θ diffraction angle of 14.5±0.1°
Data Source
AI summary
Embodiments of the present disclosure provide a method for producing waste plastic pyrolysis oil with reduced chlorine, the method including a first operation of charging a waste plastic feedstock and modified red mud into a reactor, and a second operation of pyrolyzing the waste plastic feedstock in the reactor and recovering pyrolysis oil, wherein when the modified red mud is subjected to X-ray diffraction (XRD) analysis, an intensity of a first peak at a 2θ diffraction angle of 14±0.1° is higher than an intensity of a second peak at a 2θ diffraction angle of 14.5±0.1°.