Plastic Waste-Derived CO2 Sorbents and Methods for Enhanced Selectivity and Stability

Carbon capture will be a key pathway used by heavy carbon dioxide (CO2) emitting industries, such as petroleum refining, electrical power generation, and cement production, to reduce their carbon emissions. Solid sorbent technology has been touted as the most promising method to attain emissions reduction targets; however, many of these sorbents suffer drawbacks related to their cost, performance, or both. Due to these shortcomings, carbon capture solid sorbents have only just now begun to achieve industrial relevance. Chapter 1 will discuss the carbon capture problem and general sorbent performance metrics. At the same time, plastic waste pollution threatens the environment and acts as another significant risk that must be addressed. Current recycling technologies must be improved to limit the buildup of plastic waste. Here, we develop a pyrolytic method producing a highly microporous CO2 sorbent synthesized from plastic waste-salt mixtures. Diverse plastics with applications as packaging, textile, and construction materials were all addressed in this process. Chapters 2 and 3 examine our results regarding plastic-waste sorbents. To enhance the CO2 selectivity performance of plastic-derived sorbents, an amine-containing polymer, polyethylenimine (PEI), was added to the carbon sorbent in Chapter 4. To do this, we first modulated the pore structure of the sorbent to become more mesoporous through a liquid-salt templating mechanism. More mesoporosity allowed better accommodation of PEI into the carbon pore network. The PEI-carbon sorbent, although having better uptake and selectivity performance, showed poor stability especially in the presence of oxygen. Oxidative degradation pathways of PEI lead to imine formation and ammonia evolution; these end-products greatly reduce the sorbent’s CO2 uptake capacity. While strategies to reduce oxidative degradation exist through polymer modification, we show here that oxygen-related PEI destruction could be improved by maintaining some adsorbed CO2 during cycling. This adsorbed CO2 acts as a carbamate-protecting group to the amines and prevents continual polymer degradation. In this regard, the formed carbamates prolong PEI-based sorbent lifetimes.

Name thesis:degree_name

Doctor of Philosophy

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Natural Sciences

Grantor

Rice University

Year dc:date.issued

2024

Author dc:creator

• Savas, Paul E

Advisor dc:contributor.advisor

• Tour, James M

• CO2 capture
• sorbents
• plastics
• amines

Statement dc:rights

• Copyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.

Language dc:language.iso

eng

Handle dc:identifier.uri

https://hdl.handle.net/1911/118202

OAI identifier oai:identifier

oai:repository.rice.edu:1911/118202