MSE Masters Thesis Presentation: Tyler Critz

MSE Master’s Final Thesis Presentation: Tyler Critz

TITLE: Applications of Joule Heating in Amine-Activated Carbon Fibers for Efficient Desorption in Direct Air Carbon Dioxide Capture

ADVISOR: Joerg Werner (MSE, ME)

COMMITTEE: Sean Lubner (ME, MSE)

ABSTRACT: Developing rapid and more efficient mechanisms for sorbent regeneration is imperative in the continued optimization of direct air capture. Porous sorbents coated with polymeric amines are already capable of rapid absorption of CO₂ with a moderate capacity. However, the current mechanism of regeneration requires external heating of the sorbent, which is both slow and generally inefficient. Here, the project focused on the use of spermine-activated carbon fibers, a novel CO₂ sorbent, as their own heating element via the Joule heating effect. Considering physical properties of these carbon fibers, altering the polymer concentration and the ratio of the polymer mixture (polyacrylonitrile and polyvinylpyrrolidone) was found to have significant a tuning effect on the inner pore architecture and general mechanical strength of the fibers. The optimized fiber balances pore accessibility, pore surface area (the primary property that affects CO₂ absorption capacity), and mechanical strength via these two tuning mechanisms. Electrothermally, the Joule heating effect in this material leads to consistent, rapid, and uniform heating when in ambient air. A multifiber system has similar rapid heating but does not readily reach steady-state in open air continuing to increase in temperature as current is run. This can be optimized in a variety of ways, some of which are tested and some of which are proposed in this work. When used in a dynamic gas sorption system, the multifiber system is capable of rapid regeneration or CO₂ desorption when the Joule heating effect is induced. This approach represents a novel use of Joule heating for a DAC related system, and eliminates many of the system constraints that come from the current method through the use of the CO₂ sorbent itself as its own heating element.