Reactor developed at Rice could cut energy costs in direct air capture

Reactor developed at Rice could cut energy costs in direct air capture
by Clarence Oxford
Los Angeles CA (SPX) Oct 30, 2024

Rice University researchers have created an electrochemical reactor aimed at lowering energy demands for direct air capture, a method that removes carbon dioxide from the atmosphere directly. This advancement could enable more scalable and efficient carbon dioxide mitigation, addressing key environmental concerns.

Published in *Nature Energy*, the study details the three-chambered reactor's modular structure, which centers around a specially designed porous solid electrolyte. Haotian Wang, the study's lead author and a Rice chemical and biomolecular engineer, explained that this design "represents a big milestone in carbon capture from the atmosphere." Wang's research group is focused on decarbonization and energy solutions to tackle emissions and promote sustainable industrial practices.

"Our research findings present an opportunity to make carbon capture more cost-effective and practically viable across a wide range of industries," Wang added, noting the reactor's long-term stability and adaptability to various cathode and anode reactions, which opens doors for large-scale industrial application.

The reactor's unique flexibility is among its main advantages. "One of the major draws of this technology is its flexibility," Wang explained. It allows for the integration of diverse chemistries and can cogenerate hydrogen, a process that "could translate into dramatically lower capital and operation costs for downstream manufacturing of net-zero fuels or chemicals."

Unlike typical high-temperature processes for capturing and regenerating carbon dioxide, Rice's new reactor operates at room temperature without extra chemicals or byproducts. This change means lower energy consumption and increased sustainability, especially since traditional processes often rely on high-pH liquids to filter carbon dioxide from mixed gas streams. The trapped carbon dioxide must then be extracted through heat, chemical reactions, or electrochemical means.

Zhiwei Fang, a Rice postdoctoral researcher and study co-author, noted that conventional direct air capture methods typically use thermal energy to regenerate carbon dioxide. "Our work focused on using electrical energy instead of thermal energy to regenerate carbon dioxide," Fang said, highlighting additional advantages of this method, such as zero byproduct generation and operation at room temperature.

Different sorbent chemicals bring specific challenges. While amine-based sorbents, widely used due to their low energy requirements, are unstable and toxic, greener alternatives like sodium hydroxide or potassium hydroxide demand high temperatures. Rice's reactor design addresses these limitations by separating the carbonate and bicarbonate solutions into high-purity carbon dioxide and alkaline absorbent.

"Our reactor can efficiently split carbonate and bicarbonate solutions, producing alkaline absorbent in one chamber and high-purity carbon dioxide in a separate chamber," Wang said. "Our innovative approach optimizes electrical inputs to efficiently control ion movement and mass transfer, reducing energy barriers."

Wang expressed hope that the research will inspire other industries to embrace sustainable processes and accelerate progress toward net-zero targets. "Rice is the place to be if you are passionate about sustainability and energy innovation," he said, noting that Rice's commitment to sustainable energy research aligns with his team's work.

Additional contributors to the study include former Rice postdoctoral researcher Xiao Zhang and Rice doctoral alumni and former postdoctoral scientists Peng Zhu and Yang Xia.

Research Report:Electrochemical regeneration of high-purity CO2 from (bi)carbonates in a porous solid electrolyte reactor for efficient carbon capture