Electrosynthesis of Syngas from Carbonate Capture Liquid

Electrosynthesis of Syngas from Carbonate Capture Liquid

NU 2023-081

INVENTORS

• Edward Sargent*
• Ammar Alahmed
• Issam Gereige
• Hengzhou Liu
• Heejong Shin
• Ke Xie

SHORT DESCRIPTION

This invention discloses an advanced electrosynthesis process that converts carbonate liquid from CO₂‐capture directly into syngas using a bipolar membrane-based electrolyzer. By integrating reactive CO₂ capture with in situ regeneration, it bypasses energy-intensive gas concentration steps to produce a valuable CO/H₂ mixture.

BACKGROUND

With global efforts to achieve net-zero emissions, converting captured CO₂ into value-added chemicals is critical. Traditional direct air capture requires high-temperature fluctuations to release gas-phase CO₂, followed by complex conversion processes that reduce efficiency. This invention leverages reactive capture by using carbonate capture liquid, where CO₂ is regenerated in situ via acid/base reactions within a bipolar membrane electrolyzer. Modeling studies demonstrated that optimizing the gap between the cation-exchange layer and the catalyst surface is key to enhancing the local CO₂ concentration and the selectivity toward syngas production. This approach offers a streamlined, carbon-negative pathway for converting an abundant greenhouse gas into chemical feedstocks.

ABSTRACT

The disclosed technology presents a novel system for the electrosynthesis of syngas directly from a CO₂‐captured carbonate liquid. A bipolar membrane-based electrolyzer is used to generate protons that react with carbonate, regenerating CO₂ in situ, which is then reduced at the surface of an optimized electrocatalyst. This process produces a syngas mixture suitable for downstream chemical upgrading.

Detailed modeling of species generation and diffusion indicates that controlling the spacing between the cation‐exchange layer of the bipolar membrane and the electrocatalyst is crucial for maximizing the local concentration of regenerated CO₂. By overcoming the traditional limitations of low CO₂ utilization in alkaline and neutral electrolysis systems, this innovative design achieves improved product selectivity and energy efficiency, paving the way toward scalable, carbon-negative chemical production.

APPLICATIONS

• CO₂-to-Syngas Conversion: Enables direct conversion of carbonate capture liquid into syngas for fuel and chemical synthesis.
• CO₂ Capture Systems: Integrates with advanced carbon capture processes to upgrade CO₂ into valuable chemical feedstocks.
• Chemical Feedstock Production: Supplies a sustainable source of CO and H₂ for the manufacture of C1 and multicarbon products.
• Carbon-Negative Manufacturing: Supports cradle-to-gate strategies by utilizing captured CO₂ in industrial processes.

ADVANTAGES

• Bypasses CO₂ Concentration: Direct conversion from carbonate liquid eliminates energy-intensive gas-phase CO₂ regeneration.
• Enhanced CO₂ Utilization: In situ acid/base reactions maximize the availability of CO₂ for reduction.
• Simplified System Architecture: Integrates CO₂ capture and electrochemical conversion in a single streamlined process.
• Carbon-Negative: Converts captured CO₂ into syngas, contributing to overall emission reduction strategies.
• Optimized Catalyst Interface: Modeling-driven design improves reactant concentration and product selectivity.

PUBLICATIONS

• Scott Barnett et al, CO₂ electroreduction to multicarbon products from carbonate capture liquid, Joule, [Date not provided]

IP STATUS

US Patent Pending