Continuous Direct Air Capture and Electrochemical Conversion of CO2 and H2O into Ethylene and Oxygen in Solid Electrolyte Reactor

Smart overview of the Invention

The patent application introduces a solid electrolyte electrochemical cell designed for direct air capture (DAC) and conversion of CO2 and H2O into ethylene and oxygen. This process operates at a low voltage potential of 0.6 V and a current of 1 A, achieving approximately 70 mg of ethylene production per hour with about 80% energy efficiency. The system operates at a lower temperature, making it a practical and scalable solution for reducing carbon emissions by transforming CO2 into valuable petrochemicals.

Background

The chemical industry significantly contributes to CO2 emissions, primarily through the production of ethylene. Traditional methods like ethane and naphtha cracking are carbon-intensive. Electrochemical reduction of CO2 using renewable electricity offers a carbon-neutral or negative alternative. It can potentially save 4.14-5.14 Mt of CO2 emissions per Mt of ethylene produced. Current lab-scale methods often use commercial CO2, which involves additional emissions for capture, storage, and transportation, challenging the goal of carbon neutrality.

Technical Details

The invention utilizes a solid-state electrolyte reactor incorporating CO2 sorbents such as polyethyleneimine PEI800/zeolite and gyroscopic salt CaCb. The reactor's anode is made from copper or copper oxide-covered single-walled carbon nanotubes and polyethylene glycol PEO/KOH filled nickel. The cathode is a highly conductive nickel-coated carbon foam. This setup allows for continuous operation with high energy efficiency, maintaining device temperature below 25°C.

Operational Mechanism

The DAC system employs a series of reactions where CO2 and H2O are absorbed and converted into ethylene and oxygen. CO2 is reduced to ethylene on a nano-scale copper surface, while OH- ions migrate through the solid polyelectrolyte from cathode to anode. The anode oxidizes OH- into oxygen, with the generated water being recycled back to the cathode. This continuous cycle is facilitated by the design of the electrolyte layer and the cathode, which includes copper nanoparticles as a catalyst for ethylene formation.

System Configuration

The DAC cathode, solid PEO/KOH PP electrolyte layer, and nickel foam anode are assembled to form the electrochemical cell (E-cell). Activation requires a DC voltage of 10-15 V, which stabilizes at 0.4-0.6 V during operation. The system can run continuously for extended periods, maintaining a stable temperature around 25°C. This configuration ensures efficient charge supply and effective conversion of CO2 and H2O into ethylene and oxygen.