(621n) Optimization of Production of Syn-Gas, Methane, and Ethylene in Solid Oxide Electrochemical Reactors

The utilization of renewable energy and finding ways to store it in valuable products is increasingly important. Energy systems which harvest CO2 and use the excess electricity for the the production of syn gas for Fischer Tropsch synthesis are sensitive to oil price volatility. Diversification of products helps to shield the integrated system from price volatility. We explored diversification through energy storage and alternate products using solid oxide electrolyte to synthesize methane and ethylene in addition to syngas. An additional benefit of the synthesis of ethylene is better long term carbon sequestration as the carbon embodied in the ethylene frequently ends up in plastics.   In contrast, FT synthesis results in liquid fuel production which is then used as fuel leading to only a carbon neutral use of energy instead of a carbon negative use of excess renewable energy.

The production of methane and oxidative coupling of methane in situ with the high temperature electrolysis of steam and carbon dioxide results in a synergy that lowers the overall energy use by the electrochemical cell. This occurs because both methanation and oxidative coupling of methane are exothermic and can therefore supply some of the energy necessary to the overall reaction and lower the thermoneutral voltage of the cell. It is also well known that perovskite materials are active oxidative coupling catalysts and fuel cell materials are designed to prevent many of the challenges associated with high temperature catalytic reactions of hydrocarbons. The enhanced economics of in-situ methane and ethylene generation in combination with standard syn-gas to FT are discussed. We will show the optimized ethylene production rates for a 1kW high temperature electrolyzer.