(544hc) Electrochemical Cycling Strategy for Selective C­-C Bonded, Acetylene Production from CO2 or CH4 Using Water at Atmospheric Pressure

Authors: 
McEnaney, J. M., Stanford University
Rohr, B. A., Stanford University
Nielander, A., Stanford University
Singh, A. R., Stanford University
Nørskov, J. K., Stanford University and SUNCAT
Jaramillo, T. F., Stanford University
Carbon dioxide and methane are two major emitted chemicals with global impact as greenhouse gases. The limited demand for these gasses also makes them inexpensive materials. Thus, these gasses are targeted as precursors for chemical processing to produce higher value, more useful products. Aqueous electrochemical CO2 reduction or CH4 oxidation are promising routes toward sustainably converting these chemicals into higher value chemicals and fuels. However, CO2 reduction is often dominated by the hydrogen evolution reaction (HER), with selective routes to very few products like CO, while CH4 is difficult to selectively oxidize on surfaces and often fully oxidizes to CO2, if it reacts at all. We have developed an electrochemical cycling strategy as an alternative pathway for COreduction and CH4 oxidation to selectively produce acetylene from either precursor (as well as from CO). The process comprises three distinct steps of electrochemical reactive surface preparation, carbon activation, and acetylene synthesis which can be combined and cycled for continuous acetylene production. This strategy circumvents the HER for CO2 reduction, and inhibits the complete oxidation to CO2 for CH4 oxidation. Acetylene, importantly, is a C-C bonded chemical and fuel with exceptionally diverse chemistry as a chemical precursor to polymers, fuels, and other carbon-based products. Theoretical considerations elucidate the feasibility and general applicability of this cycle and the process steps are characterized with specific electrochemical and materials chemistry techniques. Acetylene is quantified gas chromatography and verified by Fourier transform infrared radiation techniques.