Electrocatalysis for Environmentally Friendly Energy Production SystemsEPA Grant Number: R831495
Title: Electrocatalysis for Environmentally Friendly Energy Production Systems
Investigators: Pfefferle, Lisa , Ciuparu, Dragos
Current Investigators: Pfefferle, Lisa , McEnally, Charles
Institution: Yale University
EPA Project Officer: Klieforth, Barbara I
Project Period: December 1, 2003 through November 30, 2006 (Extended to November 30, 2007)
Project Amount: $375,000
RFA: Technology for a Sustainable Environment (2003) RFA Text | Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , Sustainability , Nanotechnology
The proposed research is aimed at using electrically driven catalytic processes to provide the design basis for cleaner energy production. The envisioned technologies are based on electrochemical manipulation of reaction intermediates adsorbed at the surface of catalysts by applying electrical potentials in different circuit configurations and on the use of electrochemical pumping of oxygen through electrolyte membranes permeable to oxygen for membrane reactors with separate feeds of reactants. The direct applications include "zero emissions" combustors and fuel cell components. To reach the overall application objective of controlling the inhibitory effect of water on the activity of PdO catalysts for complete oxidation reactions, the scientific objectives of our research are to understand and manipulate hydroxyl coverage of PdO catalysts dispersed on solid electrolytes with various charge carriers and to investigate the effect of applying over potentials in different electric circuit configurations to this catalyst. A more general objective is to investigate the possibility of using electrochemical pumping of oxygen in a membrane reactor configuration for methane combustion with separate feed of reactants, which allow economically efficient CO2 sequestration and storage from combustors and partial oxidation reactors. This "zero emission" burner can contribute significantly to the reduction of CO2 emissions.
We will use in situ characterization techniques that will provide fundamental mechanistic understanding of hydroxyl bonding at the PdO surface and how this can be manipulated using electrochemical methods in order to diminish or eliminate the inhibition caused by the presence of water in the reaction environment. The hydroxyl radical coverage and it's response to changes under methane oxidation reaction conditions will be studied using in-situ Fourier Transform Infrared Spectroscopy (FTIR) for the Pd catalyst supported on a variety of solid electrolytes. We will then repeat the experiments using electrochemical pumping of oxygen through electrolyte membranes for reactors with reactants fed to opposite sides of the membrane. These reactors will also be designed such that the OH on the catalyst surface and it's response to the electrochemical pumping can be monitored using in-situ-FTIR.
We expect that electrochemical pumping and the use of supports with high oxygen mobility will increase the low temperature activity of Pd-based catalysts for methane oxidation. We have preliminary evidence that this will work based on our work showing that OH coverage severely inhibits reactivity at temperatures less than 700K and that perturbing OH coverage by enhancing oxygen mobility improves reactivity. A second major result that we anticipate is the increase in the oxygen transport rate through the electrolyte membrane potentiated by the electrochemical pumping. The optimization of the electrolyte material and way the over potentials are applied to the catalyst in different electric circuit configurations would allow an economic "zero emission" combustor as discussed below.
Impact of Results on Pollution Prevention: Increasing low temperature activity, strongly affected by water inhibition, is necessary to achieve combustion catalysts that light off at compressor outlet temperatures avoiding preheating and consequent NOx production. These results would also be important for extended applications of solid oxide fuel cell technology by providing a way to reduce methane emissions to values acceptable for industrial application. In addition, we will develop high temperature resistant electrolytes for electrochemically pumping oxygen to increase transport rates for use in combustors and partial oxidation reactors. This technology will allow efficient sequestration of CO2 as well as significantly reducing NOx emissions without post-process clean-up. Several companies currently have prototype burners of this type and have nearly economic designs but need to increase the oxygen transport rate by around a factor of two. We estimate that electrochemical pumping should be