We are developing a hybrid intermediate temperature (500-700Â°C) proton-conducting fuel cell (PCFC) system that operates directly on natural gas or natural gas liquids to generate electrical power and to produce high value chemicals such as ethylene or propylene as part of a U.S. Department of Energy Advanced Research Projects Agency â?? Energy (ARPA-E) funded project under its REBELS Program. For natural gas, non-oxidative coupling of methane (NOCM) catalyst technology is integrated into the anode compartment of the fuel cell to produce C2
alkanes, olefins and H2
. For natural gas liquids, propane dehydrogenation (PDH) catalyst technology is integrated into the anode compartment to produce propylene and H2
. The benefit of integrating severely thermodynamically-limited reactions such as NOCM or PDH into a PCFC is that the H2
produced by these reactions is oxidized within the anode, generating protons which migrate through the electrolyte to the cathode where they react with oxygen to form water. By removing H2
from the product mixture using the fuel cell, higher conversion levels for these reactions can be achieved at lower temperatures than in a conventional thermal catalytic process (Le Chatelierâ??s Principle). Additional benefits of our hybrid fuel cell system are that the lower operating temperature allows for a wider choice of less-costly materials compared to conventional reactor processes, the use of a proton-conducting electrolyte eliminates the loss of carbon due to the formation of CO and CO2
that occurs in oxidative coupling of methane (OCM) when oxygen is co-introduced using an oxide ion-conducting electrolyte, and the lower operating temperature minimizes coke formation during propane dehydrogenation due to thermal cracking of propylene.
To develop this hybrid system, we have had to develop (1) a novel proton-conducting fuel cell that is capable of operating efficiently at 500-700°C, (2) NOCM and PDH catalyst technologies that operate with high activity and selectivity at these temperatures, and (3) a methodology for integrating the NOCM or PDH catalysts into the PCFC. This talk will summarize our efforts to develop the proton-conducting fuel cell technology based on a barium-cerium-yttrium electrolyte; the NOCM and PDH catalyst technologies based on single-site catalysts that exhibit high yield and selectivity while minimizing coke formation, methodologies for integrating the catalysts into the anode compartment of the fuel cell, and preliminary test results. Preliminary results from a techno-economic analysis (TEA) comparing of our technology to competing technologies will be presented.
This work is supported by the U.S. Department of Energy, Advanced Research Projects Agency â?? Energy (ARPA-E) under Contract DE-AC02-06CH11357