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Study of Direct Utilization of Solid Carbon and CH4/CO2 Reforming on Solid Oxide Fuel Cell

Siengchum, Tritti
http://rave.ohiolink.edu/etdc/view?acc_num=akron1353313324

Abstract Details

2012, Doctor of Philosophy, University of Akron, Chemical Engineering.
This study demonstrates the feasibility and optimization of utilizing carbon and CH4 to generate electricity with solid oxide fuel cell (SOFC). Carbon sources including coconut shell biomass, coal, coke injecting into the anode compartment of the SOFC were heated rapidly. The detail reactions that occur on the carbon during this process were studied in the Chapter 4, fast pyrolysis of coconut biomass. The products of biomass fast pyrolysis consist of char, liquid and gases. The utilization of CH4 and CO2, which are the major pyrolysis products, was investigated in Chapter 5 with Rh-modification of the SOFC anode. The purpose of Rh-modification is to avoid carbon deposition in the anode matrix by promoting the dissociation of CO2, as a result, increasing the rate of carbon oxidation. The importance of the rate of carbon electrochemical oxidation has been highlighted in the study of carbon-based SOFC in Chapter 3. The rate of carbon oxidation and CO oxidation was studied as a function of operating current density of carbon-based SOFC with Ag impregnated Ni/YSZ anode. Chapter 3 reports the study of evolution of gases from direct utilization of carbon in a solid oxide fuel cell (C-SOFC) with coconut carbon, a carbonaceous material with low ash and sulfur content. The addition of CO2 to the anode chamber increased CO formation and maximum power density from 0.09 Wcm-2 to 0.13 Wcm-2, indicating the occurrence of Boudouard reaction coupling with CO electrochemical oxidation on the C-SOFC. Analysis of CO and CO2 concentration as a function of current and voltage revealed that electricity was mainly produced from the electrochemical oxidation of carbon at low current density and produced from the electrochemical oxidation of CO at high current density. The operating efficiencies of SOFC operated with coconut carbon and Ohio coal was evaluated to be less than 2 % in Chapter 4. This low efficiency was mainly due to gaseous product of carbon pyrolysis leaving the anode chamber unreacted, which lead to the study of fast pyrolysis. The fast pyrolysis reactions occur on the carbon fuel during the feeding step into the SOFC at high temperature. The reaction pathway of coconut shell fast pyrolysis was studied by analysis of the transient evolution product profiles as a function of temperature, measured directly in the sample bed. Fast pyrolysis of coconut shell produced (i) pyrolysis liquid containing C-H, C=O, and C-O-C bands, (ii) char with the absence of C-OH and C=O suggesting that ether and carbonyl compounds were decomposed below 600 °C, and (iii) gaseous product majorly consisting of CO2. The results of this study suggest the importance of utilization of gaseous species of fast pyrolysis, i.e., CH4, CO, CO2, and H2. The utilization of CH4 and CO2 to produce electricity was studied in SOFC comprising a Ni/YSZ anode impregnation of Rh. The Rh-Ni/YSZ anode SOFC and Ni/YSZ anode SOFC were tested simultaneously in the multiple SOFC reactor under flowing CH4/CO2. Exposure of the Ni/YSZ anode SOFC to CH4/CO2 produced a maximum power density that degraded from 0.06 to 0.01 W/cm2 after 41 h. Impregnation of Rh at 0.01 and 0.03 wt.% onto the Ni/YSZ anode produced the Rh-Ni/YSZ anode that exhibited a maximum power density of 0.06 and 0.08 W/cm2 , respectively, for more than 185 h. Extensive testing of SOFC with various concentration of Rh in H2/Ar and CH4/CO2 suggests the optimum Rh concentration of 0.07 ' 0.10 wt%
Steven Chuang, PhD (Advisor)
Jie Zheng, Dr. (Committee Member)
Nic D. Leipzig, Dr. (Committee Member)
Guo-Xiang Wang, Dr. (Committee Member)
Stephen Z. Cheng, Dr. (Committee Member)
175 p.
Chemical Engineering
SOFC; CH4; CO2 reforming; Rh; carbon fuel cell; fuel cell; fast pyrolysis; coconut shell

Recommended Citations

Citations

  • Siengchum, T. (2012). Study of Direct Utilization of Solid Carbon and CH4/CO2 Reforming on Solid Oxide Fuel Cell [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1353313324

    APA Style (7th edition)

  • Siengchum, Tritti. Study of Direct Utilization of Solid Carbon and CH4/CO2 Reforming on Solid Oxide Fuel Cell. 2012. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1353313324.

    MLA Style (8th edition)

  • Siengchum, Tritti. "Study of Direct Utilization of Solid Carbon and CH4/CO2 Reforming on Solid Oxide Fuel Cell." Doctoral dissertation, University of Akron, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1353313324

    Chicago Manual of Style (17th edition)

akron1353313324
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© 2012, all rights reserved.
This open access ETD is published by University of Akron and OhioLINK.