TY - JOUR
T1 - Carbon deposition over Fe, Ni, and Co foils from CO-H2-CH4-CO2-H2O, CO-CO2, CH4-H2, and CO-H2-H2O gas mixtures
T2 - II. Kinetics
AU - Jablonski, G. A.
AU - Geurts, F. W.A.H.
AU - Sacco, A.
PY - 1992
Y1 - 1992
N2 - Nonequilibrium C-H-O phase diagrams were used to investigate the effect of gas composition on the kinetics of carbon deposition over Fe, Ni, and Co foils at 900 K and 1 atm. The gasphase carbon activity, which is proportional to the driving force for carbon deposition, was fixed at 10.0 for all experiments. The reduced metal foils were initially exposed to five-component gas mixtures of CO, H2, CH4, CO2, and H2O, after which the gas composition was switched to a binary CO-CO2 or CH4-H2 gas mixture, or a ternary CO-H2-H2O gas mixture. On exposure to either of the binary gas pairs, the rate of carbon deposition over all three metals was found to be approximately the same (≈10 * 10-6 min-1), and the rate was not observed to be a function of the partial pressure of the carbonbearing gas alone, either CO or CH4. In the case of Fe and Co, the rate of carbon deposition from the binary gas pairs dropped two orders of magnitude (2500 * 10-6 to ≈10 * 10-6 min-1) and one order of magnitude (500 * 10-6 to ≈10 * 10-6 min-1), respectively, compared to the rate from the five-component gas mixture. In the case of Ni, the rate of carbon deposition from the binary gas pairs was not observed to change from the rate of the five-component gas mixture (≈10 * 10-6 min-6). On exposure of Fe and Co foils to ternary gas mixtures, the rate changed proportionally to the product of the PCOPH2. Exposure of Ni foils to the ternary gas mixture had no effect on the rate of carbon deposition.
AB - Nonequilibrium C-H-O phase diagrams were used to investigate the effect of gas composition on the kinetics of carbon deposition over Fe, Ni, and Co foils at 900 K and 1 atm. The gasphase carbon activity, which is proportional to the driving force for carbon deposition, was fixed at 10.0 for all experiments. The reduced metal foils were initially exposed to five-component gas mixtures of CO, H2, CH4, CO2, and H2O, after which the gas composition was switched to a binary CO-CO2 or CH4-H2 gas mixture, or a ternary CO-H2-H2O gas mixture. On exposure to either of the binary gas pairs, the rate of carbon deposition over all three metals was found to be approximately the same (≈10 * 10-6 min-1), and the rate was not observed to be a function of the partial pressure of the carbonbearing gas alone, either CO or CH4. In the case of Fe and Co, the rate of carbon deposition from the binary gas pairs dropped two orders of magnitude (2500 * 10-6 to ≈10 * 10-6 min-1) and one order of magnitude (500 * 10-6 to ≈10 * 10-6 min-1), respectively, compared to the rate from the five-component gas mixture. In the case of Ni, the rate of carbon deposition from the binary gas pairs was not observed to change from the rate of the five-component gas mixture (≈10 * 10-6 min-6). On exposure of Fe and Co foils to ternary gas mixtures, the rate changed proportionally to the product of the PCOPH2. Exposure of Ni foils to the ternary gas mixture had no effect on the rate of carbon deposition.
KW - Catalysis
KW - cobalt
KW - deposition
KW - iron
KW - kinetics
KW - nickel
UR - http://www.scopus.com/inward/record.url?scp=0026641878&partnerID=8YFLogxK
U2 - 10.1016/0008-6223(92)90112-A
DO - 10.1016/0008-6223(92)90112-A
M3 - Article
AN - SCOPUS:0026641878
SN - 0008-6223
VL - 30
SP - 99
EP - 106
JO - Carbon
JF - Carbon
IS - 1
ER -