Kinetics and Mechanisms of the Two Opposing Reactions of the Equilibrium CO + H2O = CO2 + H21

Graven, Wendell M.; Long, Frank

doi:10.1021/ja01639a002

Cited by 77 publications

(59 citation statements)

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“…The scattering of the low-pressure rate constant data was primarily attributable to experimental fluctuations in maintaining a constant volumetric flowrate of low-pressure steam through the reactor. The rate constants appear to be similar to the low-pressure results reported by Graven and Long (1954), although the scatter of the low pressure data doesn't allow for a correlation for the rate constant to be established. In our previous study (Bustamante et al, 2003) on the kinetics of the hightemperature gas-phase RWGS we reported that our experimental energy of activation, as well as the value reported by Graven and Long (1954), were significantly lower than the predicted from the Bradford mechanism.…”

supporting

confidence: 73%

“…the sticking coefficient, only provide an upper bound for the effect of radical quenching. Consequently, the simulation predicted a large inhibition in the rate of reaction even at high temperature (>1148 K) where such inhibition has not been observed experimentally (Graven and Long, 1954;Kochubei and Moin, 1969).Therefore, no reliable estimation could be obtained from these calculations. Figure 15 presents the experimental results from the quartz reactor packed with small cylinders of quartz, Table 2, that increased the quartz surface area by a factor of three.…”

mentioning

confidence: 86%

“…This is manifested in the tailing of the Residence Time Distribution, RTD, plot, Figure 11, which exhibits a distribution broader than that expected for a laminar flow reactor with axial dispersion (Fogler, 1999). Despite the almost ideal behavior observed in the reactors used by Graven and Long (1954) and Tingey (1966), there was a four-fold difference in the reaction rate constants reported for these investigators suggesting that the discrepancy was not related to the geometry of the reactor. The results, shown in Table 3, indicate that the outlet concentrations were within 7% of one another, confirming that the reactor geometry was not responsible for the differences observed in the reported reaction rate expressions.…”

mentioning

confidence: 88%

“…Tingey (1966) and Kochubei and Moin (1969) published results that were in very good agreement, with both obtaining lower values for the rate of reaction than Graven and Long (1954). Tingey suggested that the higher reaction rate reported by Graven and Long (1954) may have been caused by traces of oxygen in their feed stream that acted as a homogeneous catalyst, but was unable to substantiate this claim.The values of the rate constant, k, for the low-pressure rWGSR are presented as a function of inverse absolute temperature over the 1123 -1223 K in Figure 1. The preexponential constant and activation energy of each correlation is listed in Table 1.…”

mentioning

confidence: 97%

“…This effect was addressed to some extent in the prior investigations of the low-pressure rWGSR. Graven and Long (1954) noted an induction period for the rWGSR, a common feature in chain-reaction chemistry. Kochubei and Moin (1969) kept the H 2 stream at the reaction temperature for a time long enough (15 -1000 s) to achieve a stationary state concentration of H (i.e., the equilibrium concentration from the H 2 dissociation (Eq.…”

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confidence: 99%

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University/NETL Student Partnership Program

Holder¹

2003

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Renewed interest in methane hydrates as a potential, unconventional energy source has prompted investigation into their thermal properties, which are necessary to determine heat flow through the hydrate for resource production.In this investigation thermal property measurements have been made on unconsolidated pure methane hydrate samples formed in a high-pressure variable-volume viewcell (HVVC). Using a transient plane source (TPS) technique, a single measurement was used tosimultaneously determine the thermal conductivity and thermal diffusivity of the methane hydrate inside the viewcell. A vessel was designed to contain the sample around the TPS for thermal property measurements while inside the HVVC. The vessel was successful in containing the sample during the hydrate formation experiments and its design made it possible to recover a methane hydrate sample, which was analyzed with Raman spectroscopy.The striking quality of methane hydrate is that its thermal conductivity is much lower than ice, despite its structural similarities to ice. The thermal conductivity of pure methane hydrate for a temperature range of 264 K to 277 K and pressure range of 11.6 MPa to 13.0 MPa, respectively, can be described by k = (-0.0034 T + 1.2324) W/mK, where T is in Kelvin. The average of the thermal conductivity values within this range of temperatures and pressures is k = 0.30 ± 0.02 W/mK. The sample was recovered and analyzed with Raman spectroscopy, confirming that the sample was pure hydrate.The thermal diffusivity of methane hydrate has only been reported by one other investigator in preliminary experiments. The thermal diffusivity of methane hydrates determined in the work reported herein for a temperature range of 264 K to 277 K and pressure range of 11.6MPa to 13.0 MPa, respectively, is α = (2.59 ± 0.16) × 10 -7 m 2 /s. The thermal diffusivity can also be described by α × 10 7 = (0.0005 T + 2.4424) m 2 /s where T is in Kelvin.iv Derivation ...................................................................................................................................116 Different τ -Values ...................................................... Dr. Gerald Holder, Dean of Engineering at the University of Pittsburgh, was my research advisor and though his role was remote, his support, knowledge, and advice was integral to my work. B.1.2 H(τ) Values From Numerical Integration at LIST OF TABLES LIST OF FIGURESI would like to thank Ronald Lynn of NETL. Ron played an integral role in upgrading and automating our experimental setup. He wrote the data acquisition program, automating data collection. He supplied his vast knowledge of National Instrument's software and hardware and was a great resource for learning LabVIEW.Dr. David Shaw of Geneva College developed most of the data analysis described here. He hired me as a research assistant while I was an undergraduate which led to an internship at NETL. As such, I was able to continue this work as a graduate student at Pitt. I thank him for his vast knowledge and w...

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confidence: 73%

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confidence: 86%

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confidence: 88%

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confidence: 97%

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confidence: 99%

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