Frequency response method for the study of kinetics of a heterogeneous catalytic reaction of gases

Journal Article · Thu Oct 05 04:00:00 EDT 1989 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100357a032· OSTI ID:6816234

Yasuda, Yusuke ^[1]

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1. Toyama Univ. (Japan)

A new frequency response method is proposed on the basis of actual data on C{sub 3}H{sub 6} + H{sub 2} {yields} C{sub 3}H{sub 8} over Pt/Al{sub 2}O{sub 3} at 273 K observed under each partial pressure of ca. 10 Pa: the gas space of a continuous-flow reactor was varied sinusoidally, and every partial pressure variation induced was followed by a mass spectrometer. Both amplitude and phase difference of {Delta}R observed in the angular frequency region from 4 to 60 rad/min were described well by {Delta}R (P{sub H}, P{sub H}) = (R{sub S}/P{sub H}{sup (s)})(n{Delta}P{sub H}(t) - {kappa}{Delta}P{sub H}(t)), where R{sub S} and P{sub H}{sup (s)} denote the overall reaction rate and the partial pressure of H{sub 2} at the steady state before the oscillation and {Delta}P{sub H} is the time derivative of the pressure variation, d{Delta}P{sub H}/dt. The rate constant n and {kappa} were 0.15 and 7 {times} 10{sup {minus}2} min. respectively. The unordinary rate equation involving P{sub H} was interpreted by R = {sigma}{sub d}{mu}{sub d} in terms of the driving force or the free energy drop, {mu}{sub d}, and the frequency factor, {sigma}{sub d}, at the rate-limiting step; {Delta}{sigma}{sub d}/{sigma}{sub d} = n{Delta}P{sub H}/P{sub H}{sup (s)} and {Delta}{mu}{sub d}/{mu}{sub d} = -{kappa}{Delta}P{sub H}/P{sub H}{sup (s)}. The newly derived rate constant {kappa} seemed to decrease with increasing temperature. The turnover frequency could be given by n/{kappa}.

• OSTI ID: 6816234
• Journal Information: Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 93:20; ISSN JPCHA; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
360104 -- Metals & Alloys-- Physical Properties
ALKANES
CATALYSIS
CHEMICAL REACTION KINETICS
DATA
DATA ANALYSIS
EXPERIMENTAL DATA
FREQUENCY RESPONSE TESTING
HYDROCARBONS
INFORMATION
KINETICS
MEASURING INSTRUMENTS
MEASURING METHODS
NUMERICAL DATA
ORGANIC COMPOUNDS
PROPANE
REACTION KINETICS
TESTING