LHHW Kinetic Analysis Example

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LHHW KineticAnalysis Example

• David A. Rockstraw, Ph.D., P.E.
• New Mexico State University
• Chemical Engineering

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Analysis of Catalytic Rate Data

• Data for the gas-phase catalytic reaction A B ?
  C, are given. The limiting step in the reaction
  is known to be irreversible, so the overall
  reaction is also. The reaction was carried out in
  a differential reactor to which A, B, and C were
  all fed. Find the rate law.

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Reactant A analysis

• As PA increases (at fixed PB and PC) the rate
  increases then levels off. Thus, PA must be in
  both numerator denominator

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Product C Analysis

• Because the reaction is irreversible, PC must be
  in the demoninator.

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Reactant B Analysis

• Rate increases by x10 when PB increases by x10.
• PB is only in the numerator

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Summary of Data Consideration

• PA is in the numerator and the denominator
• PB is in the numerator
• PC is in the demoninator
• which suggests

mechanistic clues Items in the denominator are
likely adsorbed on surface
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Linearize
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Regress rate and adsorption constants
Use a data point to extract all the constants
from the regressed slopes
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Identify mechanism leading to rate law
A S ? AS
AS B ? CS
CS ? C S