Consider a heterogeneous gas-phase catalytic reaction: AB(g)→A(g)+B(g) (Catalyst) The surface reaction mechanism follows three steps: AB(g) +S <----> AB*S (Adsorption) AB*S<----> B*S+A(g) (Surface reaction) B*S <---> B(g) + S (Desorption) (a) Derive the rate law assuming each of the three cases: (1) adsorption is rate-limiting, (2) surface reaction is rate limiting, and (3) desorption is rate-limiting. Express the overall reaction rate (- Tan) in terms of total number of sites on the surface, C. partial pressures of the gas species (ie., PA. PA and Pa), rate constants of adsorption, the surface reaction, and desorption (kaks, and ko), and the equilibrium constants of adsorption, the surface reaction, and desorption (ie., K. Ks and Ko). Hint: Based on the reaction mechanism, only AB and B are adsorbed on the surface, i.e., there is no evidence that A alone can be adsorbed on the surface.
Consider a heterogeneous gas-phase catalytic reaction:
AB(g)→A(g)+B(g) (Catalyst)
The surface reaction
AB(g) +S <----> AB*S (Adsorption)
AB*S<----> B*S+A(g) (Surface reaction)
B*S <---> B(g) + S (Desorption)
(a) Derive the rate law assuming each of the three cases: (1) adsorption is rate-limiting, (2) surface reaction is rate limiting, and (3) desorption is rate-limiting. Express the overall reaction rate (- Tan) in terms of total number of sites on the surface, C. partial pressures of the gas species (ie., PA. PA and Pa), rate constants of adsorption, the surface reaction, and desorption (kaks, and ko), and the equilibrium constants of adsorption, the surface reaction, and desorption (ie., K. Ks and Ko).
Hint: Based on the reaction mechanism, only AB and B are adsorbed on the surface, i.e., there is no evidence that A alone can be adsorbed on the surface.
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Consider a heterogeneous gas-phase catalytic reaction:
AB(g)→A(g)+B(g) (Catalyst)
The surface reaction
AB(g) +S <----> AB*S (Adsorption)
AB*S<----> B*S+A(g) (Surface reaction)
B*S <---> B(g) + S (Desorption)
(a) Derive the rate law assuming
(1) surface reaction is rate limiting, and (2) desorption is rate-limiting. Express the overall reaction rate (- Tan) in terms of total number of sites on the surface, C. partial pressures of the gas species (ie., Pab Pa and Pb), rate constants of adsorption, the surface reaction, and desorption (ka,ks, and kd), and the equilibrium constants of adsorption, the surface reaction, and desorption (ie., Ka. Ks and Kd).
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