Chemical Reactions on Solid Surfaces - Bioprocess Engineering: Kinetics, Biosystems, Sustainability and Reactor Design - page 469

(2)

The designated active site, , is consumed in the first step and regenerated in the second,

thus forming a closed sequence. Derive a rate equation for the rate of dehydration of alcohol
assuming that
(a) Both reactions occur at the comparable rates.
(b) Reaction (1) is much faster than reaction (2), and (2) is irreversible.
9.5. Methanol synthesis from syn gas

2 H 2 þ CO CH 3 OH (1)

%

May be described by the following mechanism

H 2 þ s % H 2 $s (2)

CO þ s % CO $s (3)

CO $s þ H 2 $s % HCOH $s þ s (4)

HCOH $s þ H 2 $s % CH 3 OH $s þ s (5)

Derive a rate expression if the surface is ideal and reaction (4) is rate limiting.
9.6. Synthesis of ammonia from nitrogen and hydrogen over Ru/C catalyst is found to
follow the following steps:

N 2 þ s % N 2 $s (1)

N 2 $s þ s % 2 N $s (2)

H 2 þ 2s % 2 H $s (3)

H $s þ N $s % NH $s þ s (4)

H $s þ NH $s % NH 2 $s þ s (5)

H $s þ NH 2 $s % NH 3 $s þ s (6)

NH 3 $s % NH 3 þ s (7)

þÞ ¼ overall N þ 3 H 2 % 2 NH 3 (8)

The adsorption of nitrogen, step (1) is found to be the rate-limiting step. Derive a rate
expression that is consistent with the mechanism based on ideal surface.
9.7. Christoph and Baerns (R. Christoph and M. Baerns, Chem-Ing-Tech. , 58, 494, 1968)
conducted extensive studies on the methanation of CO

CO þ 3 H 2 / CH 4 þ H 2 O (1)