102
Fig. 4.6 Path (a):
proposed mechanism
involving CO 2 insertion
into the Rh-H bond
followed by a sequence of
oxidative addition and
reductive elimination steps
for the H 2 activation
process. Path (b): the
formation of formic acid is
a result of a [2 + 2]
addition of H 2 on the
rhodium formate
intermediate obtained after
CO 2 insertion. (Reprinted
from reference 101 with
permission from ACS
publication)
HCOOH
LDH
LDH
LDH
LDH
LDH
O
H 2 O
OH
H 2
OH 2
2H 2 O
H
H
OH
OH
H 2 O
CO 2
Ru
O O O
O
O
O
O
O
C
C
O
HO
H
HO
H
H
OH
OH
H 2 O
H 2 O
H 2 O
H 2 O
Step 5
Step 4
Step 3
Step 2
Step 1
H 2 O
Ru
Ru
O
O
O
O
HO
Ru
O
Ru
O
Fig. 4.7 Possible reaction pathway for CO 2 hydrogenation to produce formic acid with a Ru/LDH
catalyst. (Reprinted from reference 103 with permission from ACS publication). (LDH = lactate
dehydrogenase)
U. Fegade and G. Jethave