D.N. Briggs et al. / Journal of Catalysis 276 (2010) 215–228
227
4
.4.3. Role of Cl and catalyst stability
Cl must be retained on KCP/carbon catalysts to maintain their
the addition of ethoxide species, the process that is thought to be
rate-limiting.
activity. A similar observation has been made for oxidative carbon-
ylation of alcohols carried out in CuCl suspensions [57]. The loss of
chlorine from heterogeneous catalysts can be explained by the
slow formation of ethyl chloride (Reaction (29)) and paratacamite,
2
Acknowledgments
The authors acknowledge support from the National Center for
Electron Microscopy, Lawrence Berkeley National Laboratory,
which is supported by the US Department of Energy, under Con-
tract No. DE-AC02-05CH11231.We gratefully acknowledge Chris-
tian Kisielowski and Chengyu Song for their assistance in the
collection and analysis of HR-TEM data. This work was supported
Cu
2 3
Cl(OH) , both of which have been observed in studies of gas-
phase synthesis of DEC [13,36].
2
CuCl þ 1=2O
2
þ H
2
O þ C
2
H
5
OH ! Cu
2
ClðOHÞ þ C
2
H
5
Cl
ð29Þ
3
Catalyst activity and selectivity to DEC can be maintained by the
addition of ppm levels of CCl to the feed; however, high feed con-
centrations of CCl reduce catalytic activity. CCl
store Cl-depleted species, whereas excess CCl
conversion of CuCl to catalytically inactive CuCl
2
by the Methane Conversion Cooperative (MC ) funded by BP.
4
4
4
is needed to re-
may lead to the
4
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formed in the absence of Pd2 , CO adsorbed on Pd is more electro-
+
2+
+
philic than CO adsorbed on Cu , and, hence, more reactive towards