(411c) Simultaneous Generation of Mesoxalic Acid and Electricity From Glycerol On Au Anode Catalyst in Anion Exchange Membrane Fuel Cell Reactors

Biomass is an intriguing renewable
and carbon-neutral resource, and is expected to share a big portion in our
future energy landscape. Glycerol is mass-produced as a low value by-product
(0.3 US$ kg^-1) in biodiesel manufacturing process. Glycerol is a
highly functionalized molecule and has great potential to constitute major
building blocks for future production of novel polymers, fine chemicals, and
pharmaceuticals, etc. Moreover, Glycerol has also been considered a potential
fuel for direct alcohol fuel cells (DAFC), due to its relatively low price,
simple purification and storage, as well as its non-volatile and environmental
friendly properties.

From energy conservation, economic,
and environmental aspect, we herein report selective electro-catalytic
oxidation of glycerol for cogeneration of mesoxalic acid and electricity on Au
anode catalyst in anion exchange membrane fuel cells (AEMFCs) reactor (Scheme
1). Small Au nanoparticles (3.5 nm) were uniformly deposited on carbon black
with a 40 wt% loading through a solution phase method. An AEMFC with the Au/C
anode catalyst and a Fe-based cathode catalyst exhibited a peak power density
of 57.9 mW cm^-2 at 80°C. Valuable mesoxalic acid was produced with a
high selectivity of 46% from electro-oxidation of glycerol on Au/C at the fuel cell
operation voltage of 0.3
V, while very small
amount of mesoxalic
acid (selectivity: < 3%) was obtained on a Pt/C anode catalyst in AEMFC. The product distribution was found
to be dependent on the anode
overpotential. At 1.2 V
vs. SHE in an
electrolysis cell,
glycolic acid was the major product (selectivity: 65%), and no mesoxalic acid was observed.
Based on the product analysis, it was discovered that Au facilitated deeper-oxidation of glycerol to the fully-oxidized C₃ mesoxalic acid, not C-C cleavage under a mild potential range (0.4-0.7 V vs. SHE), which fortunately is within the fuel cell working
voltage region.