(129c) Development of Pt-Based Electrocatalysts for the Upgrading of Biomass-Derived Compounds Via the Kolbe Reaction

In
recent years, there has been growing interest in the upgrading of biomass-derived
molecules through an electrochemical method to produce biofuels and value-added
chemicals. As compared to classical thermal-catalytic upgrading processes, the
electrocatalytic process can be performed at low temperatures and pressures
(293 K and 101 kPa) without the need to supply hydrogen. Whereas aldehydes,
ketones, and phenolic compounds can be electrocatalytically reduced, carboxylic
acids cannot be reduced.

Among
all electrochemical processes, Kolbe electrolysis is the one of the oldest and
best-known process for electrocatalytic conversion of carboxylic acid to
alkanes and olefins via decarboxylation. However, the high current and
electrode stability requirements combined with the complex reaction mechanism (including
non-Kolbe) and low Faradaic efficiency has limited its application.

Herein,
we reported the use of Pt-based electrocatalysts for Kolbe electrolysis. The
effect Pt structure, supporting materials, electrolyte composition, and applied
potential on the selectivity and Faradaic Efficiency of valeric acid oxidation
were investigated. As shown in Figure 1, the valeric acid could be oxidized to
octane (Kolbe), butene (Kolbe), and butanol (non-Kolbe) and their corresponding
selectivities could be controlled by tuning the electrolyte composition and the
applied potential.

Figure
1. Electrochemical
oxidation of valeric acid on Pt-based electrocatalysts under different applied
potentials (left); and major reaction pathways (right).