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Electrocatalytic oxidation of polyhydric alcohols represents an important route for coproduction of biorenewable chemicals and energy. However, the governing factors leading to high product selectivity remain unclear. Herein, we investigate the selective oxidation of 1,2-propanediol (PDO) to pyruvate or lactate in electrocatalytic reactors over carbon-supported platinum (Pt/C) and gold (Au/C) anode catalysts. PDO-fed alkaline anion-exchange membrane fuel cells successfully cogenerated electricity and valuable chemicals with peak power densities of 46.3 mW cm–2 on Pt/C and 10.0 mW cm–2 on Au/C. Pt/C was highly selective for primary alcohol group oxidation to lactate (86.8%) under fuel cell conditions, but Au/C yielded significant amounts of pyruvate, a product that has previously eluded heterogeneous catalytic studies on Au. Sequential oxidation of lactate to pyruvate was not observed on Au/C but did occur slowly on Pt/C. The electrode potential dependent product distribution was investigated, and it was revealed that pyruvate selectivity on Au/C was sensitive to anode potential and could be varied from 20 to 56%. On the basis of observed product distributions and linear sweep voltammetry of intermediate products, we propose that the intermediates hydroxyacetone and pyruvaldehyde, which are not stable in high pH electrolyte, can be further oxidized to pyruvate on Au/C only if they are trapped within the thick liquid diffusion layer of the carbon cloth supported catalyst layer. Density functional theory (DFT) calculations of reaction energies identified the most favorable reaction intermediates and provided insight into the likely reaction pathways.

Absolute partial and total crosssection functions for the electron impact ionization of C60 and C70Absolute photodissociation cross sections of gas phase sodium chloride at room temperature

Rates of ozone decomposition on aluminum oxide (alumina) particles were measured in a flow tube reactor equipped with molecular beam sampling mass spectrometry and ultraviolet absorption spectroscopy, and in a static reaction cell equipped with ultraviolet absorption spectroscopy. Reaction probabilities η are reported for ozone on α‐alumina, γ‐alumina, and Chromatographic alumina (hydroxylated alumina), respectively, over the temperature range −60 to 200°C. This work addresses the potential for stratospheric ozone depletion by launch vehicle solid rocket motor exhaust. Considering best estimates of plume particle size distributions and dispersion rates, we calculate ozone depletion profiles, for direct decomposition on alumina only. The calculated ozone holes are rather narrow. In the worst case, ozone levels are within 5 × 10−5 of ambient in the center of the plume. A simple analysis of the global impact of alumina particles on ozone decomposition indicates a potential steady‐state daytime depletion of < 2.6 × 10−8 at present launch rates.

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