Electrification of a Milstein-type Catalyst for Alcohol Reformation

Novel energy and atom efficiency processes will be keys to develop the sustainable chemical industry of the future. Electrification could play an important role, by allowing to fine-tune energy input and using the ideal redox agent: the electron. Here we demonstrate that a commercially available Milstein ruthenium cata-lyst (1) can be used to promote the electrochemical oxidation of ethanol to ethyl acetate and acetate, thus demonstrating the four electron oxidation under preparative conditions. Cyclic voltammetry and DFT-calculations are used to devise a possible catalytic cycle based on a thermal chemical step generating the key hydride intermediate. Successful electrification of Milstein-type catalysts opens pathway to use alcohols as renewable feedstock for the generation of esters and other key building blocks in organic chemistry, thus contributing to increase energy efficiency in organic redox chemistry.

Sorption and Reaction of Biomass Derived HC Blends and Their Constituents on a Commercial Pt–Pd/Al2O3 Oxidation Catalyst

Within the Research Cluster of Excellence “The Fuel Science Center” at RWTH Aachen University, the production and application of new fuels from bio-based carbon feedstocks and CO2 with hydrogen from renewable electricity generation is being investigated. In this study, the storage and oxidation of ethanol, 1-butanol, 2-butanone, cyclopentanone, and cyclopentane as well as two blends thereof on a series production Pt–Pd/Al2O3 oxidation catalyst were investigated. Hydrocarbon (HC) storage and temperature-programmed surface reaction (TPSR) experiments were carried out to analyze their adsorption and desorption behavior. In addition, the individual HCs and both blends were investigated using Diffuse Reflectance Infrared Fourier Transform Spectroscopy (TP-DRIFTS). In general, all oxygenated HCs are adsorbed more strongly than cyclopentane due to their higher polarity. Interestingly, it could be observed that the two different blends [blend 1: ethanol (50 mol %), 2-butanone (21 mol %), cyclopentanone (14 mol %) and cyclopentane (15 mol %); blend 2: 1-butanol (45 mol %), ethanol (29 mol %) and cyclopentane (27 mol %)] exhibit a different storage behavior compared to the single hydrocarbons. It was shown that the presence of 1-butanol and cyclopentane in blend 2 strongly inhibits the oxidation of ethanol. As a result, the ethanol light-off temperature was increased by at least 100 K. A difference was also found in the storage behavior of cyclopentane. While no significant storage could be detected in the pure compound experiment, the experiments with both mixtures showed a larger amount stored. The presence of adsorbed species of the hydrocarbons and their corresponding reaction products has been demonstrated and gives an insight into the storage mechanism of blends. Graphic Abstract

SOME ISSUES OF THE MECHANISM OF DEEP OXIDATION OF ETHANOL ON THE SURFACE OF THE CATALYST OF A THERMOCATALYTIC SENSOR

In this work, the effect of the partial pressures of the starting materials and reaction products on the patterns of deep oxidation of ethanol on the surface of the catalyst of the thermocatalytic sensor was studied experimentally. At the same time, the regularities of the oxidation of combustible substances on selected catalysts have been established and the optimal conditions have been identified that ensure the flow of the process under study in the kinetic region. It is shown that the reaction on the sensor catalyst surface proceeds along two kinetically independent (basic) routes. Taking into account the above, a more detailed scheme of the heterogeneous catalytic oxidation of ethanol in the presence of a sensor catalyst is proposed.