Effect of the iron amount on the physicochemical properties of Fe–ZrO2 aerogel catalysts for the total oxidation of Toluene in the presence of water vapor

International audienceIn this work, a series of xFe–ZrO2 aerogel catalysts, with different amounts of iron were prepared and tested in the total oxidation of toluene. The xFe–ZrO2 aerogel catalysts obtained demonstrate the diffraction peaks of ZrO2 tetragonal phase and a high surface area and porosity. The iron content influences the physicochemical and catalytic properties of the samples. Among the iron-based catalysts, the one with 5% Fe shows the best activity between 300 and 550 °C with 96% C6H5–CH3 conversion to CO2 at 550 °C

Ag/ZrO2 and Ag/Fe–ZrO2 catalysts for the low temperature total oxidation of toluene in the presence of water vapor

International audienceNew mesoporous and well-structured Ag-based catalysts (xAg/ZrO2 and xAg/Fe–ZrO2 with x = 2 wt%) have been investigated in the total oxidation of toluene with water vapor. The results showed that the catalytic activity of systems increases, in the 350–550 °C temperature range, following this order: ZrO2 < Fe–ZrO2 < Ag/ZrO2 ≈ Ag/Fe–ZrO2. Nevertheless, it was revealed that Ag/Fe–ZrO2 is the most active solid for the low temperature total oxidation of toluene (< 350 °C). The highest low temperature activity of this new catalyst can be related to the presence of more reactive surface oxygen, new active redox and acidic sites at Ag/Fe–ZrO2 surface, most probably generated by the simultaneous presence of Ag and Fe species

Photosulfoxidation catalysis as the driving principle for the deazaoxaflavin photoredox catalyst formation

Catalysts are essential for sustainability because they decrease the energy and resource consumption in the production of high value-added products. The design of a novel catalyst is a challenging and expensive target, and a simplified methodology for catalyst development can trigger burgeoning progress in both academic and applied research. Here, we demonstrate a reaction network that autonomously yields the photoredoxcatalyst for transformation of the provided substrate under applied catalytic conditions. The system stems from the reversible condensation pathway leading to deazaoxaflavins, 2H-chromeno[2,3-d]pyrimidine synthetic analogs of flavins, with which they share photoorganocatalytic activity. We report on the photocatalytic activity of deazaoxaflavins and their covalently dynamic behavior. The reversibility principle allows for the exchange of one of the deazaoxaflavin constituents for a different moiety, thus leading to the adaptability of the catalyst. We argue that the observed phenomenon is of thermodynamic origin and thus can be applied to other photo/organocatalytic reactions, in which the combination of a suitable substrate and conditions are the governing principle for catalyst formation

Potentiometric Performance of Ion-Selective Electrodes Based on Polyaniline and Chelating Agents: Detection of Fe²⁺ or Fe³⁺ Ions

We constructed a sensor for the determination of Fe2+ and/or Fe3+ ions that consists of a polyaniline layer as an ion-to-electron transducer; on top of it, chelating molecules are deposited (which can selectively chelate specific ions) and protected with a non-biofouling poly(2-methyl-2-oxazoline)s layer. We have shown that our potentiometric sensing layers show a rapid response to the presence of Fe2+ or Fe3+ ions, do not experience interference with other ions (such as Cu2+), and work in a biological environment in the presence of bovine serum albumin (as a model serum protein). The sensing layers detect iron ions in the concentration range from 5 nM to 50 µM