Oxalic acid hydrogenation to glycolic acid:heterogeneous catalysts screening

To meet our ambitions of a future circular economy and drastically reduce CO2 emissions, we need to make use of CO2 as a feedstock. Turning CO2 into monomers to produce sustainable plastics is an attractive option for this purpose. It can be achieved by electrochemical reduction of CO2 to formic acid derivatives, that can subsequently be converted into oxalic acid. Oxalic acid can be a monomer itself and it is a potential new platform chemical for material production, as useful monomers such as glycolic acid and ethylene glycol can be derived from it. Today the most common route from oxalic acid to glycolic acid requires multiple steps as it proceeds via oxalic acid di-esters as intermediates. In this work, we aim to avoid the extra reaction step of esterification. We explore the direct conversion of oxalic acid to glycolic acid in a two-step approach. In the first step, we define the ideal reaction conditions and test commercially available catalysts. We show that the reduction of oxalic acid can be performed at much lower temperatures and glycolic acid yields higher than those reported previously can be obtained. In the second step, we explore the design principles required for ideal catalysts which avoid the formation of acetic acid and ethylene glycol as side products. We show that ruthenium is the most active metal for the reaction and that carbon appears the most suitable support for these catalysts. By adding tin as a promotor, we could increase the selectivity and yield further whilst maintaining high activity of the resulting catalyst. This research lays the foundation for the efficient direct reduction of oxalic acid to glycolic acid and defines the design parameters for even better catalysts and the ideal process and conditions.</p

Gold nanoparticles supported on magnesium oxide for CO oxidation

Au was loaded (1 wt%) on a commercial MgO support by three different methods: double impregnation, liquid-phase reductive deposition and ultrasonication. Samples were characterised by adsorption of N2 at -96°C, temperature-programmed reduction, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction. Upon loading with Au, MgO changed into Mg(OH)2 (the hydroxide was most likely formed by reaction with water, in which the gold precursor was dissolved). The size range for gold nanoparticles was 2-12 nm for the DIM method and 3-15 nm for LPRD and US. The average size of gold particles was 5.4 nm for DIM and larger than 6.5 for the other methods. CO oxidation was used as a test reaction to compare the catalytic activity. The best results were obtained with the DIM method, followed by LPRD and US. This can be explained in terms of the nanoparticle size, well known to determine the catalytic activity of gold catalysts

Effects of cold plasma treatment on growth enhancement and on the chemical composition of sweet basil plants (

The current report is a continuation of our ongoing studies on the effect of cold plasma treatment on the physical and the biochemical properties of the Ocimum basilicum (sweet basil). Our previous work in this area revealed an enhanced growth effect by plasma treatment as well as higher levels of antioxidant components present in the essential oil extracts recovered from the plasma-treated plants. In the present study, the sweet basil was grown from seeds under controlled conditions with the plants separated into four groups. The first Group A (GA) is a control group where no plasma treatment was applied. In the second Group B (GB), the cold plasma treatment was applied to the seeds only. For Group C (GC-1X) and Group D (GD-2X), in addition to the seed treatment, the growing plants in these two groups received an additional body treatment, which was applied once (for Group C) and twice (for Group D) (weekly), following a standard treatment protocol. The total growing period was 14 weeks at which point the plants were harvested. Results revealed that the plants treated with plasma showed increased growth in their leaves and stems particularly in the later stages of vegetation. The essential oils from the sweet basil were recovered by Soxhlet extraction, and their composition was analyzed quantitatively by GC-FID and GC–MS. The extracts of the essential oil both in the control and plasma-treated plant groups showed five major components: eucalyptol, linalool, estragole, eugenol, and methyl cinnamate. Estragole was found to be in the highest concentration in the leaves, while linalool was the dominant product in the flowers, followed by estragole, eugenol, eucalyptol, and methyl cinnamate. In general, plasma treatment resulted in a significant increase in the concentration of both the estragole and linalool in the leaves, while lower concentrations of these two components were registered in the flowers for the plasma-treated groups