Catalytic Synthesis of Methyl Glycolate from Glyoxal Methanol Solution over Base Catalysts

The process of obtaining methyl glycolate from a methanolic solution of glyoxal over solid basic catalysts based on mixed oxides of magnesium, zirconium, and aluminum has been studied. According to obtained results, the selectivity of the methyl glycolate formation increases with increasing the basicity of the catalyst. The most selective coprecipitated MgO-ZrO2 provides almost 100 % methyl glycolate yield. The supported MgO-ZrO2/Al2O3 gives to 95 % yield of methyl glycolate with the formation of the glyoxal dimethyl acetal as a by-product. This catalyst could be reused several consecutive cycles without the need for intermediate regeneration. Methyl glycolate in a high 93 % yield can be obtained at 453 K over this solid catalyst in flow mode, which may be of practical interest.

Synthesis of methyl glycolate by hydrogenation of dimethyl oxalate with a P modified Co/SiO2 catalyst

A P-modified Co/SiO₂ catalyst was reported for the first time in the selective hydrogenation of dimethyl oxalate (DMO) to methyl glycolate (MG) reaction and the synthesized Co₈P/SiO₂ exhibited 94.6% conversion of DMO and 88.1% selectivity to MG during a 300 h continuous test. The doping element of P in the catalyst was indispensable and played an important role in improving the catalytic performance of the Co/SiO₂ catalyst.

Support, composition, and ligand effects in partial oxidation of benzyl alcohol using gold–copper clusters

The effect of metallic composition, support, and ligands on catalytic performance using AuCu clusters in benzyl alcohol oxidation is investigated.

Oxidation of Monoethylene Glycol to Glycolic Acid with Gold-Based Catalyst and Glycolic Acid Isolation by Electrodialysis

In this work, a highly selective and active gold-based catalyst for the oxidation of high concentrated monoethylene glycol (MEG) in aqueous solution (3 M, 20 wt%) is described. High glycolic acid (GA) selectivity was achieved under mild reaction conditions. The optimization of the catalyst composition and of the reaction conditions for the oxidation of MEG in semi-batch mode under alkaline conditions led to a GA yield of >80% with a GA selectivity of about 90% in short reaction time. The bimetallic catalyst 0.1 wt% AuPt (9:1)/CeO2 showed very high activity (>2000 mmolMEG/gmetalmin) in the oxidation of MEG and, contrary to other studies, an extremely high educt to metal mole ratio of >25,000 was used. Additionally, the gold–platinum catalyst showed a high GA selectivity over more than 10 runs. A very efficient and highly selective process for the GA production from MEG under industrial relevant reaction conditions was established. In order to obtain a GA solution with high purity for the subsequent polymerization, the received reaction solution containing sodium glycolate, unreacted MEG and sodium oxalate is purified by a novel down-stream process via electrodialysis. The overall GA yield of the process exceeds 90% as unreacted MEG can be recycled.

Investigation of Au/Co3O4 nanocomposites in glycol oxidation by tailoring Co3O4 morphology

The interfacial perimeter of nanogold and supports is often deemed as the catalytically active site for multiple reactions while the geometrical configuration of the interfacial perimeter at atomic scale is less studied. Herein, gold nanoparticles (NPs) of ca. 2.0 nm are dispersed on Co₃O₄ support in the shape of nanocubes (dominant Co₃O₄(001) facet) and nanoplates (Co₃O₄(111)), which forms different Au-Co₃O₄ interfaces with respect to the specific facet of the oxide support. A comparison is made on the basis of the interfacial structures and catalytic behavior of ethylene glycol oxidation. STEM analysis identifies that these metallic Au NPs interact with Co₃O₄ with an orientation relationship of Au/Co₃O₄(001) and Au/Co₃O₄(111). XPS and Raman spectroscopy investigations reveal the important variations in the reactivity of surface oxygen, surface O_ads/O_L ratio, and evolution of surface oxygen vacancies upon variation of the Co₃O₄ shape. Au/Co₃O₄-P exhibits much better catalytic activity than the Au/Co₃O₄-C counterpart in the aerobic oxidation of ethylene glycol, which is promoted by surface oxygen vacancies and intrinsic defects. It has been revealed that the surface oxygen vacancies participate in activating O₂, thus making Co₃O₄-P a superior support for Au NPs in the catalysis of ethylene glycol oxidation.

Cu–Al composite oxides: a highly efficient support for the selective oxidation of glycerol to 1,3-dihydroxyacetone

A series of Au catalysts supported on Cu–Al composite oxides were prepared and applied for the selective catalytic oxidation of glycerol to 1,3-dihydroxyacetone (DHA) in base-free conditions.

Nanoporous Ni3P Evolutionarily Structured onto a Ni Foam for Highly Selective Hydrogenation of Dimethyl Oxalate to Methyl Glycolate

Methyl glycolate (MG) is a versatile platform molecule to produce numerous important chemicals and materials, especially new-generation biocompatible and biodegradable poly(glycolic acid). In principle, it can be massively produced from syngas (CO + H₂) via gas-phase hydrogenation of CO-derived dimethyl oxalate (DMO), but the groundbreaking catalyst represents a grand challenge. Here, we report the discovery of a Ni-foam-structured nanoporous Ni₃P catalyst, evolutionarily transformed from a Ni₂P/Ni-foam engineered from nano- to macro-scale, being capable of nearly fully converting DMO into MG at >95% selectivity and stable for at least 1000 h without any sign of deactivation. As revealed by kinetic experiments and theoretical calculations, in comparison with Ni₂P, Ni₃P achieves a higher surface electron density that is favorable for MG adsorption in a molecular manner rather than in a dissociative manner and has much higher activation energy for MG hydrogenation to ethylene glycol (EG), thereby markedly suppressing its overhydrogenation to EG.

Straight Access to Indoles from Anilines and Ethylene Glycol by Heterogeneous Acceptorless Dehydrogenative Condensation

The development of original strategies for the preparation of indole derivatives is a major goal in drug design. Herein, we report the first straight access to indoles from anilines and ethylene glycol by heterogeneous catalysis, based on an acceptorless dehydrogenative condensation, under noninert conditions. In order to achieve high selectivity, a combination of Pt/Al₂O₃ and ZnO have been found to slowly dehydrogenate ethylene glycol generating, after condensation with the amine and tautomeric equilibrium, the corresponding pyrrole-ring unsubstituted indoles.

Direct conversion of C6 sugars to methyl glycerate and glycolate in methanol

The present work deals with the one-pot conversion of C6 sugars to methyl glycerate and glycolate via a cascade of retro-aldol condensation and oxidation processes catalyzed by using MoO₃ as the Lewis acid catalyst and Au/TiO₂ as the oxidation catalyst in methanol. Methyl glycerate (MGLY) is the product of C6 ketose (fructose), while methyl glycolate (MG) is produced from C6 aldose (mannose, glucose). It is found that a good one-pot match between two reactive processes is the key to the production of MGLY and MG with high yield (27.6% MGLY and 39.2% MG). A separated retro-aldol condensation and oxidation process greatly decreases their yields, and even no MGLY can be obtained in this separated process. We attribute this to high instability of glyceraldehyde/glycolaldehyde and their different reaction pathways which mainly depend on whether acetalization of retro-aldol products (glyceraldehyde and glycolaldehyde) occurs with methanol or not. This result opens a new prospect on the accumulation of C3 products other than lactate from biomass-derived carbohydrates.

Methyl glycerate (MGLY) and methyl glycolate (MG) are directly produced in maximum yield by the one-pot conversion of hexose, and the formation of MGLY and MG experience different reaction routes.

Au/BiPO4 nanorod catalysts: synthesis, characterization and their catalytic performance for CO oxidation

Au/BiPO₄ catalysts exhibit high catalytic activity in low temperature CO oxidation.

Unusual behaviour of Au/ZnO catalysts in selective hydrogenation of butadiene due to the formation of a AuZn nanoalloy

The loss of activity observed when Au/ZnO was activated under H₂ was explained by the formation of AuZn alloy.