Selective Aerobic Oxidation of 5‐(Hydroxymethyl)furfural to 5‐Formyl‐2‐furancarboxylic Acid in Water

Abstract

A simple, cheap, and selective catalyst based on copper/cerium oxides is described for the oxidation of 5-(hydroxymethyl)furfural (5-HMF) in water. An almost quantitative conversion (99 %) with excellent (90 %) selectivity towards the formation of 5-formyl-2-furancarboxylic acid, a platform molecule for other high value chemicals, is observed. The catalyst does not require any pretreatment or additives, such as bases, to obtain high yield and selectivity in water as solvent and using oxygen as oxidant. When a physical mixture of the oxides is used, low conversion and selectivity are observed. Air can be used instead of oxygen, but a lower conversion rate is observed if the same overall pressure is used, and the selectivity remains high. The catalyst can be recovered almost quantitatively and reused. Deactivation of the catalyst, observed in repeated runs, is due to the deposition of humins on its surface. Upon calcination the catalyst almost completely recovers its activity and selectivity, proving that the catalyst is robust.

Butanol synthesis from ethanol over CuMgAl mixed oxides modified with palladium (II) and indium (III)

“…The total amount of acid sites increases with copper insertion (Table 2). However, the inclusion of palladium or indium ions while decreases the total acidity of the oxides due to a decrease in the number of weak and medium strength acid sites, increases the number of strong acid sites, most likely the most active in catalysis [23,24].…”

Acidic Zeolite L as a Highly Efficient Catalyst for Dehydration of Fructose to 5‐Hydroxymethylfurfural in Ionic Liquid

“…[29] Althought hese byproducts can be partially removed by calcination, the zeolite will gradually lose its activity after several recycle runs. [29] Althought hese byproducts can be partially removed by calcination, the zeolite will gradually lose its activity after several recycle runs.…”

“…Recyclability is an essential characteristic of any promising catalystu sed in the dehydration of fructoset oH MF.B yproducts such as huminsa re known to deposit on the active sites during the dehydration of fructose, leadingt oadecrease in the activityo ft he zeolite. [29] Althought hese byproducts can be partially removed by calcination, the zeolite will gradually lose its activity after several recycle runs. In this work, the 99.1 % yield of HMF overK L-80 8C-1 hi mplies that the byproducts and the active sites occupied by huminsa fter reaction were very few.A dditionally,t he KL-80 8C-1 hs ample maintained its high performance even after four recycles ( Figure 5), demonstrating the excellent recyclability of the NH 4 -exchanged zeoliteL.…”

Sustainable Synthesis of Oxalic and Succinic Acid through Aerobic Oxidation of C6 Polyols Under Mild Conditions

“…We have recently developede nvironmentally friendly technologies based on the use of water as as olvent and oxygen or even air as an oxidantf or the conversion of 5-HMF into 2,5-diformylfuran (DFF), 2-formyl-5-furancarboxylic acid (FFCA) and 2,5-furandicarboxylica cid (FDCA), [2,15] targetingh igh conversion and selectivity. ( Scheme 1, left side) Earth-abundant metal catalysts in the form of mixed oxideshave been used for selectiveo xidationo ft he ring-pending functionalities without touchingt he integrity of the furan ring.…”