5-Hydroxymethylfurfural (HMF) is a platform chemical derived from C6 sugars, which can be transformed into various important chemicals and fuels because of the presence of CO, C–O and furan ring functional groups. In this review, the selective tailoring of these groups in HMF to form 2,5-dimethylfuran, 2,5-dihydromethylfuran, 2,5-dihydromethyltetrahydrofuran, 5-ethoxymethylfurfural, 1,6-hexanediol, long-chain alkanes, 3-(hydroxy-methyl)cyclopentanone, p-xylene, 2,5-diformylfuran, 2,5-furandicarboxylic acid and maleic anhydride will be described to gain more insight into the transformation of HMF under various conditions. The focus of this review is on the mechanisms of the catalytic processes and potential design strategies for future catalysts. The activation of the functional groups and the key challenges involved in the precise design of bifunctional catalysts are highlighted. Some examples of “one-pot” transformations of fructose into various chemicals using the HMF platform are also presented.

In this study, renewable pyridines could be directly produced from glycerol and ammonia via a thermo-catalytic conversion process with zeolites. The major factors, including catalyst, temperature, weight hourly space velocity (WHSV) of glycerol to catalyst, and the molar ratio of ammonia to glycerol, which may affect the pyridine production, were investigated systematically. The optimal conditions for producing pyridines from glycerol were achieved with HZSM-5 (Si/Al = 25) at 550 °C with a WHSV of glycerol to catalyst of 1 h⁻¹ and an ammonia to glycerol molar ratio of 12 : 1. The carbon yield of pyridines was up to 35.6%. The addition of water to the feed decreased the pyridine yield, because water competed with glycerol on the acid sites of the catalyst and therefore impacted the acidity of the catalyst. After five reaction/regeneration cycles, a slight deactivation of the catalyst was observed. The catalysts were investigated by N₂ adsorption/desorption, XRD, XRF and NH₃-TPD and the results indicated that the deactivation could be due to the structure changes and the acid site loss of the catalyst. The reaction pathway from glycerol to pyridines was studied and the main pathway should be that glycerol was initially dehydrated to form acrolein and some by-products such as acetaldehyde, acetol, acetone, etc., and then acrolein, a mixture of acrolein and acetaldehyde, or other by-products reacted with ammonia to form imines and finally pyridines.