Structure–activity relationships of Au/ZrO2 catalysts for 5-hydroxymethylfurfural oxidative esterification: Effects of zirconia sulphation on gold dispersion, position and shape

The oxidative esterification of 5-hydroxymethylfurfural (HMF) to furan-2,5-dimethylcarboxylate (FDMC) has been investigated on Au/ZrO2 catalysts. We have examined bare zirconia and sulphated zirconia with different amounts of sulphates in order to identify the effects of the sulphation pretreatment. The amount of sulphate groups present on zirconia regulate the gold amount and dispersion, as well as its shape and position. It has been found that the reactivity is associated not only to the Au active phase, in terms of loading and size, but it is also closely tied to its shape and distribution on the support. Irregular plate-like gold nanoparticles have been observed on the sulphated samples and they affect the selectivity to FDMC. Structure–properties relationships have been determined and a model has been proposed.