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A continuous process for the manufacture of 5‐hydroxy methylfurfural (HMF), using a stirred tank reactor with simultaneous reaction and extraction was studied. Methylisobutylketone (MIBK) was used as the extraction agent. The experiments were carried out at elevated temperatures and moderate acidity. Other process parameters were the initial concentration of D‐fructose, the residence time, and the ratio of MIBK and H2O. Though the effect of extraction was limited due to the fact that the formation of HMF was faster than its breakdown, the use of MIBK as a cosolvent appeared to have a beneficial influence on the course of the reaction. The productivity at short residence times is lowered due to the stability of intermediate products.

The effects on the platinum particle diameter and the available platinum surface area of a graphite-supported platinum catalyst resulting from pretreatments and from performing a selective oxidation reaction are investigated. In the gas phase considerable catalyst sintering occurs only in the presence of oxygen at 773 K due to extensive carbon burn-off, whereas in an aqueous phase platinum particle growth is limited upon oxidative treatment. A hydrogen treatment in aqueous phase at 363 K causes platinum particle growth, aggregate formation, and covering of metal sites. These phenomena become more important with increasing pH. Platinum particle growth and aggregate formation are attributed to platinum particle rather than platinum adatom mobility and is caused by the destruction of the oxygen-containing surface groups on the graphite support, which serve as anchorage sites for the platinum particles. Site covering is caused by products originating from the graphite support, which are formed as a result of the reductive treatments. When performing the aqueous phase oxidation of methyl α-D-glucopyranoside at 323 K and a pH of 9, catalyst modifications are small under oxidative conditions. Exposure of the catalyst for several hours to methyl α-D-glucopyranoside under the same conditions but in the absence of oxygen causes site covering.