Accelerated Conversion of Fructose to 5-Hydroxymethylfurfural Using Sulfonated Tungsten Oxide Catalysts: Impact of Crystalline Phases in a Continuous Microreactor

The efficient conversion of fructose to 5-hydroxymethylfurfural (HMF) with high yields is challenging in biorefinery processes. In this study, we synthesized nonprecious metal WO3–SO3H catalysts with various crystalline phases using a simple hydrothermal method for HMF production from fructose. The experimental results revealed that the catalytic performance of the WO3–SO3H catalysts with different crystalline phases followed the order: o-WO3–SO3H > h-WO3–SO3H > m-WO3–SO3H > t-WO3–SO3H. In a conventional batch reactor, the o-WO3–SO3H catalyst exhibited remarkable performance, achieving an HMF yield of 99.2% and nearly complete fructose conversion after 100 min of reaction at 140 °C. When used in our developed modular microreactor, the reaction time was drastically reduced, achieving the same yield as in the batch reactor in just 20 min. This research offers a new approach for the rapid and efficient synthesis of HMF.