Efficient Continuous Production of the Biofuel Additive 5‐(t‐Butoxymethyl) Furfural from 5‐Hydroxymethylfurfural

The catalytic etherification of 5‐hydroxymethylfurfural (HMF) with t‐butanol to a biofuel additive 5‐(t‐butoxymethyl) furfural (t‐BMF) is studied by screening 27 heterogeneous protic and/or Lewis acids. Preyssler heteropolyacid H14[NaP5W30O110] and Montmorillonite‐based CLOI_CSP catalysts are identified as the most efficient ones, allowing the etherification to reach the t‐BMF/HMF equilibrium faster (≈1:1), thus promoting minimum side reactions. Further optimization of the batch experimental conditions, namely catalyst loading, temperature, HMF concentration, time, t‐BMF stability, and additives, allows the t‐BMF/HMF equilibrium to be reached in less than 3 h with outstanding selectivity >95%. Under optimized conditions, CLOI_CSP is reused for four cycles without significant loss of efficiency. In addition, it exhibits high efficiency under flow conditions, allowing continuous production of t‐BMF up to 0.7 g t‐BMF g−1 catalyst min−1 at high concentrations of HMF. The catalytic etherification of 5‐hydroxymethylfurfural (HMF) with t‐butanol to a biofuel additive 5‐(t‐butoxymethyl) furfural (t‐BMF) is studied by screening 27 heterogeneous protic and/or Lewis acids under batch conditions. The studies identify the most suited catalysts that are further applied for the development of a continuous flow operation.