Fe–SBA-15 Catalysts for Hemicellulose Depolymerization

Abstract Using cocondensation in an acidic medium (1.6 M HCl) at a Fe/Si molar ratio of 5, 15 and 20% in the initial gel, iron-containing catalysts based on mesostructured silicate SBA-15 were synthesized. Powder X-ray diffraction, nitrogen sorption, and electron microscopy showed that the obtained catalysts retain the ordered characteristic of the hexagonal SBA-15 mesostructure. Using X-ray fluorescence analysis, it was established that the iron content in the resulting samples is less than 0.06 mol %. For SBA-15, fibers have a length of ~2 µm and a thickness of ~0.2 µm. The introduction of an iron precursor into the synthetic solution leads to the elongation of iron-containing catalyst particles to 10–30 µm, while the thickness remains virtually unchanged. The catalytic properties of the synthesized catalysts were studied in the reaction of hydrolysis and oxidation by atmospheric oxygen for soluble hemicellulose sugars derived from aspen wood by means of hydrolytic treatment. The maximum formic acid yield was 25.8 wt % (150°C, 5 h).