Dehydration of d-xylose to furfural using selective and hydrothermally stable arenesulfonic SBA-15 catalysts

Furfural (FUR), produced from pentosan-rich biomass, is extensively used as precursor for the furan based chemistry. However, the manufacturing process presents several disadvantages, such as toxic effluents or corrosion issues. Novel heterogeneous catalysts feature high Brönsted acidity and adequate textural-properties to increase FUR selectivity. Modified mesoporous supports have been reported as very appropriate to selectively produce FUR from xylose. This work summarizes the xylose dehydration activity of arenesulfonic SBA-15 catalysts synthesized at high aging-temperature. The SBA-15 catalysts synthesized via co-condensation showed a hexagonal pore arrangement, high arenesulfonic-site incorporation and suitable textural-properties. The activity results in water/toluene revealed that catalysts aged at 180 °C could achieve FUR yield of 80% at 99% conversion on reactions at 160 °C. This was mainly attributed to the high hydrothermal stability of the arenesulfonic-sites and to the porous structure. The catalysts aged at 180 °C showed negligible acid-site leaching effects. The used catalysts were regenerated by a thermal treatment at 290 °C and these showed good reusability on repetitive runs at the investigated reaction-temperatures. However, the catalysts aged at lower temperatures showed important deactivation rates.

The arenesulfonic SBA-15 catalysts were tested during the dehydration of d-xylose to furfural. There was a direct correlation between synthesis conditions and sulfonic-site stability. The materials aged at 180 °C showed the highest stability (structure and acid-site preservation). These were tested at different temperatures, leading to a maximum furfural yield of 82% at 160 °C. They showed high recyclability in repetitive runs. Finally, a direct influence of the nature of the sulfonic site on their stability was also found.Figure optionsDownload as PowerPoint slideHighlights
► Arenesulfonic sites were incorporated on SBA-15 at different aging temperatures.
► Furfural production from xylose was optimized using SBA-15 catalysts.
► The SBA-15 catalysts aged at 180 °C showed high hydrothermal stability.
► An optimum furfural yield of 82% was achieved at 160 °C of reaction-temperature.
► Reused catalysts showed high furfural yield and stability after repetitive tests.