Catalyst Characterizations. Fourier transform infrared (FT-IR) spectra was conducted on a Vector-33 FT-IR spectrometer in the wavenumber range of 400−4000 cm−1. The thermal stability of lignosulfonate and LS was determined by using an SDT-Q500 thermogravimetric analyzer (TGA) with temperature varying from room temperature to 700 °C in a nitrogen atmosphere and at a heating rate of 20 °C/min. A Zeiss EVO 18 (Jena, Germany) scanning electron microscope (SEM) was also used to investigate the morphology of lignosulfonate and LS. An Agilent 1100 (Santa Clara, CA, USA) high-performance liquid chromatograph (HPLC) was used to determine the yields of furfural