sulfonated reduced graphene oxide as highly efficient solid acid catalyst in acid-catalyzed esterification and acetalization reactions

Solid acid catalysts have attracted significant attention in past few decades owing to many advantages such as easy separation and reusability, no equipment corrosion and eco-friendly behaviour [1, 2]. among the various solid materials used as catalyst supports, graphene oxide (go) nonosheets have gained researchers special attentions due to their exclusive properties including high surface area, excellent thermal and chemical stabilities and great activity toward surface functionalization [3, 4]. herein, we prepared a solid acid catalyst based on reduced graphene oxide via surface modification with 4-aminobenzene sulfonic acid. the prepared sulfonated catalyst was fully characterized by means of various physicochemical techniques such as fourier transform infrared (ft-ir) and raman spectroscopies, n2 adsorption-desorption, x-ray diffraction (xrd), ammonia temperature programmed desorption (nh3-tpd) analyses and transmission electron microscopy (tem). the esterification of acetic acid with butanol and acetalization of benzaldehyde with ethylene glycol were used to evaluate the catalytic performance of this solid acid catalyst. consequently, the outstanding results were obtained for butyl acetate and 2-phenyl-1,3-dioxolane production with 98% and 97% conversions at short reaction time, respectively. the reusability of catalyst was examined in 5 reaction cycles without any significant loss of activity.