Sulfonated tobacco stem carbon as efficient catalyst for dehydration of C6 carbohydrate to 5-hydroxymethylfurfural in γ-valerolactone/water

Abstract

A carbon solid acid was made by grafting benzenesulfonic acid groups on the tobacco stem-derived porous carbon, which was prepared from waste tobacco stem by simple carbonization. The catalyst was characterized by scanning electron microscope (SEM), N2 adsorption-desorption, Fourier transform infrared spectroscopy (FT-IR), elemental analysis (EA), pyridine FT-IR spectroscopy and X-ray photoelectron spectroscopy (XPS). The catalyst exhibited excellent catalytic activity for 5-hydroxymethylfurfural (HMF) production from fructose and glucose in γ-valerolactone/water solvent, and high yields of HMF reached 93.7 and 43.8%, respectively. In addition, the high yields of total furans derived from fructose and glucose reached 96.8 and 54.1%, respectively. The benzenesulfonic acid group grafted onto the surface of inner pores of carbon allowed reusing the catalyst for at least five runs without obvious activity reduction. The good performance of the tobacco stem-derived carbon solid acid was determined by the unique surface active sites, such as high density of Brønsted acid, Lewis acid sites, oxygen-containing weak acidic sites and protonated nitrogen-containing functional groups. This study offered a promising approach for efficient carbohydrate conversion.