Glycerol conversion into value-added products in presence of a green recyclable catalyst: Acid black carbon obtained from coffee ground wastes

Abstract

Black carbon from coffee grounds (BCC) was treated with sulfuric acid (BCC-S) or fuming sulfuric acid (BCC-SF) and utilized as catalysts in glycerol etherification reactions. The BCC-SF showed a high amount of sulfur groups, about 8%. However, the treated BCC-S showed the lowest amount of sulfur groups, about 3%. Furthermore, these catalysts show high catalytic activity in the glycerol etherification with tert-butyl alcohol (TBA), the activity being higher for the BCC-SF. The yields for mono-tert-butyl glycerol (MTBG), di-tert-butyl glycerol (DTBG) and tri-tert-butyl-glycerol (TTBG) were very similar to those obtained using a commercial resin, Amberlyst-15. The yields for BCC-SF were about 40 and 20% for the MTBG and DTBG + TTBG, respectively. Furthermore, the acid black carbons showed high stability of the active groups and can be reused in consecutive reactions.