Catalyst Screening for the Production of Furfural from Corncob Pyrolysis

Acidic pyrolysis of corncobs is carried out at 800 K in a packed-bed reactor using several catalysts (H 2 SO 4, H 3 PO 4, H 3 BO 3, (NH 4 ) 2 SO 4, ZnCl 2, NiCl 2, MgCl 2, and Fe 2 (SO 4 ) 3 ). In all cases, the yields of char, water, and some condensable organic compounds (acetic acid, levoglucosenone, 1,4:3,6-dyanhydro-α- d -glucopyranose, and furfural) are significantly increased at the expense of the phenolic and carbohydrate products typical of uncatalyzed pyrolysis. The maximum yields of furfural (FF) are around 5–6% for the H 2 SO 4, Fe 2 (SO 4 ) 3,and ZnCl 2 treatments, with potential further increase, following secondary degradation of the main anhydrosugars, up to 8.5% (H 2 SO 4, Fe 2 (SO 4 ) 3 ) or 6.5% (ZnCl 2 ). Additional experiments made with a wide range of Fe 2 (SO 4 ) 3 concentrations, and a comparison with previous results obtained for H 2 SO 4 and ZnCl 2 treatments indicate that the best performances are shown by the first catalyst with potential FF yields up to 10%. Moreover, at low concentrations, it also highly promotes the formation of levoglucosan, 5-methylfurfural, 5-hydroxymethylfurfural, 4-hydroxy-5,6-dihydro-(2H)-pyran-2-one, and 3-hydroxy-2-penteno-1,5-lactone, 1-hydroxy-3,6-dioxabicyclo[3.2.1]octan-2-one.