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 (H2SO4, H3PO4, H3BO3, (NH4)2SO4, ZnCl2, NiCl2, MgCl2, and Fe2(SO4)3). In all cases, the yields of char, water, and some condensable organic compounds (acetic acid, levoglucosenone, 1,4:3,6-dyanhydro-?-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 H2SO4, Fe2(SO4)3 ,and ZnCl2 treatments, with potential further increase, following secondary degradation of the main anhydrosugars, up to 8.5% (H2SO4, Fe2(SO4)3) or 6.5% (ZnCl2). Additional experiments made with a wide range of Fe2(SO4)3 concentrations, and a comparison with previous results obtained for H2SO4 and ZnCl2 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.