γ-Valerolactone from pyrolysis of calcium salts of levulinic-formic acid mixtures derived from cellulose

Hydrothermal degradation of cellulose (DP ∼ 450) in 0.02-0.20 mol dm−3 aq. hydrochloric acid at 160 °C, for 2-8 h and neutralization of the filtrate with calcium hydroxide can be used to prepare a mixture of carboxylic acid calcium salts. The mixture consists of calcium levulinate and calcium formate in approximately 1:0.65 mol ratio, together with CaCl2. Pyrolysis of this crude mixture at 350 °C for 3.0 min produces pyrolyzate oil yield of 140-210 g kg−1 of dry salt mixture. The pyrolyzate was identified as ∼97% γ-valerolactone, with the minor products; levulinic acid, 3-methyl-2-cyclopentenone, and 2,3-dimethyl-2-cyclopentenone by using a combination of GC-MS and NMR spectroscopy.