Polyoxometalate-catalyzed hydrolysis of the hemicelluloses by (Mo-V-P)-heteropolyacids-Statistical modeling using...

The mixed-addenda Keggin-type molybdovanadophosphate heteropolyacids (Mo-V-P)-HPAs of series H_(n+3)[PMo_(12-n)V_nO₄₀] with n = 3,4 (HPA-3 and HPA-4) were found to be extremely effective acid catalysts for green hydrolytic conversion of plant (wood and agro-crop) hemicelluloses into soluble mono and oligosaccharides (XOS) within an integrated biorefining scheme. Response surface methodology (RSM) has been applied for statistical modeling and optimization of (Mo-V-P)-HPA catalyzed hemicellulose hydrolysis using potential European energy agro-crop giant reed (Arundo donax) as a model lignocellulosic feedstock. In much diluted (0.01-0.05 mol/L) aqueous HPA solutions, the linear effect of reaction temperature, as well as the interaction effect between temperature and HPA concentration, were the main factors affecting efficiency and selectivity of the hydrolysis reaction. Under established optimum conditions (0.033 mol/L HPA-4, 141.8 °C, 89.7 min), 98.5 % of total crop xylan was hydrolytically converted into soluble sugars, vs. 98.9 % by model, with loss of only ca. 6.3 % of cellulose and formation ca. 0.8 % furfural.