2-53: Effect and Mechanism of Metal Salt Catalysts in Biomass Pretreatment and Enzymatic Hydrolysis

Effect and Mechanism of Metal Salt Catalysts in Biomass Pretreatment and Enzymatic Hydrolysis

Srinivas Reddy Kamireddy¹, John C. Degenstein², Melvin P. Tucker³, Yun Ji¹.

1.         University of North Dakota, Grand Forks, ND

2.         Purdue University, West Lafayette, IN

3.         National Renewable Energy Laboratory, Golden, CO

The goal of this research is to understand the effects of different metal cations on biomass pretreatments (i.e. xylose and glucose yields and inhibitor product formation) and to evaluate the enzymatic saccharification performance of the metal salt enhanced pretreated solids. The metal salts chosen for the study were CuCl₂, FeCl₃, FeCl₂, MgCl₂ and AlCl₃. The effects of these metal salts were studied at 150°C and 160 °C), molar concentrations of 0.1M and 0.15M. The reaction time was kept constant at 10 min.

            Preliminary results show that xylose solubilization of 91 and  81 % was observed for corn stover samples pretreated at 160 °C and 0.15 M of FeCl₃ orCuCl₂. The glucose yield after enzymatic hydrolysis was found to be 95% and 81 % for CuCl₂ and FeCl₃ at same conditions.  This implies that Fe³⁺ and Cu²⁺ cations salts acidify the solution possibly through undergoing hydrolysis reactions. The acid generated diffuse through the wet lignocellulosic matrix to hydrolyze xylan to xylose. However, low conversion of xylan to xylose was found with samples treated with FeCl₂ and MgCl₂ as these metal salts are more stable and reduced hydrolysis reaction rates were found due to the high hydration constants (pK_h >9.5).