Bifunctional Ni/CaO-HZSM-5 Catalysts as a Two-Step Strategy To Produce n-Hexanol from Alkali Lignin

The production of high-value-added chemicals from the degradation of real lignin still has been an unresolved issue. In this study, a two-step strategy was proposed to obtain n-hexanol from alkali lignin, and high conversion of alkali lignin and selectivity of n-hexanol were achieved. The deoxygenation performance of the synthesized Ni-HZSM-5 catalyst, modified by Ca, was efficiently improved. At first, through the deoxygenation of alkali lignin via Ni/CaO-HZSM-5, the C–O bonds of the material were broken effectively and 44% degree of deoxygenation (DOD) was obtained. Second, n-hexanol was selectively produced over the Ni/HZSM-5 catalyst from the liquid product obtained by the first step. The efficiency of deoxygenation (DOD) was attained at 71%, and the heat value increased to 51.6 MJ/kg from 19.9 MJ/kg after the two-step strategy. This strategy showed a high catalytic effect to produce n-hexanol from alkali lignin using Ni/CaO-HZSM-5 and Ni/HZSM-5 catalysts and revealed a superior advantage in the hydrodeoxygenation of real lignin to form high additional value chemicals.