Ni-MOFs and lignin modified biochar: An environmentally-friendly and efficient catalyst for catalytic transfer hydrodeoxygenation of lignin derivatives

In this study, different kinds of lignin, including enzymatic hydrolysis of lignin (EHL), alkaline lignin (AL), kraft lignin (KL) and sodium lignosulfonate (LS) were investigated as precursor to prepare Ni@BTC@X (X= EHL, AL, KL, LS) catalysts using a traditional hydrothermal method with Ni-MOF for HDO upgrading of lignin derivative vanillin (VAN) to generate high value chemical 2-methoxy-4-methylphenol (MMP). The catalytic performance of these catalysts was investigated under different reaction conditions, and it was explored that the conversion of VAN was close to 100 % and the MMP yield was close to 90 % under the optimal conditions (Ni@BTC@LS catalyst, 220 ℃, 4 h, isopropanol, 2 MPa N 2 ). Various physical-chemical characterization results verified that the effects of active sites Ni, porous structure of lignin biochar support and electronic properties of the catalysts played a significiant role in HDO of lignin derived VAN. Additionally, synergistic effect of the highly homogeneously dispersed oxygen vacancies and acidic sites also promoted the VAN conversion efficiency. This work developed a strategy combing the advantages of MOFs and biomass derived substrates for manufacturing novel lignin/MOFs materials in the catalytic field. • The heterogeneity of lignin was studied for preparation of lignin-MOF catalysts. • Ni@BTC@LS showed the best catalytic HDO activity at 220 °C, 2 MPa N 2 , and 4 h. • Oxygen vacancies and acidic sites were the key for VAN conversion to obtain MMP. • The advantages of MOFs and biomass materials were combined in catalytic HDO field.