Catalytic pyrolysis of guaiacol on Enteromorpha-based biochar: A combination of experiments and density functional theory

Abstract

This study investigated the catalytic effect of Enteromorpha-based char (EPC) on guaiacol. FTIR and XPS characterization were used to confirm the functional groups of EPC, mainly oxygen-containing and nitrogen-containing. The experimental results of catalytic pyrolysis of guaiacol showed that the conversion of guaiacol without catalyst was 38.09%, and after the addition of EPC the conversion of guaiacol increased with the increase of EPC mass until complete conversion. Based on the experimental and characterization results, the catalytic mechanism of guaiacol over EPCs with different kinds of functional groups was investigated by density functional theory (DFT). According to the energy analysis of DFT, the catalytic model containing carboxyl and hydroxyl groups showed excellent adsorption performance for guaiacol. The DFT calculation result also indicates that guaiacol can be converted to phenol over EPC catalytic model with carboxyl and hydroxyl groups through elementary reactions with lower reaction energy barriers. Pyridine and pyrrole functional groups also have a good catalytic effect of lowering the energy barrier in N-containing species. This contribution provides an alternative way to gain insight into the mechanism of catalytic pyrolysis of guaiacol on EPC at both the experimental and molecular levels, and may help to design more efficient biochar catalysts.