Catalytic mechanism of cellulose pyrolysis using AAEMs, TMs and binary metals based on in-situ DRIFTS

It is well known that AAEMs (alkali and alkaline earth metals) and TMs (transition metals) have different catalytic mechanisms for the cellulose pyrolysis. There is potential for synergy among different metals during the pyrolysis. This study mainly used in-situ DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy) to comprehensively study the catalytic mechanism of different metals (Na, Ca, Fe, Co, and Ni) during cellulose pyrolysis. The mechanism of synergistic interaction between different metals was explained according to the catalytic characteristics of different metals. The results showed that different metals had different effects on the activation pathway. Na and Ca retained a part of O in the char, thereby inhibiting the graphitization process, while Fe, Co, and Ni tended to interact directly with the carbon structure to enhance its stability. When binary metals co-catalyzed, Na and Ca showed a competitive mechanism for combining with O, while the cooperation of Na and Fe accelerated the depolymerization of cellulose. In this study, the proposed improved in-situ diffuse reflection infrared reaction chamber with more accurate temperature control could become a solid foundation for studying the catalytic properties of different single in the pyrolysis of cellulose. • Improved in-situ DRIFTS helps get information at an accurate temperature. • Different metals show different catalytic properties at each stage of pyrolysis. • Metals enhance the aromaticity of char and promote the release of H 2 and CH 4 . • The binary metals show synergistic catalytic effects on pyrolysis.