Catalytic degradation of pine sawdust over heterotopic Ca–Fe and HZSM-5 to produce aromatic hydrocarbons†

Abstract

The effects of Ca and Fe of a bimetallic Ca–Fe catalyst when applied to pine sawdust pyrolysis were investigated by thermogravimetry-mass spectrometry. Trials were also performed using heterotopic Ca–Fe and HZSM-5 to catalyse the degradation of pine sawdust to produce aromatic hydrocarbons, employing a fixed bed reactor and gas chromatography-mass spectrometry. The presence of CaO was found to promote deoxygenation while Fe enhanced in situ hydrogen supply, whereas the Ca–Fe catalyst combined these effects. This material promoted the formation of low-oxygen compounds to generate precursors that were transformed into aromatics via HZSM-5. Up to 90.47% aromatic proportion and a 31.02 mg g⁻¹ benzene/toluene/ethylbenzene/xylene yield were obtained at 600 °C using a 1 : 1 mass ratio of Ca–Fe to HZSM-5 and a 2 : 1 mass ratio of catalysts to pine sawdust. This combination of catalysts is evidently an effective means of strengthening the pyrolysis of pine sawdust to produce aromatic hydrocarbons.