Converting pine sawdust to advanced biofuel over HZSM-5 using a two-stage catalytic pyrolysis reactor

•Pyrolysis at 500 °C and catalysis at 500 °C are the optimal condition to get advanced biofuel for the two-stage catalytic pyrolysis process.•The deposition of coke into pores of HZSM-5 resulted in the distortion of zeolite lattice.•The two-stage catalytic pyrolysis system combined with HZSM-5 catalyst showed a good potential for converting sawdust to advanced biofuel.

In this study, the pine sawdust thermal conversions over HZSM-5 catalyst were carried out under different reaction temperatures in a two-stage catalytic pyrolysis reactor. Higher temperatures in the catalytic reactor tended to decrease the yield of bio-oil and change the component of bio-oil. The results from the gas chromatography–mass spectrometry (GC–MS) analysis showed that the pyrolysis reaction at 500 °C and catalytic reaction at 500 °C treatment obtained the highest hydrocarbon content (58.63%) and the highest C8–C12 content (48.03%) in the oil phase of the bio-oil. The X-ray diffraction (XRD) and selected-area-electron-diffraction (SEAD) characterization showed that the distortion of the ZSM-5 zeolite lattice occurred before and after use. The Brunauer–Emmett–Teller (BET) characterization indicated that the formation of coke increased as the catalytic temperature rose. The physical characterization of bio-oils, such as water content, density, viscosity, pH, and higher heating value (HHV) further demonstrated that HZSM-5 catalyst was beneficial in achieving low viscosity and higher HHV bio-oils. All the results suggest that the two-stage catalytic pyrolysis reactor with HZSM-5 catalyst has a great potential for achieving advanced biofuel.

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