Preparation of aromatic hydrocarbons from pinecone pyrolysis synergistically catalyzed by Ca-Fe and HZSM-5

In this study, a combination of Ca-Fe and HZSM-5 catalysts for enhancing the aromatic hydrocarbons yields from pinecone pyrolysis was proposed. The catalysts performance and the enhanced mechanism of aromatic hydrocarbons generation were investigated by pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) and a bench-scaled fixed bed reactor. The catalysts crystallization and pore structure characteristics were characterized by X-ray diffraction (XRD) and N2 adsorption/desorption. The results showed that the combination of Ca-Fe and HZSM-5 catalysts produced the largest peak area and the highest relative content of aromatic hydrocarbons relative to HZSM-5, CaO/HZSM-5 and Fe/HZSM-5 catalysts. Relative to single HZSM-5 catalytic pyrolysis, the introduction of Ca-Fe components increased the yield of aromatics, especially increased the yield of benzene, toluene, ethylbenzene and xylene (BTEX) to 17.21 mg/g, with an increase of 61.60 %. The heterotopic arrangement of pinecone, Ca-Fe catalyst and HZSM-5 catalyst facilitated the production of high-quality aromatic hydrocarbons relative to the in situ catalytic pyrolysis technique. The Ca-Fe bimetallic catalyst decomposed the primary volatiles from pinecone pyrolysis into oxygenated compounds with smaller molecular weights, thereby increasing the proportions of pyrolysis volatiles entering the HZSM-5 channels, and subsequently enhancing the yield of aromatic hydrocarbons. This study implies that the combination of Ca-Fe and HZSM-5 catalyst is a promising approach for converting biomass materials into aromatic hydrocarbons.