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

Abstract

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.