Modeling The Catalytic Conversion Of Anthracene Oil Fraction To Light Aromatics Over Mesoporous HZSM-5

Facing the inherent resource structer of“poor oil,little gas and relatively rich coal”,it is such difficult for China to change the energy which is still dominated by coal for a long period.Coal tar is the liquid product originated from coal pyrolysis and is a valuable chemical raw material.However,the high boiling fractions of coal tar has the characteristics of large molecular weight,strong polarity and high content of heteroatoms,and it is difficult to prepare light aromatics in the process of catalytic pyrolysis to achieve high value-added utilization.This paper adopts double templates to synthesize mesoporous HZSM-5.In this paper,tetrapropylammonium hydroxide（TPAOH）and trimethoxy[3-（phenylamino）propyl]silane（YJGW）were used as templating for MFI skeleton and mesoporous sturcture,respectively.Mesoporous HZSM-5（YJGW-X,X=0,5 and 10）were successfully synthesized by adjusting the addition of YJGW（0 wt%,5 wt%and 10 wt%）.The physicochemical properties of YJGW-X were analyzed by X-Ray Diffraction（XRD）,Scanning Electron Microscope（SEM）,N₂-sorption desorption,NH₃-Temperature-Programmed Desorption（NH₃-TPD）and Pyridine Fourier Transform Infrared Spectroscopy（Py-IR）.Naphthol（Nap-ol）,methylnaphthalene（Nap-met）,methylanthracene（Ant-met）,C22 alkane（C22）and their mixture（modeling anthracene oil fraction,M-MCs）were selected as raw materials,BTEXN（benzene,toluene,ethylbenzene,xylene and naphthalene）were selected as target products,pyrolysis gas chromatography-mass spectrometer（Py-GC-MS）was used to investigate the product distribution originated from single model compounds（MCs）and M-MCs pyrolysis and the interaction of each MCs in the pyrolysis process.Using MCs as raw material,the performance of YJGW-X was investigated in fixed bed.Based on above studies,the possible mechanism of MCs catalytic conversion is proposed.The main results are as follows:（1）YJGW-X has a mesoporous structure with pore size above 2.1 nm.YJGW-5 has the largest external specific surface area and mesopore volume,which are 116.23 m²/g and 0.1 cm³/g,respectively.The amount of weak acid decreased from 1.14 mmol/g to 0.41 mmol/g with the addition of YJGW,while the amount of strong acid first increased to 0.42 mmol/g and then decreased to 0.25 mmol/g.Compared with the addition of 0 wt%of YJGW,the Br（?）nsted acid（BA）and Lewis acid（LA）amounts decreased by 50.47%and 55.66%when the addition of YJGW was 10 wt%.（2）Py-GC-MS shows that when the temperature of Nap-ol pyrolysis was 450 ℃,YJGW-10exhibited the highest BTEXN yield,which is 2951.19 mg/kg,and the toluene yield was as high as 2541.41 mg/kg.When YJGW-0 was adopted in Nap-met catalytic pyrolysis process,the yield of BTEXN increased from 1840.42 mg/kg（400 ℃）to 2054.04 mg/kg（500 ℃）.When the final temperature was 450 ℃ and YJGW-0 was used,the yield of BTEXN originated from Ant-met pyrolysis was the highest,which up to 547.63 mg/kg.The BTEXN yield of C22 pyrolysis can reach 3689.23 mg/kg,and the product contains many C5-C7 aliphatics.The BTEXN yield originated from M-MCs at 450 ℃,catalyzed by YJGW-10,was 2578.35 mg/kg.The order of BTEXN yield was C22>Nap-ol>M-MCs>Nap-met>Ant-met,which is related to the fact that C22 provides hydrogen species to promote the cleavage of polycyclic aromatic hydrocarbons leading to the increase of BTEXN yield.（3）The fixed bed studies show that MCs can efficiently convert into light aromatics using YJGW-X,such as BTEXN.When cyclohexane+MCs pyrolyzed at 500 ℃,YJGW-0 showed the highest yield of BTEXN,which was 399.57 mg/g.While the cyclohexane pyrolyzed at 450℃,YJGW-0 showed the highest yield of BTEXN which can reach up to 339.10 mg/g.Py-GC-MS and fixed-bed studies found that the optimal condition was 5 wt%of the addition YJGW and 500 ℃.