过渡金属改性HZSM-5催化转化煤油共炼重油制轻质芳烃的研究

Study on catalytic conversion of coal-oil co-refining heavy oil to light aromatic hydrocarbons with HZSM-5 modified by transition metal

煤油共炼技术为煤炭和重质油清洁高效利用开辟了新途径,但其产品单一,附加值低。为实现煤油共炼液体产物的高值化利用,本研究以煤油共炼重油(H-CT)为原料,利用热裂解-气相色谱质谱联用仪(Py-GC/MS),通过单、双金属改性的HZSM-5对H-CT催化转化制苯、甲苯、乙苯、二甲苯和萘(BTEXN,B—苯,T—甲苯,E—乙苯,X—二甲苯,N—萘)的性能进行了考察,探究了裂解温度、升温速率和催化剂与原料的质量比对BTEXN峰面积和选择性的影响,利用红外快速加热炉对H-CT的Py-GC/MS结果进行了校正。结果表明:单、双金属负载使HZSM-5的强酸酸性减弱,中强酸酸性增强;Mo,Fe及双金属Mo-Fe的负载增大了HZSM-5介孔比表面积;H-CT裂解的最佳条件为温度700℃、升温速率5℃/ms,催化剂与原料的质量比8∶1,在此最优条件下,催化剂按转化效果由大到小依次为Mo-Fe,Mo-Ni,Mo,Ni,Fe,HZSM-5;HZSM-5和Mo-Fe/HZSM-5催化转化制备BTEXN的总选择性分别为39.78%和60.30%,修正后的BTEXN产率分别为197.3 mg/g与339.0 mg/g。过渡金属改性HZSM-5促进了BTEXN的生成,金属与HZSM-5的结合加速了催化转化过程中氢转移、脱羟基、开环、脱烷基和其他反应。

Coal-oil co-refining technology has opened up a new way for the clean and efficient utilization of coal and heavy oil,but its products are single and low value-added.In order to achieve the high-value utilization of liquid products from coal-oil co-refining,the coal-oil co-refining heavy oil(H-CT)was selected as the raw material to examine the performance of the catalytic conversion of H-CT into benzene,toluene,ethylbenzene,xylene and naphthalene(BTEXN)by single-bimetallic-modified HZSM-5 using the fast pyrolysis-gas chromatography/mass spectrometry(Py-GC/MS)in this work.The effects of pyrolysis temperature,heating rate and the mass ratio of H-CT to catalyst on the peak area and selectivity of BTEXN were explored.The Py-GC/MS results of H-CT were calibrated using an infrared fast heating furnace.The results show that the single and bimetal loading weakens the strong acidity of HZSM-5 and increases the moderate acidity.The loading of Mo,Fe and bimetallic Mo-Fe increases the mesoporous specific surface area of HZSM-5.The optimal temperature for H-CT cracking is 700℃,the heating rate is 5℃/ms,and the mass ratio of H-CT to catalyst is 8∶1.Under the optimal conditions,the order of catalyst conversion effect from the largest to the smallest is Mo-Fe,Mo-Ni,Mo,Ni,Fe,HZSM-5.The total selectivity of BTEXN prepared by catalytic conversion of HZSM-5 and Mo-Fe/HZSM-5 are 39.78%and 60.30%,respectively.The total selectivity of BTEXN are 197.3 mg/g and 339.0 mg/g,respectively.The transition metal modified HZSM-5 promotes the formation of BTEXN.The combination of metal and HZSM-5 accelerates the hydrogen transfer,dehydroxylation,ring opening,dealkylation and other reactions in the catalytic conversion process.