Zn-Na2CO3复合改性HZSM-5在线催化生物质热解制备芳烃

Production of Aromatic Hydrocarbon by Catalytic Pyrolysis Vapor Upgrading of Biomass with Zn-Na2CO3/HZSM-5 Mesoporous Catalyst

  • 摘要: 为进一步提高芳烃的产率,减少催化剂的失活,采用Zn和Na2CO3对HZSM-5催化剂复合改性,探讨了Zn的负载量对生物质催化热解气相重整制备芳烃的产率、选择性以及抗结焦性能的影响,同时采用XRD、BET、NH3-TPD以及SEM对反应前后催化剂进行表征。结果表明:Zn-Na2CO3复合改性没有改变HZSM-5晶体骨架结构,Zn均匀的负载在催化剂的表面,比表面积随着Zn的负载量的增加而减少,孔径随着Zn的负载量的增加而加大;改性Zn-Na2CO3/HZSM-5催化剂具有较强的催化活性以及脱氧效果,有效的提高芳烃的产率,抑制了稠环芳烃以及焦炭的生成,使BTXE的选择性增加;当Zn的负载量为5%时,单环芳烃含量最高为88.05%,BEXT增加12.92%,而焦炭含量最低为23.69%。Zn的添加有效的提高了催化剂抗积碳能力,促进了氢转移反应的形成,使其芳构化能力提升。

     

    Abstract: In order to further improve the yield, selectivity of aromatics and reduce the deactivation of catalysts, Zn and Na2CO3 were selected to modified the HZSM-5 zeolite catalyst, the effects of zinc loading on the yield, selectivity of aromatics and coking resistance from biomass catalytic pyrolysis by vapor phase upgrading were investigated, at the same time, the modified HZSM-5 catalysts before and after the reaction were characterized by X-ray diffraction (XRD), surface area and pore size analyzer (BET), temperature programmed desorption (NH3-TPD) and scanning electron microscope (SEM). The results show that the crystal skeleton structure of HZSM-5 were not changed by the modification of Zn and Na2CO3, which was distributed on the surface of the HZSM-5 catalyst uniformLy, the specific surface area were decreased with the increase of Zn loading and the pore size were enlarged with the increase of Zn loading; Zn-Na2CO3/HZSM-5 catalyst has strong catalytic activity and deoxidization effect, which exhibited better catalyst performance to improve bio-crude quality due to the additional decarbonylation, decarboxylation and dehydrogenation reactions induced by Zn loading and also could effectively increase the yield of aromatic hydrocarbons, inhibit the formation of polycyclic aromatic hydrocarbons and coke, simultaneously increase the selectivity of BTXE, 5% Zn-Na2CO3/HZSM-5 catalyst produced bio-crude with the highest hydrocarbons content at 88.05% and with the lowest coke content at 23.69%. The addition of Zn effectively improves the carbon deposition resistance, promotes the formation of hydrogen transfer reaction and enhances its aromatization ability.

     

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