摘要
多级孔化和调控酸量是提高MSE分子筛催化裂解性能的有效途径。通过珠磨-重结晶法合成了具有纳米尺度、窄粒径分布的多级孔UZM-35分子筛,探讨了制备过程中珠磨时间和重结晶时间等因素对分子筛结构的影响,并通过硝酸溶液脱铝降低MSE分子筛的酸量。采用X-射线衍射(XRD)、扫描电子显微镜(SEM)、氮气物理吸附-脱附、固体核磁、氨气程序升温脱附(NH 3-TPD)和吡啶红外(Py-IR)等手段对分子筛的形貌、孔道结构和酸性质进行表征测定。以正庚烷催化裂解制备低碳烯烃为探针反应,对MSE分子筛进行性能评价,结果表明:通过引入多级孔结构和降低酸量促进MSE孔道中的单分子裂解反应,抑制氢转移副反应,使乙烯+丙烯收率提高,失活速率降低。在反应温度913 K、质量空速5 h-1的条件下,脱铝多级孔UZM-35分子筛的裂化机理比达到73.5,氢转移系数低至0.11;乙烯+丙烯收率为48.6%,比初始UZM-35分子筛提高了6.1%;反应10 h的失活率为4.1%,比初始UZM-35分子筛降低了14.3%。
Hierarchical porosity and acid amount modulation are effective ways to improve the catalytic cracking performance of MSE zeolite.Hierarchical UZM-35 zeolite with nano-scale and narrow particle size distribution was synthesized by bead milling-recrystallization method,the effects of factors such as bead milling time and recrystallization time on zeolite structure in the preparation process were explored,and the acid amount of MSE zeolite was reduced by dealumination with nitric acid solution.The morphology,pore structure and acidic properties of the zeolite were characterized and determined by X-ray diffraction(XRD),scanning electron microscopy(SEM),N 2 adsorption-desorption,solid-state NMR,ammonia programmed temperature desorption(NH 3-TPD)and pyridine infrared(Py-IR).The performance of MSE zeolite was evaluated using n-heptane catalytic cracking for the preparation of light olefins as a probe reaction.The results show that the mono-molecular cracking in MSE pore channel can be promoted by introducing hierarchical pore structure and reducing the acid amount,and the hydrogen transfer side reaction is inhibited,thus increasing ethylene and propylene yield and lowering deactivation rate.At the reaction temperature of 913 K and the mass hourly space velocity(MHSV)of 5 h-1,the cracking mechanism ratio of the dealuminated hierarchical pore UZM-35 zeolite is up to 73.5,the hydrogen transfer coefficient is as low as 0.11,and the ethylene and propylene yield is 48.6%,which is 6.1%higher than that of the initial UZM-35 zeolite;the deactivation rate of the reaction for 10 h is 4.1%,which is 14.3%lower than that of the initial UZM-35 zeolite.
作者
范军
杨诗棋
濮鑫
叶磊
朱卡克
纪晔
刘纪昌
FAN Jun;YANG Shiqi;PU Xin;YE Lei;ZHU Kake;JI Ye;LIU Jichang(School of Chemical Engineering,East China University of Science and Technology,Shanghai 200237,China;PetroChina Planning&Engineering Institute,PetroChina Company Limited,Beijing 100083,China;Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan,Shihezi University,Shihezi 832003,China)
出处
《石油学报(石油加工)》
北大核心
2025年第1期1-13,共13页
Acta Petrolei Sinica(Petroleum Processing Section)
基金
企业创新发展联合基金重点项目(U22B20141)
上海市启明星项目(扬帆专项)(23YF1409200)资助。
关键词
低碳烯烃
催化裂解
多级孔
UZM-35分子筛
珠磨-重结晶
light olefin
catalytic cracking
hierarchical pore
UZM-35 zeolite
bead milling-recrystallization
