摘要
通过在小晶粒Y分子筛合成的过程中原位引入Ni源合成了一系列不同Ni掺入量的小晶粒Y-xNi分子筛,将活性金属Ni预浸渍到Y分子筛的骨架中。将Y-xNi分子筛和ASA混合物作为载体并采用等体积浸渍法负载Ni和W,制备了系列Cat-xNi加氢裂化催化剂,以正十六烷为反应物,探究其加氢裂化催化反应性能。采用扫描电子显微镜(SEM)、X射线衍射(XRD)、N2吸附-脱附、氨气程序升温脱附(NH3-TPD)、氢气程序升温还原(H2-TPR)、透射电子显微镜(TEM)和X射线光电子能谱(XPS)等表征手段分析了Ni的掺入对Y分子筛及Cat-xNi催化剂理化性质的影响。结果表明,Ni主要取代Al引入Y分子筛骨架;在Y分子筛中适量掺入Ni会提高Y分子筛的相对结晶度以及Bronsted酸和Lewis酸位点的数量,但过量的Ni掺入不利于Y分子筛的结晶。Ni的掺入削弱了金属与载体间的相互作用,提高了活性金属的硫化度及NiWS活性相的堆积数及分散度,调节了催化剂上金属中心与酸中心的匹配。催化性能评价结果显示,由于Ni改性能同时增加Br?nsted酸中心与NiWS活性中心数量,增强金属中心与酸中心之间的协同作用,因而在提高正十六烷加氢裂化活性的同时可避免其过度裂化,获得较高的中间馏分产物(C8-C12)选择性及收率。在360℃反应条件下,与Cat-0Ni催化剂相比,Cat-0.2Ni催化剂具有较高的n-C16转化率和C8-C12产物收率(达65.4%)。综上可知,采用原位合成法将活性金属Ni预浸渍在Y分子筛上可以有效调节裂化活性中心与加氢活性中心之间的平衡,从而提高其催化活性和中间馏分产物的收率。
A series of small crystal Y-xNi zeolites with different amounts of Ni doping were synthesized by in situ introducing the Ni precursors during the synthesis,through which the active Ni metal was incorporated into the framework of the Y zeolites.With the mechanical mixture of Y-xNi zeolites and amorphous silica-alumina(ASA)as the support,a series of Cat-xNi catalysts were prepared through loading the Ni and W components by incipient wet impregnation and the catalytic performance of Cat-xNi in the hydrocracking of n-hexadecane was then investigated.In addition,the effect of Ni doping on the physicochemical properties of Y zeolite and Cat-xNi catalysts was elucidated with the help of scanning electron microscopy(SEM),X-ray diffraction(XRD),N2-adsorption desorption,NH3 temperature programmed desorption(NH3-TPD),H2 temperature programmed reduction(H2-TPR),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS),and so on.The results indicate that Ni can replace Al to enter the framework of the Y zeolites.The incorporation of appropriate amount of Ni into the Y zeolites can increase their relative crystallinity and the number of Brønsted and Lewis acid sites;however,excessive Ni incorporation is detrimental to the crystallization of Y zeolite and excessive non-framework Ni species will cover the surface Brønsted acid sites.Moreover,Ni doping can weaken the metal-support interaction,increase the sulfation extent of the active metal and the stacking number and dispersion of the active NiWS phase,and then improve the matching between the metal and acid sites on the Cat-xNi catalysts.As a results,in comparison with the counterpart Cat-0Ni catalyst,the Cat-xNi catalysts display more Brønsted acid sites and active NiWS sites as well as improved the synergy between the metal sites and acid sites,which can enhance the conversion of n-hexadecane whereas inhibit the over-cracking,and then booster the yield of the middle distillate products(C8–C12).In particular,for the n-hexadecane hydrocracking at 360°C,
作者
孙劲晓
王晓晗
魏强
周亚松
SUN Jinxiao;WANG Xiaohan;WEI Qiang;ZHOU Yasong(State Key Laboratory of Heavy Oil Processing,China University of Petroleum,Beijing 102249,China)
出处
《燃料化学学报（中英文）》
EI
CAS
CSCD
北大核心
2024年第6期775-789,共15页
Journal of Fuel Chemistry and Technology
基金
国家自然科学基金(22078360)资助。
