赖氨酸辅助合成β分子筛及其催化四氢萘加氢裂化性能

Lysine-Assisted Synthesis of β Zeolite and Its Catalytic Performance for Tetralin Hydrocracking

为了减少β分子筛晶格缺陷,强化其酸性和稳定性,在工业合成体系中使用少量L-赖氨酸辅助β分子筛晶化,并对所合成的样品进行X射线衍射(XRD)、X射线荧光光谱(XRF)、场发射扫描电镜(FESEM)、氨气程序升温脱附(NH3-TPD)、吡啶红外(Py-IR)和氮气吸附脱附表征。结果表明:使用L-赖氨酸辅助合成β分子筛可有效提高β分子筛产物的相对结晶度、硅铝物质的量之比和微孔比表面积,并改变晶粒形貌。NH_(3)-TPD和Py-IR表征结果显示,L-赖氨酸辅助合成的Hβ分子筛较常规Hβ分子筛具有更高的酸强度和更大的中强酸、强酸酸量。将其制备成双功能催化剂并用于催化四氢萘的加氢裂化反应,L-赖氨酸辅助合成β分子筛基催化剂表现出优异的催化活性和稳定性,这主要归因于β分子筛的中强酸、强酸性质、热和水热稳定性以及十二元环孔道体系得到改善。

In order to reduce the crystal defect and improve the acidity and stability of β zeolite,a new route to synthesize the β zeolite using a tiny amount of L-lysine in the industrial synthesis system was proposed in this study.The as-synthesized β zeolites were characterized by X-ray diffraction(XRD),X-ray fluorescence(XRF),field emission scanning electron microscopy(FESEM),NH_(3) temperature programmed desorption(NH_(3)-TPD)and pyridine adsorbed infrared(Py-IR)and N_(2) adsorption-desorption.The results showed that the as-synthesized β zeolites owned the higher crystallinity,SiO_(2)/Al_(2)O_(3) molar ratio,larger microporous specific area and different crystal morphology compared with the conventional β zeolite.Besides,the strength of acid and the amount of medium strong acid were also promoted on the H β zeolites synthesized by lysine-assisted,according to the results of NH_(3)-TPD and Py-IR.When the as-synthesied β zeolites were prepared for the bifunctional catalysts and used in the tetralin hydrocracking reaction,the remarkable catalytic activity and long-term stability were achieved,which was attributed to the improved properties of medium strong acid,thermal and hytrothermal stability,and twelve-membered porous system of theβzeolite.