基于串联脱硅-脱铝法的HZSM-5分子筛调控及其超临界催化裂解活性评价

Regulation of HZSM-5 zeolite based on tandem desiliconization-dealumination and evaluation of its supercritical catalytic cracking activity

本文以HZSM-5(SiO_(2)/Al_(2)O_(3)=50)分子筛为原料,采用不同浓度的NaOH溶液对分子筛进行碱处理脱硅,引入介孔,完成对分子筛孔道的调控;再通过柠檬酸及酒石酸对分子筛进行酸处理脱铝以实现对其酸性进行调控。由正丙胺-程序升温裂解(n-propylamine-tempreture programmed desorption,n-propylamine TPD)法及正十二烷程序升温表面反应(n-dodecane-tempreture programmed surface reaction,n-C_(12)-TPSR)法测量处理后分子筛的酸性及本征催化活性变化,X-射线衍射(X-ray diffraction,XRD)测量各样品的结晶度。最后通过正十二烷超临界催化裂解反应评价处理后HZSM-5分子筛催化剂的实际反应活性和寿命,利用程序升温氧化(temperature programmed oxidation,TPO)与恒温氧化(isothermal oxidation,ITO)分析反应后催化剂上的积炭量及空间分布情况,得到了分子筛孔道结构及酸性调控对催化剂失活的影响机制。

In this paper,HZSM-5(SiO_(2)/Al_(2)O_(3)=50)zeolite was used as the raw material,and the zeolite was desiliconized by alkali treatment with different concentrations of NaOH solution,and mesopores were introduced to complete the regulation of the zeolite pores.Zeolites were acid-treated to dealuminate to control their acidity.The acidity and intrinsic catalytic activity of the zeolite after treatment were measured by n-propylamine-tempreture programmed desorption(n-propylamine TPD)method and n-dodecane-tempreture programmed surface reaction(n-C_(12)-TPSR)method,and the crystallinity of each sample was measured by X-ray diffraction(XRD).Finally,the actual activity and life of the treated HZSM-5 zeolite catalyst were evaluated by the supercritical catalytic cracking reaction of n-dodecane,and the amount of carbon deposits and space on the catalyst after the reaction were analyzed by temperature programmed oxidation(TPO)and isothermal oxidation(ITO).According to the distribution,the influence mechanism of zeolite pore structure and acid regulation on catalyst deactivation was obtained.