FER Molecular Sieve Modification And Application To Catalytic Isomerization Of N-butene

Isobutene is an important basic organic chemical with a wide range of uses.In this study,using ferrous alkali zeolite FER as catalyst and applying various modification and post-treatment methods.the composition and surface acidity of the catalysts were investigated via HNO3 treatment,urea treatment,ion exchange modification.The effects of these treatments on the catalytic properties(activity,selectivity and stability)thus the isomerization of butene were investigated.The catalysts were characterized by TG,BET,XRD,Py-IR,NH3-TPD,NMR and XRF.The main results are as follows:1.The removal of skeleton aluminum by HNO3 treatment results in reducing the strong B acid center,simultaneously the removal of the skeleton of aluminum will change aluminum-silicon coordination as well as the microstructure on FER molecular sieve.Thus the acidic nature of the catalysts was not well controlled,so as to the catalytic reaction performance.2.Having the basic nature with special lone-pair electrons,urea was utilized as modification material on the purpose of maintaining the overall skeleton structure of FER molecular sieve at the same time poisoning strong acid sites.In this way,the number of acidic sites on the FER molecular sieve catalyst will be changed(decreased),while the aluminum-silicon coordination did not change.As such a treatment is only poisoned the active site but not changed the skeleton structure of the catalysts,some corresponding effects could be observed.The modification results in reducing the conversion of butane while increasing the selectivity of isobutene,but the yield of butene also tend to decrecse.3.Hpplying Ti4+ to substitute the aluminum on the skeleton structure of the catalysts.The experimental results show that the low Ti4+ concentration modification can help to fine tune the acidic properties of FER molecular sieve,and its skeleton structure remains intact.Therefore,the corresponding effects of substitution on catalytic performance was not well regulated when the high Ti4+ concentration was used as modification agent,because both the acidity and skeleton structure will be changed at high Ti4+ concentration.