摘要
研究了SiCl_4、(NH_4)_2SiF_6、H_2C_2O_4及水热脱铝沸石的孔道结构。结果表明,所有脱铝方法均不能影响沸石晶粒大小的变化;SiCl)_4和(NH_4)_2SiF_6脱铝沸石基本上保持了沸石原有的孔道结构,而H_2C_2O_4和水热法脱铝则可导致沸石中出现40(?)左右的大量中孔结构,且H_2C_2O_4脱铝沸石的中孔孔径较为集中;在脱铝过程中,沸石的骨架崩塌以及中孔的形成都存在有某些规律性。随着沸石骨架Si/Al 比的增加,沸石由亲水性逐渐变为憎水性,而对烃的吸附能力则与体相铝含量有一致关系。
From the pore diameter distribution data of dealuminated Y-zeolites,the following facts can be
observed:NH_4Y has almost no secondary pores;H_2C_2O_4 and hydrothermal dealumination causes the
formation of mesopore system at a diameter of 40(?) which is not evident for(NH_4)_2SiF_6,SiCl_4
dealuminated Y-zeolites.As to high-temperature hydrothermally treated Y-zeolites,mesopores with
larger diameter around 60~200(?) emerge.Pore structure among crystal particles does not change
by the analysis of N_2-isotherms and TEM regardless the dealumination method.
Much attention should be paid to the fact that mesopores of dealuminated Y-zeolites concentrate
on 40(?),with no obvious relation to dealumination method.It is perhaps due to partial β cages
collapse and finially to two to three suppercages connected.Further collapse of β cages of Y-zeolites
under high temperature hydrothermal treatment contributes to larger mesopores formation around
60~200(?).
No matter what dealumination method is used,the amount of H_2O adsorption on Y-zeolites de-
creases with increasing framework Si/Al ratios.Comparing to chemically dealuminated Y-zeolites
with the same framework Si/Al ratio,hydrothermally dealuminated Y-zeolites show low H_2O ad-
sorption amounting only to a quarter of NH_4Y's for HUSY-750.The results demonstrate that high
temperature hydrothermal treatment can reduce Y-zeolite's polarity greatly.
As to hydrocarbons,n-hexane,decalin,Al content in Y-zeolite bulk has a decisive effect on
their hydrocarbon adsorption amount.
出处
《石油学报(石油加工)》
EI
CAS
CSCD
北大核心
1993年第4期43-49,共7页
Acta Petrolei Sinica(Petroleum Processing Section)
基金
国家自然科学基金。