Effects of Alkali and Acid Modification Treatments Method on Size Distribution and Textural Property of β Zeolites
The mesoporous modification of Hβ zeolite (n (Si) ∶ n (Al) =18.7) was carried out by a sequential scheme,namely hydrothermal alkali pre-etching,bulk alkali leaching and acid washing.The effects of the modification on the mesoporous formation,pore size distribution and textural properties of the zeolite were investigated by means of powder XRD,N2 adsorption-desorption,SEM and TEM.A semi-empirical model for calculating the volume fraction of the intraparticle mesopores was established.It was confirmed that the Hβ zeolites treated with alkaline and acid had bigger specific surface area,higher mesoporosity and uniform mesopore size distribution.In the modification,the hydrothermal alkali pre-etching promoted the uniform mesopore size distribution,the alkali leaching for desilication played a crucial role in the mesopore formation,and acid washing for dealumination led to the increase of the mesopore size.Based on the calculated results,the volume fraction of the intraparticle mesopores reached more than 70％ when the concentration of NaOH solution changed in the range of 0.1-0.3 mol/L.
mesoporous β zeolitealkali-acid treatmentmesopore distributionmesoporous volume model
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NSTL
万方数据
维普
