Characterization of Natural Clinoptilolites and Skeletal Isomerization of Cyclohexene

Abstract

From the point of view of the effective utilization as high additional value of natural sedimentary zeolites, characterization and catalytic reaction tests have been made. The samples in this study was natural clinoptilolite (FZ) produced in Futatsui, Akita Prefecture, and its specimens (HFZ) chemically treated with hydrochloric acid in various concentrations.
Identification of clinoptilolite and in vestigation of crystallinities were made by X-ray diffraction. Structural analysis of microenvironments of zeolitic framework was made by high-resolution solid-state MASNMR. The amount of solid acid of zeolite surface was determined by micro-calorimetry of NH3 adsorption at 473 K.
As the concen tration of hydrochloric acid is increased, the Si/Al atomic ratio of zeolites increased. The reaction rates on dehydration of 2-propanol over HFZ was proportional to the acid amount. On the skeletal isomerization reaction of cyclohexene into methylcyclopentenes over HFZ, as the concentration of hydrochloric acid increased, the yields of methylcyclopentane and aromatic hydrocarbons increased, while the yield of methylcyclopentenes decreased. The reaction over HZSM 5 gave only aromatic hydrocarbons.