The Modification, Characterization of H-Mordenite and Their Catalytic Activity in Isomerization of α-Pinene

Abstract The views on catalytic activity of zeolite in isomerization of α -pinene have not came to an agreement. Thus, the key active substance in zeolite was further studied through experiments. H-mordenite was treated in three ways: (i) calcination under nitrogen flows, (ii) calcination under oxygen flows, (iii) calcination under nitrogen flows after alkali treatment. The properties of modified zeolites were investigated by methods of SEM, EDS, XRD, nitrogen adsorption, NH 3 -TPD, Py-IR, and 29 Si and 27 Al MAS NMR. The results showed that the zeolites produced mesoporous after 0.4M NaOH solution soaking and calcinations above 500 °C, but it had a slight effect on the change of micropore volumes. Comparison of zeolite acid sites amount under different roasting temperature by NH 3 -TPD showed that the decrease of acid sites amount was mainly related to the roasting temperature. Py-IR and 27 Al MAS NMR experiment revealed that Lewis acid was produced by framework aluminum. Finally, Analysis on the influencing factors we studied of H-mordenite catalytic activity in this paper suggested that, in isomerization of α -pinene, the relative concentration of six-coordination aluminum in zeolite is the dominant factor of provided catalytic activity of H-mordenite. Graphical abstract