A water resistant solid superbase derived from calcium: Synthesis, characterization and catalytic performance

In comparison with the development of new materials with strong basicity, less attention is paid to the improvement of water resistance of solid bases. In the present study, Ca(NO₃)₂ and γ-Al₂O₃ was employed as base precursor and support, respectively, producing the materials denoted as CaNA. The results show that calcium ions can insert into the vacancies on the surface of γ-Al₂O₃, thus generating a strong guest-host interaction. The decomposition temperature of Ca(NO₃)₂ on γ-Al₂O₃ (e.g. 460 °C for 20CaNA) is therefore obviously lower than unsupported Ca(NO₃)₂ (600 °C). The materials after activation possess both superbasicity with high strength of 27.0 and excellent water resistance. This can be attributed to the strong guest-host interaction and low solubility of guest. Moreover, the CaNA materials are catalytically active in 2-propanol dehydrogenation as well as 1-hexene isomerization. On the basis of the present study, it is possible to fabricate a variety of water resistant functional materials by judicious choice of guest and host, which provides valuable candidates for catalysis and adsorption involving water.