A review on solid base heterogeneous catalysts: preparation, characterization and applications

The development of suitable catalysts that have high activity, abundant efficiency, and easy recovery as well as lesser ecological contamination suitable for various industrial processes is the rising area concerning green chemical processes. In recent times, solid heterogeneous catalysts with several industrial applications have attracted widespread attention because of characteristics like simple synthesis processes, even pore size distribution, large specific surface area, and high alkalinity. Solid base catalysts include metal oxides, zeolites, supported alkali metal compounds, clay minerals, waste solid base catalysts, mesoporous solid base catalysts, etc. They can be synthesized by using precipitation, co-precipitation, sol-gel, hydrothermal, impregnation, vapor phase deposition, and sonochemical methods which are thoroughly discussed in this paper. There has been tremendous development in characterization techniques for the solid base catalysts such as Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, Energy dispersive spectroscopy, Brunauer-Emmett-Teller technique, Barrett-Joyner-Halenda method, etc. which are briefly explored. Various industrial processes catalyzed by solid base catalysts dehydration, condensation, isomerization, alkylation, polymerization, hydrogenation, esterification, and amination are also discussed in this paper.