21. Pd-MCM-41 and Ni–Boride–Silica Catalyst Synthesis, Characterization and Its Application for Reduction of Substituted Aromatics: An Environmentally Benevolent Approach

Microporous and mesoporous silica catalysts, MCM-41, derived from zeolite type catalysts, are easily synthesized in laboratory scale and commercially available SiO₂ have applications in reduction reactions. Nickel boride (Ni B) silica catalysts denoted as Cat A were characterized by XRD, IR, SEM, BET surface area and chemisorption studies. Nickel boride generated in situ on silica were found to be super active catalysts for reduction of nitro aromatics, aldehydes, ketones, alkenes, phenols and in reductive amination of aldehydes and ketones at low temperatures, whereas Pd(II)-MCM-41 denoted as Cat B exhibited catalytic activity for reduction of nitro aromatics, aldehydes, and hydrodehalogenation reactions. Efficient catalytic activity for reduction reactions was exhibited by the Ni and Pd catalysts which were found to be reusable, atom economy, reproducible and environmentally friendly. A comparative study of these catalysts is presented.