Novel rice husk ash - reduced graphene oxide nanocomposite catalysts for solvent free Biginelli reaction with a statistical approach for the optimization of reaction parameters

• Published in: Materials chemistry and physics 2019-01, Vol.222, p.63-74
• Main Authors: Narayanan, Divya P., Sankaran, Sugunan, Narayanan, Binitha N.
• Format: Article
• Language: English
• Subjects: Ashes; Biginelli reaction; Catalysis; Catalysts; Chemical reactions; Chemical synthesis; Graphene; Hydrothermal treatment; Nanocomposite; Nanocomposites; Optimization; Parameters; Reduction; Response surface methodology; Rice husk ash; Silicon dioxide; Solvents; Statistical models; Statistical optimization; Temperature effects; X ray photoelectron spectroscopy
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2018.09.078

Here we report the preparation of novel rice husk ash – reduced graphene oxide nanocomposites and their catalytic application in Biginelli reaction. Hydrothermal treatment is given to a mixture of rice husk ash and graphene oxide for the formation of a uniform composite. XRD and FTIR spectral analyses confirmed the partial reduction of graphene oxide in the nanocomposites during hydrothermal treatment. The binding between rice husk silica particles and graphene sheets through SiOC bonding is revealed from XPS analysis. Graphene is found to be less defective in nature in the composite as evident from the reduced ID/IG value in the Raman spectrum. SEM and TEM images showed the effective dispersion of rice husk SiO2 particles on the wrinkled graphene layers. Present study also exploited the use of a statistical model, response surface methodology, for the optimization of reaction parameters on the catalytic synthesis of dihydropyrimidinones via multicomponent solvent free Biginelli reaction. The cost effective highly efficient rice husk ash - reduced graphene oxide catalyst is found to be reusable till 7 repeated cycles with only about 4% reduction of its initial activity. A facile synthesis of novel rice husk ash – reduced graphene oxide nanocomposite is achieved and its catalytic activity is evaluated in the multicomponent Biginelli reaction with statistical optimization for the optimization of reaction parameters. [Display omitted] •A highly efficient novel heterogeneous catalyst for the multicomponent Biginelli reaction is prepared from rice husk ash and graphene oxide.•Present study exploited the use of experimental design, Box-Behnken to optimize the effect of reaction parameters with restricted number of experiments.•Novel catalyst prepared using 10 wt% GO sheets were found to be highly reusable while retaining the structure even after 7 repeated runs.