Podma Pollov Sarmah

Chemoselective reduction of a nitro group through transfer hydrogenation catalysed by Ru0-nanoparticles stabilized on modified Montmorillonite clay

Ru0-nanoparticles of approximately 5 nm size were generated by incipient impregnation of RuCl3 into the nanopores of the acid activated Montmorillonite clay followed by polyol reduction. Acid activation of the clay increases the surface area by generating nanopores (0–10 nm), which act as a host and stabilize nanoparticles in the pores. The generated Ru0-nanoparticles exhibit inter-planar lattice fringe spacing of 0.21 nm of the face centered cubic lattice of Ru0 crystals, and show efficient catalytic activity in the chemoselective transfer hydrogenation reduction of substituted nitrobenzenes to corresponding anilines with high yield of conversion (56–97%) and selectivity (91–100%) depending upon the nature of the substituents. The reactions were carried out in the presence of isopropanol, which served as the solvent as well as the reductant. The catalysts were found to be active for several catalytic runs.

Stabilized Fe3O4 magnetic nanoparticles into nanopores of modified montmorillonite clay: a highly efficient catalyst for the Baeyer–Villiger oxidation under solvent free conditions

In situ generation of Fe3O4 magnetic nanoparticles (Fe3O4@AT-mont.) into the nanopores of modified montmorillonite (AT-mont.) clay has been carried out. Modification of the montmorillonite was done by acid (4 M HCl) activation under controlled conditions for generating nanopores, which act as a “host” for the Fe3O4 nanoparticles. The synthesized Fe3O4@AT-mont. was characterized by PXRD, TEM, SEM-EDX, XPS, VSM and surface area analysis. The average particle size of Fe3O4 nanoparticles was found to be around 10 nm and exhibit a face centered cubic (fcc) lattice geometry. Fe3O4@AT-mont. showed efficient catalytic activity for the Baeyer–Villiger oxidation of various cyclic and aromatic ketones in the presence of hydrogen peroxide as an oxidant at room temperature under solvent free conditions and exhibited conversion of up to 98%. The catalyst was magnetically recovered and recycled up to the third run without any significant loss of efficiency.

Recent Advances in Metal Nanoparticles Stabilization into Nanopores of Montmorillonite and Their Catalytic Applications for Fine Chemicals Synthesis

Metal nanoparticles supported montmorillonite with innovative characteristics has led to a new generation of heterogeneous “nanocatalyst.” Such catalysts are superior to the conventional catalysts because of several factors like: higher surface area; higher activity; higher selectivity and longer life and thus, developing a newer type of sustainable environmentally friendly catalysts. Metal clay supported nanocatalysts may find a wide range of applications in the area of fine and bulk chemical industries, pharmaceuticals, fuel cell, petroleum refineries, environmental catalysis, and many other fields. This article summarizes the recent advances in the synthesis and characterization of metal nanoparticles supported on modified montmorillonite and their catalytic applications for fine chemicals synthesis.Metal nanoparticles supported montmorillonite with innovative characteristics has led to a new generation of heterogeneous “nanocatalyst.” Such catalysts are superior to the conventional catalysts because of several factors like: higher surface area; higher activity; higher selectivity and longer life and thus, developing a newer type of sustainable environmentally friendly catalysts. Metal clay supported nanocatalysts may find a wide range of applications in the area of fine and bulk chemical industries, pharmaceuticals, fuel cell, petroleum refineries, environmental catalysis, and many other fields. This article summarizes the recent advances in the synthesis and characterization of metal nanoparticles supported on modified montmorillonite and their catalytic applications for fine chemicals synthesis.

A green synthesis of Pd nanoparticles supported on modified montmorillonite using aqueous Ocimum sanctum leaf extract: a sustainable catalyst for hydrodechlorination of 4-chlorophenol

A green synthesis process in water has been developed with the aid of Ocimun sanctum (tulsi) leaf extract for the production of Pd nanoparticles (NPs) supported on modified montmorillonite. The leaf extract serves as a mild, natural and non-toxic reducing agent for converting the K2[PdCl4] to Pd NPs. The synthesized Pd NPs were characterized by using PXRD, SEM, TEM, EDX, XPS, H2-TPR and surface area analysis. TEM analysis reveals that particle sizes of the Pd NPs lie between a minimum of 10 nm and a maximum of 80 nm. The supported Pd NPs are used in the catalytic hydrodechlorination of toxic pollutant, 4-chlorophenol in water under base free conditions and showed conversion up to 98%. The catalyst is recoverable by filtration and could be recycled for several runs without any significant loss of catalytic efficiency.

Aromatic ring hydrogenation catalysed by nanoporous montmorillonite supported Ir(0)-nanoparticle composites under solvent free conditions

Ir(0)-nanoparticles (Ir-NPs) were synthesized into the nanopores of modified montmorillonite clay by incipient wetness impregnation of IrCl3 followed by reduction with ethylene glycol. The activation of the montmorillonite clay was carried out by treatment with HCl under controlled conditions to increase the surface area by generating nanopores which act as host for the metal nanoparticles. The synthesized Ir-NP–montmorillonite composites were characterized by N2-sorption, powder XRD, SEM, EDS, TEM, XPS, etc. The composites exhibit high surface area of 327 m2 g−1 and the Ir-NPs with size around 4 nm are uniformly distributed on the support. The Ir-NPs show efficient catalytic activity in aromatic ring hydrogenation under solvent free conditions with maximum conversion up to 100% and Turn Over Frequency (TOF) up to 79 h−1. The catalyst can be easily separated by simple filtration and remained active for several runs without significant loss of catalytic efficiency.