A nanoparticle is generally defined as a particle which has at least one of its dimensions in the range of 1 to 100 nm. They have exhibits different properties as compared to their bulk metals which are due to degenerated density of energy states and a large surface to volume ratio. These impart remarkable chemical activity and specificity of interaction to nanoparticles and so, it is not surprising that the interest in nanoparticles has experienced a staggering exponential increase. Their successful utilization in broad research area such as electronics, biochemical sensors, catalysis and energy. The amplitude of research efforts is likely to increase as beneficial applications at the nano-level become increasingly apparent. They (NPs) have extended the limitation of technology in ways that the researcher had never dreamed a century ago [1-2].
In the last several years, nanoparticles have appeared as sustainable alternatives for conventional catalysts. The catalytic activity of nanoparticles represents a rich resource for chemical processes, employed both in industry as well as in academia. Nanoform enhances the exposed surface area of the catalyst, thereby enhancing the contact between reactants molecules and catalyst dramatically and thus mimicking homogeneous catalysts. However, isolation and recovery of these tiny nanocatalysts from the reaction mixture is very difficult. In addition, nanoparticles are very small and in a thermodynamically unstable state. To overcome these problems, the use of supported metal nanoparticles has emerged as a viable solution as their insoluble nature enables easy and efficient separation like heterogeneous catalysts from the liquid or gas phase reaction medium. It should be emphasized that the nanocatalysts are bridging the gap between the homogeneous catalysis and heterogeneous catalysis. Moreover, the activity as well as the selectivity of nanocatalyst can be further manipulated by tailoring the chemical and physical properties such as particle size, shape, composition and morphology [3-4].
Supported Metal Nanocatalyst (Heterogeneous Catalyst)
Supported catalysts are broadly used in industrial-scale oxidation and hydrogenation reactions and have been shown to display good catalytic performance coupled with easy separation and recyclability. Best example is that of palladium supported on charcoal. There are several aspects that stimulus the catalytic performance of supported catalysts, including the particle size, composition, surface morphology and structure of the active phase, the nature of the support, as well as interaction between the active phase and the support . Supported nanocatalysts are sustainable alternatives to conventional homogeneous catalysts as they combine the easiness of separation from the liquid reaction mixture and shows excellent catalytic activity and reusability. It is most challenging to achieve homogenous distribution of metal nanoparticles with approximately uniform size on different kind of supports materials. A lot of research is being done to find new supports which can fulfil all the prospects of a good catalyst .
Type of Supports Material
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