Innovations in catalysis as a tool for greener chemical products

Prof. G D Yadav

Heterogeneous catalysis, solventless synthesis, use of microwaves, ultrasound, etc. have  been attempted by many researchers all over the world to suggest how atom economical processes are also the most cost effective. Green Chemistry is typically illustrated with the dozen principles. However, there are certain  other approaches in this area which will be equally important  to make the chemical industry clean and green. From the process economics and environmental view points, the intensification of reaction rates and enhancement of selectivities can be achieved through selectivity engineering principle which adopts the following strategies. 

a) in a biphasic reaction, addition of a third solid phase (porous or non-porous and/or catalytic or non-catalytic), with particle size smaller than diffusion film thickness. The triphasic system can lead to an enhancement in rates by orders of magnitude with reference to the original gas-liquid, and liquid-liquid systems (micro-phase catalysis);
b) converting a liquid-liquid reaction into liquid-liquid-liquid or liquid-liquid-solid phase transfer catalysis;c)  cascade engineering or single pot synthesis combining many steps including same catalyst (homogeneous or heterogeneous);d) deliberate incorporation of mass transfer and/heat transfer resistance; f) on a larger scale, integration of different plants on the same site to achieve environmental goals.

The use of solid acids and bases has been studied with several new applications with novel UDCaT series of catalysts developed in our laboratory. These catalysts have been used for  important reactions in pharmaceutical and fine chemical industries.  Several challenges are posed by oxidation reactions since reproducibility of oxidation catalyst preparation, development of redox catalysts with acid and basic properties, i.e., oxidation reactions in the presence of materials with acid or basic or acid/base sites, activation of oxygen by hydrogen, etc. are formidable tasks.  We developed a novel material UDCaT-3 which has been found to be very effective for oxidations, reductions and hydroxylations.  This lecture is focus on novelites associated with cascade engineered acid, base and PTC reactions as well as oxidations.