Cross Canada Tour Lecture
Sponsored by the Canadian Catalysis Foundation
We have been fascinated by phenomena occurring at the boundaries which has grown over the years with confluence of chemical and biological sciences and engineering, the formation of nanoparticles, pores and the interfaces residing within them. On one hand, network models and percolation processes in reservoir rocks, enhanced oil recovery and coal gasification, hydrogen generation to the finer aspects of multiphase reaction engineering and Green Chemistry. There is a very interesting thread among this areas which can be broadly viewed as Science & Engineering of Pores, Particles and Interfaces to develop clean and green processes, whether physical, chemical or biological or otherwise.
In recent years, my group has been working in three different areas of Green Chemistry using heterogeneous chemical catalysis, biocatalysis and phase transfer catalysis. New opportunities for the conversion of glycerol into value-added chemicals have emerged in recent years as a result of glycerol’s unique structure, properties, bioavailability, and renewability. Different reaction pathways for selective catalytic conversion of bioglycerol into commodity chemicals include oxidation, hydrogenation (commonly called hydrogenolysis), dehydration, pyrolysis and gasification, steam reforming, thermal reduction into syngas, transesterification, etherification, oligomerization, polymerization, acetalization and carbonylation. The development of novel solid acids, bases, hydrogenation and oxidation catalysts for glycerol conversion will be discussed with examples. A recent area of great interest includes synthesis of enantiopure drugs, separation of racemic mixture and biocatalytic synthesis of fine chemicals. Our work encompasses different approaches to synthesize important pharmaceutical intermediates to overcome the limitations of conventional organic synthesis methods. Immobilized lipases were employed to study some pharmaceutically important reactions, under enzyme catalysis and microwave irradiation including development of kinetic models.
The liquid-liquid phase transfer catalyzed reaction can be intensified by converting it into three-liquid phases. An attractive process for the production of mandelic acid is through reaction between benzaldehyde, sodium hydroxide and chloroform in the presence of polyethylene glycol 4000 as a phase transfer catalyst. We address the modeling of a well-stirred reactor for the foregoing process in which organic droplets surrounded by a thin film of catalyst-rich phase are suspended in the aqueous phase. A population balance model is formulated L-L-L PTC reaction and solved by Monte Carlo simulation using interval of quiescence technique. Transport processes and intrinsic reaction kinetics are extracted from the experiments. This population balance model serves to assess and interpret the relative roles of various processes in L-L-L PTC reaction, such as diffusive transport, reaction and interaction between dispersed phase droplets. The model is expected to be an effective tool for reactor design and scale up.
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