Polymer Anchored Cu(II) and Mn(II) Complex Catalysts for the Oxidation of Styrene

 Polymer Anchored Cu(II) and Mn(II) Complex Catalysts for the Oxidation of Styrene

Sweta, Shishir Sinha, Prakash Biswas, Shri Chand^*

            Department of Chemical Engineering, Indian Institute of Technology Roorkee, India

Styrene oxidation is of interest from both academic and commercial point of view for the synthesis of two important products, styrene oxide and benzaldehyde. Traditionally oxidation of styrene is carried out by using stoichiometric amounts of organic peracids such as peracetic acid and m-chlorobenzoic acid with permanganate as the oxidizing agent. However, peracids are very expensive, hazardous and also propagate the formation of undesirable side products which create environmental pollution. Therefore much attention has been paid for the development of new epoxidation methods which employ safer oxidants and produce little waste. The employment of hydrogen peroxide, tert-butyl hydroperoxide (TBHP) and oxygen are attractive options both on environmental and economic grounds.

Immobilisation of active homogeneous catalysts on solid supports has attracted a lot of interest as heterogeneous catalysts are inert, easily separated from the product mixture and can be recycled.Polymer anchored metal complexes are gaining importance as efficient heterogeneous catalysts in a variety of organic transformations including oxidation and hydrogenation reactions.

In the present work, polymer anchored Cu(II) and Mn(II) complex catalysts for the oxidation of styrene using 30% H₂O₂ as oxidant has been investigated. The effect of various reaction parameters such as temperature, styrene to H₂O₂ mole ratio and amount of catalyst on the activity and selectivity of catalysts is studied. The reaction is also carried in batch reactor (Parr reactor, 4843 series) under pressurized conditions. The kinetic parameters have been evaluated to understand the reaction mechanism. The Cu(II) based catalysts showed better catalytic activity than Mn(II) based catalysts. The catalyst recyclability was studied at optimum reaction conditions. It has been observed that the catalysts can be reused three times without any loss of conversion and selectivity to the products.

Keywords: Batch reactor, Oxidation, Polymer anchored complexes, Styrene

 

 

 

 

 

* Corresponding author. Email: schanfch@iitr.ernet.in; Telephone: +91-1332-285383