Roshan Jeet Jee Jachuck

Process intensification: spinning disk reactor for styrene polymerisation

Abstract In this paper the performance of a thin film reactor using the spinning disc technology has been described. The objective of the study was to develop a compact reactor with good heat and mass transfer characteristics for continuous processing of free radical polymerisation. Solution polymerisation of styrene was therefore chosen as an example of free-radical polymerisation system and it may be concluded that a spinning disc reactor (SDR) can significantly enhance the reaction rates when the viscosity of the polymer mass is in excess of 3–4 N/m 2 s. It also improves the product quality by producing polystyrene with tight molecular weight distribution (MWD). The inherent safety of the process is also improved.

Process intensification: oxidation of benzyl alcohol using a continuous isothermal reactor under microwave irradiation

In the past two decades, several investigations have been carried out using microwave radiation for performing chemical transformations. These transformations have been largely performed in conventional batch reactors with limited mixing and heat transfer capabilities. The reactions were performed under adiabatic conditions where the enhancements in the reaction rate reported in these publications may be due to the rapid increase in the reaction temperature during the course of the reaction. The concept of process intensification has been used to develop a narrow channel reactor that is capable of carrying out reactions under isothermal conditions while being exposed to microwave irradiation. Oxidation of benzyl alcohol to benzaldehyde has been carried out using the above-mentioned isothermal micro reactor. Results and the findings of this investigation are discussed in this paper.

Comparative performance of ion exchange membranes for electrodialysis of nickel and cobalt

The extraction of nickel and cobalt from their sulfate solutions by electrodialysis in a modified three compartment cell is described. Two cation exchange membranes, the perfluorosulfonic Nafion® 117 and a new sulfonated PVDF membrane, are compared under similar operating conditions. The membranes are used as either flat structures or as corrugated structures. The effect of flow rate, current density, salt concentration and temperature on the performance of each membrane is described. The performance is characterised in terms of transport properties, current efficiencies and concentrations of metal ions transported through each membrane. The performance of the PVDF membrane was as good as; if not slightly better, than that of the commercial Nafion 117. A significant improvement with the use of corrugated membranes on the amounts of metal extracted is observed. The corrugated Nafion 117 membrane gave superior current efficiencies compared to the flat one with the same amount of charged passed. Separation of cobalt from nickel by electrodialysis in mixed solution has also been investigated.

Measurement of liquid film thickness and the determination of spin-up radius on a rotating disc using an electrical resistance technique

A method of rapid measurement of liquid film thickness on a spinning disc surface is presented. The concepts used are based on the analysis of the electrical resistance of the liquid film and its relationship to film thickness when high frequency voltages are applied. A comparison with the Nusselt model is made for a wide range of operating conditions. Experimental data are presented and calculations of mean radial flow velocity based on film thickness measurements are made and shown to compare well with a simplified two-dimensional model. An empirical model for the extent of the spin-up radius is developed to provide a guide to the zone at which the Nusselt model breaks down.

Process intensification: Spinning disc reactor for condensation polymerisation

This paper describes the performance of a thin film reactor in the form of a spinning disc reactor which may be used for continuous condensation polymerisation of esters. Test results suggest that it may be possible to significantly enhance the rate of polymerisation by addressing the mass transfer and mixing limitations thereby performing the reaction at its inherently faster kinetic speed. This technology may provide an opportunity for the intensification of condensation polymerisation processes.

Condensation studies using cross-corrugated polymer film compact heat exchanger

Abstract Heat transfer has been examined in a polymer film compact heat exchanger between cross flowing liquid and gas. Condensation of water vapour through a non-condensable gas was used to supply heat through a corrugated poly-ether-ether-ketone (PEEK) film to a cooling liquid. Measurements of heat transfer rates in the system indicated overall heat transfer coefficients in the range of 50–300 W m −2 K −1 were achieved. Visual analysis and pressure drop measurements were used to provide insight into the fluid flow and the models used for heat transfer.

Determination of mass transfer coefficient of a cross-corrugated membrane reactor by the limiting-current technique

Abstract We report mass transfer coefficient correlations, at low Reynolds numbers for a novel cross-corrugated membrane reactor, which is being developed for a number of processes, most notably phase-transfer catalysed reactions. The presence of Tollmien–Schlichting (T–S) waves saw a noticeable enhancement in mass transfer, giving characteristics usually only found in turbulent flow. Correlations for the channel wall and the channel corrugations are given in terms of dimensionless Sherwood numbers: Sh CW =0.0209Re 0.7675 Sc 0.333 (200 Sh COR =0.2477Re 0.489 Sc 0.333 (200

Catalytic oxidation of alkyl aromatics using a novel silica supported Schiff base complex

A new heterogeneous catalyst based on a chemically modified mesoporous silica gel and possessing immobilised chromium ions has been prepared and successfully applied to the aerial oxidation of alkyl aromatics at atmospheric pressure and in the absence of solvent.

Continuous flow synthesis of small silver nanoparticles involving hydrogen as the reducing agent

Two narrow-channel reactor designs have been developed and used in conjunction with gas–liquid segmented flow in order to intensify reactions and to effect synthesis under continuous flow conditions, incorporating single pass and recirculating capability, under high pressure and temperature. Silver nanoparticles approximately 3–5 nm in diameter are accessible with the average size depending on the reaction temperature and polyphosphate concentration, with smaller and more monodisperse nanoparticles produced at low polyphosphate concentrations and low temperatures. The use of continuous flow conditions leads to the possibility of simple scale-up to commercial production.

Rearrangement of α-pinene oxide using a surface catalysed spinning disc reactor (SDR)

Isomerisation of α-pinene oxide to campholenic aldehyde was performed by immobilising zinc triflate based catalysts on the surface of a spinning disc reactor (SDR). Two types of catalyst have been studied and the influence of operating parameters such as rotational speed, feed flow rate and reaction temperature on conversion and selectivity towards campholenic aldehyde has been investigated in considerable detail. The findings of the study suggest that immobilising the catalyst on the reactor surface and performing the reaction in continuous mode has potential for achieving benefits of Green Chemical Technology (GCT).