Professor David W. Rooney

Research

'Clean' Engineering through design
It is well known that the next generation of chemical plant will be inherently safer, produce less waste and be more efficient. In order to achieve this it is important to understand the reactions which are occurring and to control them to give us the products we want. Novel solvent systems such as ionic liquids or catalytic reactor design can help to achieve this.

 

On-line measurement in high pressure rotating disc reactors
The rate of any three phase, solid, liquid, gas reaction is often limited by the transport of either the liquid or gaseous reagent to the active catalyst site. By comparing the results from thin film reactors such as the rotating disc reactor (Figure 1) in conjunction with results from standard stirred tank reactors it is possible to disentangle the mass transfer contributions within heterogeneously catalysed systems. This is particularly important when studying ionic liquids which tend to be more viscous than the currently used organic solvents. Also for ionic liquids, analysis can sometimes be problematic, in that their lack of volatility, which is often a desirable property, precludes them for being analysed by GC. Here we have demonstrated that it is possible to obtain quantitative concentration data using chemometrics techniques employing a PLS algorithm which are applied to spectroscopic (Raman) data within the reactor. For the oxidation of cinnamyl alcohol we have shown that mass transfer is beneficial in that it limits the supply of oxygen to the catalyst, preventing it from becoming over oxidised and hence effectively poisoned

 

In Figure 1, which shows results from the hydrogenation of Phenyl acetylene we can see that the relative concentrations in ionic liquid and toluene are very different from one another showing us that there are differences in the chemistry within both fluids. Such affects where not observed in standard reactors.

 

In addition to on-line analysis it is possible to use techniques such as calorimetry (i.e. heat measurement) during a reaction to gain insight into the mechanism of a chemical reaction. Figure 2 shows the data obtained from the hydrogenation of an alkene in a Hazard Evaluations Laboratory high pressure reactor.

 

 

In this reactor a cooling jacket tries to cool down the reactor, however a heating element tries to balance this. For the reaction shown this value is 9.6 W. In an exothermic reaction, heat is given out so that the required power is less. In the figure the heating power required to maintain an isothermal reaction is shown. By using this information we can further calculate the heat released at specific times which tells us about the reactions taking place.