Bubbling under

Slurry bubble columns are extremely common in many processes, in sectors as diverse as hydrocarbon synthesis and water treatment. Cheap and easy to build, the reactors are filled with a suspension of solids, often including catalyst particles.

The process stream, in a vapour phase, is bubbled up through the slurry. Keshav Ruthiya, a doctoral student at Eindhoven University of Technology, has investigated the fluid and reaction mechanics of these columns, and has devised a way to boost reaction rates.

Ruthiya’s work involved developing a model to describe how the catalyst particles and other suspended solids affect mass transfer, hydrodynamics and reaction rate in the column.

He found that if the surface area of the catalyst particles is increased, the particles stick to the gas bubbles for longer. This exposes the catalyst to higher concentrations of gas, which for some reactions boosts the reaction rate, and for others decreases it.

Studying the mechanism of particular reactions will tell engineers whether to increase or reduce the surface area to achieve the best rates, Ruthiya says. Improving catalyst efficiency will allow operators to reduce the amount of catalyst they need, improving the cost-effectiveness of their processes.

Companies including Shell, Akzo Nobel, Engelhard and DSM Research have already shown interest in Ruthiya’s results.