June 1, 2005

Bubbling technology advances

Keshav Ruthiya has made considerable improvements to a slurry bubble column, which the chemical industry uses for reactions between gases and liquids-organic wastewater purification or the synthesis of hydrocarbons.

Dutch researcher Ruthiya investigated how catalyst particles adhere to gas bubbles in a slurry bubble column. In a slurry bubble column, the gases pump down and into the bottom of a column with a liquid suspension of particles (slurry) and then bubble upwards. These reactors are cheap and easy to construct and therefore very popular.

The researcher made a model that described the influence of the catalyst particles and other substances present on the mass transfer, the hydrodynamics, and the reaction rate in the column. The new insights obtained have led to improved designs and therefore cost savings for this type of reactor. This will improve the competitiveness of the chemical industry. Companies involved in the project such as Shell, Akzo Nobel, Engelhard, and DSM Research are very interested in the results of the research.

Experimenting, the researcher discovered how to increase the reaction rate in the column. It turned out catalyst particles adhered better to gas bubbles if the surface characteristics of the particles were improved. With these modifications, the catalyst contacts a higher concentration of gas and therefore the reaction rate increases. This results in an increased efficiency of the catalyst, thereby reducing the amount of the expensive catalyst needed.

Sometimes the reaction in question proceeds less well if the catalyst contacts large concentrations of gas. In such a case, the catalysts used must adhere as little as possible to the gas bubbles, said Ruthiya.