Clay for cleaner production of solvent

Dutch researcher Ferry Winter has developed a heterogeneous catalyst for the production of the industrially important solvent methyl isobutyl ketone. With the new catalyst the production process is more environmentally-friendly. The catalyst consists of hydrotalcite, a naturally-occurring clay.

The catalyst developed by Ferry Winter belongs to a new category of catalysts termed ’activated hydrotalcites’. Hydrotalcite is a clay comprised of a mixture of magnesium and aluminium hydroxide and forms a layered compound. After activation the clay can be used as a solid-base catalyst. Winter’s catalyst is made up of very small hydrotalcite platelets deposited on carbon nanofibres. This structure gives rise to a highly active catalyst, which in terms of catalyst particle size and mechanical strength is ideally suited for industrial applications.

Homogenous or heterogeneous?

The annual global production of methyl isobutyl ketone is about 250,000 tonnes. The catalysts currently used for the production of methyl isobutyl ketone from acetone and hydrogen are used in the liquid phase. These are so-called homogeneous catalysts. A major disadvantage of this type of catalyst is the enormous waste streams generated. All of the spent catalyst remains in the reaction mixture and must once again be removed via special steps.

Heterogeneous catalysts are a better solution. These are inorganic materials which are attached to a so-called support. They do not dissolve in the solvent, but are in a solid phase. Once the catalyst is spent, it can easily be removed by means of filtration. This considerably reduces the waste streams, which is an extremely important aspect from an environmental and economic perspective.

Winter’s catalyst can also be used in other applications, such as in catalysing other organic reactions. The materials developed may also be used for the purification of waste water or for the capture of carbon dioxide.

Ferry Winter’s research was funded by NWO.