Even in small amounts, catalysts have a powerful effect: 80 percent of all chemical reactions are accelerated with at least one catalyst or are dependent on catalysts to take place at all. Also, catalysts enable huge savings of energy that would otherwise be required to achieve the same result. For this reason, they are critical for efficient and resource-friendly production of chemical products.
One example is Evonik’s HPPO process. Here, hydrogen peroxide and propene are reacted to produce propylene oxide. These two starting materials would not react in the desired way without high energy expenditure. They must first be activated. This is done by a special catalyst which is produced by the Catalysts Business Line. Through a multi-step process, an inorganic mixed oxide is produced in the form of a powder and then formed into white rods just three millimeters thick. These ensure that the hydrogen peroxide oxidizes the propene, with water as the sole by-product. The main product is propylene oxide, which Evonik’s customers use to produce polyurethane foam. This foam is used to insulate refrigerators and houses, to make cars lighter and more economical, and to enhance the comfort of mattresses and upholstered furniture.
In this process, besides the high catalytic activity and selectivity, one property of the catalyst is particularly important: its tensile strength. Sufficient mechanical stability is the basic requirement for its use in reactors in the chemical industry. The catalyst must not be destroyed in the application – even if it is subjected to high pressure in the reactor. Several metric tons of catalyst are put into the reactor. The lower layers of catalyst must not disintegrate or be pulverized despite the extreme weight of the layers above them. Otherwise, the reactor would become blocked and the process would come to a stop.
To prevent this, a lot of effort is put into the forming of the catalyst. The forming process is complex – a bit like baking. A variety of ingredients must be mixed, kneaded and molded. Even a slight variation in the composition of the components would make a difference here. The moldings have the right tensile strength only if they are also dried and thermally treated under suitable conditions. Sometimes hundreds of samples must be produced before a formulation is suitable for transfer to production.
Evonik has been a market leader in catalysts for 75 years. The Catalysts Business Line operates a global production network with eight sites. These are the German sites in Hanau, Marl and Rheinfelden and the international sites in Dombivli in India, Calvert City in the USA, Americana in Brazil, Tsukuba in Japan, and Shanghai in China.