Many chemical reactions take place in the presence of a solid catalyst. Powdery catalysts based on noble metals (e.g. platinum) or zinc complexes are frequently used. These catalysts are often highly specialized and therefore very expensive. Cross-flow filtration allows for continuous catalyst recovery from reaction mixtures and subsequent return into the process. This means long-term cost savings. Again filter elements made form stainless steel or special alloys are best suited to the task due to their extensive chemical resistance. Typical examples of the application of our filters for catalyst recovery are the production of polyurethane via the intermediates toluene diamine (TDA) and toluene diisocyanate (TDI), or other olefin chemistry processes.