Recycling of Homogeneous Catalysts─Basic Principles, Industrial Practice, and Guidelines for Experiments and Evaluation

Homogeneous catalysts─organometallic complexes but also organocatalysts or nanoparticle catalysts─display attractive features that are of high academic and industrial interest. Various concepts have been established for their integrated recycling in the realization of industrial processes with metal complexes to achieve quasistationary operation. With the constant development of novel synthetic tools and improved catalyst structures, innovative methods for their effective recycling remain an important and thoroughly investigated research objective. However, recycling experiments of homogeneous catalysts on a laboratory scale need to be carried out using reliable and generalized methods to collect valuable data that allow for conclusive comparison of different approaches. In this Perspective, we first analyze and categorize the industrial applied techniques for recycling of organometallic catalysts and then present and evaluate performance indicators of recycling methods on the research stage. As a conclusion, a best practice for planning and conducting experimental studies is suggested to generate and present comparable results across different laboratories and disciplines.