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Biphasic water-based solvent systems offer the opportunity of efficient recycling of homogeneous catalysts. Water separates well from most organic solvents; therefore, water-soluble catalysts can be immobilized in this phase. Furthermore, water can substitute hazardous and environmentally unfriendly organic solvents in these systems. Within industry only the Ruhrchemie/Rhône-Poulenc process uses plain water to immobilize the homogeneous catalyst for the hydroformylation of propene. Yet for more hydrophobic substrates, no water-based system has been commercialized. This review will summarize recent developments in the field of water-based recycling strategies. Topics in this field are the intensification of the mixing process, the use of thermomorphic solvent systems, and the employment of several additives, like alcohols and surfactants. Continuously operated processes for these recycling strategies will be presented and discussed.

Upgradation of olefin-enriched Fischer–Tropsch cuts by the synthesis of alcohols leads to drop-in-capable biosynthetic fuels with low carbon emissions. As an alternative to the conventional two-step production of long-chain alcohols, tandem catalytic systems improve the energy and resource efficiency. Herein, we present an auto-tandem catalytic system for the production of alcohols from olefin–paraffin mixtures. By utilization of a tertiary alkanolamine as the ligand as well as the switchable component in the solvent system, a lean reaction system capable of catalyst recycling was developed. The system was characterized with regard to the switchable solvent separation approach and reaction parameters, resulting in alcohol yields of up to 99.5% and turnover frequencies of up to 764 h –1 . By recycling the catalyst in 10 consecutive reactions, a total turnover number of 2810 was achieved.

The production of alcohols from olefin-enriched Fischer-Tropsch cuts represents a promising route to CO2-neutral bio-synthetic fuels. Tandem-catalytic systems as alternative for the conventional two-step production of long-chain alcohols are attractive...