Solvents have a large impact on process performance due to their influence on e.g., selectivity in absorption, equilibrium conversion in reactions or exergy demand in distillation. Optimization of process performance therefore needs to integrate solvents as degree of freedom. In this work, an integrated design approach is presented to select solvent molecules as part of flowsheet-wide process optimization. The design approach is based on COSMO-RS for the prediction of thermodynamic properties and uses advanced pinch-based process models for absorption and distillation. Pinch-based process models allow for rapid and accurate process optimization. Thus, a large design space of solvents can be evaluated efficiently. The design approach is demonstrated for a novel concept for integrated CO2 capture and utilization (ICCU) to carbon monoxide. The complete flowsheet containing absorption, multiphase reaction and distillation is optimized successfully for more than 4000 solvents to minimize the overall process exergy demand. The approach is shown to discover process inherent trade-offs in molecular properties of the solvents allowing for optimal solvent and process design.