In Situ X-ray Absorption Spectroscopy Cells for High Pressure Homogeneous Catalysis

Abstract

We have designed, built, and tested two cells for in situ and, potentially, operando X-ray absorption spectroscopy experiments in transmission and fluorescence modes. The cells were developed for high-pressure and high-temperature conditions to study the catalytic processes under relevant industrial conditions. Operation of the cells was tested for Ru and Rh-based homogeneous and heterogeneous catalytic systems. Using synchrotron-based in situ X-ray absorption spectroscopy we tracked the evolution of active metal species during catalytic reactions. Our setup proved that it was capable to investigate liquid-state homogeneous and heterogenous systems under elevated temperatures, high pressures of reactive gasses, and in the presence of corrosive reagents.

In Situ XAS Diagnostics of Reductive Hydroformylation Reaction in Segmented Flow Under Elevated Pressure and Temperature

“…32 Recently, we used a 20 mm stainless steel cylindrical autoclave with coaxial holes for in situ XAS characterization of hydroformylation reaction. 33 The round holes in the body of the autoclave were 3 mm in diameter, and the Teflon liner with 2 mm thick walls was able to sustain 6.0 MPa pressure at 90 °C without additional mechanical support. Inside microfluidic chips, such a long path can be implemented by measuring along the channel that was demonstrated for Pd reduction in the liquid phase under ambient conditions.…”

“…Catalytically relevant concentrations of 4d metals in organic solvents often require traveling distances of several centimeters to achieve a good absorption step . Recently, we used a 20 mm stainless steel cylindrical autoclave with coaxial holes for in situ XAS characterization of hydroformylation reaction . The round holes in the body of the autoclave were 3 mm in diameter, and the Teflon liner with 2 mm thick walls was able to sustain 6.0 MPa pressure at 90 °C without additional mechanical support.…”

High-Quality In Situ X-ray Absorption Spectroscopy Monitoring of the Palladium Nucleation inside the 3D Printed Microfluidic Chip

“…The advantage of high X-ray energies, such as for Pd K -edge, is the higher flexibility in designing the cells and sample environment for in situ measurements due to high penetration depths of X-ray photons. In particular, the cells for high pressures and temperatures were suggested. − …”