Hydrogen in methanol catalysts by neutron imaging

Area of Science:

• Catalysis
• Materials Science
• Chemical Engineering

Background:

• The amount of hydrogen on catalysts during heterogeneous hydrogenation reactions is critical but rarely quantified.
• Understanding hydrogen dynamics is key to optimizing catalytic processes like methanol synthesis.

Purpose of the Study:

• To utilize neutron imaging for in-situ quantification of hydrogen-containing species in Cu/ZnO catalysts during methanol synthesis.
• To correlate hydrogen intermediate concentrations with reaction yields and kinetics.

Main Methods:

• Operando neutron imaging to visualize and quantify hydrogen species.
• Steady-state and time-resolved measurements.
• Hydrogen-deuterium exchange experiments.

Main Results:

• Steady-state hydrogen intermediate amounts correlate with CO and methanol yields.
• Time-resolved data show that essential hydrogen intermediates can decelerate reaction steps.
• Hydrogen-deuterium exchange reveals dynamic hydrogen absorption in ZnO nanoparticles at operating temperatures.

Conclusions:

• Neutron imaging provides unprecedented insight into operando hydrogen dynamics in Cu/ZnO catalysts.
• ZnO nanoparticles function as a hydrogen reservoir, enhancing copper catalysis by supplying hydrogen to the surface.
• The findings elucidate the mechanism behind the superior catalytic performance of copper supported on ZnO.