Synthetic fuels: Catalyst for Low-emission Use

KIT researchers are improving catalysts to reduce the formation of toxic by-products when using synthetic fuels
Molecular structure with atoms represented as colorful spheres against a dark background. ITCP, KIT
Active sites identified by in situ/operando characterization enable the minimization of secondary emissions such as hydrogen cyanide and formaldehyde.

Synthetic fuels are considered climate-friendly when they are produced using biogenic or atmospheric CO₂. However, their combustion also generates pollutants such as formaldehyde. Despite low concentrations, these compounds are not only harmful to health, they also impair the effectiveness of traditional emission control systems. In addition, formaldehyde promotes the formation of secondary emissions such as highly toxic hydrogen cyanide. Together with partners, researchers at the Karlsruhe Institute of Technology (KIT) have optimized an established catalyst to reduce these harmful emissions. The team published the results in the journal Nature Catalysis.

Effective against formaldehyde and hydrogen cyanide

“One of the factors responsible for hydrogen cyanide emissions is an undesirable reaction between formaldehyde and ammonia, which is conventionally used in exhaust gas treatment,” explains Dr. Maria Casapu from the KIT Institute for Chemical Technology and Polymer Chemistry (ITCP), whose interdisciplinary research team conducted the investigations on the Cu-SSZ-13 catalyst. It combined modern characterization methods at different synchrotron radiation facilities with quantum chemical calculations.

Using highly brilliant X-rays, the scientists were able to observe the catalyst under real reaction conditions (in situ/operando) and show that certain copper species in Cu-SSZ-13 promote the conversion of both formaldehyde and hydrogen cyanide without promoting the formation of hydrogen cyanide. “So-called ZCuOH sites proved to be particularly effective, leading to significantly lower  hydrogen cyanide emissions at temperatures above 350 degrees Celsius,” said Dr. Simon Barth from the Institute for Catalysis Research and Technology at KIT,  who was significantly involved in the study.  The results will help to further develop emission control systems and, at the same time, demonstrate the enormous potential of modern in situ/operando characterization methods.

mhe, August 28, 2025