Photocatalytic Conversion of CO2 - Containing Flue Gases to Commodity Chemical


Dr. Tracy Benson, Associate Professor, Dan F. Smith Department of Chemical Engineering


In this project, waste carbon dioxide from large point sources was converted to saleable medium chain alcohols using low-temperature, light activated catalyst powders. These powders were synthesized, characterized, and tested for their ability to convert CO2 and steam to synthesis gas (CO and H2), an intermediate used for Fischer – Tropsch Synthesis.


The conversion of waste carbon dioxide, namely from electric power generators and petroleum refineries, to saleable products was the focus of this study.  A photo-catalyst was formed from titanium and carbon nanotubes.  The conversion of CO2 to alcohols (namely C6 – C8) is a two-step process whereby the CO2 and steam are first converted to synthesis gas.  The synthesis gas is then transformed to commodity chemicals (i.e. diesel fuels and alcohols) using Fischer – Tropsch catalysts.

The catalyst materials exhibited a reduction in band gap energies, pointing towards a shift in light activation from ultra-violet to visible wavelengths.  Only 4 % of solar energy is in the ultraviolet regions, whereas, 54 % is in the visible spectrum.

photo reactor with online co2 monitoring
Photo-Reactor with CO2 Monitoring


This project was funded by Texas Air Research Center and the Center for Advances in Water & Air Quality


  • Zhang, Y., Cruz, J., Zhang, S., Lou, H., Benson, T.J. (2013) “Process Simulation and Optimization of Methanol Production Coupled to Tri-reforming Process,” International Journal of Hydrogen Energy, 38, 13617 – 13630.
  • Zhang, Y., Zhang, S., Benson, T.J. (2015) “A Conceptual Design by Integrating Dimethyl Ether (DME) Production with Tri-reforming Process for CO2 Emission Reduction,” Fuel Processing Technology, 131, 7 – 13.
sem micrograph of the tio2 surrounding the carbon nanotube bundles
SEM Micrograph of the TiO2 surrounding the carbon nanotube bundles