Currently, most produced water is disposed of by downhole injection, however, there is limited availability of disposal wells and growing concern over potential environmental contamination from produced water to groundwater wells. In this work, we explore the on-site application of supported precious metal catalysts for organic compound degradation using simple organic acids typically present in produced water. We find that Pd/Al2O3 is catalytically active for phenol degradation in simulated produced water at room temperature, atmospheric pressure in the presence of formic acid and oxygen. Au/Al2O3 is also catalytically active, but less active than Pd/Al2O3 under the same reaction conditions. To understand this result, we carried out control experiments using formic acid, O2, and catalyst in DI water without the addition of phenol. We detected hydrogen peroxide (H2O2) generation rates of ~200 and ~15 mmol-H2O2/g-mteal/hour over Pd/Al2O3 and Au/Al2O3 respectively. By monitoring the disappearance of formic acid, we determined this corresponded to initial selectivities of ~10% and ~80% for Pd/Al2O3 and Au/Al2O3 respectively. We hypothesize radicals generated from H2O2 in the simulated produced water were key to phenol degradation. These results show potential for the use of heterogeneous catalysts to remove organic compounds from produced water.

Primary Author/Conference Presenter:
Yiyuan “Ben” Yin
Rice University
Houston, Texas

Yiyuan Yin (ab), Kimberly N. Heck (ab), Camilah Powell (ab), Christian L. Coonrod (ab), Sujin Guo (ab) and Michael S. Wong (*abcde) (a) Department of Chemical and Biomolecular Engineering, Rice University, Houston, TX 77005, United States (b) Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment, Rice University, Houston, TX,77005, United States (c) Department of Civil and Environmental Engineering, Rice University, Houston, TX 77005, United States (d) Department of Chemistry, Rice University, Houston, TX 77005, United States (e) Department of Materials Science & Nanoengineering, Rice University, Houston, TX 77005, United States