Boosting low-temperature water gas shift reaction over Au/TiO2 nanocatalyst activated by oxygen plasma

The efficient removal of carbon monoxide (CO) from H2-rich stream via the water gas shift (WGS) reaction requires the catalysts that possess high activity at low temperatures to avoid the thermodynamic equilibrium limitation. We report that oxygen (O2) plasma activation enables an Au/TiO2 nanocatalyst to achieve superior activity in the WGS reaction at low temperatures. At 120 degrees C, O2 plasma activated Au/TiO2 nanocatalyst exhibits CO reaction rate of 0.51 mmol center dot mgxfffd; 1 center dot h-1, which is 5 times higher than the conventional activated counterpart. CO conversion over O2 plasma activated Au/TiO2 nanocatalyst only slightly decreases from 73% to 68% during a 4.5 h continuous WGS reaction at 150 degrees C. The catalyst characterizations indicate that O2 plasma activation could control average size of Au nanoparticles below 3.5 nm, create plenty of coordinatively unsaturated sites (on Au nanoparticles) and sufficient Au delta+-O delta--Ti sites (at interfaces between Au and TiO2), and modulate the electronic structure of interfaces, which accelerates greatly the WGS reaction. Further, the enhancement mechanism of the WGS reaction over O2 plasma activated Au/TiO2 nanocatalyst was disclosed.

Automated summary

Oxygen (O2) plasma activated Au/TiO2 nanocatalyst exhibits superior activity in the water gas shift (WGS) reaction at low temperatures, efficiently removing carbon monoxide (CO). Control of Au nanoparticle size, creation of coordinatively unsaturated sites and Auδ+-Oδ-Ti sites, modulation of electronic structure, greatly accelerates the WGS reaction.