The size, shape, and dispersion of active sites on AC-supported copper nanocatalysts with polyol process: The effect of precursors

The polyol process is simple to conduct and can enhance the diffusion of active sites and control the shape of the active phase during catalyst preparation. Activated carbon (AC) was chosen as the support, and copper nitrate, copper acetate, and copper sulfate were used as precursors to prepare the AC-supported copper catalysts. Toluene was chosen as the pollutant for the activity test. The experimental results showed that the copper particles were nanosized and were highly dispersed on the AC; such dispersion improved the thermal stabilization of the AC-supported catalyst. The copper content observed in an inductively coupled plasma-mass spectrometer was the same even for increased amounts of copper sulfate; however, for the other two precursors, the copper content increased with the amount of precursor. Different precursors gave rise to different types of active phases. For example, when copper acetate was used as the precursor, the catalyst had pellet (50-70 nm)- and cubic (>1 mu m)-shaped active phases. The activities of the copper catalysts were in the order copper nitrate > copper acetate > copper sulfate. Among the catalysts tested, Cu-N/Al2O3 with 5 wt.% Cu loading exhibited the highest activity at 158,720 h(-1). For Al2O3-supported catalysts prepared by the polyol process, the Cu-A/Al2O3 catalyst exhibited the highest activity. Thus, the polyol process has the potential to be used in catalyst preparation along with various different precursors to control gaseous pollutants. (C) 2008 Elsevier B.V. All rights reserved.