The controllable preparation of nano-gold catalyst maintains a challenge. Except the parameters have been revealed before, here we’d like to show that controllable preparation of active nano-gold catalyst can be achieved using chlorine as an indicator. By tracing the chlorine concentration in the washing step, a series of Au/Fe₂O₃ catalysts were prepared with co-precipitation method. The applying of these catalysts in CO oxidation and reductive nitrobenzene N-alkylation suggested the active catalysts were prepared from solutions containing ～2 ppm chlorine. The catalytic activity dropped dramatically if the chlorine concentration is >4–6 or <<1 ppm. Extensive characterizations revealed that the active catalyst was composed by nano-gold on the edge of Fe₂O₃ particle with 8.92 Au-Au coordination numbers. Although the real role of chlorine in the variation of catalyst structure and activity was still ambiguous, the current results should promote the controllable preparation of active nano-Au catalyst.

★★☆☆☆ Zhang CM,Liu LQ,Cui XJ,et al. Chlorine As An Indicator In The Controllable Preparation Of Active Nano-gold Catalyst[J]. Scientific Reports,2013,3:1503(1-7).