Surface capped silver nanoparticles over anatase titania: an efficient catalyst for aromatic nitration reactions

Efficient catalysts for the nitration of benzene are prepared by surface capping of Ag nanoparticles using glycerol and urea with their subsequent loading over anatase titania. Herein glucose was used as an environmentally benign reducing agent for the silver ions. The catalyst was characterized and its catalytic activity was evaluated in the low temperature preparation of nitrobenzene. Ag nanoparticle loading gives rise to improved performance when compared to bare anatase titania. The influence of stabilizers and the percentage metal loading of Ag on the catalytic activity was investigated. The increased reactivity of titania seen after Ag nanoparticle loading may be due to the presence of highly dispersed nano sized surface capped Ag. Among the two capping agents studied, glycerol provides maximum efficiency for a short reaction time. These new generation catalysts appear to be an efficient alternative for the conventional use of environmentally hazardous sulfuric acid catalyst. The side reactions are found to be minimal over the present catalytic systems which lead to excellent nitrobenzene selectivity.