Cu nanoparticles confined within ZSM-5 derived mesoporous silica (MZ) with enhanced stability for catalytic hydrogenation of 4-nitrophenol and degradation of azo dye

Abstract

The development of cost effective and efficient non-noble metal catalysts is extremely desirable in recent years for reduction of toxic nitrobenzene and azo compounds. In this work, highly reactive Cu nanoparticles (NPs) were constructed in mesoporous silica (MZ) synthesized using ZSM-5 (Si/Al = 28) via hydrothermal crystallization strategy and then tested as catalyst in the catalytic hydrogenation of 4-nitrophenol (4-NP) and methylene blue (MB) degradation to reduce their hazardous effect on environment. In comparison with ZSM-5, MZ with hierarchical pore structure effectively controls the size and dispersion extent of Cu NPs when fabricated with 5-15 wt%Cu via IWI with ultrasonic aid. Cu10/MZ displayed complete reduction of 4-NP to 4-aminopheneol (4-AP) and MB dye to LMB in 10 min with K (rate constant) value of 0.298 min and 0.65 min−1, respectively. Both catalytic conversions follow pseudo-first order kinetics. The high catalytic activity is evidently related with highly dispersive smaller sized Cu NPs and excellent physiochemical characteristics of MZ as demonstrated by various characterization techniques. Besides, the Cu/MZ catalyst displayed excellent stability and can be applied for 5 consecutive reduction cycles without any minimal loss in catalytic capabilities.