A comparative study on the dispersion of CuO-ZnO-Al2O3 nanoparticles over HZSM-5 via batch co-precipitation, semibatch co- precipitation and combined co-precipitation-ultrasound methods

A series of CuO-ZnO-Al2O3 nanoparticles over HZSM-5 were successfully prepared using different methods of batch co-precipitation, semibatch co-precipitation and combined co-precipitation-ultrasound. Nitrates of copper, zinc and aluminum were used as precursors, while Na-ZSM-5 was employed as composite support and sodium carbonate was used as precipitant agent. The effects of preparation methods on physicochemical properties of synthesized nanoparticles were studied using XRD, BET, FESEM, FTIR and TGA-DTG techniques. Furthermore, the formation mechanism of nanosized CuO-ZnO-Al2O3 over HZSM-5 was proposed. The formation of nanosized CuO-ZnO-Al2O3 over HZSM-5 with homogeneous grain size was addressed after calcination at 350°C for 5 hr. The results indicated that the crystalline structure, thermal gravimetric behavior and surface morphology of the nanocomposite were strongly dependent on preparation methods. The combined co-precipitation-ultrasound method had superior control in crystallite size and CuO-ZnO-Al2O3 dispersion. This method resulted in many small grains with almost spherical shapes and narrow particle size distribution.