Ultrasound assisted dispersion of different amount of Ni over ZSM-5 used as nanostructured catalyst for hydrogen production via CO2 reforming of methane

Abstract

Carbon dioxide reforming of methane is an interesting route for synthesis gas production especially over nanostructured catalysts. The present research deals with nanocatalyst development by sonochemical method for dry reforming of methane with the aim of reaching the most efficient nanocatalyst. Effect of Ni metal content, one of the most significant variables, on the properties of the ZSM-5 supported nanocatalysts was taken into account. The Ni/ZSM-5 nanocatalysts were prepared via assisted traditional impregnation method via ultrasound irradiation and characterized with XRD, FESEM, TEM, BET and FTIR techniques. Comparison of XRD patterns implies that the peaks related to NiO become sharper by increasing metal content over the support. In the case of nanocatalysts with lower metal content (3% and 8%), the beneficial influence of ultrasound assisted procedure become more pronounced and the observed reduction in particle size and enhancement in particle size distribution for corresponding samples can be assigned to the use of ultrasound energy during the synthesis. Average metal particle size of the nanocatalyst is about 43nm evidenced by TEM analysis. Furthermore, about more than 99% of Ni metal particles size is less than 100nm which is essential to the relative suppression of carbon formation reactions on nanocatalysts. The reforming reactions were carried out using different feed ratios, gas hourly space velocities and reaction temperatures to identify the influence of operational variables. The nanocatalyst synthesized with 8wt.% Ni represents the outstanding sample among other nanocatalysts. During the 24h stability test, products yields remained at constant values for the nanocatalyst prepared with 8% Ni loading.