Synthesizing of magnesium and nickel nanoparticles from spent methane dry reforming catalyst using sol–gel method: process flow diagram development

This study aims to recover Ni and Mg from spent catalysts of dry methane reforming. Huge amounts of spent catalyst are produced every year. Recycling of this industrial waste is important not only to save the environment but also to recover the valuable metals. Sulfuric acid leaching was employed to extract Mg and Ni from catalyst texture. The effects of solid content, acid concentration and agitation rate on the metals’ recoveries were investigated, using response surface methodology (RSM). Kinetic studies revealed that leaching mechanisms of both metals follow mix control model and the activation energy for Mg and Ni leaching were 48.98 kJ/mol and 55.12 kJ/mol, respectively. Ni and Mg then were recovered from leaching solution by increasing the pH to 9 and 12.5, respectively. Metals were precipitated in their hydroxide forms. Ni(OH)₂ and Mg(OH)₂ then were calcined to produce NiO and MgO particles in 350 °C and 400 °C, respectively. The results showed that NiO and MgO particles are in size range of 50–150 nm. A full process flow diagram was developed in this research for recovering Mg and Ni from spent dry reforming catalysts, in form of oxide nanoparticles.