Influence of CaCe ratio on the hydrogen production from ammonia over CaO-CeO2 supported Co catalysts

Abstract

Hydrogen (H2) fuel has the potential to replace fossil fuel for generating electricity, clean energy and generating power. Ammonia (NH3) has the potential to overcome the challenges associated with storage, transportation, and use of hydrogen fuel. The catalytic decomposition of ammonia into hydrogen is studied over cobalt catalysts supported on CaO-CeO2 mixed oxide. The influence of the Ca/Ce ratio in the support composition on catalytic activity was investigated. The CaO-CeO2 mixed oxide support materials prepared with different Ca/Ce ratios (1:1, 2:1 and 3:1). The overall basicity of catalyst varied with the increase of Ca to CaO-CeO2 mixed oxide and showed maximum at Ca/Ce = 2. The cobalt catalysts are prepared with a nominal 5 wt% Co over CaO-CeO2 mixed oxide support with various Ca/Ce ratios. Among all prepared catalysts 5CoCaCe-21 (5 wt%Co on CaO-CeO2 mixed oxide with Ca/Ce = 2) showed highest activity. Surface area, X-ray diffraction (XRD), Temperature Program Reduction (TPR), Scanning Electron Microscopy (SEM), and CO2 Temperature Program Desorption (TPD) methods were used to characterize the synthesized materials. The high performance of 5CoCaCe-21 catalyst is due to high basicity, suitable metal support interactions, high surface area and easy reducibility of Co species resulting from its support favorable properties. The effect of cobalt loadings also studied on CaCe-21 support. The 10 wt%Co on CaCe-21 (10CoCaCe-21) showed highest activity among all other cobalt loadings. The 10CoCaCe-21 catalyst showed excellent stability for H2 production from NH3 during 70 h of time on study with different GHSVs.