Promising zirconia-mixed Al-based nitrogen carriers for chemical looping of NH3: Reduced NH3 decomposition and improved NH3 yield

Abstract

The chemical looping ammonia generation (CLAG) of N-sorption/desorption reactions via Al-based N-carriers for producing ammonia (NH3) (a non-carbon fuel) is thought to be an important alternative to the conventional Haber–Bosh NH3 synthesis technology. However, the low yield of NH3, because of significant NH3 decomposition at the required N-desorption temperature, inhibits the development of CLAG. Accordingly, ZrO2 mixed AlN was designed in this study to investigate the NH3 generation characteristics of AlN during the N-desorption process in a stationary bed reactor. The results showed that ZrO2 can improve the formation of NH3 because the molecular adsorption of NH3 occurred on the ZrO2 surface, thus preventing NH3 from decomposing. The ZrO2 loadings and steam concentrations in the atmosphere positively affect the yield and generation efficiency of NH3, while increasing the reaction temperature increased the NH3 yield from 1.2 to 3.3 mmol, but reduced the NH3 generation efficiency from 91.7% to 60.3%.