High-Efficient hydrogenation reduction of Nitrate to Ammonia and Nitrogen via Ni-MOF-74 Reduced-Derived Ni-Based Catalyst

Abstract

The design of highly efficient catalysts is important in developing sustainable energy conversion techniques. The nickel-based MOF-derived catalysts are a class of materials synthesized by transforming metal organic frameworks containing nickel into heterostructures. In this work, a novel and efficient Ni-MOF-74-derived catalyst was developed for the catalytic hydrogenation reduction of nitrate to ammonia and nitrogen. Reaction factors containing reaction temperature, initial concentration, and interfering ions were systematically investigated. The optimized catalyst exhibited high activity with a nitrate removal rate over 90% and an ammonia selectivity of 66.5% under mild conditions. The kinetic analysis results indicated that NO3- degradation conforms to first-order kinetic reaction and the apparent activation energy was 23.67 KJ/mol. The characterization result, including XRD, XPS and SEM, confirmed the formation of highly dispersed metallic nickel within carbon carrier. The carbon support could stabilize Ni nanoparticles as well as improve electron transfer, and the presence of Ni2+ species could be conducive to enhances NO₃⁻ adsorption and modulates the local reaction environment, which was responsible for its high activity and selectivity in the catalytic nitrate reduction to ammonia and nitrogen. Besides, the nitrate hydrogenation reduction mechanism undergoes a multi-step hydrogenation pathway to ammonia and nitrogen over the Ni-MOF-74 derived-catalyst was presumed. This work highlighted the strong potential of Ni-MOF-74-derived catalyst in hydrogenation reduction and provides a promising way for sustainable nitrate wastewater treatment coupled with resource recovery.