Plasma driven ammonia synthesis over silica: The role of the catalyst morphology and porous structure

Abstract

Non-thermal plasma (NTP) has opened novel routes for ammonia production, providing a powerful and high-performance rivalling the conventional Haber-Bosch process. Yet, the enhancement of ammonia yield over NTP driven catalytic processes is still challenging. In this work, ammonia synthesis performance is tailored by the morphology and textural properties including surface area and pore size volume of various silica catalysts. Experimental results indicated the effects of different catalyst surface areas, pore sizes, and morphology on the surface discharge. Spherical macroporous silica displays the highest ammonia production rate of 0.14 mmol min-1 m-2 at a power of 15W. The spherical macroporous silica offers a more uniform discharge, enhancing the reaction of unreacted N2 and H2 and allowing their diffusion and absorption inside the pores to form ammonia. The findings from this work provide insights for tailoring catalyst porous structure and morphology for ammonia production powered by non-thermal plasma.