Nonthermal Plasma Synthesis of Ammonia over Ni-MOF-74

Abstract

Herein, we demonstrate a synergistic approach with radiofrequency plasma to synthesize ammonia in the presence of Ni-MOF-74 as catalyst. The Ni-MOF displayed higher ammonia yields as compared to the pure Ni metal. Specifically, ammonia yields as high as 0.23 g-NH3 (g-catalyst·kWh)−1 and energy cost of 265 MJ mol–1 over Ni-MOF were observed. The enhanced catalytic activity of the Ni-MOF in the presence of plasma was attributed to the presence of pores, which improved mass transfer of guest and product molecules during reaction, the presence of open Ni metal sites, and lower surface hydrogen recombination. Furthermore, the ammonia energy yield of our plasma-Ni MOF catalyst is superior to those of the state-of-the-art RF plasma catalytic systems.

Plasma-assisted catalytic formation of ammonia in N2–H2plasma on a tungsten surface

“…For the low pressure plasmas (typically at 0.01 to 10 mbar of pressure), only few experimental studies were investigating the synthesis of ammonia from nitrogen-hydrogen using low pressure radio frequency (RF) discharges 23,[30][31][32][33][34][35][36] despite that RF sources are currently the most common plasma sources employed in the semiconductor industry 37 and their use for ammonia plasma-assisted catalytic synthesis would have the advantage of adapting the process to the industrial scale. Moreover, RF plasma sources present the advantage of being less harmful than other sources in cases of radiation leakage and they have a longer lifetime as the RF coils are not in direct contact with the plasma and cannot therefore be etched.…”

Plasma-driven catalysis: green ammonia synthesis with intermittent electricity

“…Nowadays, atmospheric pressure DBDs are studied most, although some papers also describe low pressure MW and RF discharges. [181][182][183]187,[190][191][192][194][195][196] A summary of quantified plasma-driven conversions to ammonia in various plasma reactors under a wide variety of conditions is shown in Fig. 9.…”

“…The highest energy yield reported so far is Original references: DBD (AC), 144,[146][147][148][151][152][153]159,[164][165][166]169,276,277 DBD ( pulse), 158,165 Glow Discharge, 174 MW 186,278,279 and RF. 182,187,188,[190][191][192]194 In some cases, the reported units have been converted to g-NH 3 kW h −1 for the energy yield, and ppm for the ammonia concentration. We refer the reader to the recent review of Carreon 261 37.9 g-NH 3 kW h −1 .…”

A Review about the Recent Advances in Selected NonThermal Plasma Assisted Solid–Gas Phase Chemical Processes

“…Nickel-based catalysts have also been extensively studied. Shah et al [26] compared the activity of pure Ni metal with that of Ni-MOF catalyst in plasma assisted ammonia synthesis. The Ni-MOF catalyst shown superior catalytic activity that was attributed to the catalyst porous structure, which improves the mass transfer during the reaction, to the presence of open Ni metal sites and to the lower surface hydrogen recombination.…”