Mechanochemical Synthesis of RuCo/MgTiO₃ Catalysts for Nonthermal Plasma-Assisted Ammonia Synthesis

Abstract

The development of robust yet effective catalysts is vital for promoting nonthermal plasma (NTP)-assisted ammonia (NH 3 ) synthesis toward practical applications. Herein, we report a simple mechanochemical synthesis method (via ball milling) for preparing bimetallic RuCo supported on MgTiO 3 catalyst (i.e., RuCo/MgTiO 3 -6-500) to be used in NTP-assisted catalytic NH 3 synthesis. The physicochemical properties of the developed catalysts were investigated systematically with respect to the relevant process parameters of ball milling. Catalytic tests showed that, at a low specific energy input of 15 kJ L −1 , the developed RuCo/MgTiO 3 -6-500 catalyst exhibited a high NH 3 synthesis rate and an energy efficiency of ∼50 μmol min −1 g cat −1 and 1.54 g NHd 3 kWh −1 , respectively, which outperformed the monometallic Ru or Co control catalysts. Additionally, the energy barriers were calculated as a function of N 2 /H 2 ratio for the NTP-catalytic NH 3 synthesis over RuCo/MgTiO 3 -6-500, and the results were interpreted together with the activity data measured during the catalysis. It was found that the energy barrier approach may not be appropriate for discussing the energy required for the dynamics of interest in the NTP-catalytic system. Compared to MgTiO 3packed and plasma-alone systems, results by in situ optical emission spectroscopic (OES) diagnosis of the plasma-catalytic systems showed that the presence of active metal sites (i.e., Ru and/or Co) could intensify the activation and dissociation rates of N 2 and H 2 molecules, showing the relatively higher peak intensity of NH, N 2 *, N 2 + , and H α species. However, based on the obtained information, the possible roles of Ru and/or Co in NTP-assisted ammonia synthesis system are difficult to be identified.

Binary Heterogroup-Templated Scaffolds of Polyoxopalladates as Precatalysts for Plasma-Assisted Ammonia Synthesis

“…In contrast, the synthesis rate is remarkably increased to 64.42 and 60.11 μmol/(min·g cat ), respectively, using AsVPd-SBA15 and SiVPd-SBA15 as catalysts. Such performances are far better than most of the catalysts reported previously (see Table S3) as well as the referenced Al 2 O 3 (29.34 μmol/(min·g cat )) and SBA-15 (39.85 μmol/(min·g cat )). − ,− Meanwhile, V 10 -SBA15 (5 wt % V) and Pd/C (5 wt % Pd) were examined as a control, and the synthesis rate is 44.44 and 21.94 μmol/(min·g cat ), respectively, suggesting the combination advantage of Pd and SBA-15 in our catalysts. Also, the synthesis rate of the vanadate-free Pd 13 As 8 -SBA15 (1.5 wt % Pd) is 56.26 μmol/(min·g cat ), indicating the positive role of vanadates in promoting the catalytic efficiency.…”

One-Step Synthesis of Ammonia Directly from Wet Air/N2 by Plasma Combined with a γ-Al2O3 Catalyst

“…The use of nonthermal plasma technology to synthesize NH 3 has been studied extensively. Compared with traditional synthetic NH 3 technology, synthesizing NH 3 with plasma technology has the advantages of mild reaction conditions and no greenhouse gas emissions . It has been reported that H 2 and N 2 can synthesize NH 3 under the combined action of plasma and catalyst, and catalyst research is the focus.…”

“…Compared with traditional synthetic NH 3 technology, synthesizing NH 3 with plasma technology has the advantages of mild reaction conditions and no greenhouse gas emissions. 17 Mizushima et al 18 used a tubular membrane-like catalyst for a reactor with dielectric barrier discharge (DBD) plasma in NH 3 synthesis. 18,19 The results show that the catalysts can effectively increase the yield of NH 3 .…”

Stainless steel membrane distributor‐type dielectric barrier discharge plasma reactor for co‐conversion of CH4/CO2

“…Non-thermal plasma (NTP) is a promising alternative to enable many challenging and important chemical reactions (particularly limited by kinetics and/or thermodynamics), such as CO 2 hydrogenation, [1][2][3][4][5][6] water gas shift (WGS) reaction, [7][8][9] and ammonia synthesis. [10][11][12][13] Unlike thermal methods, NTP can be generated under relatively mild conditions (e.g. ambient temperature and pressure) without external heat sources, offering a number of advantages such as achieving steadystate quickly and switching on/off easily, making it promising to use the intermittent electricity (generated from abundant renewable sources such as wind and solar) for distributed production.…”

“…Non‐thermal plasma (NTP) is a promising alternative to enable many challenging and important chemical reactions (particularly limited by kinetics and/or thermodynamics), such as CO 2 hydrogenation, 1–6 water gas shift (WGS) reaction, 7–9 and ammonia synthesis 10–13 . Unlike thermal methods, NTP can be generated under relatively mild conditions (e.g.…”