Reduction of Copper Oxide by Low-Temperature Hydrogen Plasma

Abstract

The paper presents experimental results of reduction of cupric oxide (CuO) by low-temperature hydrogen plasma in a microwave-assisted plasma set-up. The experiments were carried out at low microwave powers in the range of 600-750 W and low hydrogen flow rates in the range of 0.833 9 10 -6 to 2.5 9 10 -6 m 3 s -1 . In all the experiments for reduction of CuO with hydrogen plasma, an initial induction period was observed in the kinetic plots. The induction period decreases with increase in pressure or temperature. The induction period leads to the formation of active sites for adsorption of H 2 . After the induction period, fast autocatalytic reduction takes place followed by a sluggish period towards the end. The reduction process proceeds in sequential steps through the formation of sub-oxides. The kinetic data fits the Avrami-Erofeev equation with 'n' value close to 3. The resultant activation energy measured during hydrogen plasma processing is around 75.64 kJ mol -1 . This is lower compared to activation energies measured by other methods of reduction indicating a clear advantage.

Modulation of copper(I) oxide reduction/oxidation in atmospheric pressure plasma jet

“…Richmonds, Brettholle and Meiss demonstrated that the presence of free electrons made them analogous to electrodes, by positioning a plasma discharge in contact to a liquid electrolyte they demonstrated charge-transfer processes at the plasma/liquid interface [12][13][14][15]. Plasma reduction of copper oxide layers has been described in H2/He plasma in vacuum by Sawada et al [16] and Sabat et al [17], also Inui et al showed CuO and Cu2O reduction in H2/Ar atmospheric pressure plasma [18]. In all these studies the reduction was associated to the hydrogen radicals present in the doped plasma.…”

A review on the recent progress, challenges, and perspectives of atmospheric‐pressure cold plasma for preparation of supported metal catalysts

“…Moreover, the explosive hydrogen gas in the outlet can be recycled by hydrogen gas purification equipment. Low‐temperature hydrogen plasma has also been adopted to reduce metal oxide . Last but not the least, AP cold plasma is operated at atmospheric pressure, and sophisticated and expensive vacuum systems are not required.…”

Physics and Chemistry of Solid State Direct Reduction of Iron Ore by Hydrogen Plasma

“…In search for some low-carbon footprint technologies, hydrogen (H2) has been found as the most suitable candidate to replace carbon [1,[4][5]. H2 is the strongest candidate because it possesses thermodynamic and kinetic advantages [1,4,[14][15][16][17][18][19][6][7][8][9][10][11][12][13] compared to CO2. Also, the reduction product is environmental friendly water (H2O) and a very low quantity of H2 consumed per tonne of iron.…”