The 2020 plasma catalysis roadmap Bogaerts, Annemie; Tu, Xin; Whitehead, J Christopher ...
Journal of physics. D, Applied physics,
10/2020, Letnik:
53, Številka:
44
Journal Article
Recenzirano
Odprti dostop
Plasma catalysis is gaining increasing interest for various gas conversion applications, such as CO2 conversion into value-added chemicals and fuels, CH4 activation into hydrogen, higher hydrocarbons ...or oxygenates, and NH3 synthesis. Other applications are already more established, such as for air pollution control, e.g. volatile organic compound remediation, particulate matter and NOx removal. In addition, plasma is also very promising for catalyst synthesis and treatment. Plasma catalysis clearly has benefits over 'conventional' catalysis, as outlined in the Introduction. However, a better insight into the underlying physical and chemical processes is crucial. This can be obtained by experiments applying diagnostics, studying both the chemical processes at the catalyst surface and the physicochemical mechanisms of plasma-catalyst interactions, as well as by computer modeling. The key challenge is to design cost-effective, highly active and stable catalysts tailored to the plasma environment. Therefore, insight from thermal catalysis as well as electro- and photocatalysis is crucial. All these aspects are covered in this Roadmap paper, written by specialists in their field, presenting the state-of-the-art, the current and future challenges, as well as the advances in science and technology needed to meet these challenges.
Non-thermal plasma is widely considered as an effective technology for applications in agriculture. Particularly, numerous reports studies have highlighted the role of plasma-activated water (PAW) ...for seeds germination, plant growth, stress tolerance, and antibacterial ability. The present study investigated the effects of PAW on lettuce (
Lactuca Sativa L.
) seed germination and seedling growth. PAW was achieved by using an atmospheric pressure dielectric barrier discharge in Ar (50%) –N
2
(40%)–O
2
(10%) gas mixture for treatment time ranging from 5 to 30 mn. The physicochemical properties of PAW (temperature, pH, electrical conductivity, concentrations of nitrate, nitrite, and hydrogen peroxide) were evaluated. Results show that water-activated during moderate time, 10 to 20 mn, contains reactive oxygen and nitrogen species at relevant concentration levels to have active impacts on seed germination and seedling growth. Germination potential significantly increased by about 117%, 56%, and 77% after 15 mn of treatment, for the first 3 days, respectively, compared to control. For long time PAW (25–30 mn), the germination rate is either constant or decreases. Positive effects of PAW treatments were registered on the growth parameters of seedling including stem and root length, leaf weight, leaf area and chlorophyll content, and the vigor of seedlings. Chlorophyll content significantly increased by 220% for PAW-treated 15 mn and by about 165% for PAW-treated 20 mn, respectively, compared with control. Additionally, PAW induce morphological changes on lettuce seeds which are associated with oxidizing species leading to better water and nutrients uptake.
•Plasma–catalyst oxidation of methane evidenced at low temperature.•Plasma-catalytic system more selective for CO2 formation compared to only plasma system.•Catalytic activity of Pd/Al2O3 ...significantly enhanced in presence of plasma.•In-plasma catalysis configuration seems to be more efficient for methane oxidation compared to post-plasma catalysis.
Methane oxidation was investigated in a pulsed dielectric barrier discharge at atmospheric pressure coupled with Pd/Al2O3 catalysts. Comparison between plasma, catalytic, and plasma-catalysis (both in-plasma and post-plasma catalysis) systems were performed in the temperature range of 25–500°C and specific input energy up to 148J/L. For plasma-alone experiments, CH4 conversion reached a maximum of 67% and the main products obtained were CO, CO2, O3, and HNO3. The plasma catalytic treatment leads to an increase of the CH4 oxidation even at low temperature. It is evidenced that, compared to plasma alone, both Al2O3 and Pd/Al2O3 catalysts coupled plasma discharge increase the CH4 conversion. Moreover, for all plasma-catalytic systems, the CH4 conversion plots were shifted toward lower temperature as the specific input energy increases. Although the difference is low, the in-plasma catalysis configuration seems to be more efficient compared to post-plasma catalysis. In all cases, CH4 oxidation in presence of Pd/Al2O3 catalyst becomes more selective in CO2 formation than the reaction in plasma alone.
The combined effect of non-thermal plasma treatment of water and seeds on the rate of germination and plants growth of radish (
Raphanus sativus
), tomato (
Solanum lycopersicum
), and sweet pepper (
...Capsicum annum
) have been investigated using dielectric barrier discharges in air under atmospheric pressure and room temperature. A cylindrical double dielectric barrier discharge reactor is used for water activation and a plate-to-plate double DBD reactor is employed for seed treatment. The activation of water, for 15 and 30 min, lead to acidic solutions (pH 3) with moderate concentrations of nitrate (NO
3
−
) and hydrogen peroxide (H
2
O
2
). Plasma activated water (PAW) has shown a significant impact on germination as well as plant growth for the three types of seeds used. Interestingly, the positive effect, in seed germination and seedling growth, has been observed when the PAW and plasma-treated seeds (10 and 20 min) were combined. In one hand, when the seeds were (tomato and pepper) exposed to 10 min plasma and watered with PAW-15 for first 9 days followed by tap water for 51 days, the stem length is increased about 60% as compared to control sample. On the second hand, for longer exposures of seeds and water to plasma discharges, a negative effect is observed. For instance, plasma-treated seeds watered with PAW-30, the plant growth and vitality were decreased as compared to control sample. These results revealed that the developed cold plasma reactors could be used to significantly improve the seed germination as well as plant growth, nevertheless, the plasma treatment time has to be optimized for each seeds.
Seed germination and plants growth are significantly improvement by combining plasma activated water and plasma treated seeds.
The pulsed dielectric barrier discharge (DBD) combined with the palladium supported on alumina beads, was investigated for propene (C3H6) removal from air. The effects of thermal-catalysis, ...plasma-catalysis (in-plasma catalysis and post-plasma catalysis), and plasma-alone on the propene removal were compared. Results are presented in the terms of C3H6 removal efficiency, energy consumption, and by-products production. Temperature dependence studies (20?250?C) show that in all conditions of input plasma energy density explored (23?148 J L-1), the plasma-catalysis systems exhibit better propene conversion efficiencies than the thermal catalysis at low temperature (60% at 20?C). Plasma-alone treatment has a similar effectiveness compared to plasma-catalysis at room temperature, but it leads to the formation of high by-products concentrations. It appears that in the plasma-catalyst system, C3H6 removal was the most efficient, whatever was the configuration used, and it was helpful to minimize by-products formation.
nema
•NTP discharge initiates the CO2 dissociation to CO.•NiO nano catalyst assist the hydrogenation of CO on the catalyst surface.•NTP discharge enhances the CO2 to CH4 formation at 250 °C.•High ...operating temperature assist the water gas shift reaction and partial oxidation of CH4 to CO.•Several hours of plasma discharge does not change the catalyst morphology.
Modernization, deforestation and overwhelmingly growing world population are significantly increasing the atmosphere CO2 level. The conversion of CO2 to other products has attracted much more attention, especially atmospheric pressure cold plasma for CO2 conversion to CH4. In this study the hydrogenation of CO2 to CH4 was carried out using Ni/γ-Al2O3 nanocatalyst coupled non-thermal plasma dielectric barrier discharge reactor (NTP-DBD). The effect of temperature, plasma input power on CO2 conversion rate and CH4 selectivity have been studied. It was evidenced that, compared to conventional thermal catalysis (300 °C), plasma-catalysis has shown temperature shift (T shift) of 50 °C (250 °C). Furthermore, at 250 °C, 10wt.%Ni/γ-Al2O3 nanocatalyst has shown about 40% CO2 conversion and 70% CH4 selectivity with 340 J.L−1 specific input energy (SIE). At low operating temperature, increase in SIE increases the CO2 conversion and CH4 selectivity by about 10%. The SEM and EDX analysis evidenced that NiO is homogeneously dispersed on the alumina beads surface. The TEM analysis before and after catalytic experiments showed that the average “NiO” particle size is 10–12 nm and 12–15 nm, respectively. The plasma discharge slightly increases the Ni particle size, however, it does not affect neither CO2 conversion and nor CH4 selectivity.
Low-temperature combustion engines have the potential to meet pollutant requirements and reduce fuel consumption. The present study, based on an ultraviolet light absorption diagnostic, investigates ...ozone decomposition inside a single-cylinder compression ignition engine. Experiments were performed under HCCI conditions for non-reactive and reactive cases. Experimental results showed that intake parameters, pressure and temperature, and intake flow composition have a significant impact on ozone decomposition timing. In this study H
2
O vapor and Isooctane seem to have the most significant impact on ozone decomposition.
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•A 30-min plasma treatment at 200 °C induced the formation of crystalline particles of inverse spinel CoFe2O4, a phenomenon not observed in samples without plasma treatment.•Plasma ...treatment at 200 °C, a significant reduction in particle size was observed, with the average size plummeting to 6.7 nm, nearly three times smaller than the calcined sample at 600 °C (24.1 nm).•The plasma assisted synthesized material displayed remarkable magnetic properties, boasting a magnetization (Ms) of 91.80 emu/g and a coercivity (Hc) of 888 Oe. In stark contrast, the material calcined at 600 °C exhibited a lower magnetization of 64.53 emu/g and a higher coercivity of 1289 Oe.•EDX analysis unveiled surface oxygen defects in plasma synthesized material compared to materials synthesized by conventional calcination at 600 °C, resulting in a narrower bandgap (1.9 eV).•XPS analysis unveiled the presence of Co2+ and Co3+ within the spinel crystal structure of the plasma-treated material, elucidating the mechanisms underlying its enhanced magnetic behavior.
Non-thermal plasma (NTP)-assisted catalysis offers a promising avenue with diverse applications, particularly in air and water treatment. This study aimed to investigate the utilization of NTP discharge for the synthesis of magnetically active nanoparticles (MANps). We have demonstrated that the NTP discharge-assisted low-temperature calcination effectively induces surface modification and crystallization, thereby enhancing magnetic susceptibility. Specifically, a 30 min plasma treatment at 200 °C (CF-P-200) facilitated the formation of crystalline particles, a phenomenon that was absent in materials synthesized without plasma treatment under similar operating conditions. High-resolution microscopy revealed an average particle size of about 6.7 nm, while EDX analysis unveiled surface oxygen defects in CF-P-200 compared to materials synthesized by conventional calcination at 600 °C (CF-T-600), resulting in a narrower bandgap (1.9 eV). Magnetization measurements conducted using vibrating sample magnetometry (VSM) displayed superior magnetic properties of plasma treated MANps, with a magnetization (Ms) of 91.80 emu/g and coercivity (Hc) of 888 Oe. These values outperformed those of materials calcined at 600 °C (Ms: 64.53 emu/g, Hc: 1289 Oe), emphasizing the efficacy of NTP discharge in enhancing magnetic characteristics during material synthesis.
The combination of heterogeneous catalysts with non-thermal plasma (DBD operated in sinusoidal mode) was investigated for the removal of toluene from air at room temperature. The DBD reactor gives ...the possibility to introduce the heterogeneous catalyst directly into the discharge zone (
in-plasma catalysis, IPC) or to place the catalyst downstream the plasma zone (
post-plasma catalysis, PPC). Various catalytic materials based on Ag, Au, Cu, Co, Mn, La, and Nb, supported on Al
2O
3 and CeO
2 in powder form has been tested to select the catalysts that present the highest activity in the presence of plasma.
Without plasma, the reaction of toluene conversion over perovskite, Al
2O
3, and OMS-2 based catalysts are promoted at high temperature (200–400
°C). In the absence of catalysts, the toluene removal efficiencies were in the 55–60% range.
When the plasma was combined to catalyst, the toluene removal efficiency strongly increased when the catalysts are in IPC position. Best results, up to 96% toluene conversion, were obtained when using 1
wt% Au/Al
2O
3 and Nb
2O
5 catalysts.
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