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[Display omitted] • Removal of toluene examines with honeycomb catalyst for industrial application. • Uniform corona plasma with a high flowrate with negligible pressure drop. • The surface resistance of dielectric monolith reduces by the water vapor coat. • Plasma strength largely depends on the humidity of the inlet gas. • Metal clusters on the honeycomb surface can act as floating grounds. Efficiently processing volatile organic compounds (VOCs) with nonthermal plasma and honeycomb catalyst for practical industrial applications presents a sizable challenge. An attempt has been made to generate a large volume of uniform plasma at atmospheric pressure in a practical-scale honeycomb catalyst. H-ZSM-5, a type of zeolite, was washcoated on a commercial bare honeycomb monolith as the catalyst-supporting material, after which the monolith was impregnated with Pd. The plasma discharge power can be controlled by controlling the humidity in the feed gas, metal content, applied voltage, and total flow rate of the feed gas. The plasma was characterized by the voltage and current waveforms, and optical emission spectroscopy (OES). In this study, 85% of dilute toluene (15 ppm) was successfully removed from an airstream at a large flow rate of 60 L/min with an energy density of 84 J/L. Under this condition, the selectivity of CO 2 was 76%. This investigation demonstrated the practical applicability of the plasma-honeycomb catalytic reactor to process a fast-flowing feed gas without resulting in a significant large pressure drop, which can hardly be achieved with typical packed-bed plasma reactors. [ABSTRACT FROM AUTHOR]

This work focused on the factors affecting the effective generation of corona discharge plasma in a honeycomb catalyst reactor. Pd, Co, and Ag were used as the active metal catalysts to investigate the plasma formation and decomposition of ethylene. Unlike the Ag-coated honeycomb catalyst, which resulted in excessive arcing, the Co-coated honeycomb monolith was able to generate stable plasma, but the discharge power was insufficient to decompose ethylene at an acceptable level. The incorporation of a small amount of Pd with Co significantly enhanced the discharge power and the ethylene removal performance. The catalytic activity of the prepared catalyst for the removal of ethylene was evaluated using plasma catalytic oxidation and thermal catalytic oxidation. ANOVA was used to assess the effect of single process factors and their relationships in the plasma process. All the process factors such as specific energy input (SEI), ethylene concentration, and flow rate were found to affect the ethylene conversion, CO 2 selectivity, and energy efficiency (EE). Under the optimal conditions, i.e., an SEI of 80 J/L, an ethylene concentration of 20 ppm, and a flow rate of 20 L/min, the ethylene conversion was 85 %, CO 2 selectivity was 70 %, and EE was 0.86 g/kW h. [Display omitted] • Stable corona plasma formation using Co/ZSM-5/monolith and Co-Pd/ZSM-5/monolith. • Bimetallic catalyst shows better catalytic activity than monometallic catalyst. • Ag/ZSM-5/monolith creates numerous arcing and poor plasma formations. • ANOVA with F-test investigates the relationship between the influential factors and NTP reaction activity. [ABSTRACT FROM AUTHOR]

This study deals with the preparation of SiO 2 , CuO and RuO 2 nanomaterials and RuO 2 based nanocomposites using dielectric barrier discharge (DBD) plasma. On account of an increasing attention toward the preparation of one dimensional nanostructure in recent days, the possibility to tune the morphology of the above materials by using plasma was investigated. The prepared nanomaterials were characterized by using Fourier transform infrared spectroscopy, field emission scanning electron microscopy, X-ray diffraction spectroscopy and particle size analysis. Spherical, cylindrical and nanorod structures were observed for SiO 2 , CuO and RuO 2 , respectively. The morphology and the chemical composition of the RuO 2 /SiO 2 and RuO 2 /CuO nanocomposites were analyzed using high resolution transmission electron microscopy and energy dispersive X-ray spectroscopy. It was noted that interaction of plasma species with each material differs from one another, and thus the materials exhibit different surface morphology. The reason might be the material's physico-chemical properties and in particular, depending on whether they belong to insulator or semiconductor. [ABSTRACT FROM AUTHOR]

In order to explore the effects of the shape of ZnO nanomaterials on the plasma-catalytic decomposition of butane and the distribution of byproducts, three types of ZnO nanomaterials (nanoparticles (NPs), nanorods (NRs) and nanowires (NWs)) were prepared and coated on multi-channel porous alumina ceramic membrane. The structures and morphologies of the nanomaterials were confirmed by X-ray diffraction method and scanning electron microscopy. The observed catalytic activity of ZnO in the oxidative decomposition of butane was strongly shape-dependent. It was found that the ZnO NWs exhibited higher catalytic activity than the other nanomaterials and could completely oxidize butane into carbon oxides (CO x ). When using the bare or ZnO NPs-coated ceramic membrane, several unwanted partial oxidation and decomposition products like acetaldehyde, acetylene, methane and propane were identified during the decomposition of butane. When the ZnO NWs- or ZnO NRs-coated membrane was used, however, the formation of such unwanted byproducts except methane was completely avoided, and full conversion into CO x was achieved. Better carbon balance and CO x selectivity were obtained with the ZnO NWs and NRs than with the NPs. [ABSTRACT FROM AUTHOR]

This work investigated the performance of ethylene and butane decomposition in a dielectric barrier discharge (DBD) plasma reactor packed with nanoparticle-coated γ-alumina at 150 °C. The effects of input power and type of metal oxide nanoparticle (TiO 2 and ZrO 2 coated on γ-alumina) on the decomposition efficiency and the distribution of by-products were examined and discussed. The decomposition efficiencies of ethylene and butane obtained with the nanoparticle-coated γ-alumina were higher than those with the bare γ-alumina. The main decomposition by-products were found to be carbon oxides. Nitrogen-containing by-products such as nitrous oxide and nitrogen dioxide were also detected with both ethylene and butane. Besides, some partially oxidized by-products like formaldehyde and acetaldehyde and lower molecular weight by-products like acetylene and methane were identified during the decomposition of ethylene and butane. The formations of such unwanted by-products were completely avoided and high selectivity towards carbon oxides was achieved when the ZrO 2 nanoparticle-coated γ-alumina was used as the packing material. The emission spectra of the DBD plasma showed various oxygen and nitrogen reactive species that are responsible for the decomposition of ethylene and butane. [ABSTRACT FROM AUTHOR]

Pristine Ni/γ–Al 2 O 3 and CeO 2 –Ni/γ–Al 2 O 3 catalysts were prepared by co-impregnation technique for dry reforming of propane. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) were used to examine the structure and morphology of the catalysts before and after the reforming reactions. The excellent interaction between catalyst active phases was observed in both CeO 2 –Ni/γ–Al 2 O 3 and Ni/γ–Al 2 O 3 stabilized with polyethelene glycol (Ni/γ–Al 2 O 3 –PEG). Towards C 3 H 8 and CO 2 conversion, the CeO 2 –Ni/γ–Al 2 O 3 and Ni/γ–Al 2 O 3 –PEG showed improved catalytic activity when compared to the pristine Ni/γ–Al 2 O 3 catalyst. Interestingly, high H 2 concentration was achieved with the CeO 2 –Ni/γ–Al 2 O 3 and high CO concentration with the Ni/γ–Al 2 O 3 –PEG, which is due to the nanoconfinement of nickel particles within the support and favorable metal-support interaction as a result of plasma reduction. The CeO 2 –Ni/γ–Al 2 O 3 catalyst exhibited better stability for anti-sintering and coke resistance, thus exhibiting high reactivity and durability in the dry reforming. [ABSTRACT FROM AUTHOR]

Highlights: [•] Atmospheric pressure plasma technique for RuO2 nanomaterials synthesis. [•] Substrate induced morphological variations. [•] Visible light photo-catalysis. [•] Shape dependent catalytic properties. [ABSTRACT FROM AUTHOR]

Abstract: A two-stage process consisting of an ozonizing chamber and an absorber containing a reducing agent solution was proposed to remove nitrogen oxides (NO x ) from exhaust gas. In the ozonizing chamber where the exhaust gas is treated by ozone, NO (the main component of NO x ) was oxidized to NO2, and in the next step, NO2 was reduced to N2 by sodium sulfide (Na2S) used as the reducing agent. The NO x removal efficiency obtained by this two-stage process was higher than 95%. It was found that about three fourth of sodium sulfide was consumed without reacting with NO x , and accordingly the amount of sodium sulfide required should be four times that of NO x to be removed. The problem regarding the emission of H2S from Na2S was deeply related to the pH of the reducing agent solution, which could be solved by adjusting the pH using a basic reagent (NaOH). The concentrations of NO2 − and NO3 − in the reducing agent solution after processing were analyzed, which showed that about 25% of the NO x removed from the exhaust gas was simply dissolved in the reducing agent solution, i.e., about 75% of the NO x removed was reduced to N2. [Copyright &y& Elsevier]

This study focused on the removal of styrene using a metal-coated monolith (MCM) catalyst integrated with non-thermal plasma. The MCM catalyst was prepared by depositing a ZSM-5 support impregnated with a combination of three metals (Co, Pd, La) on a practical-scale honeycomb monolith. A comparative study with a commercial metal-coated monolith (CMCM) of the same dimensions was conducted to evaluate the effectiveness of the MCM with respect to styrene removal. The plasma discharge in the monolith was characterized by measuring the voltage and current waveforms and optical emission spectroscopy (OES). The electric power of the plasma discharge largely depended on the metal loading, flow rate, and humidity of the feed gas. The removal efficiency of styrene (inlet concentration: 20 parts per million, volumetric (ppm)) was examined using both plasma catalytic oxidation (PCO) and thermal catalytic oxidation (TCO), to enable the effect of plasma to be clearly assessed. PCO with the MCM catalyst achieved styrene removal efficiency of nearly 100% at a specific energy input (SEI) of 40 J/L, whereas the CMCM catalyst achieved 92% removal for identical SEI. In comparison, TCO with the MCM and CMCM catalysts required high temperatures of 420 °C and 480 °C, respectively, for the complete removal of styrene. In addition, the CO 2 selectivity of the MCM catalyst was higher at 83% compared with 75% for the CMCM at SEI of 40 J/L. The optimal silica binder content for the deposition of a robust washcoat layer was found to be approximately 5%. [Display omitted] • Uniform robust coating layer of ZSM-5 was obtained using the washcoating method. • Uniform honeycomb plasma was generated using the MCM/CMCM catalysts. • Styrene was removed at room temperature using plasma catalytic oxidation. [ABSTRACT FROM AUTHOR]

Nonthermal plasma combined with a practical-scale honeycomb catalyst of 5.0 cm in height and 9.3 cm in diameter was investigated for the removal of toluene. The creation of plasma in the honeycomb catalyst greatly depended on the humidity of the feed gas and the presence of metals on the honeycomb surface. Compared to the bare ceramic honeycomb, the metal-loaded one gave higher toluene removal efficiency because the decomposition of toluene by the plasma-generated reactive species occurred not only homogeneously in the gas phase but also heterogeneously on the catalyst surface. The present plasma-catalytic reactor was able to successfully remove about 80% of dilute toluene (15 ppm in air) at a large flow rate of 60 L/min with a specific energy input of 58 J/L. The honeycomb-based plasma-catalytic reactor system is promising for practical applications since it can overcome such problems as high-pressure drop and difficulty in scale-up encountered in packed-bed reactors. ga1 • The removal of toluene investigates on a practical-scale honeycomb catalyst. • A large flow rate without significant pressure drop is used to generate plasma. • Plasma intensity largely depends on the humidity of the feed gas. • The metal clusters dotted on the honeycomb surface can act as floating grounds. [ABSTRACT FROM AUTHOR]

Removal of dilute N 2 O from gas streams by a cyclic adsorption–decomposition using Ca13X (Ca 2+ exchanged 13X) in combination with N 2 nonthermal plasma was studied in this work. Zeolite 13X was found to be the best for N 2 O uptake among tested commercial zeolites including 4A, H-β and 13X. By modifying 13X with Ca 2+ cation using ion-exchange method, the N 2 O adsorption capacity was greatly enhanced from ca. 3.5 × 10 −6 to 80 × 10 −6 mol g zeolite - 1 due to the stronger interaction of N 2 O with Ca 2+ cation than that with Na + cation. Ca. 96% of N 2 O removal efficiency at a SIE eq (equivalent specific input energy) of 1116 J L −1 was obtained under the cyclic operation of 60-min N 2 O adsorption (initial concentration: 510 ppm, gas flow rate: 0.5 L min −1 ) over Ca13X followed by 20-min plasma decomposition of adsorbed N 2 O in stationary N 2 atmosphere. In comparison, a similar performance was reached at a relatively high SIE of 1700 J L −1 as the reactor was operated under continuous plasma condition. The time period of plasma step and therefore the energy consumption could be reduced by properly circulating N 2 gas in the reactor. Also, SIE eq was found to decrease with increasing the adsorption time, whereby ca. 95% of N 2 O removal efficiency could be achieved at a SIE eq of 298 J L −1 as the adsorption time was 180 min. The regeneration of N 2 O-adsorbed Ca13X by N 2 plasma was initiated by plasma-induced desorption of adsorbed N 2 O followed by decomposing the desorbed N 2 O in plasma gas phase. [ABSTRACT FROM AUTHOR]