Catalyst Hybrid Reactor Research Articles

A Hybrid Reactor System Comprised of Non-Thermal Plasma and Mn/Natural Zeolite for the Removal of Acetaldehyde from Food Waste

The degradation of low concentrations of acetaldehyde while using a non-thermal plasma (NTP)/catalyst hybrid reactor system was investigated while using humidified air at ambient temperature. A series of highly active manganese-impregnated natural zeolite (Mn/NZ) catalysts were synthesized by the incipient wetness method using sonication. The Mn/NZ catalysts were analyzed by Brunauer-Emmett-Teller surface area measurements and X-ray photoelectron spectroscopy. The Mn/NZ catalyst located at the downstream of a dc corona was used for the decomposition of ozone and acetaldehyde. The decomposition efficiency of ozone and acetaldehyde was increased significantly using the Mn/NZ catalyst with NTP. Among the various types of Mn/NZ catalysts with different Mn contents, the 10 wt.% Mn/NZ catalyst under the NTP resulted the highest ozone and acetaldehyde removal efficiency, almost 100% within 5 min. Moreover, this high efficiency was maintained for 15 h. The main reason for the high catalytic activity and stability was attributed to the high dispersion of Mn on the NZ made by the appropriate impregnation method using sonication. This system is expected to be efficient to decompose a wide range of volatile organic compounds with low concentrations.

Plasma-catalyst hybrid reactor with CeO2/γ-Al2O3 for benzene decomposition with synergetic effect and nano particle by-product reduction

A dielectric barrier discharge (DBD) catalyst hybrid reactor with CeO2/γ-Al2O3 catalyst balls was investigated for benzene decomposition at atmospheric pressure and 30 °C. At an energy density of 37–40 J/L, benzene decomposition was as high as 92.5% when using the hybrid reactor with 5.0wt%CeO2/γ-Al2O3; while it was 10%–20% when using a normal DBD reactor without a catalyst. Benzene decomposition using the hybrid reactor was almost the same as that using an O3 catalyst reactor with the same CeO2/γ-Al2O3 catalyst, indicating that O3 plays a key role in the benzene decomposition. Fourier transform infrared spectroscopy analysis showed that O3 adsorption on CeO2/γ-Al2O3 promotes the production of adsorbed O2− and O22‒, which contribute benzene decomposition over heterogeneous catalysts. Nano particles as by-products (phenol and 1,4-benzoquinone) from benzene decomposition can be significantly reduced using the CeO2/γ-Al2O3 catalyst. H2O inhibits benzene decomposition; however, it improves CO2 selectivity. The deactivated CeO2/γ-Al2O3 catalyst can be regenerated by performing discharges at 100 °C and 192–204 J/L. The decomposition mechanism of benzene over CeO2/γ-Al2O3 catalyst was proposed.

Removal of dilute VOCs in air by post-plasma catalysis over Ag-based composite oxide catalysts

This paper reports toluene decomposition with a dielectric barrier discharge (DBD) and a catalyst bed reactor in air at atmospheric pressure. Three Ag-based composite oxide catalysts are used to recycle O radicals for toluene decomposition and ozone decomposition. Toluene is not only oxidized inside the DBD non-thermal plasma (NTP) reactor by active species but also within the catalyst bed reactor via ozone to O radical conversion. Moreover, the DBD generated intermediate byproducts, such as CO, formic acid and formaldehyde, are simultaneously oxidized by the post catalysis. At a DBD specific energy density of 60J/L, toluene decomposition efficiencies by the DBD and the DBD with the catalyst bed reactor are about 62% and 100%, respectively. In terms of toluene and/or ozone decomposition efficiencies, their chemical reactivity is in the order of NTP+Ag–Mn–O≈NTP+Ag–Co–O>NTP+Ag–Ce–O>NTP. The plasma and catalyst hybrid reactor always shows a better performance in comparison with either NTP or chemical catalysis alone.

Hydrogen production by reforming methane in a corona inducing dielectric barrier discharge and catalyst hybrid reactor

A novel corona inducing dielectric barrier discharge (CIDBD) and catalyst hybrid reactor was developed for reforming methane. This corona inducing technique allows dielectric barrier discharge (DBD) to occur uniformly in a large gap at relatively low applied voltage. Hydrogen production by reforming methane with steam and air was investigated with the hybrid reactor under atmospheric pressure and temperatures below 600°C. The effects of input power, O2/C molar ratio and preheat temperature on methane conversion and hydrogen selectivity were investigated experimentally. It was found that higher methane conversions were obtained at higher discharge power, and methane conversion increased significantly with input power less than 50 W; the optimized molar ratio of O2/C was 0.6 to obtain the highest hydrogen selectivity (112%); under the synergy of dielectric barrier discharge and catalyst, methane conversion was close to the thermodynamic equilibrium conversion rate.

NO x removal from the flue gas of oil-fired boiler using a multistage plasma-catalyst hybrid system

The study on removal of NO x from the flue gas of oil-fired boiler has been carried out using non-thermal plasma cum catalyst hybrid reactor at 150 °C. Propylene (C 3H 6) was used as a reducing agent. A multistage plasma-catalyst hybrid reactor was newly designed and successfully operated to clean up the flue gas stream having a flow rate of 30 Nm 3/h. TiO 2 and Pd/ZrO 2 wash-coated on cordierite honeycomb were used as catalysts in the present study. Though the plasma-catalyst hybrid reactor with TiO 2 showed good activity on the removal of NO yet it removed only 50–60% of NO x because a significant portion of NO oxidized to NO 2. On the contrary, the plasma-catalyst hybrid reactor with Pd/ZrO 2 removed about 50% of inlet NO with a negligible amount of NO oxidation into NO 2. The plasma/dual-catalysts hybrid system (front two units of plasma-Pd/ZrO 2 + rear two units of plasma/TiO 2) proved to be very promising in NO x removal in the presence of C 3H 6. DeNO x efficiency of about 74% has been achieved at a space velocity of 3300/h at 150 °C.

Kinetic Analysis of the Catalyst and Nonthermal Plasma Hybrid Reaction for Methane Steam Reforming

Bioresources, such as landfill gas and agricultural residues, attract considerable attention because of growing concerns of global energy and environmental protection. However, the efficient usage of bioresource poses major challenges and generally necessitates appropriate pre-reforming processes. We propose a low-temperature (300−500 °C) upgrading method using an atmospheric pressure nonthermal discharge generated in a reforming catalyst bed reactor for profitable recovery of poor bioresources. Excited species produced by high-energy electron impact, which proceed independent of the temperature, accelerate methane steam reforming at lower temperatures than normal catalyst reactions with minimum energy required. The resultant hydrogen-enriched biogas is then available for use in conventional energy utility systems, such as internal combustion engines. This paper introduces fundamental characteristics of nonthermal discharge and the catalyst hybrid reactor. Furthermore, a detailed mechanistic study of syne...

Hydrogen Enrichment of Low-Calorific Fuels Using Barrier Discharge Enhanced Ni/γ-Al2O3 Bed Reactor: Thermal and Nonthermal Effect of Nonequilibrium Plasma

We have developed a dielectric barrier discharge (DBD) and catalyst hybrid reactor for reforming low-calorific fuels such as biogas at low temperature (300−500 °C). This technique allows the use of low-temperature thermal energy wasted from various industries, which ultimately provides a variety of energy utility options. The idea behind the project is that radicals produced by DBD can be decomposed at much lower temperatures than in a normal reforming condition. However, the situation becomes even more complicated because DBD enhances chemical reactions in different ways: (1) Excited species, radicals, and ions decompose on the catalyst at a lower temperature than the stable molecule. (2) Byproducts such as acetylene and ethane decompose at lower temperatures than methane. (3) Heat that is generated by DBD also enhances regular catalytic reforming. A mechanistic study of steam reforming in a plasma hybrid reactor was performed to distinguish their respective contributions to the synergistic effect. Resu...

Advanced Low-Temperature Methane Reforming in Non-Thermal Plasma and Catalyst Hybrid Reactor

Advanced Low-Temperature Methane Reforming in Non-Thermal Plasma and Catalyst Hybrid Reactor

Decomposition of benzene using alumina-hybrid and catalyst-hybrid plasma reactors

In order to investigate the effects of alumina and metal ions in plasma discharge, plasma reactors packed with a mixture of BaTiO/sub 3/ pellets and porous Al/sub 2/O/sub 3/ pellets (alumina-hybrid reactor), and with a-mixture of BaTiO/sub 3/ pellets and metal-supported Al/sub 2/O/sub 3/ pellets (catalyst-hybrid reactor) were examined for oxidation of dilute benzene in air. It was found that the oxidative decomposition of benzene was enhanced by concentrating benzene on the Al/sub 2/O/sub 3/ pellets and the catalyst pellets. Furthermore, the selectivities to CO/sub 2/ in the alumina-hybrid reactor and the catalyst-hybrid reactors were higher than those in the plasma reactor packed with BaTiO/sub 3/ pellets alone. In particular, the selectivities to CO/sub 2/ in the catalyst-hybrid reactors using Ag, Co, Cu and Ni/Al/sub 2/O/sub 3/ were higher than those from the alumina-hybrid reactor. In addition, the presence of the alumina and catalysts suppressed the formation of N/sub 2/O.