Plasma-Catalysis for Volatile Organic Compounds Decomposition: Complexity of the Reaction Pathways during Acetaldehyde Removal

Abstract

Acetaldehyde removal was carried out using non-thermal plasma (NTP) at 150 J·L−1, and plasma-driven catalysis (PDC) using Ag/TiO2/SiO2, at three different input energies—70, 350 and 1150 J·L−1. For the experimental configuration used, the PDC process showed better results in acetaldehyde (CH3CHO) degradation. At the exit of the reactor, for both processes and for all the used energies, the same intermediates in CH3CHO decomposition were identified, except for acetone which was only produced in the PDC process. In order to contribute to a better understanding of the synergistic effect between the plasma and the catalyst, acetaldehyde/catalyst surface interactions were studied by diffuse-reflectance infrared Fourier transform spectroscopy (DRIFTS). These measurements showed that different species such as acetate, formate, methoxy, ethoxy and formaldehyde are present on the surface, once it has been in contact with the plasma. A reaction pathway for CH3CHO degradation is proposed taking into account all the identified compounds in both the gas phase and the catalyst surface. It is very likely that in CH3CHO degradation the presence of methanol, one of the intermediates, combined with oxygen activation by silver atoms on the surface, are key elements in the performance of the PDC process.

Plasma-Catalytic Process of Hydrogen Production from Mixture of Methanol and Water

“…Various plasma-catalytic systems are used. A catalyst may be located in a plasma zone [1][2][3][4][5][6][7], an electrode may be the catalyst [8,9], and often the catalyst is located outside the plasma zone [1,[10][11][12][13][14][15][16][17][18]. This way of placing the catalyst prevents the destruction of the catalyst by plasma and the disturbance of the discharge.…”

“…As a result of introducing the catalyst into the plasma reactor, the conversion increases, which results in a reduction of the energy cost of the process. Processes such as gas purification [1][2][3], hydrogen production [5,7], Fischer-Tropsch synthesis [6] are carried out in plasma-catalytic reactors.…”

Hansen parameter evaluation for the characterization of titania photocatalysts using particle size distributions and combinatorics

“…Volatile organic compounds (VOCs) have been identified to have a severe impact on air quality and a number of techniques have been employed to degrade them such as liquid adsorption, thermal catalysis and photocatalysis. [2][3][4] Titania has been actively investigated due to its versatility in the degradation of a variety of VOCs, ease of processing, improved charge carrier separation, non-toxicity, and possibility of composite formation. [5][6][7] Several synthesis methods are used for the preparation of titania-based photocatalysts such as gas phase, sol-gel, and solvothermal methods.…”

Catalysts: Special Issue on Plasma-Catalysis for Environmental and Energy-Related Applications

“…This special issue demonstrates the interest in plasma catalysis as solution to environmental problems caused by greenhouses gases CO 2 and CH 4 [1,2] that can be converted to value-added products and fuels, gas pollution with stable polycyclic aromatic hydrocarbons [3] and volatile organic compounds [4], as well as water pollution [5]. The special issue includes a review article and four articles devoted to particular applications.…”

“…Although recently significant research efforts have been devoted to explaining the mechanisms of plasma-catalyst interaction, the present understanding still leaves open questions related to the complex phenomena involved in plasma catalysis. In order to fill some of these gaps, the article by Vega-González et al [4] focuses on the reaction pathways occurring during the decomposition of a volatile organic compound (acetaldehyde) by DBD fluidized bed with Ag/TiO 2 catalyst deposited on 150-µm-diameter SiO 2 pellets. The authors obtained enhanced removal of the VOC and considerably higher selectivity to CO X (CO + CO 2 ) in the plasma-catalytic system as compared to plasma alone.…”