# Pentane Depletion by a Surface DBD and Catalysis Processing
## 1 Introduction  
One of the most important environmental issues at present is air pollution, which can be harmful to both the environment and to human health. Thanks to recent strict regulations, emissions of atmospheric pollutants have been reduced significantly during the last decades, especially in heavily industrialized countries. Despite all these efforts, the concentrations of pollutants within large urban zones remain too high, particularly in developing countries, and further improvement in atmospheric air quality is required. This can be accomplished by encouraging more specific studies [1]. A large and important group of pollutants is the volatile organic compounds (VOCs); due to their high volatility, these compounds rapidly evaporate, thus easily leaving the places where they are produced and diffusing into the atmosphere. It is now well-understood that they can cause a variety of deleterious effects to human health and the environment [2]. VOCs are mostly emitted during industrial processing in different types of mixtures with air, where the magnitude of fluxes ranges from 1000 m\({}^{3}\)/h to approximately 10,000 m\({}^{3}\)/h. Different methods for VOC depletion are being tested on pilot plants, with some already being employed in industries, including: adsorption [3], absorption [4], thermal decomposition [5], catalytic oxidation [6], bio-filtration [7], and membrane separation [8]. Most of these technologies present several economic and efficiency limitations when treating effluents with low VOC concentrations, high airflow rate, and with compounds that have low solubility in water [9]. Plasma can serve as an alternative in the removal of VOCs from gas streams. Various equilibrium and non-equilibrium plasma reactors are being investigated, and their selective efficiency in VOC abatement has been reported in literature reviews [10, 11]. Equilibrium plasmas are also thermal ones, since charges and neutrals are produced at high temperatures of the order of 10\({}^{4}\) K. Thermal plasmas such as torches and arches are employed for differentpurposes, including, for instance, in the gasification of coal [12] as well as in the waste gas decomposition of hard-to-convert components such as Perfluorocarbons PFCs [13]. These plasmas have the advantage of high and fast dissociation rates and rather good efficiency, but most of them are characterized by high energetic consumption, which is required to sustain the discharge itself, and high maintenance and equipment costs. They often employ noble gas carriers, liquids, or vapor water [14]. Although they can be used for the abatement of harmful toxic gases, they are economically unsustainable for the abatement of VOCs at low concentrations. Non-equilibrium plasmas, often called Non-Thermal Plasmas (NTPs), can instead be sustained with lower energy than Thermal Plasmas. NTPs are very weakly ionized and are not in thermodynamic equilibrium because electrons absorb most of the electromagnetic energy, reaching temperatures of several eV, while ionic species and neutral kinetic energies remain at room temperature. For this reason, they are also called cold plasmas. NTPs are generated by using different types of devices such as the dielectric barrier discharge [10], gliding arc discharge [15], microwave plasma [16], and plasma jets [17; 18]. Nowadays, they are employed in several environmental applications. For instance, some NTPs such as plasma jets and microwaves are intensively studied for reforming methane and carbon dioxide because of their high efficiency [16], while DBDs are often used for the removal of VOCs at low concentrations, and also for odor abatement in combination with catalysis [19]. Most of the NTP sources working at atmospheric pressure are called Cold Atmospheric Plasmas (CAPs). The abatement phenomena in CAPs are dominated by kinetic effects, where electrons are the primary source of molecular dissociation and radical formation.