Greenhouse gas treatment and H2 production, by warm plasma reforming

Abstract

Global warming is a worrying problem that has a direct negative impact on climate change, so it is necessary for all countries to reduce emissions of greenhouse gases (GHGs) and emergent treatment technologies are developing through worldwide. In this paper, a relatively new technique is proposed for the GHGs of gases using a warm plasma reactor. Carbon dioxide (CO2) and methane (CH4) have been identified as the most significant GHGs arising from anthropogenic activities, affecting the climatic global change. The technique here used is the so called Dry Reforming, assisted by a warm plasma reactor, including the reactants treatment, synthesis gas generation, and finally the syngas production (H2 + CO). The gases CO2 and CH4 are relatively stable compounds with low potential energies. The dry reforming is an endothermic reaction and external energy must be provided in order to achieve the targets inquired. More recently, plasma gas reforming is emphasized as promising technique for energy saving and environment safe purposes with increasing demand of hydrogen and synthesis gas production. In the case of plasma reforming, high electron energy provides not only radical species, but also the enthalpy required for endothermic reaction. The conversion of hydrocarbon in by-products with high added value is mainly contributed by dissociation and ionization processes. With respect to other techniques of hydrocarbons reforming by plasma discharges, there are enough references related to RF plasma discharges operating at reduced pressures, even if these low pressure plasma could achieve high hydrocarbon conversion and good H2 selectivity; the low H2 production rate and extra energy requirement for vacuum device constrain its practical use, therefore an alternative procedure and system consisting in a novel plasma reactor is here proposed. Warm plasma is environment-friendly and auto-sustainable processes, besides the electric discharge has low specific energy requirement still maintaining enough high temperature (1000–3000 K) to produce excited species, supporting subsequent chemical reactions. Such plasma discharges have significant advantages: Do not require extra cooling systems, since they work with reduced electric current flows and high voltages, avoiding electrodes erosion. Consequently, reactors can be achieved with a simpler outline and high capacity gas treatment.