GlidArc assisted preparation of the synthesis gas from natural and waste hydrocarbons gases

This article reviews utilisation of plasmas as activation media for the partial oxidation of natural or associated gases to produce synthesis gas (H-2 + CO). These feedstocks can also be converted into syngas via plasma-assisted steam reforming. In this case plasmas play a role as catalysts and, at the same time, provide the very active and necessary energy for such reactions, which are endothermic this time. Finally, the same plasmas can be useful for another endothermic reaction, the direct conversion of hydrocarbon gases with high contents of CO2 (such as biogas or certain acid natural gases) into syngas. Two bench-scale plasma reactors were used for the conversion tests: a controlled arc reactor and a more recent, multiple-gliding-arc reactor (GlidArc). In the last one, operating at up to 0.4 MPa pressure, one obtains almost total conversion of the natural gas (1.3 m(3)(n)/h) via partial oxidation-with an energy requirement of only 0.11 kWh for 1 m(3)(n) of syngas at a H-2/CO molar ratio close to 2 when using pure oxygen as the reactant. With enriched air (45% O-2), the energy requirement is 0.24 kWh. A pilot of 100 m(3)(n)/h syngas is currently undergoing field trials on natural gas.