Synthesis of catalytic fibers employing atmospheric pressure arc plasma technology

Summary form only given. Novel catalytic reactors prepared by chemical deposition of platinum group metals are expensive and often fail because of the fusion of ceramic honeycombs caused by overheat. Alternatively, a new generation of catalytic converters containing much cheaper metal oxides, zeolites and other materials that serve as active catalysts have been proposed by authors of present study. Recently the authors realized novel technology for deposition of mineral fibers in the activated state of medium (plasma ambient) where the individual types of particles, e.g. ions, electrons and neutrals can be grouped in accordance with different temperatures. So, the goal of the work was to obtain catalytic fibers including different phases with highly developed surface for catalytic application. This study contains results of an investigation of the deposition process of high thermal resistant catalytic fibres, dispersed particles and granules by plasma spray technology. Cu and Cr₂O₃ and their mixtures with 20, 50 and 80% zeolites were injected into air plasma jet generated by DC linear plasma torch (PT). Catalytic fibres were produced in the plasma chemical reactor, directly connected with a PT. The PT was constructed with special modifications to realize non-equilibrium properties in plasma. The following values of the main parameters were used during the production of catalytic fibers: power supply - 50-75 kW, arc current - 150-200 A, arc voltage - 350-450 V, the main flow rate of the plasma forming gas - 10-30 g·s^-1, the additional air flow rate - 1-3 g·s^-1. The mean mass temperature of the gas leaving PT was 3000-3500 K and the mean velocity was 500-650 m·s^-1. Determination of microstructure, elemental and phase composition of the resulting products was carried out using SEM and X-ray diffraction analysis, respectively along with studies of mechanical properties of the material. As th- data of this study show, the use of plasma spraying technology has significant consequence in the formation of high thermal resistant catalytic fiber which represents a new approach in the environmental protection area. As conclusion it can be stated that the use of the nonequilibrium plasma spraying technology at atmospheric pressure demonstrates the ability to obtain catalytic fiber with controlled characteristics suitable for special applications.