Fluidized bed plasmas reactor for catalyst pretreatment. Application for SCR NOx by hydrocarbons in stationary and mobile sources

Introduction Nowadays, almost all major chemicals are produced by catalytic processes. Among them, heterogeneous catalysis plays a very active role, because of environmental concerns. The use of plasmas for catalysis is now well developed and some authors have used plasma treatment in a low pressure system to replace the thermal calcination of the catalysts [1]Fluidized bed reactors offer the possibility to lead to homogeneous treatment and have the additional advantage of excellent heat transfer rates between the gas and the particles, so that it can modify the catalytic properties of the prepared materials [2,3]. The aim of our work is to prepare catalysts dedicated to NOx abatement in stationary (natural gas combine heat power) or mobile sources (Diesel engines). For stationary sources, the palladium based catalyst was chosen since the main reducing agent is methane [4]. In the case of mobile sources, we have worked with silver [5] based catalysts since ethanol can be chosen as a reducer for mobile sources to replace NH3 [6]. After the preparation of the different catalysts, we have used the low fluidized bed plasma reactor to modify Pd/γ-alumina and Ag/γalumina catalysts. A comparison with “classical calcination” in air at 500°C was performed in order to show the advantages of plasma treatments. Concerning the plasma process, we have studied the role of the plasma treatment time as well as the nature of the gas treatment (Ar and Ar/O2). The characterization of the catalysts is in course in order to understand the influence of plasma treatment parameters on catalytic results.