Rapid kinetic measurements in ammonia and methanol syntheses

Kinetic measurements in heterogeneous catalysis are essential for the deriv ation of rate expressions that are necessary for the design of reactors and that can serve for data extrapolation beyond the measured data range. To a ccelerate the acquisition of kinetic data, the method of quasi-isothermal t emperature-programming has been applied to a study of the kinetics of the a mmonia and methanol syntheses. Both reactions were performed in a microcata lytic reactor setup near industrial reaction conditions. For the ammonia sy nthesis, the technique turned out to be a useful screening method for Ru-ba sed catalysts, which allowed power-law rate expressions to be derived rapid ly. Moreover, the in situ temperature-programmed surface reaction of N-* wi th gas-phase H-2 (N-* TPSR) was studied in detail, allowing for its applica tion as a fast method for catalyst screening within the class of unpromoted Ru-based catalysts. However, in the methanol synthesis, the applicability of the quasi-isothermal temperature-programmed method is limited to qualita tive catalyst screening because of the methanol adsorbing capacity and the slow change of the state of the working Cu/ZnO/Al2O3 catalyst.