99-24U

# 99-24U

Kinetics of chemical reactions in nitrogen-hydrogen mixtures in the course of catalysis. Some aspects of a statistical description

A topical review of papers concerning chemical kinetic catalysis of ammonia on metal surfaces is presented. The emphasis is on proposed previously mechanisms of ammonia synthesis. One can draw a conclusion that catalytical processes on nanostructures become important. It is due to their large effective catalytic surface. We carry out a numerical calculation of transport coefficients for nitrogen-hydrogen mixture H$_2$, N$_2$, NH$_3$ changing the ammonia concentration ratio at one temperature value 450 $^0$C and three fixed values of pressure $p=70$, $p=110$ і $p=150$ atm. in a bulk phase. It was shown that bulk viscosity coefficient varies together with pressure changing the most, whereas shear viscosity and thermal conductivity vary slightly. Taking into consideration for dipole interactions between mixture components both quantitatively and qualitatively influences on a behaviour of transport coefficients. We also present a microscopic theory of electron kinetic and atomic diffusion processes in a system "metal -- adsorbate -- gas". With the help of nonequilibrium statistical operator method a generalized kinetic equation for one-electron density matrix is obtained. It is connected closely with generalized diffusion equation of adsorbed and not adsorbed gas atoms on a metal surface.