Hydrogenation of acetylene-ethylene mixtures on Pd catalysts: study of the surface mechanism by computational approaches. Metal dispersion and catalytic activity

IDEA: Interface dynamics and energetics algorithm

“…The molecular events and the corresponding energy flows, involved in the adsorption-desorption processes, were mimicked by using models framed in the statistical and in the classical thermodynamics, respectively. The basis details on the molecular events were, until now, taken from experimental data, but, as already done for other surface systems, 19,20,28,29 we think to integrate, in the future, the details mentioned earlier by qc information.…”

“…Employing IDEA, we try to describe a possible origin of the ASE distributions 18,19 and to reproduce and predict their connected phenomena, taking place within CO/metal adsorption-desorption processes. In this aim, the occurrence of local surface events and the consequent energy gradients and flows, arising on the surface and into the bulk of the metal crystallite, were studied.…”

“…25 However, here, we chose to employ the simple algorithmic approach, which already showed to be able to manage the "real time" seriality of catalytic events and the consequent local energetic effects, reproducing experimental results. 15,16,18,19,26,27 In fact, many experimental findings, concerning the hydrogenation on metal catalysts of unsaturated hydrocarbons 15,16,18 of their mixtures 19,26 and of nitro-derivatives, 27 were easily reproduced and rationalized by employing the tdMC codes.…”

“…19,20,28,29 Thereafter, the number of "arbitrary" parameters used in these qc-tdMC simulations was dramatically decreased, stimulating the deep analysis of concurrent, and usually nonconsidered, aspects involved in the heterogeneous processes. In this context, the available surface energy (ASE) concept was hypothesized and parameterized in the tdMC models.…”

“…1,2 The design of the time-dependent Monte Carlo (tdMC) algorithms, 3,4 as well as of other equilibrium and nonequilibrium Monte Carlo (MC) and Cellular Automata approaches, [5][6][7][8][9] followed the need of getting deeper insights on the kinetics and the reaction mechanisms also involved in heterogeneous catalysis. [10][11][12][13][14][15][16] The tdMC codes, to be used in catalytic applications, were built, in developing the ZGB-MC 17 model, by introducing dedicated subroutines, 15,16,[18][19][20][21] allowing for "real time" dynamic studies. The catalytic tdMC codes-the only to which we will refer from now on-constitute as, in general, the ZGB-MC ones, nonequilibrium examples of algorithmic, 22 random selection method (RSM) 23 like, and dynamic Monte Carlo (DMC) 24 approaches.…”