Selective Hydrogenation of 1‐Butene Rich Cuts: the Impact of the Intraparticle Diffusion Limitations on the Selectivity

Abstract

The impact of intraparticle diffusion limitations on the selectivity of an industrial reactor for selective hydrogenation of 1-butyne and 1,3-butadiene contained in 1-butene rich cuts was evaluated. To this end, a simple model of a trickle-bed reactor was employed and actual process operating conditions were chosen. A kinetic model was chosen whose parameters correspond to a commercial catalyst. These parameters were calculated from experiments conducted under industrial operating conditions. The complex diffusion and reaction phenomena occurring inside catalyst pellets placed at different depths of the reactor are comprehensively described. 1-Butene losses in the range 20±30 %, which are usual in commercial plants, were predicted. It was concluded that the operating pressure is crucial for enhancing process selectivity.

Mass transport effects in gas-phase selective hydrogenation of 1,3-butadiene over supported Pd

“…[33][34][35][36] The Barreto group studied the kinetics of selective hydrogenation of butyne-and butadienebutene mixtures in trickle bed reactors. 37,38 They demonstrated that the local concentration of polyunsaturated molecules sharply dropped inside the catalyst grains due to internal mass transfer limitations. These results gave valuable insights into some parameters determining selectivity during selective hydrogenation reactions.…”

Cinética de la hidrogenación catalítica selectiva de 1-Butino y 1, 3-Butadieno en presencia de N-Butenos

“…Para el H 2 se consideró una adsorción disociativa, indicada como la etapa a) en la Tabla II, en sitios (⊙) diferentes a los (x) involucrados en la adsorción de las especies de hidrocarburos. El planteo de un mecanismo "no competitivo" es ampliamente aceptado en la literatura ( [3], [13] y sus referencias). Las etapas de la Tabla II correspondientes a la adsorción del BD, etapa (b), así como las reacciones de hidrogenación de sus intermediarios superficiales, etapas (h), (j) -(l) fueron propuestos en [14].…”

“…El resto de las etapas elementales remanentes, n)-s), correspondientes a las especies superficiales de los n-butenos, son el resultado de experiencias previas en fase vapor [13]. , resultan despreciables frente a la concentración total de sitios activos, [ ] T .…”