Kinetic and reactor performance of a Ni-based catalyst during the production of ethene

Steam cracking of diverse hydrocarbon sources is nowadays the main technology used to produce ethene worldwide, however, it presents energetic and environmental limitations related to the large consumption of energy and production of carbon oxides. To overcome this, industry and academy have aimed their research at developing a new technology based on the oxidative dehydrogenation (ODH) of ethane. Main challenges for its industrial implementation are yet catalyst and industrial reactor design. In this sense, Ni based catalysts have been promising materials for the production of ethene out of ethane at laboratory scale, however there is a scarce amount of researching on engineering aspects related to the evaluation of their performance at industrial scale. This work is aimed at giving insights on the performance of a Ni-loaded Y zeolite catalyst (Ni/KY) during the ethene production via ODH of ethane in an industrial-scale wall-cooled fixed bed catalytic reactor with a low d_t/d_p. To achieve this, an industrial reactor model that couples reaction kinetics to heat and mass transport phenomena is developed following reactor engineering fundamentals. To assess the kinetics of the ODH of ethane over the aforementioned catalyst, a detailed kinetic model is developed using published experiments [J. Catal. 265 (2009) 54–62]. Then, this kinetics is coupled to the industrial-scale reactor model, a 2D heterogeneous model accounting for heat and mass transport. The kinetic model following a Langmuir–Hinshelwood–Hougen–Watson mechanism allows an accurate description of laboratory data. Activation energy, related to the formation of ethene, and enthalpy adsorption of ethene indicate that the production ethene is favored at larger reaction temperatures, however, once it is produced, this olefin is more strongly adsorbed on the catalyst surface than the other byproducts. However, from the parametric sensitivity study applied to the industrial reactor, a larger coolant temperature brings out a significant but positive effect on the yield of ethene whereas a lower concentration of ethane in the feedstock favors the oxydehydrogenation reaction rather than total oxidation reactions. To this end, the proposed industrial reactor technology, along with the Ni/KY material, overcomes the hot spot formation and enables operations at larger temperatures, hence, favoring the production of ethene rather than carbon oxides.