Toward the Industrial Exploitation of the Oxidative Dehydrogenation of Ethane over a NiO-SnO2-Based Catalyst: Regime, Parametric Sensitivity, and Optimization Analysis

Abstract

An industrial-scale catalytic reactor for ethylene production via the oxidative dehydrogenation of ethane (ODH-C2) over a highly active and selective SnO2-NiO-based catalyst is investigated using a pseudo-heterogeneous reactor model (describing both the gas and solid phase and making use of effective kinetic and transport coefficients). More particularly, the dominant phenomena at the micro- and macroscale in a packed-bed reactor configuration with a low tube-to-particle diameter ratio (dt/dp) are assessed. First, the relevance of kinetics and transport phenomena on the reactor performance is determined. The evaluation of the corresponding characteristic times demonstrated that axial mass dispersion and axial heat transfer conduction exert a negligible impact on the concentration and temperature profiles obtained in the reactor. Fluid dynamics as well as radial conductive heat transfer mechanisms, on the other hand, must be accounted for in order to have an accurate simulation of the profiles around the hot spot position. A sensitivity analysis allowed assessing the impact of the operating conditions on the performance of the industrial-scale reactor. Temperature and concentration, mainly around the hot spot, are highly sensitive to the inlet particle Reynolds number (Rep), the coolant temperature, and the inlet concentration of ethane and oxygen. Finally, a multi-parametric sensitivity analysis was used to identify the safety operating window leading to the optimal macroscopic performance of the reactor: a coolant temperature between 410 and 440 °C, an inlet concentration of ethane from 2 to 4 mol %, an inlet concentration of oxygen from 10 to 14 mol %, and a Rep from 620 to 1000. Thus, the engineering analysis led to the development of the most simplified yet comprehensive pseudo-heterogeneous model with reduced computational costs, which can be used with confidence in future studies for the industrial implementation of the ODH-C2 catalytic reaction concept.