Modeling Of Industrial Reactor Research Articles

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

ABSTRACTSteam 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 dt/dp. 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.

Modelling the morphology evolution of polymer materials undergoing phase separation

This contribution models the morphology evolution of hetero-phase polymers that undergo phase separation and inversion during their formation. High impact polystyrene (HIPS) is a selected representative of hetero-phase polymers with double-emulsion (or ‘salami’) morphology, because it consists of the continuous polystyrene (PS) phase with dispersed micron-sized polybutadiene (PB) particles containing sub-micron occlusions of the partially grafted copolymer (PB-g-PS). Our modelling effort builds on the work of Nauman and He (2001) [1], but addresses the weakest point of the Cahn–Hilliard model applied to HIPS evolution: the Ostwald ripening, which is in reality suppressed or reduced by grafting. Phase inversion is the most critical but so far least-modelled step in double-emulsion morphology evolution. Therefore we demonstrate the modelling of all three experimentally observed mechanisms of double-emulsion formation: (i) encapsulation of PS particles into PB domains by shear forces, (ii) thermodynamically consistent reaction-induced phase separation, and (iii) preservation of graft-stabilized PS particles through the phase inversion. We stress out the requirement of proper setting of three-component (polystyrene–polybutadiene–styrene) thermodynamics as the basis for the realistic description of the phenomena occurring during the evolution of hetero-phase morphology. We thus present the first phenomenological model capable to describe all principal steps in the HIPS double-emulsion morphology evolution and can thus conclude with the discussion of future efforts aimed at its quantitative refinement and modelling of industrial reactors.

ChemInform Abstract: Role of Chemical Kinetics in the Heterogeneous Catalysis Studies

AbstractReview: 131 refs.

Role of Chemical Kinetics in the Heterogeneous Catalysis Studies

The paper presents shortly some of the important elements of the theory and of the practical applications of the kinetics of heterogeneous catalytic reactions. Discussed are some of the most important concepts of the kinetics of complex heterogeneous catalytic reactions, methodology of building kinetic models and mathematical treatment of experimental data, influence of heat and mass transfer, types of laboratory reactors, kinetics and nanosized catalysts and others. Examples for use of the kinetic studies for the development and application of industrial catalysts and modeling of industrial reactors are presented.

Bisphenol A synthesis – modeling of industrial reactor and catalyst deactivation

Bisphenol A is an important starting material for production of epoxy resins and polycarbonates, which is manufactured by ion exchanger resin catalyzed condensation of acetone and phenol. Much higher reaction rate is achieved when in the reaction environment are present meracpto-group containing compounds. Alternatively, the promoter can be either dissolved in the reaction mixture or immobilized in the resin catalyst. Important problem of the process using the promoted catalyst is relatively rapid catalyst deactivation. Analysis of the reactor operation and mathematical modeling of its behavior indicate that the cause of the deactivation is a poison in the reaction mixture inhibiting the promoter. Proper design of laboratory experiments allows investigation of the deactivation process within acceptable time period and testing of possible preventive actions.