Kinetic modeling and reactor design of the direct synthesis of dimethyl ether for CO2 valorization. A review

The direct synthesis of dimethyl ether (DME) is considered one of the most attractive routes for valorizing CO2 and syngas on a large scale. DME has a high cetane number and its properties are similar to those of liquefied petroleum gases (LPG). It can be used directly as fuel, selectively converted into hydrocarbons (olefins, aro-matics) or used as H-2 vector. This review explains briefly the advances in the study of the thermodynamics of DME synthesis and in the preparation of suitable catalysts. Subsequently, analyzes in detail the studies regarding the kinetic modeling, reactors design and reaction strategies. Extensive information is given on the kinetic models described in the literature, indicating the catalysts and reaction condition ranges for which the models were proposed. These kinetic models were whether based on those previously proposed separately for methanol synthesis and methanol dehydration stages on monofunctional catalysts, or models specifically proposed for bifunctional catalysts and conditions of the integrated process. Coke deposition is considered the main cause for catalyst deactivation and is quantified with different kinetic models. The presence of H2O in the reaction medium is a limiting factor for the thermodynamics and for the extent of the reactions. This problem is overcome using hydrophilic membrane reactors, whose behavior has been studied by simulation and recently with an experimental system (with an LTA zeolite membrane). Finally, an analysis of the advantages and limitations of the different reactors and the challenges to progress towards the implementation of the direct CO2 to DME synthesis process have been addressed.

Automated summary

This review discusses the synthesis of dimethyl ether (DME) from CO2 and syngas, highlighting the thermodynamics, catalyst preparation, kinetic modeling, reactor design, and reaction strategies. It provides detailed information on the kinetic models proposed in the literature and their corresponding catalyst and reaction conditions. The article also addresses the issue of catalyst deactivation, quantifies coke deposition using various kinetic models, and explores the limitations imposed by the presence of water in the reaction medium. The advantages and limitations of different reactors and the challenges in implementing the direct CO2 to DME synthesis process are also discussed.