Modelling and simulation of a single slit micro packed bed reactor for methanol synthesis

A mathematical model for a single slit packed microstructured reactor-heat exchanger in the synthesis of methanol from syngas was developed. The model constitutes a simplified 3D-pseudo homogeneous approach for a reaction slit with integrated pillar geometry. Literature kinetic rate expressions for methanol synthesis over commercial Cu/ZnO/support type catalysts were applied at 80 bar total pressure, temperature range of 473-558 K, and syngas composition of H$_{2}$/CO/CO$_{2}$/N$_{2}$:65/25/ 5/5 mol%. The model is found capable of predicting experimental CO conversion data with acceptable accuracy. Superior thermal stability of the microchannel upon variation of different parameters such as contact time, feed gas temperature and reaction temperature were shown. The simulation results also reveal that the microchannel reactor can operate free of performance loss due to concentrations field that may arise from overlaid temperature fields. Simulations have also been used to calculate the rapid temperature transients at the inlet. The agreement between simulation results and experimental data signifies the applicability of the developed model for further design and performance optimization of microstructured reactors for methanol synthesis and other exothermic processes

Catalyst Deactivation During One-Step Dimethyl Ether Synthesis from Synthesis Gas

Catalysts for direct synthesis of dimethyl ether (DME) from synthesis gas should essentially contain two functions, i.e., methanol synthesis and methanol dehydration. In the present work, the deactivation of both functions of hybrid catalysts during direct DME synthesis under industrially relevant conditions has been investigated with special focus on the influence of each reaction step on the deactivation of the catalyst function corresponding to the other step. A physical mixture of a Cu–Zn-based methanol synthesis catalyst and a ZSM-5 methanol dehydration catalyst was used. The metallic catalyst appears to deactivate due to Cu sintering, with no apparent effect from the methanol dehydration step under the conditions applied. The acid catalyst deactivates due to accumulation of hydrocarbon species formed in its pores. Synthesis gas composition, i.e., {H}2/CO ratio and {CO}2-content (which directly affects partial pressure of water), seems to influence the zeolite deactivation

Reaktoren für spezielle technisch-chemische Prozesse: Mikrostrukturreaktoren

Mikrostrukturreaktoren haben sich mittlerweile zu einem wichtigen Bestandteil der Prozessintensivierung in der chemischen Verfahrenstechnik entwickelt. Zudem sind sie zu wichtigen Werkzeugen für die Entwicklung neuer Synthesen und die Prozessentwicklung im Labor geworden. Die wesentlichen Charakteristiken, die sich aufgrund der Miniaturisierung ergeben, werden zusammengefasst und Entwicklungen für den industriellen Einsatz und die Prozessentwicklung beschrieben