Abstract
The effects of various operating and design parameters in reactive distillation for methanol synthesis using a polar solvent (tetraglyme) and Cu–Zn-Al2O3 catalyst on the process performance are investigated in this simulation work. It is observed that trade-offs exist between the reaction (reactant conversion) and separation (methanol purity) as these parameters are varied. The most sensitive parameters are the solvent flow rate, temperature of feed streams, reflux ratio, and cooling duties on the stages. Following the parametric studies, optimization of the RD column was performed to maximize the methanol production and recovery. The optimum case resulted in a methanol productivity of 2.7 mol/kgcatalyst h which is an increase of 12.5%, and CO and H2 conversions of 44% and 31% vis-à-vis 39% and 28%, respectively, in the base case. The product purity in the distillate for the optimum case also improved to 87% from 82.4% in the base case. The observed catalyst loading in the optimum cases is explained on the basis of the approach to equilibrium for the methanol synthesis reaction. Based on comparison with the conventional packed bed reactor, it is concluded that a more active catalyst for liquid phase methanol synthesis is needed to make RD competitive in terms of methanol productivity.
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Data Availability
Most of the data generated or analyzed during this study are included in this article and its supplementary information files. It can also be made available from the corresponding author on reasonable request.
Abbreviations
- (r-)WGS:
-
(Reverse) Water gas shift
- DME:
-
Dimethyl ether
- MTBE:
-
Methyl tertiary butyl ether
- PBR:
-
Packed bed (tubular) reactor
- RD:
-
Reactive distillation
- RR:
-
Refluxed rectifier
- RS:
-
Reactive stripper
- TEGDME:
-
Tetraethylene glycol dimethyl ether
- E i :
-
Activation energy for reaction “i”
- F j :
-
Fugacity of species “j”
- k i :
-
Pre-exponential factor of rate expression for reaction “i”
- K eq ,i :
-
Equilibrium constant of reaction “i”
- R :
-
Universal gas constant
- r i :
-
Rate of reaction “i”
- T :
-
Temperature
- T ref :
-
Reference temperature
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Acknowledgements
The authors thank the Industrial Research and Consultancy Centre, Indian Institute of Technology Bombay, and Ministry of Human Resource Development, India, for providing the scholarship to SG during his graduate studentship. We also gratefully acknowledge Aspen Tech for providing the software used in this work. The authors also thank Prof. Ranjan Kumar Malik (Department of Chemical engineering, IIT Bombay) for his suggestions and comments. The authors are also thankful to the anonymous reviewers whose comments helped in increasing the quality of this manuscript.
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Ghosh, S., Seethamraju, S. Process Intensification with a Polar Solvent in Liquid Phase Methanol Synthesis. Process Integr Optim Sustain 5, 827–842 (2021). https://doi.org/10.1007/s41660-021-00180-9
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DOI: https://doi.org/10.1007/s41660-021-00180-9