(422b) Methanol Production through an Innovative Reactor: Analysis and Comparison

Methanol, nowadays has wide applications in both chemical industries and energy carriers. Methanol has high energy density (22.7 MJ/kg or 18 MJ/L) which helps in relatively easy storage and transportation. As an intermediate chemical, methanol can be further converted into various chemical products such as kerosene, sustainable aviation fuel (SAF) and dimethyl ether (DME) [1]. The global market size of methanol reached $36.0 billion in 2023 and was estimated to grow with a compound annual growth rate of 8.9 % [2]. Typically, methanol is produced from fossil-based fuels such as natural gas and coal that are converted into syngas. In addition to these conventional routes, greener routes are suggested starting from biomass or carbon dioxide [3].

Different reactors are used for methanol production and a deep analysis and review is reported in Manenti and Bozzano [4]. Here, methanol reactors can be either shell-and-tube, shell-and-coil or shell-and-plate type, with the catalyst installed either on tube/coil/plate-side or on shell-side. Methanol reactors can be either adiabatic or isothermal. Major advantages and disadvantages of some commercial methanol reactors as reported in Ebrahimzadeh Sarvestani [5].

Reactor configurations proposed in the literature aims to generally overcome thermodynamic limitations of this reaction synthesis [6, 7]. However, in addition to the thermodynamic limitation, a limit imposed by the kinetic is also present in methanol production. In this context, an innovative solution to optimize operating conditions from thermodynamic and kinetic standpoints is to install in the reactor different operating conditions of the coolant.

According to these considerations, a new methanol reactor, called as double-zone methanol reactor (DZMR), is proposed in this work. The shell-and-tube DZMR is characterized by a configuration aimed to install non-isothermal conditions on the coolant-side. In particular, the DZMR has the shell-side split into two zones operating with the coolant at different temperatures to locally better fit thermodynamic and kinetic of the methanol synthesis. Moreover, a fraction of oil is added in the second zone through an annular duct surrounding the tube side.

This work models and analyses a small-scale DZMR cooled by a diathermic oil. In particular, several operating schemes for the DZMR are compared in order to individuate the optimal configuration. The considered schemes are the following: conventional (no addition of oil in the annular duct and both shell-side zones are isothermal at the same temperature), innovative A (the oil in the first zone is non isothermal while is isothermal in the second zone and hot or cold fraction oil can be added into the annular duct), innovative B (the oil in both zones is isothermal but at different temperatures and hot or cold fraction oil can be added into the annular duct).

The proposed scheme reactors are modelled in Aspen Plus software by using the kinetic model proposed by Graaf et al. [8] and feeding a syngas with a stoichiometric number equal to 2. Technical efficiencies such as methanol production, yield, carbon conversion, oil consumption are evaluated.

Results show that the best reactor configuration is that ensuring non isothermal conditions of oil in the first zone and isothermal conditions of oil in the second zone while a cold fraction of oil at 215 °C is added into the annular duct. The scheme can have a methanol production of 332 ton/year, a carbon conversion of 41% and an oil consumption of 6263 kg/h for the fixed production. Compared to other solutions, this causes lower operating costs (e.g., a lower compression power) because a lower amount of unconverted gases will be recycled in a potential scheme with the recycling stream and for a fixed and same equipment design as in this research. However, the lower recycling stream will affect and reduce the reactor size too.

For future analysis, an economic analysis of the double zone methanol reactor is suggested.

References

[1] M. Makcharoen, A. Kaewchada, N. Akkarawatkhoosith, A. Jaree, Biojet fuel production via deoxygenation of crude palm kernel oil using Pt/C as catalyst in a continuous fixed bed reactor, Energy Convers. Manag. X 12 (2021) 100125

[2] GVR, Methanol market size & trends. https://www.grandviewresearch.com/industry-analysis/methanol-market#:~:…, 2024. December 2024

[3] Agyekum, E.B., Okonkwo, P.C., Rashid, F.L., Research on biomass energy and CO2 conversion to methanol: a combination of conventional and bibliometric review analysis, Carbon Research (2025) 4:4

[4] Manenti, F., Bozzano, G., Efficient methanol synthesis: Perspectives, technologies and optimization strategies, Progress in Energy and Combustion Science, 56, (2016) Pages 71-105

[5] Ebrahimzadeh Sarvestani, M., Norouzi, O., Di Maria, F., Dutta, A., From catalyst development to reactor Design: A comprehensive review of methanol synthesis techniques, Energy Conversion and Management 302, (2024) 118070

[6] Bazmi, M., Gong, J., Jessen, K., Tsotsis, T. Waste CO2 capture and utilization for methanol production via a novel membrane contactor reactor process: Techno-economic analysis (TEA), and comparison with other existing and emerging technologies, Chemical Engineering & Processing: Process Intensification 201, (2024) 109825

[7] Raso, R., Tovar, M., Lasobras, J., Herguido, J., Kumakiri, I., Araki, S., Menendez, M., Zeolite membranes: Comparison in the separation of H2O/H2/CO2 mixtures and test of a reactor for CO2 hydrogenation to methanol, Catalysis Today 364, (2021) 270–275

[8] Graaf, G. H., Stamhuis, E. J., Beenackers, A. A. C. M. Kinetics of Low-Pressure Methanol Synthesis. Chem. Eng. Sci. 43, (1988) 3185−3195.