(583b) Design and Intensification of Sorption-Enhanced Reaction Processes for Methanol Production

Methanol is a viable alternate fuel to depleting oil and gas reserves, and is one of the most advantageous chemicals due to clean burning, CO₂ utilization and as a raw material for synthesizing hydrocarbons [1]. Since the commercialization of methanol production in 1923, the process has undergone significant improvements [2]. However, even after improved process efficiency, the current methanol production process from syngas is equilibrium-limited and is one of the largest energy consumers in chemical industry [3]. The process inefficiencies include low single-pass conversions, low methanol yield and selectivity, high energy consumption and equipment cost, and catalyst deactivation [4].

The objective of this work is to counter currently-existing process inefficiencies by enhancing single-pass reaction conversions and preventing catalyst deactivation. To this end, we apply the sorption enhanced reaction process (SERP) concept for designing a periodic sorption-enhanced methanol synthesis (SE-MeOH) process from syngas; in-situ removal of water byproduct favorably shifts the equilibrium towards enhanced methanol synthesis in accordance with the Le Chatelier’s principle. For capturing the dynamics of the SE-MeOH process, we use the generalized adsorption-reaction modeling and simulation (GRAMS) platform. GRAMS is based on a one-dimensional, pseudo-homogeneous, non-isothermal, non-adiabatic, and non-isobaric NAPDE-based model, and has been extensively validated with experimental data for several SERP case studies [5]. GRAMS is coupled with an in-house simulation-based constrained grey-box optimizer for optimizing SE-MeOH process cycle configuration, design parameters and operating conditions [6][7]. We obtain single-pass carbon conversions as high as 80% in the Lurgi-type Methanol reactor via SE-MeOH with production capacity exceeding 109500 tons/yr, which is the typical capacity of an industrial plant [8]. The developed SE-MeOH process has smaller carbon footprint, enhanced product quality, and smaller reactor, condenser and recompressor size leading to significant savings in energy consumption and process economics. This presentation also covers the integration of the developed SE-MeOH process with a steam methane reforming reactor unit for converting natural gas to methanol via syngas route.

References

[1] G.A. Olah, Beyond oil and gas: the methanol economy, Angew. Chemie Int. Ed. 44 (2005) 2636–2639.

[2] A. Cybulski, Liquid-phase methanol synthesis: catalysts, mechanism, kinetics, chemical equilibria, vapor-liquid equilibria, and modeling—A Review, Catal. Rev. Eng. 36 (1994) 557–615.

[3] A. V Kruglov, Methanol synthesis in a simulated countercurrent moving-bed adsorptive catalytic reactor, Chem. Eng. Sci. 49 (1994) 4699–4716.

[4] M. Kuczynski, M.H. Oyevaar, R.T. Pieters, K.R. Westerterp, Methanol synthesis in a countercurrent gas—solid—solid trickle flow reactor. An experimental study, Chem. Eng. Sci. 42 (1987) 1887–1898.

[5] A. Arora, S.S. Iyer, M.M.F. Hasan, GRAMS: A General Framework Describing Adsorption, Reaction and Sorption-Enhanced Reaction Processes, Submitted. (2018).

[6] A. Arora, I. Bajaj, S.S. Iyer, M.M.F. Hasan, Optimal Synthesis of Periodic Sorption Enhanced Reaction Processes with Application to Hydrogen Production, Comput. Chem. Eng. 115 (2018) 89–111.

[7] I. Bajaj, S.S. Iyer, M.M.F. Hasan, A Trust Region-based Two Phase Algorithm for Constrained Black-box and Grey-box Optimization with Infeasible Initial Point, Comput. Chem. Eng. (2017).

[8] N. Rezaie, A. Jahanmiri, B. Moghtaderi, M.R. Rahimpour, A comparison of homogeneous and heterogeneous dynamic models for industrial methanol reactors in the presence of catalyst deactivation, Chem. Eng. Process. Process Intensif. 44 (2005) 911–921.