A new energy efficient process for hydrogen purification using ZIF-8/glycol-water slurry: Experimental study and process modeling

Effective recovery of hydrogen from refinery off-gas and coke oven gas, in which hydrogen and methane are key components, is increasingly important for the development of hydrogen energy. In this paper, we introduced a new energy efficient process for hydrogen purification from CH4/H-2 mixture. Firstly, we conducted a phase equilibrium experimental study for CH4/H-2 in zeolitic imidazolate framework-8 (ZIF-8)/glycol-water slurry. The simple absorption and desorption configuration is adopted for the continuous separation of CH4/H-2 using ZIF-8/glycol-water slurry. The multi-stage pseudo-absorption modeling approach was introduced for the modeling and simulation of the absorption-adsorption and desorption columns via using multiple flash modules in Aspen Plus. The binary interaction parameters in the thermodynamic model were fitted by experimental data within an acceptable error (4.93%). The operating conditions (i.e., the number of theoretical stages, feed stage, flash pressure, and desorption pressure) were determined to increase H-2 concentration in product and H-2 recovery ratio. The energy performance of the process was also evaluated. Given the feed gas contains 50 mol% H-2, the gas-slurry volume ratio of 43.27 is required to produce 95 mol% H-2 with a high recovery of 97.94%. The total energy consumption per unit volume of product is 0.06254 kW.h/Nm(3). Results indicate that the hybrid absorption-adsorption process is a promising energy efficient technique to separate CH4/H-2 in the future. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

This paper introduces a new energy efficient process for hydrogen purification from CH4/H-2 mixture in refinery off-gas and coke oven gas. Through experimental and simulation studies, operating conditions and energy consumption were determined, demonstrating the promising application prospects of this process.