An Efficient Technique for Ammonia Capture in the Haber–Bosch Process Loop—Membrane-Assisted Gas Absorption

Abstract

The present study continues the development and enhancement of a highly efficient unique hybrid technique—membrane-assisted gas absorption in designing the separation unit, which provides the improvement in mass-transfer of a target component during the ammonia capture process from a process loop of the Haber–Bosch technological route. In order to minimize the absorbent volume to membrane area ratio, the special separation cell was designed based on a combination of two types of hollow fiber membranes, dense gas separation membrane and porous pervaporation membrane. The separation performance tests were implemented under two sets of conditions, sweeping the bore (permeate) side of a cell with helium and hydrogen-nitrogen mix. For both cases, the membrane-assisted gas absorption cell demonstrated high separation efficiency, and the ammonia concentration in the permeate was never lower than 81 mol%; meanwhile, under the hydrogen-nitrogen bore sweep conditions, the ammonia concentration in the permeate reached 97.5 mol% in a single-step process. Nevertheless, there is a product purity–recovery rate trade-off, which is a typical issue for separation processes.

Natural Gas Sweetening via Membrane-Assisted Gas Absorption. Part 1: A Hollow-Fiber Unit with MDEA-Based Absorbent

“…Initially, a group of authors proposed the application of the MAGA method for the removal of acid gases from ammonia, and the method itself was based on the use of plane membranes [33][34][35]. Further works presented the application of hollow fiber membranes for similar purposes [36,37]. In the present work, the application of a similar system (with a different polymer as a membrane material and a different sorbent) for the removal of acid gases from a natural gas stream is proposed.…”