New Solvents for CO2 and H2S Removal from Gaseous Streams

Abstract

Acid gas removal from gaseous streams such as flue gas, natural gas and biogas is mainly performed by chemical absorption with amines, but the process is highly energy intensive and can generate emissions of harmful compounds to the atmosphere. Considering the emerging interest in carbon capture, mainly associated with increasing environmental concerns, there is much current effort to develop innovative solvents able to lower the energy and environmental impact of the acid gas removal processes. To be competitive, the new blends must show a CO2 uptake capacity comparable to the one of the traditional MEA benchmark solution. In this work, a review of the state of the art of attractive solvents alternative to the traditional MEA amine blend for acid gas removal is presented. These novel solvents are classified into three main classes: biphasic blends—involving the formation of two liquid phases, water-lean solvents and green solvents. For each solvent, the peculiar features, the level of technological development and the main expected pros and cons are discussed. At the end, a summary on the most promising perspectives and on the major limitations is provided.

Reviewing and screening ionic liquids and deep eutectic solvents for effective CO2 capture

“…and [ChCl][EG] were included as physical absorption, and phosphonium-, amine-, imidazolium-, and choline-based ILs were collected as the chemical absorption Sood et al (2021). evaluated the recent advances in the IL-based CO 2 capture in 2017-2020/2021, in which imidazolium-, phosphonium-, and amine-based ILs were reviewed, and [EMIM][NTF 2 ] was identified as a profitable IL Pellegrini et al (2021). introduced ILs as the water-lean solvent for CO 2 capture, and amine-, imidazolium-, and ammonium-based ILs were specifically discussed.…”

Integrated CO2capture and electrochemical upgradation: the underpinning mechanism and techno-chemical analysis

“…352 In contrast to that, microporous adsorbents with pore sizes between 0.35–0.8 nm had low surface areas and small pore volumes along with low CO 2 uptake capacity at high pressure. 264 Thus, the relative enhancement of CO 2 separation performance (uptake, selectivity) in the low-pressure limit 0.05–0.15 bar, upon the reduction of the pore size, is well established and corroborated that the pore opening was large enough to allow optimal gas diffusion, as well as the implementation of suitable charge density. Furthermore, the reduction in the pore size close to 0.33 nm may lead to an enhancement of CO 2 selectivity by the molecular sieving mechanism through gas diffusion.…”

“…The high viscosity of traditional ILs is a vital problem for their CO 2 capturing ability. 261,264 In order to solve this, DES with multiple polyols and several nitrogen functionalities has been synthesized. The introduced hydroxyl groups are considered to be associated with the CO 2 reaction during absorption.…”

“…However, for fabrication purposes, the huge choice of inorganic clusters and organic linkers for MOFs and specific functional groups like imidine for COFs suggest that they can be easily tuned unlike activated carbon and zeolites. Although it is difficult to monitor the structure of MOFs and COFs to control the porosity during post-combustion CO 2 capture, 264 the mammoth focus by several research groups to increase the CO 2 selectivity may open up a new door for its future implementation into the integrated coupling process for scaling up on the industrial scale.…”

Selecting Technologies for Sour and Ultra‐Sour Gas Treating

“…Most of these mixtures, often defined as ''hybrid solvents'', are still at the development stage [75]. A review of these new blends for sour gas applications is available in Pellegrini et al [76], while the already commercial technologies are reported in Tab. 5.…”