Theoretical investigation of hydrogen sulfide capture from methane binary mixture using s-heptazine-based metal-organic framework

CONTEXT

MOFs are promising candidates for the capture of H2S and CO2 from raw biogas. The presence of H2S residues in natural gas pipelines can cause corrosive damage and reduce energy efficiency. H2S capture from biogas presents several challenges due to its high toxicity and its corrosiveness. Microporous MOFs incorporating Lewis basic sites have demonstrated efficient capture of small and polar gas molecules such as CO2 and H2S from gas binary mixtures. In the quest to design and investigate functional materials to support the energy transition, specifically for the purification of RNG gas, we theoretically investigated the potential of s-heptazine-based IRH-1 for H2S capture from CH4 mixtures. IRH-1 exhibited significantly higher adsorption capacities for H2S (2.60 mmol/g) and CO2 (2.68 mmol/g) compared to CH4 (0.98 mmol/g) at 100 kPa and 298 K simulated by GCMC. All computed average energies for H2S were below 20 kJ/mol, indicating an exothermic physisorption behavior within the pores of IRH-1. IAST revealed remarkable H2S selectivity of IRH-1 for CH4/H2S binary mixtures at 5%, 10%, 15%, and 20% of H2S at 100 kPa.

METHODS

GCMC simulations were performed with the BIOVIA Materials Studio 5.0 package using LJ potentials and UFF parameters to investigate the adsorption of pure H2S gas in the IRH-1 material. The IAST method was used to predict the adsorption behavior of H2S in different H2S/CH4 gas mixtures. The IAST calculations were performed using the Python package pyIAST, which allows the prediction of adsorption isotherms for mixed gases based on the adsorption isotherms for pure gases by numerical integration of the Gibbs adsorption approach.

Two different pore architectures of Cyamelurate-Based Metal-Organic Frameworks for Highly Selective CO2 Capture at Ambient Conditions

In the context of the coordination chemistry of metal-organic frameworks (MOFs) toward CO2 capture and separation, two new microporous MOFs termed IRHs (6 and 7) were synthesized with square and...

Missing Puzzle in Crystal Engineering: 2-Pyridone and [1,3,5]-Triazine-2,4-diamine, the Two Most Common Cyclic Hydrogen Bonding Sticky Sites, in a Single Core

Herein, we report a facile method for the synthesis of eight structurally diverse compounds 1-8 bearing hydrogen bonding functional group – diaminotriazine (DAT) along with pyridine and polyether groups for...

Flexible and porous 2D layered structures based on mixed-linker metal-organic frameworks for gas sorption studies

Layered structures of flexible mixed-linker metal-organic frameworks termed IRHs-(4 and 5) (IRH = Institut de Recherche sur l'Hydrogène) were synthesized by mixing cyclam, tetrakis(4-carboxyphenyl)benzene (TCPB), and copper and zinc metal salts respectively. The new materials characterized by single-crystal X-ray diffraction exhibited the features of HOFs and MOFs. Their structures are formed by coordination and hydrogen bonds that link metallocyclam (with Cu or Zn) and TCPB to a 2D sheet which is further packed to form a 3D structure with 1D microchannels. Remarkably, the as-synthesized IRHs-(4 and 5) contain DMF in the channels that can be exchanged with DCM and afterward removed from the framework by heating without losing their single-crystallinity. This enabled an easy elucidation of the structural transformations by single-crystal and powder X-ray diffraction analyses. Experimental studies of single-component adsorption isotherms of pure CO2, CH4, and N2 gases have been carried out for all activated IRHs. Based on the obtained adsorption isotherms, theoretical calculations using Ideal Adsorbed Solution Theory (IAST) have been performed to predict the selectivity of equimolar CO2/CH4 and CO2/N2 (1 : 1) binary mixtures. The simulations predicted outstanding selectivity for CO2/N2 than for CO2/CH4 at low pressures, reaching 185 for IRH-4 and 130 for IRH-5 at 1 bar.

IL-22BP is produced by eosinophils in human gut and blocks IL-22 protective actions during colitis

Crohn's disease and ulcerative colitis, the two major forms of inflammatory bowel diseases (IBDs), are characterized by high levels of IL-22 production. Rodent studies revealed that this cytokine is protective during colitis but whether this is true in IBDs is unclear. We show here that levels of the soluble inhibitor of IL-22, interleukin 22-binding protein (IL-22BP), are significantly enhanced during IBDs owing to increased numbers of IL-22BP-producing eosinophils, that we unexpectedly identify as the most abundant source of IL-22BP protein in human gut. In addition, using IL-22BP-deficient rats, we confirm that endogenous IL-22BP is effective at blocking protective actions of IL-22 during acute colitis. In conclusion, our study provides new important insights regarding the biology of IL-22 and IL-22BP in the gut and indicates that protective actions of IL-22 are likely to be suboptimal in IBDs thus making IL-22BP a new relevant therapeutic target.