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Considering water vapor is a component in almost all CO2-rich industrial gas streams, it is of critical importance to understand interaction mechanisms between adsorbent and adsorbate. This paper aims to comprehensively analyze water effect on CO2 adsorption for metal-organic framework (MOF) in a broad working pressure range which may bring some new insights based on a molecular simulation. First, Mg-MOF-74 is selected and synthesized according to previous literature. Equilibrium adsorption capacity and enthalpy are obtained by grand canonical Monte Carlo simulation, and the results for high-pressure CO2 adsorption are validated through magnetic suspension balance experiment. It is indicated that there are three adsorption stages for pure CO2 and four adsorption stages for pure H2O under different pressure. Adsorption enthalpy also varies with adsorption capacity, which is fully explained from the angle of adsorption stages and energies. Further simulation of flue gas (CO2/H2O/N2) adsorption at different humidity are carried out, and selectivity between CO2 and H2O is analyzed. At 298 K, 100 kPa, with 3% water content, CO2/H2O selectivity is 5.6 × 10−5. When temperature rises to 388 K, CO2/H2O selectivity rises to 6.2 × 10−3. Adsorption density distributions, simulation snapshots, and radial distribution functions are used in analysis processes, which could provide a general perspective for analyzing CO2 adsorbents in the presence of H2O.

Pd speciation induced by the combined effect of CO and water on Pd/SSZ-13 samples prepared by both impregnation and ion exchange was examined by FT-IR spectroscopy of CO adsorbed at room temperature and at liquid nitrogen temperature on anhydrous and hydrated samples. Starting from the literature findings related to the CO reducing effect on Pd cations, the present work gives precise spectroscopic evidences on how water is necessary in this process not only for compensating with H + the zeolite exchange sites set free by Pd reduction, but also for mobilizing isolated Pd 2+ /Pd + cations and making possible the reduction reactions. The aggregation of some Pd + sites, just formed by the reduction and mobilized by the hydration, gives rise to the formation of Pd 2 O particles. Also, Pd 0 (100) sites are observed with CO on hydrated sample, formed by the aggregation and reduction of isolated Pd cations. Moreover, Pd 0 (111) sites are formed on the surface of PdO x particles during CO outgassing. The observation of the combined effect of water and CO allowed to define assignments of IR bands related to carbonyls of Pd in different oxidation states and coordination degrees., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

In the field of nitrogen oxides (NO x ) abatement, developing selective catalytic reduction (SCR) catalysts that can operate stably in the practical conditions remains a big challenge because of the complexity and uncertainty of actual flue gas emissions. As water vapor is unavoidable in the actual flue gas, it is indispensable to explore its effect on the performance of SCR catalysts. Many studies have proved that the effects of H 2 O on de-NO x activity of SCR catalysts were indeed observed during SCR reactions operated under wet conditions. Whether the effect is promotive or inhibitory depends on the reaction conditions, catalyst types and reducing agents used in SCR reaction. This review focuses on the effect of H 2 O on SCR catalysts and SCR reaction, including promoting effect, inhibiting effect, as well as the effecting mechanism. Besides, various strategies for developing a water-resistant SCR catalyst are also included. We hope that this work can give a more comprehensive insight into the effects of H 2 O on SCR catalysts and help with the rational design of water-resistant SCR catalysts for further practical application in NO x abatement field., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

A series of well-mixed Ce-containing MgAlCe rare earth catalysts derived from layered double hydroxides were synthesized and tested for H 2 S selective catalytic oxidation. Particularly, no chemisorption O-vacancies but intrinsic defect sites were present on catalyst surface. Significantly, the catalysts exhibited excellent catalytic activity, reasonable durability, and outstanding sulfur selectivity (100%) at relatively low temperatures. Furthermore, the catalyst followed a step-wise mechanism, and the catalyst deactivation was due mainly to the slower oxidation rate of Ce 3+ to Ce 4+ by O 2 as compared to the reduction rate of Ce 4+ to Ce 3+ by H 2 S. Particularly, the added water, a Lewis base, can compete with inefficient S 8 catalyst for the occupation of Lewis acid sites and active sites. Meanwhile, it can change the characteristics of catalyst surface, resulting in sulfur existing form transforming from inefficient S 8 catalyst to inactive S 3 . Thus, lead to a decrease of deposited inefficient S 8 catalyst content. Consequently, decrease the catalytic activity., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The tautomerism of curcumin has been investigated in ethanol/water binary mixtures by using UV-Vis spectroscopy and advanced quantum-chemical calculations. The spectral changes were processed by using advanced chemometric procedure, based on resolution of overlapping bands technique. As a result, molar fractions of the tautomers and their individual spectra have been estimated. It has been shown that in ethanol the enol-keto tautomer only is presented. The addition of water leads to appearance of a new spectral band, which was assigned to the diketo tautomeric form. The results show that in 90% water/10% ethanol the diketo form is dominating. The observed shift in the equilibrium is explained by the quantum chemical calculations, which show that water molecules stabilize diketo tautomer through formation of stable complexes. To our best knowledge we report for the first time quantitative data for the tautomerism of curcumin and the effect of the water., (Copyright © 2014 Elsevier B.V. All rights reserved.)