Influence of Surface Basic Sites and Oxygen Vacancies on the Performance of Metal-Modified Rod-Like Ceria Catalysts for Low-Temperature Hydrolysis of Carbonyl Sulfide

This study utilized a hydrothermal method to synthesize various metal-modified rod-like ceria catalysts (Fe, Co, Cu, Ni, La), achieving efficient COS removal at low temperatures. The research identified surface oxygen vacancies and basic sites as critical factors that influence the catalytic performance of COS hydrolysis. The addition of different metals to pristine ceria rods increased the specific surface area, oxygen vacancy content (Ov), and basicity, which enhanced the catalysts' sulfur resistance and stability. Among all the catalysts tested, 10La-CeO2 demonstrated the highest COS removal rate. This is because La doping significantly augmented Ov, providing more H2O adsorption and activation sites. Furthermore, 10La-CeO2 showed enhanced Lewis basicity, making it easier for COS to adsorb and promote hydrolysis. The in situ DRIFTS results confirmed that appropriate oxygen vacancies and basic sites favored the formation of intermediates such as HCO3 - and HSCO2 -, promoting the decomposition of COS into H2S and CO2.

Progress on hydrogen sulfide removal: From catalytic oxidation to plasma-assisted treatment

Air pollution is a long-standing environmental challenge as well an important economic subject. Hydrogen sulfide is one the major pollutants in the industrial releases. This review focuses on the thermochemical treatment of hydrogen sulfide based on the most recent works to date regarding its removal. By analyzing fundamental steps in chemical reaction engineering, some useful factors are emphasized since they are often neglected in scientific studies, catalysts design and process scale-up. From processing side, the fluid flow conditions including velocity, H2S concentration, relative humidity, temperature and pressure strongly influence the kinetic behavior and so the catalytic performance of the H2S removal reactor. From material side, the catalyst properties including nature, porosity, pore types, size, sites distribution and layer structuration largely influence the removal performance via among others the accessibility to catalytic sites, pores connection and mass transfer resistance. Plasma-assisted catalytic removal of H2S combines many novelties in comparison with a classical thermo-catalytic process. From patents review, we can see that main concerns are about electrodes mounting, reactor lifetime and modular design to solve the problems in the industrial practice. We attempt to provide for scientists, engineers and industrialists a guidance on the design of catalysts and processes for H2S removal which could be applied in laboratorial studies and industrial processes as well.

Efficiently Integrated Desulfurization from Natural Gas over Zn-ZIF-Derived Hierarchical Lamellar Carbon Frameworks

Selective removal of carbonyl sulfide (COS) and hydrogen sulfide (H₂S) is the key step for natural gas desulfurization due to the highly toxic and corrosive features of these gaseous sulfides, and efficient and stable desulfurizers are urgently needed in the industry. Herein, we report a class of nitrogen-functionalized, hierarchically lamellar carbon frameworks (N-HLCF-xs), which are obtained from the structural transformation of Zn zeolitic imidazolate frameworks via controllable carbonization. The N-HLCF-xs possess the desirable characteristics of large Brunauer-Emmett-Teller surface areas (645-923 m²/g), combined primary three-dimensional microporosity and secondary two-dimensional lamellar microstructure, and high density of nitrogen base sites with enhanced pyridine ratio (17.52 wt %, 59.91%). The anchored nitrogen base sites in N-HLCF-xs show improved accessibility, which boosts their interaction with acidic COS and H₂S. As expected, N-HLCF-xs can be employed as multifunctional and efficient desulfurizers for selective removal of COS and H₂S from natural gas. COS was first transformed into H₂S via catalytic hydrolysis, and the produced H₂S was then captured and separated and catalyzed oxidation into elemental sulfur. The above continuous processes can be achieved with solo N-HLCF-xs, giving extremely high efficiencies and reusability. Their integrated desulfurization performance was better than many desulfurizers used in the area, such as activated carbon, β zeolite, MIL-101(Fe), K₂CO₃/γ-Al₂O₃, and FeO_x/TiO₂.

The role of nickel–iron based layered double hydroxide on the crystallinity, electrochemical performance, and thermal and mechanical properties of the poly(ethylene-oxide) solid electrolyte

The electrochemical performance and physical properties of PEO-based composite electrolytes were improved with the addition of a NILDH filler.