Catalytic hydrogenation of CO2 to light olefins by using K-doped FeCx catalysts derived from the Fe-chitosan complex

K-doped FeC_x catalysts derived from the carbothermal reduction of the Fe-chitosan complex were investigated and tested in the hydrogenation of CO₂ to light olefins (C_2-6⁼). Catalyst characterization, including bulk composition, porosity, crystallinity, Fe coordination, morphology, surface property, and basicity, was conducted. The physicochemical properties of tested catalysts were correlated with their performances. The mechanistic study discovered that bidentate carbonates, monodentate carbonate, bicarbonate, and formate species were intermediates involved in C_2-6⁼ synthesis. The yield of C_2-6⁼ was found to be dependent on the composition of the carbide phases of K-doped FeC_x catalysts. The most active catalyst, i.e., FeK@CS-(0.5)-py, showed the most promising space-time yield of C_2-6⁼ (13.7 μmol_C2-6=/g_Fe/s).     

Enhanced reversibility of fluorine substituted bis-BN cyclohexane for hydrogen storage: A first-principles approach

Liquid organic hydrogen carrier (LOHC) technology, in which hydrogen is captured in a liquid-phase compound, is a key enabler in realizing hydrogen economy. Among the LOHC materials, bis-BN cyclohexane is thermodynamically stable at 150°C and does not release detectable volatile contaminants during catalytic dehydrogenation at room temperature. In this study, we identified other potential bis-BN cyclohexane-based hydrogen storage materials with improved dehydrogenation efficiency and reversibility using density functional theory (DFT) calculations. The dehydrogenation mechanisms of bis-BN cyclohexane with and without functional group (F, Cl, NH₂, CH₃, and CN) substitutions were investigated by calculating the reaction enthalpies and free energies. With the Pt catalyst surface, F-bis-BN cyclohexane has slightly lower dehydrogenation reaction efficiency than the existing bis-BN cyclohexane; however, it was found that the efficiency of the reverse reaction of hydrogenation is significantly improved owing to the F substitution in bis-BN cyclohexane. Therefore, F-bis-BN cyclohexane can exhibit enhanced reversible dehydrogenation–hydrogenation cycles in the presence of a Pt catalyst and is expected to be suitable as an alternative hydrogen carrier. Details of dehydrogenation reaction pathways with activation energies and electronic properties of the dehydrogenation mechanisms have also been discussed herein.     

Selective coordination activation regulating the selectivity for photocatalytic hydrogenation of α, β-unsaturated aldehyde over Pd/MIL-100(FeaCub)

Here, the mixed metal nodes MOFs, Pd/MIL-100(Fe_aCu_b), were constructed as photocatalysts for hydrogenation of α, β-unsaturated aldehyde (UAL) under visible light. 1 wt% Pd/MIL-100(Fe_0.81Cu_0.19) can convert a range of UAL to saturated aldehydes (SAL) with a high efficiency (≈ 100 %) and selectivity (≈ 98 %). The results of XPS and in situ DRIFTS reveal that UAL can be selectively activated via a coordination of -CC- on Cu²⁺ sites, determining the high selectivity of the photocatalytic reaction. The mixed metal nodes and Pd clusters can improve the transformation and separation of photogenerated electrons-holes. EPR result suggests that photogenerated carriers can facilitate the generation of H·on Pd/MIL-100(Fe_0.81Cu_0.19), enhancing the catalytic activity. A possible mechanism is proposed for elucidating the catalytic processes at the molecular level. This work provides a valuable strategy for tailoring the selectivity of photocatalytic hydrogenation via selective coordination activation.     

Hydrogen for CO2 processing in heterogeneous catalytic reactions

Efficient catalytic technologies for converting CO₂ with hydrogen into value-added chemicals and fuels can help to solve the environmental problems related with large CO₂ emissions. Among of the most interesting products that can be synthesized from CO₂ are synthetic natural gas, methanol and DME, methane and higher hydrocarbons, higher alcohols. In this mini review, we highlight the recent advances in the development of heterogeneous catalysts and processes for of CO₂ hydrogenation to these products. Recent research to develop highly active and selective catalysts based on controlled synthesis – active phases, promoters, supports, thermodynamics, are presented.     

一种新的常压加氢负压取样装置及其油脂加氢工艺

推荐一种新的常压油脂加氢装置及其加氢工艺。该装置带有一只新的隔绝空气条件下取样的负压取样器，采用常压通氢（计量）、电磁搅拌、自动温度控制和负压取样。我们用此装置进行ＣＩＭ油脂氢化催化剂的研制和开发，取得了突破性的进展。该装置的特点是：性能可靠、易于制作、价格便宜、便于观察、使用方便。