Catalysis Science & Technology最新文献

Retraction of ‘Photocatalytic activation and utilization of CO₂ for N-formylation of amines promoted by a zinc(II) phthalocyanine grafted on g-carbon nitride hybrid’ by Anil Malik et al., Catal. Sci. Technol., 2022, 12, 2688–2702, https://doi.org/10.1039/D1CY02286E.

Retraction of ‘Light-assisted coupling of phenols with CO₂ to 2-hydroxybenzaldehydes catalyzed by a g-C₃N₄/NH₂-MIL-101(Fe) composite’ by Sakshi Bhatt et al., Catal. Sci. Technol., 2022, 12, 6805–6818, https://doi.org/10.1039/D2CY01430K.

A new class of nitrogen-coordinated Rh heterogeneous catalyst was synthesized by a simple one-pot method for hydroformylation of alkenes with high activity and superior resuability, which could be ascribed to the uniform dispersion of Rh species and enhanced metal–support interactions after the in situ introduction of nitrogen.

Engineered heme proteins possess excellent biocatalytic carbene N-H insertion abilities for sustainable synthesis, and most of them have His as the Fe axial ligand. However, information on the basic reaction mechanisms is limited, and ground states of heme carbenes involved in the prior computational mechanistic studies are under debate. A comprehensive quantum chemical reaction pathway study was performed for the heme model with a His analogue as the axial ligand and carbene from the widely used precursor ethyl diazoacetate with aniline as the substrate. The ground state of this heme carbene was calculated by the high-level complete active space self-consistent field (CASSCF) approach, which shows a closed-shell singlet that is consistent with many experimental works. Based on this, DFT calculations of ten main reaction pathways were compared. Results showed that the most favorable pathway involved the initial formation of the metal-bound ylide, followed by a concerted rearrangement/dissociation transition state to form the free enol, which then underwent a water-assisted proton transfer process to yield the final N-H insertion product. This computational prediction was validated via new experimental data using His-ligated myoglobin variants with different types of carbenes. Overall, this is the first comprehensive computational mechanistic study of heme carbene N-H insertions, particularly for neutral His ligated heme proteins and the first high-level CASSCF confirmation of the ground state of the used heme carbene. The experimental results are also the first in this field. Overall, these results build a solid basis for the proposed reaction mechanism to facilitate future biocatalytic carbene N-H insertion studies.

There is no universal recipe for the proper structure tuning of Ni(OH)₂ nanoparticle (NP)-based catalysts for efficient urea electrooxidation (UOR) in alkaline media. However, it is known that fast generation of Ni³⁺OOH-type catalytic centers that are sustained and resilient during the overall catalytic process is crucial. Towards this, we report how we optimized and compared operating conditions and structural tuning of poly[NP-Ni(OH)₂SaltMe] and poly[meso-NP-Ni(OH)₂SaldMe] electrocatalysts active in alkaline media towards UOR. We started with studies of morphological differences evoked by the use of different NaOH_aq concentrations for catalyst fabrication by SEM and TEM. Then, we distinguished the most promising molecular structures of fabricated catalysts featuring the highest poisoning resistance and in situ generation of poly(NP-Ni³⁺OOHsalen) electrocatalytic centers for UOR. Furthermore, we found the best conditions for operation of both structured UOR catalysts using a comprehensive electrochemical approach. This approach involved multiple scan rate, Tafel slope, and activation energy (E_ac) analysis to finally compare which structured poly[NP-Ni(OH)₂salen] catalyst produces catalytic current more efficiently in response to a change in applied potential. Ultimately, we performed a longevity/durability test under real-system mimicking conditions. The fabricated catalysts constituted good platforms for studying the surface-remaining and bulk-remaining types of catalytically active sites of poly[NP-Ni(OH)₂salen]s for UOR activity. Our findings point to the bulk-structure-reactivity requirements of poly[NP-Ni(OH)₂salen]s, emphasizing their catalytic durability and effectiveness.

Replacing the sluggish oxygen evolution reaction with ethanol oxidation can reduce the overpotential while generating value-added products. In this study, a highly active and stable catalyst was synthesized via electrochemical deposition, enabling the leaching of Ni and co-deposition of Au and Ni to form an Au–Ni alloy on Ni foam. The Au–Ni synergy enhances ethanol adsorption, tailors surface oxygen species, and shortens the distance between reaction intermediates, driving ethanol oxidation to acetate at low potentials and favoring acetaldehyde formation at higher potentials. The resulting electrode achieves 163 mA cm⁻² at 1.57 V vs. RHE and 209 mA cm⁻² at 1.90 V vs. RHE with excellent stability, offering a cost-effective alternative for the anode reaction in hydrogen production.

One of the main drawbacks of stereoretentive ruthenium catalysts that allow the synthesis of olefins with a defined double bond geometry is their limited stability in the presence of oxygen. To remove the bottleneck that inhibits their widespread use, we prepared a series of Hoveyda–Grubbs-type complexes with a modified ether moiety in the benzylidene substituent. The yields obtained in air remain lower than those obtained under an inert atmosphere. Unexpectedly, however, O-benzyl catalyst Ru14b typically led to better yields with high selectivities compared to the benchmark OiPr catalyst Ru4. A parallel DFT study confirmed that the four-coordinate Ru(IV)-oxo product reported earlier by Fogg results from the oxygen attack on the Ru–C bond and the elimination of aldehyde from a metalladioxetane-like transition state.

Selective catalytic reduction (SCR) technology is one of the main measures to achieve the pollutant emission reduction target of diesel engines, and the NH₃-SCR exhaust gas aftertreatment technology systems used at present are all based on the design scheme using liquid urea aqueous solution as a reducing agent. However, the SCR system using urea aqueous solution as the reducing agent has some problems in the process of use, such as freezing of the reducing agent (−11 °C) resulting in blocking of the reducing agent transport pipeline; incomplete hydrolysis of urea aqueous solution will not only form crystallization in the pipeline, but also lead to a certain error between the amount of urea injection and the amount of ammonia (urea pyrolysis and hydrolysis to produce ammonia), which affects the conversion efficiency of SCR system. The effective ammonia content per unit volume of urea aqueous solution is low (17.3%), and urea aqueous solution needs to be supplemented at 1500–2500 km, which is not conducive to the quality control of urea aqueous solution, and it is difficult to ensure the consistency of nitrogen oxide (NOx) conversion effect in the SCR system. Because there are many insurmountable defects in urea SCR technology, researchers at home and abroad have turned their research focus to SSCR (solid SCR) technology. Solid selective catalytic reduction (SSCR) technology utilizes solid ammonia storage, releasing ammonia gas directly upon heating. This approach offers significant advantages over urea-based SCR, addressing its inherent limitations. This paper provides an overview of SCR and SSCR technologies, discusses the formation of nitrogen oxides, the NH₃-SCR mechanism, and the principles of operation for both urea SCR and solid ammonia storage materials. It also explores the development of SSCR systems, highlighting their potential to overcome the challenges faced by conventional SCR methods.

Developing complex microkinetic models for heterogeneous catalysis is a cumbersome task, often lacking accuracy if proper kinetic properties are unknown. Therefore, a novel rule-based microkinetic model generator for heterogeneous catalysis called Genesys-Cat is presented. Genesys-Cat automatically generates an elementary reaction network based on user-defined reaction families. One of the main advantages of Genesys-Cat is the determination of kinetic properties based on a limited set of experimental data when ab initio data is absent. Genesys-Cat employs an improved, highly efficient Bayesian optimization algorithm to estimate accurate kinetic properties with limited computational and experimental effort. In this way, computationally and experimentally efficient, accurate microkinetic models (R² = 0.89–0.99) can be generated for a wide range of processes involving heterogeneous catalysts. Genesys-Cat facilitates the automatic generation of gas and surface-phase mechanisms in parallel, which is compatible with standard reactor model simulators like Chemkin and Cantera. The benefits of our approach are demonstrated in the catalytic cracking of iso-octane for three different zeolites, while our model generator is also applicable to conventional metal catalysts. The obtained microkinetic models identify the dominant reaction pathways and can be employed for rational catalyst and reactor design.

Herein, we present the first example of earth-abundant 3d metal-catalyzed ambient pressure carbon dioxide transfer hydrogenation to formate using isopropanol as an inexpensive and environmentally benign hydrogen source. The bidentate phosphine bis(diphenylphosphino)propane (DPPP, β_n = 91°)-derived low-valent Cr(0) complex Cr(DPPP)(CO)₄C-3 emerged as the most efficient catalyst yielding sodium formate with a TON of up to 1974 under 1 bar CO₂ and 2231 under 5 bar CO₂ in the presence of NaOH in a THF : H₂O mixture after 24 h at 130 °C. The catalyst was also found to be active in the transfer hydrogenation of sodium bicarbonate and carbonate to produce their corresponding formates in low yields. Mechanistic experiments revealed formation of an anionic hydride complex, which is believed to be an active catalyst for CO₂ transfer hydrogenation.