Design Principle of Molybdenum-Based Metal Nitrides for Lattice Nitrogen-Mediated Ammonia Production.

Chemical looping ammonia synthesis (CLAS) is a promising technology for reducing the high energy consumption of the conventional ammonia synthesis process. However, the comprehensive understanding of reaction mechanisms and rational design of novel nitrogen carriers has not been achieved due to the high complexity of catalyst structures and the unrevealed relationship between electronic structure and intrinsic activity. Herein, we propose a multistage strategy to establish the connection between catalyst intrinsic activity and microscopic electronic structure fingerprints using density functional theory computational energetics as bridges and apply it to the rational design of metal nitride catalysts for lattice nitrogen-mediated ammonia production.

Tuning Adsorbate-Mediated Strong Metal-Support Interaction by Oxygen Vacancy: A Case Study in Ru/TiO.

The adsorbate-mediated strong metal-support interaction (A-SMSI) offers a reversible means of altering the selectivity of supported metal catalysts, thereby providing a powerful tool for facile modulation of catalytic performance. However, the fundamental understanding of A-SMSI remains inadequate and methods for tuning A-SMSI are still in their nascent stages, impeding its stabilization under reaction conditions. Here, we report that the initial concentration of oxygen vacancy in oxide supports plays a key role in tuning the A-SMSI between Ru nanoparticles and defected titania (TiO).

Upgrading CO to sustainable aromatics via perovskite-mediated tandem catalysis.

The directional transformation of carbon dioxide (CO) with renewable hydrogen into specific carbon-heavy products (C) of high value presents a sustainable route for net-zero chemical manufacture. However, it is still challenging to simultaneously achieve high activity and selectivity due to the unbalanced CO hydrogenation and C-C coupling rates on complementary active sites in a bifunctional catalyst, thus causing unexpected secondary reaction. Here we report LaFeO perovskite-mediated directional tandem conversion of CO towards heavy aromatics with high CO conversion (> 60%), exceptional aromatics selectivity among hydrocarbons (> 85%), and no obvious deactivation for 1000 hours.

Defect-Driven Efficient Selective CO Hydrogenation with Mo-Based Clusters.

Synthetic fuels produced from CO show promise in combating climate change. The reverse water gas shift (RWGS) reaction is the key to opening the CO molecule, and CO serves as a versatile intermediate for creating various hydrocarbons. Mo-based catalysts are of great interest for RWGS reactions featured for their stability and strong metal-oxygen interactions.

Hydrolase mimic via second coordination sphere engineering in metal-organic frameworks for environmental remediation.

Enzymes achieve high catalytic activity with their elaborate arrangements of amino acid residues in confined optimized spaces. Nevertheless, when exposed to complicated environmental implementation scenarios, including high acidity, organic solvent and high ionic strength, enzymes exhibit low operational stability and poor activity. Here, we report a metal-organic frameworks (MOFs)-based artificial enzyme system via second coordination sphere engineering to achieve high hydrolytic activity under mild conditions.

Interfacial Electron Engineering of PdSn-NbN/C for Highly Efficient Cleavage of the C-C Bonds in Alkaline Ethanol Electrooxidation.

The splitting of the C-C bonds of ethanol remains a key issue to be addressed, despite tremendous efforts made over the past several decades. This study highlights the enhancement mechanism of inexpensive NbN-modified Pd Sn -NbN/C towards the C-C bonds cleavage for alkaline ethanol oxidation reaction (EOR). The optimal Pd Sn -NbN/C delivers a catalytic activity up to 43.

Accelerating syngas-to-aromatic conversion via spontaneously monodispersed Fe in ZnCrO spinel.

Spontaneous monodispersion of reducible active species (e.g., Fe, Co) and their stabilization in reductive atmospheres remain a key challenge in catalytic syngas chemistry.

Atomically Dispersed Zn-Stabilized Ni Enabling Tunable Selectivity for CO Hydrogenation.

For a heterogeneous catalytic process, the performance of catalysts could be improved by modifying the active metal with a second element. Determining the enhanced mechanism of the second element is essential to the rational design of catalysts. In this work, Zn was introduced as a second element into Ni/ZrO for CO hydrogenation.

Stable Cu Catalysts Supported by Two-dimensional SiO with Strong Metal-Support Interaction.

Cu-based catalysts exhibit excellent performance in hydrogenation reactions. However, the poor stability of Cu catalysts under high temperatures has restricted their practical applications. The preparation of stable Cu catalysts supported by SiO with strong metal-support interaction (SMSI) has thus aroused great interest due to the high abundance, low toxicity, feasible processability, and low cost of SiO .

Reactive separation of β-bromoethylbenzene from α-β-bromoethylbenzene mixtures: a Zn-mediated radical polymerization mechanism.

A Zn-induced reactive separation method for the purification of β-bromoethylbenzene from α-β-bromoethylbenzene mixtures is discovered, where the selective decomposition of α-bromoethylbenzene follows a radical mechanism. Zn facilitates the homolysis of the C-Br bond of halohydrocarbons with benzyl bromide, enabling the separation of the corresponding isomers with almost identical physical properties.

Stabilization of Exposed Metal Nanocrystals in High-Temperature Heterogeneous Catalysis.

Colloidal metal nanocrystals with uniform sizes, shapes, compositions, and architectures are ideal building blocks for constructing heterogeneous catalysts with well-defined characteristics toward the investigation of accurate structure-property relationships and better understanding of catalytic mechanism. However, their applications in high-temperature heterogeneous catalysis are often restricted by the difficulty in maintaining the high metal dispersity and easy accessibility to active sites under harsh operating conditions. Here, a partial-oxide-coating strategy is proposed to stabilize metal nanocrystals against sintering and meanwhile enable an effective exposure of active sites.

Inverse ZrO/Cu as a highly efficient methanol synthesis catalyst from CO hydrogenation.

Enhancing the intrinsic activity and space time yield of Cu based heterogeneous methanol synthesis catalysts through CO hydrogenation is one of the major topics in CO conversion into value-added liquid fuels and chemicals. Here we report inverse ZrO/Cu catalysts with a tunable Zr/Cu ratio have been prepared via an oxalate co-precipitation method, showing excellent performance for CO hydrogenation to methanol. Under optimal condition, the catalyst composed by 10% of ZrO supported over 90% of Cu exhibits the highest mass-specific methanol formation rate of 524 gkgh at 220 °C, 3.

Cobalt Plasmonic Superstructures Enable Almost 100% Broadband Photon Efficient CO Photocatalysis.

The efficiency of heterogeneous photocatalysis for converting solar to chemical energy is low on a per photon basis mainly because of the difficulty of capturing and utilizing light across the entire solar spectral wavelength range. This challenge is addressed herein with a plasmonic superstructure, fashioned as an array of nanoscale needles comprising cobalt nanocrystals assembled within a sheath of porous silica grown on a fluorine tin oxide substrate. This plasmonic superstructure can strongly absorb sunlight through different mechanisms including enhanced plasmonic excitation by the hybridization of Co nanoparticles in close proximity, as well as inter- and intra-band transitions.

A recyclable heterogeneous-homogeneous-heterogeneous NiO/AlOOH catalysis system for hydrocarboxylation of acetylene to acrylic acid.

Concerns about the high-valued utilization of coal- and natural gas-based acetylene has provided particular impetus for exploration of acrylic acid (AA) production one-step hydrocarboxylation reaction. Motivated by simple recovery, recycling and reuse of the catalyst, we report a high-performance NiO/AlOOH catalyst with AA space-time-yield of 412 g g h, obtainable by a simple incipient wetness impregnation method. Detailed kinetic and controlled experiments confirmed that nickel species on such a solid catalyst provide a heterogeneous-homogeneous-heterogeneous catalytic cycle where the chelates formed between CO and leached nickel act as the active species.

Active sites for tandem reactions of CO reduction and ethane dehydrogenation.

Ethylene (CH) is one of the most important raw materials for chemical industry. The tandem reactions of CO-assisted dehydrogenation of ethane (CH) to ethylene creates an opportunity to effectively use the underutilized ethane from shale gas while mitigating anthropogenic CO emissions. Here we identify the most likely active sites over CeO-supported NiFe catalysts by using combined in situ characterization with density-functional theory (DFT) calculations.

High selectivity of CO hydrogenation to CO by controlling the valence state of nickel using perovskite.

The selectivity of CO2 hydrogenation can be significantly tuned by controlling the valence state of nickel using lanthanum-iron-nickel perovskites. Nickel with higher valence states weakens the binding of CO and increases the activation barrier for further CO hydrogenation, leading to a higher CO selectivity than the metallic nickel.

Combining CO reduction with propane oxidative dehydrogenation over bimetallic catalysts.

The inherent variability and insufficiencies in the co-production of propylene from steam crackers has raised concerns regarding the global propylene production gap and has directed industry to develop more on-purpose propylene technologies. The oxidative dehydrogenation of propane by CO (CO-ODHP) can potentially fill this gap while consuming a greenhouse gas. Non-precious FeNi and precious NiPt catalysts supported on CeO have been identified as promising catalysts for CO-ODHP and dry reforming, respectively, in flow reactor studies conducted at 823 K.

Optimizing Binding Energies of Key Intermediates for CO2 Hydrogenation to Methanol over Oxide-Supported Copper.

Rational optimization of catalytic performance has been one of the major challenges in catalysis. Here we report a bottom-up study on the ability of TiO2 and ZrO2 to optimize the CO2 conversion to methanol on Cu, using combined density functional theory (DFT) calculations, kinetic Monte Carlo (KMC) simulations, in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) measurements, and steady-state flow reactor tests. The theoretical results from DFT and KMC agree with in situ DRIFTS measurements, showing that both TiO2 and ZrO2 help to promote methanol synthesis on Cu via carboxyl intermediates and the reverse water-gas-shift (RWGS) pathway; the formate intermediates, on the other hand, likely act as a spectator eventually.

CO2 Hydrogenation over Oxide-Supported PtCo Catalysts: The Role of the Oxide Support in Determining the Product Selectivity.

By simply changing the oxide support, the selectivity of a metal-oxide catalysts can be tuned. For the CO2 hydrogenation over PtCo bimetallic catalysts supported on different reducible oxides (CeO2 , ZrO2 , and TiO2 ), replacing a TiO2 support by CeO2 or ZrO2 selectively strengthens the binding of C,O-bound and O-bound species at the PtCo-oxide interface, leading to a different product selectivity. These results reveal mechanistic insights into how the catalytic performance of metal-oxide catalysts can be fine-tuned.