Rationally Designed Water Enriched Nano Reactor for Stable CO₂ Hydrogenation with Near 100% Ethanol Selectivity over Diatomic Palladium Active Sites

CO2 (CO) hydrogenation presents the widest route to synthesis of various valuable organic molecules, but precise carbon–carbon coupling control to targeted products along with the elimination of byproducts remains a challenge. We overcome these limitations by synthesizing a CeO2-supported dual Pd site catalyst that could actively catalyze CO2 conversion into single-product ethanol almost without C1 byproducts in a continuous-flow fixed-bed reactor. This surprising finding is derived from the observation that the synergistic catalysis between dual Pd atoms leads to extraordinary ability for the cleavage of C–O bond in *CHxOH species and the carbon–carbon coupling between *CHx and *CO species. Furthermore, the dual Pd sites could be stabilized through enriching in situ formed water in the nano reactor with a hydrophobic shell layer, thus leading to remarkably improved catalytic stability for ethanol production. As a result, the as-constructed dual Pd site catalyst exhibited superior selectivity to ethanol at 98.7%, corresponding to a productivity up to 11.6 g per gram of Pd per hour and excellent stability during the continuous test for 60 h. Our results demonstrate that multifunctional synergistic catalysis of dual active sites can break through the restriction of a reaction involving a single active site catalyst

Selective Hydrodeoxygenation of Lignin-Derived Phenols to Cyclohexanols or Cyclohexanes over Magnetic CoNx@NC Catalysts under Mild Conditions

The hydrodeoxygenation (HDO) of lignin-derived phenols is important to produce the renewable biofuels. Herein, we reported a simple method to prepare magnetic nitrogen-doped carbon supported cobalt nitride catalysts (CoNx@NC) by copyrolysis of cellulose and cobalt nitrate under ammonia atmosphere. The catalysts were prepared at different temperatures and characterized by elemental analysis, atomic absorption spectroscopy (AAS), Brunauer–Emmett–Teller (BET) surface area analysis, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and temperature-programmed reduction (TPR). The CoNx@NC-650 (pyrolyzed at 650 °C) exhibited the best HDO activity for eugenol conversion among a series of Co-based catalysts. The yield of propylcyclohexanol from eugenol was >99.9% under 2 MPa H₂ at 200 °C for 2 h. Moreover, a high yield of propylcyclohexane (99.1%) could be achieved when the solid acid HZSM-5 was added to the reaction system. Other lignin-derived phenolic compounds were also investigated and the yield of alkanes was >90%. Based on the mechanism investigation, the catalyst demonstrated a high selectivity to cleave the C_aryl–OR bond under mild conditions

One-Pot Synthesis of Indoles and Aniline Derivatives from Nitroarenes under Hydrogenation Condition with Supported Gold Nanoparticles

One-pot sequences of hydrogenation/hydroamination to form indoles from (2-nitroaryl)alkynes and hydrogenation/reductive amination to form aniline derivatives from nitroarenes and aldehydes were catalyzed by Au nanoparticles supported on Fe2O3. Nitro group selective hydrogenations and successive reactions were efficiently catalyzed under the conditions

Manipulating the Cobalt Species States to Break the Conversion–Selectivity Trade-Off Relationship for Stable Ethane Dehydrogenation over Ligand-Free-Synthesized Co@MFI Catalysts

Nonoxidative dehydrogenation of low-cost alkanes provides a promising route to produce valuable olefins. Herein, we hydrothermally synthesized various non-noble-metal-based, environment-friendly, and Al-free Co@MFI catalysts without the assistance of any additional coordination agents. The Co2+ species were successfully incorporated into well-crystallized MFI to form a stable and atomically dispersed −Coδ+–Oδ−– structure. The Co@MFI catalyst could show a stably high activity for ethane dehydrogenation with equilibrium-approached conversions at 600 °C and at the same time gave an extremely high selectivity to ethylene (∼99%), which is owed to the relatively unreducible −Co–O– species and its appropriate chemical state at the right reaction-temperature window. However, the Co@MFI catalyst showed equilibrium-deviated conversions at lower temperatures (such as 550 °C) and a suppressed activity in the H2O or CO2 co-feeding tests. Then, with characterizations, density functional theory calculations, and abundant experiments over different catalysts, including impregnated Co/MFI and amorphous Co@MFI, this study has impressively demonstrated that the chemical state of Coδ+ species manipulates the conversion–selectivity trade-off relationship in the conversion of alkanes. It is suggested that Co with a lower valence like Co0 promotes both C–C and C–H bond scissions of alkanes into coke and CH4, while Co with a higher one shows a decreased activity or even inactivity for alkane dehydrogenation. In this study, the possible causes for the success in the synthesis of the ligand-unassisted Co@MFI catalyst, the catalyst deactivation modes and the strategies for improving catalyst stability were also demonstrated in detail. This work not only contributes a performance-advanced Co-based catalyst for alkane dehydrogenation but also provides new insights into incorporation of a metal into zeolites

Acetic Acid Production from CH₄ and CO₂ via Synergistic Catalysis between Pd Particles and Oxygen Vacancies Generated in ZrO₂

Co-conversion of CO2 and CH4 into acetic acid is of great significance to the environment but is challenged by their chemical stability. Herein, Pd–ZrO2 catalysts exhibit excellent performance for acetic acid production, which is about 5 times higher than that for pure ZrO2. Combined catalytic tests, characterization, and density functional theory (DFT) calculations have revealed a synergistic catalysis mechanism between Pd and H2-reduced ZrO2, which not only facilitates CO2 adsorption and activation owing to generating more oxygen vacancies (Ov) but also promotes CH4 activation owing to resulting larger-sized metallic Pd particles. DFT calculations demonstrate that the C–C coupling between CH3* and COOH* exhibits a lower barrier, which favors acetic acid formation

Suppressing C–C Bond Dissociation for Efficient Ethane Dehydrogenation over the Isolated Co(II) Sites in SAPO-34

Various Co-based SAPO-34 catalysts were prepared using different methods, including ion exchange (IE), incipient-wetness impregnation (IWI), and solid-phase grinding (SPG), to correlate the chemical states of Co species with the C–H and C–C bond scissions in ethane dehydrogenation. The IE-prepared Co/SAPO-34 led to stable, unreducible, and isolated exchanged Co sites anchored on the zeolite framework with a structure of −AlF–O–Co–O– and showed the highest selectivity to ethylene of close to 98% at 600 °C, which suggests that these Co sites favors suppressing the C–C bond scission in ethane. In comparison, the IWI- and SPG-prepared Co/SAPO-34 catalysts, especially for those with a high Co loading, inevitably give Co oxide clusters that are easily reduced into metallic Co. Together with catalytic results, characterizations, and DFT calculations, it is confirmed that the reduced Co clusters, especially for those outside SAPO-34 channels without the confinement effect, favor both C–H and C–C bond scission, boosting the conversion of ethane into CH4 or/and coke; however, the ionic-state −Co–O– species can smoothly terminate the ethane dehydrogenation for the ethylene product due to relatively high energy barriers for both C–H and C–C bond scission, avoiding a deep dehydrogenation and C–C cracking. As expected, the unreducible −Co–O– sites are very stable in the title reaction without deanchoring from the zeolite framework in a 100 h cyclic test. This study not only demonstrates the stable −Mδ+–Oδ− structure favorable for suppressing C–C bond scission but also highlights a catalyst-constructing strategy for Co-based and similar metal-based catalysts for dehydrogenation of other light alkanes

Direct Selective Hydrogenation of Fatty Acids and Jatropha Oil to Fatty Alcohols over Cobalt-Based Catalysts in Water

Inedible natural oils are desired resources for renewable fuel and chemical production. Herein, a nonprecious metal cobalt catalytic system was developed for selectively hydrogenating fatty acids and natural oil into fatty alcohols or long-chain alkanes. The cobalt-based catalysts were prepared by a wet-impregnation method with a series of supports including HZSM-5, CeO₂, ZrO₂, SiO₂, Al₂O₃, TiO₂, and hydroxyapatite (HAP) for hydrogenating stearic acid. Among these catalysts, Co/HAP exhibited the highest activity and 97.1% yield of 1-octadecanol was obtained at 190 °C and 4 MPa H₂ in water. Additionally, the Co/HAP was capable of directly hydrogenating the natural oil, Jatropha oil, to fatty alcohols without any preprocessing, and 83.1 wt % yield of alcohols could be achieved at 190 °C and 4 MPa H₂ in water. Co/HAP could also catalyze the complete conversion of stearic acid and Jatropha oil to long-chain alkanes when dodecane was used as solvent. X-ray power diffraction, transmission electron microscopy, H₂ temperature-programmed reduction, and NH₃ temperature-programmed desorption were carried out, and the high catalytic activity of Co/HAP could be due to its desired acidity, cobalt particle dispersion, and stronger metal–support interaction. The Fourier transform infrared results indicated that the high efficiency of Co/HAP could also be due to the absorption of fatty acid on the surface of catalyst which thus promoted the hydrogenation process over Co species. The possible reaction pathway was also proposed according to the conversion process tracking of stearic acid

Pore-Confined and Diffusion-Dependent Olefin Catalytic Cracking for the Production of Propylene over SAPO Zeolites

Higher-olefin cracking into propylene is an ideal process to meet the increasing demand for propylene driven by polymer industries. However, this process is usually stuck in poor propylene selectivity owing to the complicated reaction routes for facile side reactions and evident catalyst deactivation from severe coking. In this work, various SAPO zeolites with moderate acidity were synthesized for the 1-hexene cracking reaction. Among them, SAPO-41 exhibited an excellent propylene selectivity of ∼90% at a super high 1-hexene conversion of ∼95% and superior stability. It is ascribed to the dominant monomolecular cracking mechanism derived from the pore-confined effect with elliptical channels (10-membered ring, 4.3 × 7.0 Å) and shorter diffusional distance with nanosheet-like morphology, which could effectively suppress the side reactions such as hydrogen transfer and coking. In contrast, fast deactivation and obviously lower propylene selectivity were found over SAPO-5 and SAPO-41/5 with larger circular channels (12-membered ring, 7.3 × 7.3 Å), resulting from much longer diffusional distance and enhanced bimolecular cracking route to give more undesired light alkanes, butenes, aromatics, and cokes. Especially, a systematic experimental investigation combined with molecular dynamics simulation demonstrates that medium chain length alkenes (C6–C8) are more suitable for a stable cracking process along with a high conversion level, owing to the synergistic effects between moderate diffusion ability and higher cracking activity

Highly Potent, Selective, Biostable, and Cell-Permeable Cyclic d‑Peptide for Dual-Targeting Therapy of Lung Cancer

The application of peptide drugs in cancer therapy is impeded by their poor biostability and weak cell permeability. Therefore, it is imperative to find biostable and cell-permeable peptide drugs for cancer treatment. Here, we identified a potent, selective, biostable, and cell-permeable cyclic d-peptide, NKTP-3, that targets NRP1 and KRASG12D using structure-based virtual screening. NKTP-3 exhibited strong biostability and cellular uptake ability. Importantly, it significantly inhibited the growth of A427 cells with the KRASG12D mutation. Moreover, NKTP-3 showed strong antitumor activity against A427 cell-derived xenograft and KRASG12D-driven primary lung cancer models without obvious toxicity. This study demonstrates that the dual NRP1/KRASG12D-targeting cyclic d-peptide NKTP-3 may be used as a potential chemotherapeutic agent for KRASG12D-driven lung cancer treatment