Synthesis of Co-Doped Tungsten Phosphide Nanoparticles Supported on Carbon Supports as High-Efficiency HER Catalysts

Tungsten phosphide (WP) is believed to be a promising electrocatalyst in the electrochemical hydrogen evolution reaction (HER) for its unique catalytic performances. Nevertheless, its further application is severely limited by the agglomeration caused by the high preparation temperature (over 600 °C). Herein, we adopt a citric acid-guided two-stage aging method to prepare Co-doped WP with small particle size and higher dispersity on the surface of seven different carbon supports. Co is successfully incorporated into the lattice of WP, causing preferable catalytic performance. The introduction of seven different carbon supports enhances electronic metal-supported interaction and proves this two-stage aging method universal. The as-derived CoWP-CA/KB (two-step aging) featured a low overpotential of 111 mV to achieve a current density of 10 mA cm–2, along with a desirable Tafel slope of 58 mV dec–1, outperforming most of the WP-based electrocatalysts. Besides, the electrode possesses excellent stability for 60 h without significant attenuation. Its remarkable performance results from its structure (delicate particle size, uniform dispersion, and large specific surface area) and its electrocatalytic properties (large electrochemically active surface area, excellent electrical conductivity, enhanced interfacial charge transfer kinetics, and high turnover frequency). This novel synthesis strategy will be pivotal for designing robust non-noble metal-based electrocatalysts with high HER activity and durability to meet the future keen demand for hydrogen

Efficient Ni₂P/SiO₂ Catalysts with Enhanced Performance for the Hydrogenation of 4,6-Dimethyldibenzothiophene and Phenanthrene

Highly dispersed Ni2P catalysts (Ni2P/SiO2-DPx) were prepared by reducing the passivation-free precursors, which were obtained through the phosphidation of nickel phyllosilicate with sodium hypophosphite. The strong metal–support interaction of nickel phyllosilicate and the mild phosphidation conditions prevented the agglomeration of Ni particles and resulted in a smaller Ni2P particle size. The superior catalytic performance of the as-prepared Ni2P/SiO2-DP catalysts was evaluated in hydrodesulfurization (HDS) of 4,6-dimethyldibenzothiophene and the hydrogenation of phenanthrene, in comparison with Ni2P/SiO2-IM and CoMoS/γ-Al2O3 prepared from a conventional incipient wetness impregnation method. The passivation-free Ni-P/SiO2-DPx precursors showed great storage stability, and Ni2P/SiO2-DP derived from the stored Ni-P/SiO2-DP precursors exhibited negligible loss of HDS activity. This method provides a potential preparation strategy for the industrial applications of transition metal phosphides without the temperature-programmed reduction and the subsequent passivation process

Fabrication of a Monolith Reactor in a Copper Tube by Polymerization of Acetylene for Flow Catalysis

Continuous-flow processing is considered as a disruptive technology in the synthesis of active pharmaceutical ingredients and other fine chemicals. However, it remains extremely challenging to immobilize heterogeneous catalysts in the channels of microreactors in a facile and flexible manner. In the present investigation, a polymer monolith coiled copper reactor was fabricated by Cu-catalyzed polymerization of acetylene at atmospheric pressure in the temperature range of 290–370 °C. The polymerization yielded a cotton-like structure of carbonaceous fibers, which were able to assemble by themselves to form a monolith inside the copper tube. The characterization results revealed that unsaturated CC groups, which are favorable for post-surface modification, were present on the carbonaceous fibers. After air oxidation at 160 °C for 10 h, a fraction of the CC groups were converted to CO groups. By strong interaction with CO groups, Pd was immobilized in the polymer monolith by circulating an ethanol solution of palladium acetate through the copper tube. A 1000 mm-long monolith tube reactor with an inner diameter of 2 mm with a Pd loading of 1.15 wt % was fabricated and used in the continuous Suzuki–Miyaura coupling reaction. An ethanol–water (2:1 in volume) solution of iodobenzene (0.0125 M), phenylboronic acid (0.0188 M), and potassium carbonate (0.0250 M) was used as the feed, and the reaction took place at 100 °C and 1.0 MPa. The selectivity to biphenyl was kept at >99% with complete conversion of iodobenzene in a 100 h run

Fabrication of a Monolith Reactor in a Copper Tube by Polymerization of Acetylene for Flow Catalysis

Continuous-flow processing is considered as a disruptive technology in the synthesis of active pharmaceutical ingredients and other fine chemicals. However, it remains extremely challenging to immobilize heterogeneous catalysts in the channels of microreactors in a facile and flexible manner. In the present investigation, a polymer monolith coiled copper reactor was fabricated by Cu-catalyzed polymerization of acetylene at atmospheric pressure in the temperature range of 290–370 °C. The polymerization yielded a cotton-like structure of carbonaceous fibers, which were able to assemble by themselves to form a monolith inside the copper tube. The characterization results revealed that unsaturated CC groups, which are favorable for post-surface modification, were present on the carbonaceous fibers. After air oxidation at 160 °C for 10 h, a fraction of the CC groups were converted to CO groups. By strong interaction with CO groups, Pd was immobilized in the polymer monolith by circulating an ethanol solution of palladium acetate through the copper tube. A 1000 mm-long monolith tube reactor with an inner diameter of 2 mm with a Pd loading of 1.15 wt % was fabricated and used in the continuous Suzuki–Miyaura coupling reaction. An ethanol–water (2:1 in volume) solution of iodobenzene (0.0125 M), phenylboronic acid (0.0188 M), and potassium carbonate (0.0250 M) was used as the feed, and the reaction took place at 100 °C and 1.0 MPa. The selectivity to biphenyl was kept at >99% with complete conversion of iodobenzene in a 100 h run

In-Depth Understanding of Highly Active Silicotungstic Acid Catalysts for Ethanol Dehydration to Ethylene under Industrially Favorable Conditions

A series of SiO2-supported silicotungstic acid (STA/SiO2) catalysts were prepared by the incipient impregnation method and utilized in dehydration of ethanol to ethylene. The catalysts were characterized through X-ray diffraction (XRD), N2 physical adsorption, transmission electron microscopy (TEM), X-ray fluorescence (XRF), Fourier transform infrared spectroscopy (FTIR), pyridine-adsorbed FTIR (Py-FTIR), Raman spectroscopy, and thermogravimetry/differential scanning calorimetry (TG/DSC). The influence of loading amount and calcination temperature on the properties and catalytic activities were investigated. The yield of ethylene was 93.9% at an ethanol conversion of 96.9% over the 36-STA/SiO2(250) catalyst at 240 °C and 1.0 MPa. The kinetics study indicated that diethyl ether was an intermediate under the investigated reaction conditions. A consecutive slow decrease in ethanol conversion and ethylene yield was observed after the 800-h run, which was due to the decreased Brønsted amount caused by carbon deposition, rather than the change of crystal phase or leaching of active sites

Aqueous Phase Hydrodeoxygenation of Phenol over Ni₃P‑CePO₄ Catalysts

Unsupported Ni₃P-CePO₄ catalysts were prepared by coprecipitation, followed by drying, calcination, and temperature-programmed reduction. The prepared catalysts were characterized by XRD, N₂ adsorption–desorption, TEM, STEM-EDS elemental mapping, XPS, NH₃-TPD, FT-IR of adsorbed pyridine, and H₂-TPR. Their catalytic performances in hydrodeoxygenation (HDO) were investigated using an aqueous solution of phenol (5.0 wt %) as the feed. CePO₄ was generated in coprecipitation and stable in the subsequent drying, calcination, and temperature-programmed reduction (final temperature 500 °C). It is shown that the addition of CePO₄ resulted in enhanced HDO activity, and a maximum activity appeared at a Ce/Ni ratio of 0.3. The presence of CePO₄ improved the dispersion of Ni₃P significantly, leading to enhanced hydrogenation activity. CePO₄ served as the major dehydration sites as well because of its surface acidity (mainly Lewis acid). In addition, the kinetics of the aqueous phase HDO of phenol and cyclohexanol catalyzed by Ni₃P and by Ni₃P-CePO₄ with Ce/Ni ratio of 0.3 were investigated