Xiujing Zou’s research while affiliated with Shanghai University and other places

P2O5 has been widely used as an acid‐base catalyst for the O‐methylation of catechol to guaiacol due to its suitable acid strength; however, its stability, which is a significant concern for industrial applications, has not seen significant breakthroughs. Herein, we developed a facile impregnation strategy to synthesize Ce promote P2O5 supported on mesoporous silica (CeP/SBA). The CeP/SBA‐500 carbonized at 500 °C exhibited the highest catalytic activity with a catechol conversion of 71.5 %. The high activity stems from the addition of Ce, forming CePO4, which exhibits improved surface acidity compared to P2O5. Importantly, chemisorption and in situ infrared studies revealed that CePO4 shows stronger adsorption of catechol, which then rapidly converts to guaiacol. The CeP/SBA‐500 exhibits excellent stability with no activity decrease after 10 h of continuous flow reaction, attributed to the absence of a decrease in CePO4 surface acidity.

SBA-15-supported Al2O3-P2O5 with 10 wt% Al2O3 and different P2O5 mass percentages (10Al2O3-xP2O5/SBA-15) were prepared by simple impregnation method and used for gas-phase selective O-methylation of catechol to guaiacol with dimethyl carbonate. The 10Al2O3-xP2O5/SBA-15 catalysts maintained ordered mesoporous structures, but their specific surface areas, pore volumes, and pores decreased with the addition of Al and P oxides. The addition of P2O5 decreased the strength of weak acid, but with the P2O5 content increasing, the additional pseudo-bridging bonds that are similar to amorphous silica-alumina were formed, which enhanced the acidity of weak acid. Brønsted acid sites introduced by P2O5 promoted more acid sites and lower the strength of acid sites. The basic sites increased with the increase of P2O5 content. Acidic sites are the key to control the catalytic activity, and basic sites are the key to control the catalytic selectivity. 10Al2O3-5P2O5/SBA-15 exhibited excellent catalytic activities and high selectivity to guaiacol for the O-methylation of catechol, due to the synergistic effect of acid and base sites.

g-C3N4 supported Pd nanotetrahedrons (Pd NTs@g-C3N4) are first prepared by an in-situ growth method with water-induced process. The unique Pd nanotetrahedrons with four (111) facets exposed have been prepared by simply varying the dosage of water without the other synthesis condition changed. The optimized Pd NTs@gC3N4 exhibits higher activity (TOF value: 51462 h− 1 ) toward the hydrogenation of nitrobenzene with respect to the commercial Pd/C. The enhanced activity is attributed to the small size and tetrahedral shape with higher surface energy and more active surface. Most importantly, the Pd NTs@g-C3N4 still shows excellent activity and selectivity for nitrobenzene hydrogenation without obviously deactivation after ten cycles. In addition, the vertical and parallel adsorption behaviors of nitrobenzene molecules on Pd (111) surface are analyzed in detail using the density functional theory (DFT) method, and the interaction mechanism between nitrobenzene and palladium is studied by the charge density difference method.

The O-methylation of catechol is an effective method for the industrial production of guaiacol used as an important chemical. However, the low catechol conversion and poor catalyst stability are the most critical issues that need to be addressed. Herein, the O-methylation of catechol with dimethyl carbonate was investigated over aluminophosphate (APO) catalysts, using a continuous-flow system to produce guaiacol. APO catalysts were synthesized with varying P/Al molar ratios and calcination temperatures to study their effects on catalytic performance for the reaction. The physico-chemical properties of the APO catalysts were thoroughly investigated using XRD, NH3-TPD, CO2-TPD, FTIR, and Py-FTIR. The P/Al molar ratio and catalyst calcination temperature significantly influenced the structure and texture, as well as the surface acid-base properties of APO. Both the medium acid and medium base sites were observed over APO catalysts, and the Lewis acid sites acted as the main active sites. The APO (P/Al = 0.7) exhibited the highest catalytic activity and excellent stability, due to the suitable medium acid-base pairs.

The integrated CO2 capture and utilization has recently attracted attention as a promising approach to reduce CO2 emissions as well as produce value-added chemicals and fuels. Herein, metal oxides (MxOy, M = Mg, Zr, La, and Ce) modified Ni/CaO dual functional materials (M-Ni/Ca DFMs) were synthesized and applied to the combined CO2 capture and hydrogenation using a single reactor at one temperature. The La–Ni/Ca showed the highest CO2 adsorption capacity (13.8 mmol/g), CO2 conversion (64.3%) and CO yield (8.7 mmol/g). Results indicated that the addition of metal oxides increased the number of basic sites which played important role in efficient CO2 capture. The high activities of M-Ni/Ca were attributed to the formation of highly dispersed small-sized Ni particles. Furthermore, the La–Ni/Ca exhibited excellent cyclic stability after 20 cycles due to the La2O3 as a physical barrier and a support for inhibiting the growth and sintering of CaO and Ni particles.

Hydrogenation of nitrobenzene to p-aminophenol over solid metal catalysts in acid medium is a sustainable and efficient protocol. However, it is challenging to fabricate such a catalyst that can achieve both high activity and unparalleled selectivity. Herein, a facile incipient wetness impregnation strategy is proposed and employed to synthesize an activated carbon supported Pt–Rh alloy catalyst. The Pt–Rh/AC catalyst exhibits simultaneously improved activity (TOF value: 10872 h⁻¹) and p-aminophenol selectivity (ca. 95.4%). The enhanced activity is attributed to the formation of well dispersed Pt–Rh bimetallic nanoparticles caused by the promoting effect of Rh for the reduction of Pt²⁺. Chemisorption and in situ infrared studies reveal that Pt–Rh bimetallic nanoparticles surfaces were enriched by Pt accompanying with possible electron transfer from Rh to Pt. The density functional theory calculations suggest that the adsorption of generated phenylhydroxylamine intermediate was inhibited over electron-rich Pt to avoid its subsequent hydrogenation to form aniline, resulting in excellent selectivity for p-aminophenol.

The development of new hydrodesulfurization (HDS) catalysts with suitable electronic structure and metal-support interaction are critical for the efficient removal of sulfur from oil. In this work, cobalt-promoted molybdenum carbide supported on mesoporous alumina (CoxMo2C/MA) catalysts were prepared by a simple one-step hydrolysis method combined with a temperature programmed carbonization process, and the effects of Co on the physicochemical properties and HDS performance of the catalysts were systematically investigated. The results show that the appropriate Co addition can reduce the interaction between Mo species and alumina support, which is beneficial for the carbonization of Mo. Besides, the introduction of Co makes Mo species electron-rich, causing the C–S bond is vulnerable to attack. Taking dibenzothiophene (DBT) as a probe, Co0.3Mo2C/MA shows significant high sulfur removal efficiency (about 100%) and effective direct desulfurization selectivity. Furthermore, the density functional theory calculations further prove that the activation energy barrier of DBT HDS at the Co–Mo2C site is lower than that of Mo2C, confirming its reaction is easier to proceed. This work may provide a strategy for accessing new efficient modified molybdenum carbide catalysts for the HDS field.

Highly dispersed Pt nanoparticles (∼2.5 nm) on phosphorus-doped activated coconut shell carbon (Pt/P-ACC) were synthesized by a two-step impregnation route. Pt/P-ACC showed a high activity, chemoselectivity, and reusability toward the hydrogenation of nitrobenzene to p-aminophenol, with hydrogen as the reducing agent in sulfuric acid. The effects of P species on the catalyst structure, surface properties, and catalytic performance were investigated. It was found that the Pt/P-ACC catalyst had an excellent catalytic activity due to its smaller Pt nanoparticles and higher content of surface-active metal compared with Pt/ACC. Besides, the experimental results and in situ infrared studies demonstrated that the interaction effect between the Pt and P species imbued the surface of Pt with an electron-rich feature, which decreased the adsorption of electron-rich substrates (that is, phenylhydroxylamine) and prevented their full hydrogenation, leading to enhanced selectivity during the hydrogenation of nitrobenzene to p-aminophenol.

Carbon doped silica‐supported NiCu alloy nanoparticles (Ni1Cux/C@SiO2) with different Cu/Ni molar ratio (x=0.12, 0.24, 0.36) were fabricated via one‐step impregnation, following in situ carbonization reduction. Effects of Cu content on catalyst structure, surface properties and particle sizes were investigated by Brunauer‐Emmett‐Teller (BET), inductively coupled plasma (ICP), Raman, X‐ray diffraction (XRD), transmission electron microscopy (TEM) and X‐ray photoelectron spectroscopy (XPS). The surface Ni⁰ content increased with increasing Cu content, but showed a maximum at 0.24 of Cu/Ni molar ratio, because the smaller NiCu alloy nanoparticle formed and the segregation of antioxidative Cu atoms on the surface protected the metallic Ni from oxidation. The Ni1Cux/C@SiO2 were investigated for nitrobenzene hydrogenation with H2. The optimal Ni1Cu0.24/C@SiO2 catalyst with the highest Ni⁰ content showed markedly improved catalytic activity compared to monometallic Ni/C@SiO2. The Ni⁰ species were the active sites for the hydrogenation of nitrobenzene. The Ni1Cu0.24/C@SiO2 could transform various substituted nitroarenes to corresponding aromatic amines. Moreover, the Ni1Cu0.24/C@SiO2 could be recycled for 8 times without decrease in catalytic performance, exhibiting superior anti‐oxidation and anti‐leaching abilities.

Mesoporous γ‐Al2O3‐supported Mo oxides precursors were prepared by one‐step hydrolysis method without organic template at different calcination temperatures (MoOx/γ‐MA‐T) from 400 to 700 °C. Then MoS2 catalysts (MoS2/γ‐MA‐T) were obtained from the precursors through in‐situ sulfurization and applied for hydrodesulfurization (HDS) of dibenzothiophene (DBT). Effects of precursors calcination temperature on physicochemical properties and catalytic performances of catalysts were systematically investigated. With the increase of calcination temperature, the strength of metal‐support interactions and slab lengths of MoS2 increased. The slab stacks were inhibited by the strengthened strong interaction, leading to the reduction of edge/rim sites ratio that are favour for the HDS reaction. Appropriate calcination temperature (500 °C) could make the MoS2/γ‐MA‐500 possess favourable pore structure, particle dispersion, and edge/rim sites ratio, which were conducive to the mass transfer process of reactants and products, and lowered the carbon deposition rate, thus improving its catalytic activity, stability and direct hydrogenolysis desulfurization selectivity.