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Using cinchonine as a raw material, a cinchonine-based isonitrile monomer was prepared after multistep transformation, and finally cinchonine-based catalyst was prepared by polymerization initiated by 4-methoxyphenylethynyl(chloro)bis(triethylphosphine)palladium(II). The new catalyst was used to catalyze asymmetric aldol reactions between cyclohexanone and aromatic aldehydes with different substituent groups. The reaction of cyclohexanone and 3-nitrobenzaldehyde in methanol afforded an enantiomeric excess (ee) value of up to 55% and a diastereomeric ratio (dr) of up to 30:70, indicating high performance of the catalyst. The synthesized compounds were characterized by HPLC, IR, and 1H NMR. [ABSTRACT FROM AUTHOR]

High concentration of H2S in acidic natural gas will lead to poisoning of catalysts for hydrogen production by methane steam reforming, thus limiting the further use of natural gas. Reforming CH4 by H2S can be considered as an alternative route to hydrogen production from methane. This process not only achieves the removal of H2S but also obtains chemical raw material CS2 and clean energy H2. By impregnating the Mo source on SiO2 treated with hydrogen peroxide and then using the catalyst in the CH4/H2S reforming reaction, we surprisingly found that the conversion rate of CH4 and H2S increased from 28 and 32% to 34% and 43%, respectively, after hydrogen peroxide treatment. The H2 production rate and the yield of CS2 increased from 20 mmolH2/(gMo*min) and 52% to 30 mmolH2/(gMo*min) and 65%, respectively. Combining with characterization methods such as X-ray diffraction (XRD), hydrogen temperature programmed reduction (H2-TPR), 1H-based solid-state nuclear magnetic resonance (1H MAS NMR), X-ray photoelectron spectroscopy (XPS), Raman spectra (RS), and transmission electron microscopy (TEM), we found that the hydroxyl concentration of the support increased after hydrogen peroxide treatment, which led to the strengthening of the force between the metal and the support, which was easy to form low-level and small-size MoS2, exposing more active sites, and further improving the catalytic activity. This method provides a new idea for hydrogen production by CH4/H2S reforming and the development of high-performance MoS2-based catalysts. [ABSTRACT FROM AUTHOR]

A novel helical polymer (compound poly-1200) containing side chains of L-leucine was synthesized. This chiral L-leucine polymer catalyst exhibited excellent catalytic activity and stereoselectivity in Aldol reaction. Poly-1200 catalyzed Aldol reaction of cyclopentanone and 4-nitrobenzaldehyde in saturated brine solution with a high enantiomeric excess (ee) value of up to 99% and a diastereomeric selectivity (dr) value of 58/42. Furthermore, the chiral polymer catalyst could be recycled three times in the asymmetric Aldol reaction without significant loss of catalytic activity.Graphic Abstract: A novel helical polymer (compound poly-1200) containing side chains of L-leucine was synthesized. This chiral L-leucine polymer catalyst exhibited excellent catalytic activity and stereoselectivity in Aldol reaction. Poly-1200 catalyzed Aldol reaction of cyclopentanone and 4-nitrobenzaldehyde in saturated brine solution with a high enantiomeric excess (ee) value of up to 99% and a diastereomeric selectivity (dr) value of 58/42. Furthermore, the chiral polymer catalyst could be recycled three times in the asymmetric Aldol reaction without significant loss of catalytic activity. [ABSTRACT FROM AUTHOR]

Sulfur poisoning is a major challenge in the design of high-performance heterogeneous catalysts. In this study, an effective sulfur-resistant catalyst for the catalytic decomposition of CH 3 SH was prepared by a secondary crystallization method. Compared with the conventional impregnation method, this method can effectively regulate the position of Fe on the S-1 support and the property of the acidic site. The strong redox properties, strong acidity and highly dispersed Fe species on the modified 2.5 % Fe@S-1 catalyst contributed to the improvement of the low-temperature activity of the catalytic decomposition of CH 3 SH, and increased the sulfur and coke resistantce of the catalyst. As expected, the 2.5 % Fe@S-1 catalyst maintained 90 % CH 3 SH conversion within 80 h of TOS. By contrast, Fe particles in 2.5 % Fe/S-1 catalysts was large and prone to agglomeration, resulting in poor catalyst stability. It was shown that Fe-based catalysts prepared by the secondary crystallization method have potential applications in CH 3 SH degradation. [Display omitted] • Dispersion and acidity of Fe-based catalysts are well modulated with secondary crystallization. • The formation of framework iron limits the aggregation of Fe particles. • The obtained Fe@S-1 catalysts show excellent sulfur-resistance towards CH 3 SH decomposition. [ABSTRACT FROM AUTHOR]

Selective hydrogenation of phenol to cyclohexanone is a vital step in the manufacture of fiber (nylon), which is currently carried out over expensive Pd catalyst with low productivity. In this work, a series of Ru-promoted Pd catalysts were synthesized in a facile microwave-assisted method and tested in the hydrogenation of phenol to cyclohexanone. It was found that small amount of Ru in Ru-Pd alloy can increase the conversion of phenol obviously without loss of cyclohexanone selectivity. The selectivity of cyclohexanone over Ru 0.15 Pd 4.85 /ZrHP remained higher than 99%, while the conversion of phenol increased from 20.5% (over Pd 5 /ZrHP) to 97.9% at 100 °C and 1 MPa. And the highest turnover frequency (TOF) of surface metal in Ru 0.15 Pd 4.85 /ZrHP at 100 °C and 2 MPa reached 1605 h−1. Characterization results revealed that the addition of Ru can improve the dispersion of Ru-Pd alloy and enhance its electron density. In addition, the activated hydrogen on Ru-Pd alloy and acid sites in ZrHP played a synergistic effect for the selective formation of cyclohexanone from phenol. [Display omitted] • ZrHP and it supported Ru-Pd alloy were synthesized in a facile microwave-assisted method. • Ru can promote the dispersion of Pd or Ru-Pd alloy in Ru x Pd y /ZrHP. • Well-structured Ru 0.03 Pd 0.97 alloy formed in Ru 0.15 Pd 4.85 /ZrHP catalyst. • Ru-Pd alloy and ZrHP exhibited a synergistic effect for the hydrogenation of phenol to cyclohexanone. • The selectivity of cyclohexanone remained higher than 93% even at a complete conversion of phenol. [ABSTRACT FROM AUTHOR]

[Display omitted] • Electrochemical active surface area is affected by humidity and temperature. • A fitting equation of electrochemical active surface area has been proposed. • The equation can be universally applied in different catalyst layer compositions. • Validations are completed on data measured in low humidity operations. • Including the equation in models helps predict more accurate cell performances. The electrochemical active surface area has a vital influence on the performance of proton exchange membrane fuel cells. In this study, a universal semi-empirical equation of the electrochemical active surface area in the catalyst layer of fuel cells is proposed based on self-designed experiments, aiming to improve the predictive accuracy of numerical models under low humidity conditions. The generalization of this equation is also verified with the other nine catalyst layers of different compositions. At very low water content corresponding to low inlet humidification operations, the electrochemical active surface area is generally low and increases sharply with the increment of water content. When the water content exceeds a certain threshold value, the electrochemical active surface area becomes independent of water content. In addition, the electrochemical active surface area significantly decreases as the operating temperature increases. Consequently, including this newly proposed electrochemical active surface area equation in conventional full-cell models is of significant importance to accurately predict the activation loss and performance of fuel cells under both cold-start and normal operation conditions, especially at low humidification, which is validated against experimental data. In contrast with the conventional constant electrochemical active surface area assumption, this equation improves the model accuracy from about 70% to be higher than 90% under low humidity conditions. [ABSTRACT FROM AUTHOR]

• The study proposes a new preparation system, micro-plasma electrolytic oxidation. • Au/MgO with defects is fabricated by combining liquid nitrogen as cooling source. • Au/MgO exhibits an excellent catalytic activity in nitrophenol hydrogenation. The defect-rich Au nanoparticles (NPs) catalyst on Mg surface was prepared by the micro-plasma electrolyte oxidation (MPEO) utilizing liquid nitrogen as the cooling medium. MPEO is a high-temperature plasma oxidation process that decomposes the [AuCl 4 ]-precursor salt to form metastable state Au NPs. The rapid quenching effect of liquid nitrogen occurs during this non-equilibrium process and generates numerous defects on the Au NPs, thereby altering their electronic state. Consequently, the catalytic performance of this Au/MgO catalyst was outstanding, exceeding that of the sample prepared without using liquid nitrogen. This finding indicates that the harsh environment plays a crucial role in producing defect-rich Au NPs and improving the catalytic efficiency. [ABSTRACT FROM AUTHOR]

CaO-based dual function materials (DFMs) with different metallic catalysts (Ni, Co, Mn or Fe) incorporated were prepared by the one-pot synthesis method for integrated CO 2 capture and reverse water gas shift reaction (ICCU-RWGS) for CO production. [Display omitted] • M@CaO (M = Ni, Co, Mn and Fe) DFMs are prepared for CaL-RWGS applications. • Influence of catalyst component on CaL-RWGS performance is investigated. • The interactions between catalyst and CaO affect the physicochemical properties of the DFMs. • Carbonation and regeneration kinetics of the DFMs in CaL-RWGS are demonstrated. • Mn@CaO exhibits good CaL-RWGS performance with high CO 2 uptake and great CO yield. Integrating calcium-looping cycle (CaL) with reverse-water–gas-shift (RWGS) reaction represents an effective path to realizing integrated CO 2 capture and utilization (ICCU). Screening a suitable catalyst to construct highly efficient CaO-based dual function materials (DFMs) is essential for CaL-RWGS. In the current work, M@CaO (M = Ni, Co, Mn, and Fe) DFMs are prepared for CaL-RWGS, and the influence of catalyst component on the structure, CO 2 capture and RWGS performance, and kinetic behaviors of the CaO-based DFMs is investigated. Results show that the interaction between CaO and catalyst affects the average grain size and dispersion of metallic catalyst, oxygen vacancy concentration, surface basicity, and reducibility of CaO-based DFMs. The desired Mn@CaO DFMs exhibit outstanding CaL-RWGS performance at 650 °C, 15%CO 2 and 50%H 2 , with a great CO 2 uptake (12.30 mmol CO 2 /g), a favorable CO yield (5.92 mmol CO/g), and an impressive CO 2 conversion (53.53%), as well as a high CO selectivity (89.98%). Furthermore, Mn@CaO exhibits excellent carbonation and regeneration kinetics but inferior working stability for CO 2 capture and CO production in multiple CaL-RWGS cycles. Overall, Mn could be a competitive and cost-effective catalyst candidate for high-performance CaO-based DFMs for CaL-RWGS applications, while further work is needed to improve cyclic stability. [ABSTRACT FROM AUTHOR]

The instant synthesis of ultrafine, clean surface Ru nanoparticle (NP) catalysts embedded on a porous MgO support was achieved by instant micro-arc oxidation (IMAO). The high temperature from the micro-arc discharge facilitates the rapid decomposition of the catalyst precursor RuCl 3 into homogeneous nanoparticles, while the fast quenching process ensures instantaneous encapsulation of the formed NPs by the MgO support. The obtained Ru/MgO catalyst exhibited attractive catalytic behaviour for sodium borohydride and ammonia borane hydrolysis, with activities of 100,917 mL min−1·g−1 and 2336 mol min−1·mol−1, respectively. Moreover, this catalyst exhibited an excellent sintering resistance in high-temperature environment that was well retained after 40 cycles, indicating superior recyclability. This work provides a novel pathway for the direct and rapid synthesis of high-quality nanocatalyst and can be generalized to prepare other supported metal nanocatalyst (e.g. Pd/MgO). The accurate building of high-quality nano-catalyst and its application in catalytic hydrogen production. [Display omitted] • The small and surface clean Ru NP improves the catalytic activity. • The embedded structure that endows catalyst excellent structure stability. • The microarcing intensity is firstly proposed as a crucial factor to determine the particles size and monodispersity. • Ru/MgO exhibits a highest TOF value compared to the literatures in ammonia borane hydrolysis with a low activity energy. • This method could be served as a universal platform for the preparation other nanocatalyst such as Pd/TiO 2. [ABSTRACT FROM AUTHOR]

To develop efficient catalysts is one of the major ways to solve the energy and environmental problems. Spinel ferrites, with the general chemical formula of MFe 2 O 4 (where M = Mg2+, Co2+, Ni2+, Zn2+, Fe2+, Mn2+, etc.), have attracted considerable attention in catalytic research. The flexible position and valence variability of metal cations endow spinel ferrites with diverse physicochemical properties, such as abundant surface active sites, high catalytic activity and easy to be modified. Meanwhile, their unique advantages in regenerating and recycling on account of the magnetic performances facilitate their practical application potential. Herein, the conventional as well as green chemistry synthesis of spinel ferrites is reviewed. Most importantly, the critical pathways to improve the catalytic performance are discussed in detail, mainly covering selective doping, site substitution, structure reversal, defect introduction and coupled composites. Furthermore, the catalytic applications of spinel ferrites and their derivative composites are exclusively reviewed, including Fenton-type catalysis, photocatalysis, electrocatalysis and photoelectro-chemical catalysis. In addition, some vital remarks, including toxicity, recovery and reuse, are also covered. Future applications of spinel ferrites are envisioned focusing on environmental and energy issues, which will be pushed by the development of precise synthesis, skilled modification and advanced characterization along with emerging theoretical calculation. [Display omitted] • This review is started off with a short outlook on crystal structure of spinel ferrites and its synthesis methods. • Five strategies for catalytic performance improvement are innovatively proposed. • The catalytic applications of spinel ferrites in environment and energy field are detailed discussed. • Some vital remarks about toxicity are included. [ABSTRACT FROM AUTHOR]