Efficient, continuous oxidation of durene to pyromellitic dianhydride mediated by a V-Ti-P ternary catalyst: The remarkable doping effect

Continuous preparation of pyromellitic dianhydride(PMDA) from durene has been studied using a fixedbed reactor. The reaction was performed using a phosphorus-vanadium-titanium ternary catalyst.Relatively high selectivity and yield of PMDA was obtained. The in-situ characterization was combined with theoretical calculation to reveal the reaction mechanisms, and the remarkable doping effect was discussed.

Platinum-based ternary catalysts for the electrooxidation of ethanol

Direct ethanol fuel cell(DEFC)as a promising device for converting chemical energy to electricity has been paid ever-increasing attention.However,the slow kinetics of ethanol electrooxidation at an anode hinders the application of DEFCs.Although Pt is the best catalyst among all the pure metal catalysts,it still has a relatively poor ability to break the Csingle bondC bond,is deactivated by the accumulated CO_(ad) intermediates,and undergoes unwanted desired structure change over long-term operation.In recent years,the addition of other metals to form binary,ternary,and quaternary catalysts have significantly improved electroactivity and stability.Ternary catalysts can have numerous element combinations and complicated architectures and,therefore,have been the subject of considerable research.In this review,most of the reported ternary catalysts will be summarized and categorized according to their structure while discussing the essence of the role of each component.

One step NaBH_4 reduction of Pt-Ru-Ni catalysts on different types of carbon supports for direct ethanol fuel cells : Synthe sis and characte rization

The ternary catalyst Pt75Ru5Ni20 was conducted on various types of carbon supports including functionalized Vulcan XC-72R(f-CB),functionalized multi-walled carbon nanotubes(f-MWCNT),and mesoporous carbon(PC-Zn-succinic)by sodium borohydride chemical reduction method to improve the ethanol electrooxidation reaction(EOR)for direct ethanol fuel cell(DEFC).It was found that the particle size of the metals on f-MWCNT was 5.20 nm with good particle dispersion.The alloy formation of ternary catalyst was confirmed by XRD and more clearly described by SEM element mapping,which was relevant to the efficiency of the catalysts.Moreover,the mechanism of ethanol electrooxidation reaction based on the surface reaction was more understanding.The activity and stability for ethanol electrooxidation reaction(EOR)were investigated using cyclic voltammetry and chronoamperometry,respectively.The highest activity and stability for EOR were observed from Pt75Ru5Ni20/f-MWCNT due to a good metal-carbon interaction.Ru and Ni presented in Pt-Ru-Ni alloy improved the activity and stability of ternary catalysts for EOR.Moreover,the reduction of Pt content in ternary catalyst led to the catalyst cost deduction in DEFC.

Ternary Pt/Re/SnO2/C catalyst for EOR:Electrocatalytic activity and durability enhancement

Carbon-supported Pt/C,Pt/Re/C,Pt/SnO2/C and Pt/Re/SnO2/C,with 20 wt.%overall metal loading were prepared and their electrochemical activity towards ethanol oxidation reaction(EOR)was investigated.Transmission electron microscopy(TEM)combined with energy dispersive X-ray spectroscopy(EDS)revealed,that indeed binary and ternary combinations of the designed nanoparticles(NPs)were formed and successfully uniformly deposited on a carbon support.Fourier transform infrared spectroscopy(FTIR)allowed to assess the chemical composition of the nanocatalysts and X-ray diffraction(XRD)allowed to determine the catalyst structure.Potentiodynamic and chronoamperometric measurements were used to establish its catalytic activity and stability.The influence of Re addition on the electrochemical activity towards ethanol oxidation reaction(EOR)was verified.Indeed,the addition of Re to the binary Pt/SnO2/C catalyst leads to the formation of ternary Pt/Re/SnO2/C with physical contact between the individual NPs,enhancing the EOR.Furthermore,the onset potential of the synthesized ternary catalyst is shifted to more negative potentials and the current densities and specific activity are nearly 11 and 5 times higher,respectively,than for commercial Pt catalyst.Additionally ternary Pt/Re/SnO2/C catalyst retained 96%of its electrochemical surface area.

Enhancement of oxygen reduction activity and stability via introducing acid-resistant refractory Mo and regulating the near-surface Pt content

Although Pt Ni catalyst possesses good oxygen reduction activity, its poor stability is the main obstacle for the commercialization of proton exchange membrane fuel cells(PEMFCs). In this work, we introduce the acid-resistant refractory Mo to enhance the structure stability and modify the electronic structure of Pt in the prepared PtNi catalyst, improving the catalytic activity for oxygen reduction reaction(ORR). In addition, near-surface Pt content in the nanoparticle is also optimized to balance the ORR activity and stability. The electrochemical results show that the alloy formed by Mo and Pt Ni is obviously more stable than the PtNi alloy alone, because the acid-resistant Mo and its oxides effectively prevent the dissolution of Pt. Especially, the Pt3 Ni3 MoN/C exhibits the optimal ORR catalytic performance in O2-saturated 0.1 mol L^(-1) HClO4 aqueous solutions, with mass activity(MA) of 900 m A mg^(-1) Pt at 0.90 V vs. RHE, which is 3.75 times enhancement compared with the commercial Pt/C(240 mA mg^(-1) Pt). After 30 k accelerated durability tests, its MA(690 m A mg^(-1) Pt) is still 2.88 times higher than the pristine Pt/C. This study thus provides a valuable method to design stable ORR catalysts with high efficiency and has great significance for the commercialization of PEMFCs.