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The suppression of soot generated from acetylene nonpremixed combustion was investigated by following the numerical simulation method. The combustion and soot formation were predicted by the eddy-dissipation and Moss–Brookes models, respectively. The rate of soot formation was decreased by applying acoustic oscillation. The influences of oscillating velocity, frequency, flow rate of acetylene, and Reynolds number on the rate of soot formation were studied. Results showed that the maximum efficiency of soot suppression exceeded 90%. An increase in Reynolds number resulted in enhanced soot suppression efficiency. It is considered that the boundary layer of the soot particles was reduced when the Reynolds number increased. This could potentially result in the enhancement of mass transfer, thus causing the reoxidation of the soot in the oxidation zone. Reoxidation of soot resulted in reduced soot generation. The flame temperature increased simultaneously. [ABSTRACT FROM AUTHOR]

Abstract: In this work, we reported the synthesis of a novel electro‐catalyst composed of Fe and Co bimetallic nanoalloys embedded in N‐enriched carbon framework (FeCo@NC) for oxygen reduction reaction. The FeCo@NC was synthesized through pyrolyzing a dual metal‐organic framework (MOF) under argon atmosphere. This FeCo@NC electrocatalyst showed remarkable performance towards ORR with a high half‐wave potential of 0.827 V versus reversible hydrogen potential (RHE), which was comparable to the state‐of‐the‐art commercial Pt/C catalyst. The enhanced activity could be ascribed to the large specific surface area, the abundant active sites and the synergistic effect of bimetallic alloy. [ABSTRACT FROM AUTHOR]

The global climate change induced by greenhouse gases has stimulated active research for developing efficient strategies to mitigate CO2 emission. In the present study, we prepared a series of polyamine/metal-organic framework (MOF) composites as highly selective CO2 adsorbents from a CO2/N2 mixture, which is relevant to CO2 capture in flue gas. We show that loading polyethyleneimine (PEI) into MIL-101(Cr) frameworks can significantly enhance the selective CO2 adsorption capacity at low pressure and ambient temperature. Further, the comparative study reveals that both the particle size of the MOF and the molecular-weight of PEI play an important role in the CO2 capture ability. Regarding the particle size, smaller MIL-101(Cr) particles can facilitate the loading of PEI into the inner pores and result in lower surface area/pore volume. Thus, the resulting PEI/MIL-101(Cr) composites possess lower CO2 adsorption capacity, but are compensated by higher selectivity of CO2 over N2. On the other hand, lower molecular-weight linear PEI could readily diffuse into the inner pores and effectively block the N2 adsorption. As a result, the as-prepared A-PEI-300 sample in this work exhibits an excellent CO2 uptake of 3.6 mmol g-1 and ultrahigh CO2/N2 selectivity at 0.15 bar and 25 °C. In contrast, the higher molecular-weight branched PEI is advantageous at elevated temperature, since the composites can retain high CO2 adsorption capacity owing to the large amount of primary amine groups. Overall, polyamine/MOF composites are shown to be good candidate adsorbents for CO2 capture from flue gas. To achieve the optimal CO2 capture ability, comprehensive optimization of the polyamine and MOF structures should be performed. [ABSTRACT FROM AUTHOR]

Abstract: We report the synthesis and electrochemical characterization of rhodium/carbon (Rh/C) and palladium–rhodium/carbon (Pd–Rh/C) nanocatalysts for ethanol oxidation. Our results, for the first time, demonstrated that in an alkaline environment, Rh/C shows a much higher catalytic activity at low potential range than that of Pd–Rh/C and Pd/C. Intermediate species are produced during the oxidation process on Rh/C, as revealed by the complex impedance spectra (e.g., pseudo-inductive loop) at low potential range (i.e., −0.5 to −0.3V). Adsorbed oxygen species, which are generated at high potentials, block active surface sites of Rh/C, resulting in the negative polarization resistance. [Copyright &y& Elsevier]

Rational design of efficient, cost-effective electrocatalyst towards oxygen reduction reaction (ORR) is of vital importance to the wide application of polymer electrolyte membrane fuel cells. In this work, a novel and simple Na 2 SO 4 -assisted pyrolysis strategy with ZIF-12 as the precursor is reported for the synthesis of cobalt, sulfur, nitrogen, co-doped carbon (termed as CoSNC- x Na 2 SO 4 -T) materials towards ORR. Different from CoNC-800 derived from pure ZIF-12, with the presence of Na 2 SO 4 , the derived CoSNC-0.5Na 2 SO 4 -800 material exhibits layered flake morphology with hierarchical meso-microporous structure. Besides, CoSNC-0.5Na 2 SO 4 -800 material shows higher content of pyridinic-N and graphitic-N, higher relative intensity of Co-N x , higher content of carbon defect, as well as larger specific surface area in comparison with CoNC-800, which results in higher activity of CoSNC-0.5Na 2 SO 4 -800. The CoSNC-0.5Na 2 SO 4 -800 material displays a half-wave potential of 0.88 V, which is superior to that of commercial Pt/C (half-wave potential being 0.86 V). Moreover, CoSNC-0.5Na 2 SO 4 -800 demonstrates a better durability compared with Pt/C. The pyrolysis temperature and the amount of Na 2 SO 4 are found to affect the physiochemical properties and electrochemical performance of the CoSNC- x Na 2 SO 4 -T materials. This work not only provides a facile and novel synthesis approach for the preparation of highly active Co, S, N co-doped carbon materials for ORR, but also disclosing the key structure properties for enhancing the performance of these catalysts. [Display omitted] • A novel and facile method for synthesizing Co, S, N co-doped porous carbon is provided. • CoSNCs show layered flake morphology with rich transfer channels and active sites. • The Na 2 SO 4 additive and annealing temperature affect the properties of CoSNCs. • CoSNC-0.5Na 2 SO 4 -800 exhibits superior ORR activity and stability than Pt/C. [ABSTRACT FROM AUTHOR]

• The CoNC-0.5C 3 H 6 N 6 -700 catalyst derived from ZIF-67@melamine exhibits excellent performance towards ORR. In this work, highly active cobalt- and nitrogen-doped carbon (Co-N-C) materials were prepared for oxygen reduction reaction (ORR). The Co-N-C materials were synthesized through co-pyrolysis of ZIF-67 and melamine (ZIF-67@melamine). Detailed powder X-ray diffraction (XRD), fourier transform infrared (FTIR) spectroscopy and thermo-gravimentry (TG) analyses suggest melamine could accelerate the decomposition of the ZIF-67 framework. Compared with CoNC derived from pure ZIF-67, the CoNC- x C 3 H 6 N 6 materials derived from ZIF-67@melamine exhibit more carbon defects, larger BET specific surface area, higher content of pyridinic-N and graphitic-N, resulting in the enhanced activity of the CoNC- x C 3 H 6 N 6 samples. The onset potential of CoNC-0.5C 3 H 6 N 6 -700 catalyst towards ORR is 0.96 V (vs. RHE) and the half-wave potential is 0.87 V (vs. RHE), which are close to the state-of-the-art commercial Pt/C. Besides, the electrochemical stability of the CoNC-0.5C 3 H 6 N 6 -700 catalyst is much higher than that of commercial Pt/C. [ABSTRACT FROM AUTHOR]