查看更多>>摘要：Poly/perfluoroalkyl substances (PFASs) are ubiquitous organic pollutants and the strong C-F bonds make them recalcitrant for degradation. In this study, novel In-MOF/BiOF heterojunctions at different doping ratios were synthesized, characterized and evaluated for the photocatalytic removal performance on Perfluorooctanonate (PFOA), perfluorooctane sulfonate (PFOS), hexafluoropropylene oxide trimer acid (HFPO-TA) and 6:2 chlori-nated polyfluorinated ether sulfonate (6:2 Cl-PFESA). 20% In-MOF/BiOF exhibited effective and complete degradation of PFOA (15 mg/L) under illumination. The reaction rate constants decreased in the order of PFOS > 6:2 Cl-PFESA > PFOA > HFPO-TA. The density functional theory calculation revealed that the reaction rate constant positively correlated with adsorption energies of the PFASs on the catalyst. Additionally, the generation of built-in electric field at the In-MOF and BiOF interfaces enhanced the efficient separation of photogenerated carriers, thus intrinsically facilitated the catalytic performance. The study sheds light on the construction of built-in electric field to improve photocatalytic performance.
Shi, YingzhangWang, ZhiwenLiu, ChengWu, Tai Kang...
11页
查看更多>>摘要：Pt clusters supported on monolayer Bi2MoO6 nanosheets (Pt/BMO-NS) are constructed for the photocatalytic selective reduction of 4-nitrostyrene to 4-vinylaniline in the presence of HCOONH4 and exhibit high conversion (approximate to 100%) of 4-nitrostyrene and high selectivity (approximate to 100%) of 4-vinylaniline. In situ FTIR spectra and XPS spectra of BMO-NS absorbed 4-nitrostyrene further demonstrate that 4-nitrostyrene can be selectively absorbed and activated on surface Mo5+ and Bi2+ sites of BMO-NS via the Bi center dot center dot center dot O-N or Mo center dot center dot center dot O-N coordination. The Pt clusters and photogenerated carriers synergistically make the efficient dissociation of HCOO- to form rich center dot CO2- and active center dot H, greatly supporting the selective reduction of 4-nitrostyrene to 4-vinyaniline. This work not only highlights the complete utilization of photo-generated carriers to achieve the selective reduction of 4-nitrostyrene to 4-vinylaniline via photocatalytic hydrogen transfer, but also uses metal/monolayer nanosheets as a molecule platform to deeply study the surface/interface synergetic mechanism at the molecule level.
查看更多>>摘要：To construct an efficient electrocatalyst for HER, the high binding energy of MXene must be mitigated through electronic modulation of active sites. Here, we propose atomic Pt substitution in V2CTx MXene to modulate the electronic structure and promote catalytic activity toward HER. Pt-V2CTx exhibits high HER performance with a low overpotential of 27 mV at -10 mA cm(-2) in acidic media, comparable to the commercial Pt/C catalyst. X-ray absorption spectroscopy and DFT calculations indicate that the Pt atoms are efficiently confined to the V vacancy sites of V2CTx , accompanied by a unique electronic structure. The atomic substitution of Pt with higher occupied d states at the Fermi energy of Pt and surface oxygen sites can significantly indicate an optimum hydrogen binding free energy (Delta G(H)*), promoting HER performance. This work introduces further prospects for developing efficient electrocatalysts by feasible electronic regulation and highly improved catalytic activity through rational atomic engineering.
查看更多>>摘要：Hydrocracking converts heavy feeds mainly into middle distillate products. Co-processing these bio-feeds with vacuum gas oil is a possible production route for biofuels. Stabilized bio-liquid from fast pyrolysis and hydro thermal liquefaction bio-crude were mixed with vacuum gas oil (10-20 wt%) and hydrocracked over a bifunctional catalyst. The impact of the bio-liquids on conversion and middle distillate selectivity were investigated. The liquid products were analyzed by several methods such as 2-dimensional gas chromatography coupled with simulated distillation to obtain quantitative distribution of monoaromatics, polyaromatics and saturated hydrocarbons. A quantification study of different types of carbons was performed by C-13 NMR and showed the evolution of products. The nature of bio-liquid impacts slightly on the conversion and gas production but not on the selectivity of middle distillates and naphtha. This is explained by a decoupled hydrodeoxygenation and hydrocracking process. This also resulted in a high hydrodesulfurization conversion.
查看更多>>摘要：It is an insurmountable challenge to synthesize carrier-supported ultra-small immiscible alloy catalyst with simple one-step method today. Here, we creatively report the first preparation of immiscible Ru-based alloys (RuRE-rGO NPs, RE=Gd, Er, Yb, La) with ~5 nm by solvent-free microwave reduction. Additionally, in alkaline electrocatalytic hydrogen evolution reaction (HER), RuGd-rGO NPs performed admirable (eta = 12 mV at 10 mA cm(-2), TOF=30.6 H-2 s(- 1) at 0.1 V), which also can be stable for 500 h even if it provides industry-related current density of 500 mA cm(-2). Density functional theory further indicates that from initial to final state of the reaction, RuGd-rGO NPs have large exothermic energy (-1.34 eV), while the dissociation energy barrier of H2O is relatively low, causing the most likely occurrence of HER. This work provides sufficient space for the synthesis of ultra-small immiscible nano-alloy supported catalysts.
查看更多>>摘要：The rational design of an artificial system that mimics natural photosynthesis for H-2 evolution remains a sub-stantial yet engaging challenge. Efficient light absorption, charge separation and associated surface reactions are crucial aspects of semiconductor photocatalytic system for efficient water splitting. Herein, a catalyst assembly of p-SiO2-NH3-Fe11POM@CdS was constructed by partially etched SiO2-NH2 coating CdS (p-SiO2-NH2@CdS) bound iron-based polyoxometalate (Fe11POM) in the interstitial space. In the hybrid catalyst, Fe11POM acts as catalyst and p-SiO2-NH2@CdS as light-harvesting material as well as Fe11POM enrichment center, respectively. The p- SiO2-NH3-Fe11POM@CdS catalyst exhibits a high H-2 evolution activity of 23.1 mmol g(-1) h(-1) with turnover number (TON) of 3225 and apparent quantum efficiency (AQE) of 71% under 420 nm LED illumination. The electrons transfer from p-SiO2-NH2@CdS to Fe11POM, affording electrons accumulated in Fe11POM for H-2 evolution. Our strategy of building hybrid photocatalyst will provide a new way to construct efficient catalyst assembly for water splitting.
Efstathiou, Angelos M.Polychronopoulou, KyriakiHussien, Aseel G. S.Khaleel, Maryam T. A....
21页
查看更多>>摘要：The different effects of the presence of La3+ and Sm3+ heteroatoms in the 5 wt% Ni/45Ce-45(Sm or La)-10Cu-O catalytic system on the carbon deposition and removal reaction paths in the dry reforming of methane (DRM) at 750 ? were investigated using transient kinetic and isotopic experiments. The relative initial rates of carbon oxidation by lattice oxygen of support and that by oxygen derived from CO2 dissociation under DRM reaction conditions were quantified. Ni nanoparticles (23-nm) supported on La3+-doped ceria exhibited at least 3 times higher initial rates of carbon oxidation to CO by lattice oxygen, and ~ 13 times lower rates of carbon accumulation than Ni (18-nm) supported on Sm3+-doped ceria. The concentration and mobility of labile surface oxygen at the Ni-support interface region seems to correlate with carbon accumulation. Ni/Ce-La(or Sm)-10Cu-O formed NiCu alloy nanoparticles, partly responsible for lowering carbon deposition and increasing carbon oxidation rates to CO.
查看更多>>摘要：Balancing the NH3 selective catalytic reduction (NH3-SCR) and catalytic oxidation performance is difficult but necessary for the synergistic elimination of NOx and chlorine-containing volatile organic compounds (CVOCs). We herein unveiled that electronic structure tailoring of the applied catalyst was an efficient pathway for balancing the catalytic behaviors in the NH3-SCR of NO and chlorobenzene catalytic oxidation (CBCO). Specifically, environmentally friendly CeO2 substituted by low valent Al3+ exhibited better NH3-SCR of NO and CBCO activity in comparison with the CeO2 sample without doping. Detailed characterizations and theoretical simulations revealed that the strong dopant-oxide pairs in the CeO2 with Al3+ doping significantly tailored the electronic structure of O 2p states, enhancing the amount of Lewis acid sites and promoting the ability of lattice oxygen to act as an oxidizing agent, thereby leading to superior performance for the synergistic elimination of NO/CB. The counterpart with substitution of high valent Ta5+ showed an opposite trend, due to that Ta5+ donated more electrons to the coordination oxygen than Ce4+ inhibiting lattice oxygen separating from the surface of the catalyst, and Lewis base sites were formed.
查看更多>>摘要：Herein, we report an integrated coagulation/ photo-Fenton (CPF) process for advanced treatment of mature landfill leachate using nascent aluminum ions as coagulant and hydrogen peroxide (H2O2) as oxidant for Fenton reaction, which were in-situ produced by a novel chlorine and nitrogen co-doped aluminum-graphite (Cl, N-Al -Gr) composite. The coagulation of the MBR-treated landfill leachate was performed by nascent aluminum ions generated in Cl, N-Al-Gr/O-2 system; and the resulting coagulation effluent was treated by photo-Fenton oxidation in the presence of ultraviolet (UVA). The Cl, N-Al-Gr composite exhibited excellent performance for in-situ H2O2 production (813.9 mg/L). The humic substances in landfill leachate could promote the cycle of Fe3+/Fe2+, and the removal efficiency of total organic carbon (TOC) and color was 88.1% and 97.6%, respectively under the optimized condition. The current study suggested that "coagulation + Fenton " process using nascent Al3+ as coagulant and in-situ generated H2O2 for Fenton oxidation could be a new way for wastewater treatment.
Cuello-Penaloza, Paolo A.Dastidar, Raka G.Wang, Shao-ChunDu, Yi...
12页
查看更多>>摘要：A series of calcined MgAl mixed metal oxide catalysts with low Cu loadings (0.1-1.5 wt%) were tested for ethanol oligomerization to distillate-range molecules. The low Cu loading catalysts (0.1-0.6 wt%) had high selectivity to linear chain C4+ alcohols (49-63% selectivity) and C6+ esters (45-66% of total esters). More specifically, the diesel fuel precursor selectivities were over 75% for low Cu loading catalysts (0.1-0.6 wt%), with a decrease to 49% for a higher Cu loading catalyst (> 1.2 wt% Cu) due to increased ethyl acetate and acetone formation. Alcohol and ester product selectivities follow a Schultz-Flory distribution. Alcohol selectivity was found to vary inversely with BET surface areas of the catalysts, whereas ester selectivity was found to increase with higher base site counts. However, Cu wt% loading was found to have a stronger impact in overall catalyst activity. The catalysts deactivated proportionally to the number of turnovers mainly due to coking, but could be regenerated by calcination.
NSTL
Elsevier