Enhanced ethylene selectivity and stability of Mo/ZSM5 upon modification with phosphorus in ethane dehydrogenation

Nonoxidative conversion of ethane to ethylene and/or BTX (benzene, toluene, and xylene) suffers rapid deactivation due to coke deposition. We report here the effects of phosphorus modification on the stability and activity of Mo/ZSM5 for nonoxidative conversion of ethane. The results show that the ethylene and BTX yield and stability are significantly enhanced upon modification with 2.5 wt.% P center dot NH3OP TPD, pyridine FTIR, H-1 MAS NMR, (27)AI MAS NMR, P-31 MAS NMR, Xe-129 NMR, XPS, UV-visible diffuse reflectance spectra (UV-vis DRS), and nitrogen physisorption were carried out to understand the effects of P on the structure of Mo/ZSM5 and its correlation with catalytic performance. The presence of P reduces the acid strength and density, changes the channel system of ZSM5 by forming thermally stable SAPO-like interfaces with the framework AI, and improves the dispersion of molybdenum. Rapid deactivation still occurs on Mo/ZSM5 with 1 wt.% P due to the existence of denser silanol groups, more isolated Mo species, and reduced aperture size with little change in effective micropore volume. A higher P loading (2.5 wt.%) leads to less dense silanol groups and less reduced but stable molybdenum species, and simultaneously reduces channel diameter and internal volume. Consequently, the ethylene selectivity is enhanced and the formation of coke precursors is restricted, resulting in improved stability. (C) 2018 Elsevier Inc. All rights reserved

Infiltration of Ce0.8Gd0.2O1.9 nanoparticles on Sr2Fe1.5Mo0.5O6-delta cathode for CO2 electroreduction in solid oxide electrolysis cell

Solid oxide electrolysis cell (SOEC) can electrochemically convert CO2 to CO at the gas-solid interface with a high current density and Faradaic efficiency, which has attracted increasing attentions in recent years. Exploring efficient catalyst for electrochemical CO2 reduction reaction (CO2RR) at the cathode is a grand challenge for the research and development of SOEC. Sr2Fe1.5Mo0.5O6-delta (SFM) is one kind of promising cathode materials for SOEC, but suffers from insufficient activity for CO2RR. Herein, Gd0.2Ce0.8O1.9 (GDC) nanoparticles were infiltrated onto the SFM surface to construct a composite GDC-SFM cathode and improve the CO2RR performance in SOEC. The current density over the GDC infiltrated SFM cathode with a GDC loading of 12.8 wt% reaches 0.446 A cm(-2) at 1.6V and 800 degrees C, which is much higher than that over the SFM cathode (0.283 A cm(-2)). Temperature-programmed desorption of CO2 measurements suggest that the infiltration of GDC nanoparticles significantly increases the density of surface active sites and three phase boundaries (TPBs), which are beneficial for CO2 adsorption and subsequent conversion. Electrochemical impedance spectroscopy results indicate that the polarization resistance of 12.8 wt% GDC-SFM cathode was obviously decreased from 0.46 to 0.30 Omega cm(2) after the infiltration of GDC nanoparticles. (C) 2018 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved

Enhancing electrocatalytic CO2 reduction in solid oxide electrolysis cell with Ce0.9Mn0.1O2-delta nanoparticles-modified LSCM-GDC cathode

(La,Sr)(Cr,Mn)O-3 perovskite (LSCM) is one of the most promising cathode materials for solid oxide electrolysis cell (SOEC) at high temperature, but suffers from poor electrocatalytic activity towards CO2 reduction. Here we report that a modified LSCM based composite cathode fabricated via infiltrating Ce0.9Mn0.1O2-delta (CMO) nanoparticles onto (La0.75Sr0.25)(0.95)(CrasMn(0.5))O3-delta-Ce0.8Gd0.2O1.9 (LSCM-GDC) composite materials, shows greatly improved electrocatalytic activity and stability towards CO2 reduction compared with the unmodified LSCM cathode. Physicochemical characterizations and electrochemical impedance spectroscopy analysis of electrocatalytic CO2 reduction in SOEC show that CO2 adsorption and the following carbonate intermediate dissociation processes on the CMO nanoparticles-modified LSCM-GDC cathode are significantly improved, which is attributed to the increased active three phase boundaries and surface oxygen vacancies by the infiltration of CMO nanoparticles on the LSCM-GDC cathode. (C) 2018 Elsevier Inc. All rights reserved

(La0.75Sr0.25)(0.95)(Cr0.5Mn0.5)O3-delta-Ce0.8Gd0.2O1.9 scaffolded composite cathode for high temperature CO2 electroreduction in solid oxide electrolysis cell

As a promising cathode material for CO2 electroreduction in solid oxide electrolysis cell, (La,Sr) (Cr,Mn)O-3 perovskite usually suffers from insufficient electrocatalytic activity and poor stability. We report here that a (La,Sr) (Cr,Mn)O-3-based scaffolded composite cathode fabricated through co-loading (La0.75Sr0.25)(0.95)(Cr0.5Mn0.5)O3-delta-Ce0.8Gd0.2O1.9 composite within the porous yttria-stabilized zirconia scaffold, enables the electrolyte-supported solid oxide electrolysis cell to exhibit high electrocatalytic activity and stability towards CO2 electroreduction in comparison with the conventional (La0.25Sr0.25)(0.95)(Cr0.5Mn0.5)O3-delta-Ce0.8Gd0.2O1.9 cathode. This scaffolded architecture design provides micro-sized pores for CO2 transportation, well-connected yttria-stabilized zirconia network for oxygen ion conduction, (La0.25Sr0.25)(0.95)(Cr0.5Mn0.5)O3-delta-Ce0.8Gd0.2O1.9 composite catalyst layer for creating highly active (La0.75Sr0.25)(0.95)(Cr0.5Mn0.5)O3-delta-Ce0.8Gd0.2O1.9-gas three-phase boundaries and increasing surface oxygen vacancies concentration. Furthermore, the intimate interaction between (La0.25Sr0.25)(0.95)(Cr0.5Mn0.5)O3-delta and Ce0.8Gd0.2O1.9 nanoparticles in the composites effectively suppresses particles aggregation. The (La0.25Sr0.25)(0.95)(Cr0.5Mn0.5)O3-delta perovskite-Ce0.8Gd0.2O1.9 fluorite scaffolded composite cathode offers a promising approach to prepare highly active and stable (La,Sr) (Cr,Mn)O-3 based cathode for CO2 electroreduction in high temperature solid oxide electrolysis cell

In-situ exsolution of cobalt nanoparticles from La0.5Sr0.5Fe0.8Co0.2O3-δ cathode for enhanced CO2 electrolysis performance

Solid oxide electrolysis cell (SOEC) is a promising technology for CO2 conversion and renewable energy storage with high efficiency. It is highly desirable to develop catalytically active cathodes for CO2 electrolysis. Herein, cathode materials with different structural stabilities are designed by Nb substitution on La0.5Sr0.5Fe0.8Co0.2O3-δ (LSFC82) to obtain La0.5Sr0.5Fe0.7Co0.2Nb0.1O3-δ (LSFCN721) and La0.5Sr0.5Fe0.8Co0.1Nb0.1O3-δ (LSFCN811), respectively. LSFC82-Sm0.2Ce0.8O2-δ (SDC) cathode with inferior structural stability (ability to maintain the structure) shows desirable CO2 electrolysis performance with the generated current density of 1.80 A cm−2 at 1.6 V and stable performance during 110 h operation at 1.2 V and 800 °C. However, LSFC82 particles are collapsed into pieces after stability test with the generation of Co nanoparticles simultaneously. The frameworks of LSFCN721 and LSFCN811 particles maintain well because of the high-valent niobium, but Co exsolution, oxygen vacancy content and the corresponding CO2 electrolysis performance are restricted. This work confirms that Co nanoparticles can be exsolved from LSFC82-SDC cathode during CO2 electrolysis, providing references for constructing metallic nanoparticles decorated-perovskite cathodes for SOECs

Improving the performance of solid oxide electrolysis cell with gold nanoparticles-modified LSM-YSZ anode

Gold, as the common current collector in solid oxide electrolysis cell (SOEC), is traditionally considered to be inert for oxygen evolution reaction at the anode of SOEC. Herein, gold nanoparticles were loaded onto conventional strontium doped lanthanum manganite-yttria stabilized zirconia (LSM-YSZ) anode, which evidently improved the performance of oxygen evolution reaction at 800 degrees C. The current densities at 1.2V and 1.4V increased by 60.0% and 46.9%, respectively, after loading gold nanoparticles onto the LSM-YSZ anode. Physicochemical characterizations and electrochemical measurements suggested that the improved SOEC performance was attributed to the accelerated electron transfer of elementary process in anodic polarization reaction and the newly generated triple phase boundaries in gold nanoparticles-loaded LSM-YSZ anode. (C) 2019 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved

In situ exsolved FeNi3 nanoparticles on nickel doped Sr2Fe1.5Mo0.5O6- perovskite for efficient electrochemical CO2 reduction reaction

Solid oxide electrolysis cells (SOECs) have attracted increasing attention as a promising device for the electrochemical CO2 reduction reaction (CO2RR) due to their high efficiency and fast kinetics. Exploring active cathode catalysts for the CO2RR is highly desirable for the research and development of SOECs. Herein, in situ exsolved FeNi3 nanoparticles on a Sr2Fe1.35Mo0.45Ni0.2O6- (SFMN) double perovskite substrate (FeNi3@SFMN) is developed to efficiently catalyze the CO2RR in SOECs. The SOEC with the FeNi3@SFMN-GDC (Gd0.2Ce0.8O1.9) cathode shows a current density of 0.934 A cm(-2) at 1.6 V and 800 degrees C, as well as high stability and no coke deposition for 40 h at 1.2 V. CO2-temperature programmed desorption and quasi in situ Fourier-transform infrared spectroscopy measurements verify the intensive adsorption of CO2 on the FeNi3@SFMN-GDC cathode. Distribution of relaxation time analysis combined with density functional theory calculations discloses the stimulative activation of CO2 at the interface between the exsolved FeNi3 nanoparticles and the SFMN substrate with abundant oxygen vacancies, which improves the CO2RR performance at the FeNi3@SFMN-GDC cathode

Metal Bond Strength Regulation Enables Large-scale Synthesis of Intermetallic Nanocrystals for Practical Fuel Cells

Structurally ordered L10-PtM (M = Fe, Co, Ni, etc) intermetallic nanocrystals (iNCs), benefiting from the chemically ordered structure and higher stability, are one of the best electrocatalysts used for PEMFC. However, their practical development is greatly plagued by the challenge that high-temperature annealing (> 700 °C) has to be used for realizing disorder-order phase transition (DOPT) due to the high activation barrier (Ea), which always leads to severe particle sintering, morphology change, and makes it highly challenging for gram-scale preparation of desirable PtM iNCs. Here, we report a general low-melting-point metal induced bond strength weakening strategy to promote DOPT of PtM (M = Ni, Fe, Cu, Zn) alloy catalysts. We demonstrate that the introduction of Sn can reduce DOPT temperature to a record-low temperature (≤ 450 °C), which enables ten-gram-scale preparation of high-performance L10-PtM iNCs. X-ray spectroscopic studies, in-situ electron microscopy and theoretical calculations reveal that the Sn-facilitated DOPT mechanism at record-low temperature involves the weakened bond strength and reduced Ea via Sn doping, the formation and fast diffusion of low coordinated surface free atom, and subsequent L10 nucleation. Most importantly, the 15% Sn-doped L10-PtNi iNCs display outstanding performance in H2-air fuel cells with a high peak power density of 1.45 W cm-2 for Pt alloy catalysts and less than 25% activity loss after 30000 cycles at a quite low cathode Pt loading amount of 0.12 mg¬Pt cm-2, representing as one of the most efficient cathodic electrocatalyst for PEMFCs

Interfacial Enhancement by gamma-Al2O3 of Electrochemical Oxidative Dehydrogenation of Ethane to Ethylene in Solid Oxide Electrolysis Cells

Oxidative dehydrogenation of ethane (ODE) is limited by the facile deep oxidation and potential safety hazards. Now, electrochemical ODE reaction is incorporated into the anode of a solid oxide electrolysis cell, utilizing the oxygen species generated at anode to catalytically convert ethane. By infiltrating gamma-Al2O3 onto the surface of La0.6Sr0.4Co0.2Fe0.8O3-delta-Sm0.2Ce0.8O2-delta (LSCF-SDC) anode, the ethylene selectivity reaches as high as 92.5 %, while the highest ethane conversion is up to 29.1 % at 600 degrees C with optimized current and ethane flow rate. Density functional theory calculations and in situ X-ray photoelectron spectroscopy characterizations reveal that the Al2O3/LSCF interfaces effectively reduce the amount of adsorbed oxygen species, leading to improved ethylene selectivity and stability, and that the formation of Al-O-Fe alters the electronic structure of interfacial Fe center with increased density of state around Fermi level and downshift of the empty band, which enhances ethane adsorption and conversion