Design of Multiple Metal Doped Ni Based Catalyst for Hydrogen Generation from Bio-oil Reforming at Mild-temperature

A new kind of multiple metal （Cu, Mg, Ce） doped Ni based mixed oxide catalyst, synthesized by the co-precipitation method, was used for efficient production of hydrogen from bio-oil reforming at 250-500℃. Two reforming processes, the conventional steam reforming （CSR） and the electrochemical catalytic reforming （ECR）, were performed for the bio-oil reforming. The catalyst with an atomic mol ratio of Ni：Cu：Mg：Ce：AI=5.6：1.1：1.9：1.0：9.9 exhibited very high reforming activity both in CSR and ECR processes, reaching 82.8% hydrogen yield at 500℃ in the CSR, yield of 91.1% at 400℃ and 3.1 A in the ECR, respectively. The influences of reforming temperature and the current through the catalyst in the ECR were investigated. It was observed that the reforming and decomposition of the bio-oil were significantly enhanced by the current. The promoting effects of current on the decomposition and reforming processes of bio-oil were further studied by using the model compounds of bio- oil （acetic acid and ethanol） under 101 kPa or low pressure （0.1 Pa） through the time of flight analysis. The catalyst also shows high water gas shift activity in the range of 300-600 ℃. The catalyst features and alterations in the bio-oil reforming were characterized by the ICP, XRD, XPS and BET measurements. The mechanism of bio-oil reforming was discussed based on the study of the elemental reactions and catalyst characterizations. The research catalyst, potentially, may be a practical catalyst for high efficient production of hydrogen from reforming of bio-oil at mild-temperature.

Hot corrosion behavior of Ni–16Cr–xAl based alloys in mixture of Na_2SO_4-NaCl at 600 ℃

The hot corrosion behaviors of Ni–16Cr–xAl（x=4.5%, 6.8%, 9.0%, mass fraction） based alloys in Na2SO4–25% NaCl molten salts at 600 °C were investigated. The effects of pre-oxidation and Al content on the resistance to hot corrosion were examined. The hot corrosion resistance of Ni–16Cr–xAl based alloy with Al addition from 4.5% to 9.0% increases with increasing Al content. The alloy with Al content of 9.0% shows the highest hot corrosion resistance among the examined alloys because more β–NiAl phases are obtained to sustain the Al2O3 scale repaired during hot corrosion. Pre-oxidized specimens have a superior hot corrosion resistance compared with the as-cast specimens, due to a protective oxide scale formed after pre-treatment.

Kinetics and microstructural evolution during recrystallization of a Ni_3Al-based single crystal superalloy

The recrystallization kinetics and microstructural evolution of a Ni3Al-based single crystal superalloy were presented, especially the different recrystallization behaviors between the dendrite arm and the interdendritic region. The single crystal alloy was deformed by grit blasting. A succeeding annealing under inert atmosphere at 1280 ℃ for different time led to the formation of recrystallized grains close to the grit blasting surface. It was found that the recrystallization depth and velocity in the dendrite arm were respectively deeper and faster than those in the interdendritic region where the Y-NiMo phase existed. The recrystallization process in the interdendritic region was significantly inhibited by the Y-NiMo precipitates. However, the pinning effect gradually weakened with the annealing time due to the dissolution of the Y-NiMo phase, and the recrystallization depth in the dendrite arm was deeper than that in the interdendritic region.

Effect of Re element on oxidation resistance of Ni_3Al-Mo based alloys at 1150 ℃

The isothermal oxidation behaviors of three kinds of Ni3Al-Mo based alloys at 1150 ℃ were studied.The morphology,structure and element distribution of oxide scales of the alloys were researched by scanning electron microscopy,X-ray diffraction and electron probe microanalysis.The research results show that there are three oxide layers,an outer layer of NiO,an intermediate layer mainly composed of NiO,NiAl2O4 and a small amount of NiMoO4,and an inner layer of NiAl2O4 and Al2O3.Re element was mainly distributed in the intermediate layer,which plays a role as ＂diffusion barrier＂ in the process of oxidation,and effectively reduces the diffusion rate of Al and Mo elements outward and diffusion rate of O element inward.As a result,a Al-rich oxide layer formed in the inner layer inhibits the growth of oxide layer and improves the oxidation resistance of the alloy.

Insight into MgO promoter with low concentration for the carbon-deposition resistance of Ni-based catalysts in the CO_2 reforming of CH_4

The CO2reforming of CH4is studied over MgO‐promoted Ni catalysts,which were supported on alumina prepared from hydrotalcite.This presents an improved stability compared with non‐promoted catalysts.The introduction of the MgO promoter was achieved through the‘‘memory effect’’of the Ni‐Al hydrotalcite structure,and ICP‐MS confirmed that only0.42wt.%of Mg2+ions were added into the Ni‐Mg/Al catalyst.Although no differences in the Ni particle size and basicity strength were observed,the Ni‐Mg/Al catalyst showed a higher catalytic stability than the Ni/Al catalyst.A series of surface reaction experiments were used and showed that the addition of a MgO promoter with low concentration can promote CO2dissociation to form active surface oxygen arising from the formation of the Ni‐MgO interface sites.Therefore,the carbon‐resistance promotion by nature was suggested to contribute to an oxidative environment around Ni particles,which would increase the conversion of carbon residues from CH4cracking to yield CO on the Ni metal surface.?2018,Dalian Institute of Chemical Physics,Chinese Academy of Sciences.Published by Elsevier B.V.All rights reserved.

Surface recrystallization of a Ni_3Al based single crystal superalloy at different annealing temperatures and blasting pressure

The effects of annealing temperature and grit blasting pressure on the recrystallization behavior of a Ni3Al based single crystal superalloy were studied in this work. The results show that the precipitation of the Y-NiMo phase occurs at 900 and 1000 °C, which precedes recrystallization. The initial recrystallization temperature was between 1000 and 1100 °C. Cellular recrystallization was formed at 1100 and 1200 °C, which consisted of large columnar γ′ and fine γ + γ′. The dendrite arm closed to the interdendritic region may act as nucleation sites during initial recrystallization by a particle simulated nucleation mechanism at 1280 °C. The size of the grains first turned large and then became small upon the pressure while the recrystallization depth increased all the time.

Weldability and Microstructure of Nickel-Silicon Based Alloys

The NiSix based alloy typically has poor weldability due to its lower ductility. A limited amount of work has been performed on the weldability of NiSix based alloys. Therefore, the effect of heat treatment and welding parameters on weldability of the alloys, and the relationship between the weldability and microstructure were studied. The results show that the as-cast Ni-Si-Nb-B alloy （Ni 76. 5%, Si 20%, Nb 3%, and B 0. 5%） could be successfully welded after preheating at 600 ℃. The welding procedure should be performed on the alloys before any heat treatment and a preheating at 600 ℃ should be used. The fusion zone is harder than the matrix due to a large amount of 7 phase and a finer microstructure. The cracks are predominantly intergranular in heat affected zone and associated with the needle-like ）, phase. The heat treatment before welding increases the tendency of cracking in the fusion zone.

Octa-membered Water Ring Chain Based on Sulfonic Group in Ni(II) Complex with 2-[(E)-(2-Oxidophenyl)methyleneamino] Ethanesulfonato and 2,2′-Bipyridinyl

The title compound, [Ni（tssb）（2,2-bipy）2].5（H2O） 1 （tssbH2 =2-[（E）-（2-oxido- phenyl）methyleneamino]ethanesulfonato, 2,2-bipy = 2,2＇-bipyridinyl）, belongs to orthorhombic, space group Pbcn with a = 20.3983（18）, b = 17.6929（15）, c = 17.0897（15） nm, V= 6167.8（9） nm^3, Mr= 688.38, Z = 8, De = 1.481 g.cm^-3, F（000） = 2880,μ = 0.758 mm-1 and S =1.099. Each NiIr atom is six-coordinated by one N and one O atoms from one tssb^2- anion and four N atoms from two 2,2-bipy ligands to give a distorted octahedral geometry. Noticeably, there exists a rare octa-mem- bered water ring which presents a 1D chain by sulfonic group.

Investigation on Cracking in the Surfacing Welding Layer of Ni_3Al Based Alloy

Investigation has been made into the causes of cracking in the Surfacing welding layer of Ni3Al based alloy by analysing both the liqu id-to-solid transformation in the molten pool and the distribution of thermal stress within the surfacing welding layer. The results show that cracking in the surfacing welding layer is directly related to the producing of eutectic phase β' (NiAl) in the interdendritic region and high thermal stress within the surfacing welding layer. When the process of electric arc surfacing welding is changed from along straight line to along' Z' pattern, cracking in the surfacing welding layer of Ni3Al based alloy is prevented due to being reduced of both the cooling rate of liquid in the molten pool and the moving speed of the heat source. Reducing the melting volume of the substrate material by lowering the output power of electric arc welding would make the content of iron atoms in the molten pool decrease. and this also can reduce the trend of the eutectic reaction in the interdendfitic region and is helpful to Suppress cracking in the surfacing welding layer.

Partial oxidation of methane on Ni/CeO_2-ZrO_2/γ-Al_2O_3 prepared using different processes

The influences of CeO2-ZrO2 and γ-Al2O3 mixing methods on the catalytic activity and stability of partial oxidation of methane （POM） were investigated over Ni/Ce0.7Zr0.3O2-Al2O3 catalysts. The catalysts were characterized by XRD, TPR, H2-chemsorption, and TG-DTA. For fresh catalysts, the results showed that the salt precursor mixing catalyst （ATOM） presented better performance than the catalysts prepared by the precipitator mixing method （MOL） and the powder mechanically mixing method （MECH）. The result of XRD suggested that the interaction between CeO2-ZrO2 and Al2O3 in ATOM sample was stronger than the others, which led to more lattice defects and thereby better initial activity. Moreover, the MECH sample had the best stability and the least coke deposition in 24 h stability tests. The results of TPR and H2-chemsorption indicated that the intimate contact of Ni-Al in MECH sample enhanced the ability of resisting coke deposition and metal sintering.

Microstructures and properties of transient liquid phase diffusion bonded joints of Ni_3Al-base superalloy

An investigation of transient liquid phase (TLP) diffusion bonding of a Ni 3Al base directionally solidified superalloy, IC6 alloy, was presented. The interlayer alloy employed was Ni Mo Cr B powder alloy. The results show that the microstructure of the TLP diffusion bonded joints is a combination of γ solid solution (or a γ+γ′ structure) and borides. With the bonding time increasing, the quantity of the borides both in bonding seam and adjacent zones is gradually reduced, and the joint stress rupture property is improved. The obtained stress rupture property of the TLP bonded joints is on a level with the transverse property of IC6 base materials. [

Interaction Rule between Rare Earths and LowMelting Point Elements in Fe-,Cu-,AI-,Ni-Base Liquid Solutions

Interaction rule between representative RE and Sn, Sb, Pb, Cu, S, P low melting point elements respectively in Fe , Cu , Al , Ni base liquid solutions including totally 34 ternary and quarternary systems was investigated. For each system some thermodynamic properties were obtained, such as the standard free energies of equilibrium reactions, activity interaction coefficients etc ..

Improving Wear Resistance of the Ni-base Thermal Spray-Welding Coating Using Rare Earths

By adding rare earth alloy and cerium oxide, the effect of rare earths on tribological properties of nickel base alloy layer was studied to approach the possibility of applying rare earths to Ni base thermal spray welding coating. Wear test results showed that the wear rates of the nickel base coating without rare earths were quite high, and the load bearing capacity of coating was low, in contrast, the wear rates of the coating with rare earths were low and the coating had higher load bearing capacity. The results show that rare earths can refine the structure of nickel base alloy, improve the interface of the coating and substrate.

Anion-cation dual doping: An effective electronic modulation strategy of Ni2P for high-performance oxygen evolution

Developing of high-performance and low-cost electrocatalysts is of great significance to reduce the overpotential and accelerated the reaction rate of oxygen evolution in water splitting and related energy conversion applications.Herein,Fe,O-dual doped Ni2P(Fe,O-Ni2P)nanoarray is successfully synthesized on carbon cloth demonstrating enhanced electrocatalytic activity and stability for oxygen evolution reaction(OER)under alkaline media.The as-synthesized Fe,O-Ni2P nanoarray exhibits obviously improved OER performance with a low overpotential of 210 mV at 10 mA cm^-2 current density and a Tafel slope of48 mV dec^-1,as well as long-term durability.The strong coupling interaction induced changes in electronic structure lead to relatively higher oxidation state and stronger oxidation ability of the Fe,O-Ni2P nanoarray,together with the high electrochemical surface area and good conductivity contribute to the superior OER performance.This work highlights the anion-cation dual doping strategy may be an effective method for fabrication of catalysts relating to energy conversion applications.

Microstructure of Carbides at Grain Boundaries in Nickel Based Superalloys

It is well known that carbides at grain boundaries play an nickel based superalloys. In order to deeply understand the mportant role in affecting mechanical properties of relationship between grain boundary structures and properties, in this work, we have investigated the microstructure of grain boundaries with different misorienta- tion angles in bicrystals of nickel based superalloys. It is found that the bicrystals with smaller misorientation angles contain denser M23C6 but sparse MC particles at grain boundaries, and this kind of bicrystals presents longer stress rupture lives. It was observed that MC carbides were decorated by M23C6 and M6C particles at grain boundaries. The formation of these carbide particles, therefore, is likely due to the local fluctuation of chemical composition around MC carbides. In addition, the orientation relationships between MC carbides and γ/γ1 matrix were also determined.

Autothermal reforming of biogas over a monolithic catalyst

This study focused on measurement of the autothermal reforming of biogas over a Ni based monolithic catalyst. The effects of the steam/CH4 （S/C） ratio, O2/CH4 （O2/C） ratio and temperature were investigated. The CH4 conversions were higher under all examined temperatures than the equilibrium conversion calculated using the blank outlet temperature, because the catalyst layer was heated by the exothermic catalytic partial oxidation reaction. The CH 4conversion increased with increasing O2/C ratio. Moreover, the CH4 conversion was higher than the equilibrium conversion calculated using the blank outlet temperature for O2/C〉0.42 and reached about 100% at O2/C=0.55. However, the hydrogen concentration decreased for O2/C〉0.45 because hydrogen was combusted to steam in the presence of excess oxygen. On the other hand, the hydrogen and CO2 concentrations increased and the CO concentration decreased with increasing SIC ratio. As a result, it was found that the highest hydrogen concentrations and CH4 conversions were attained at the O2/C ratios of 0.45-0.55 and the SIC ratios of 1.5-2.5. Moreover, the H2/CO ratio could also be controlled in the range from about 2 to 3.5 to give at least 90% CH4 conversion, by regulating the O2/C or S/C ratios.

The dependence of stress and strain rate on the deformation behavior of a Ni‐based single crystal superalloy at 1050°C

Ni‐based single crystal(SX)superalloys are important high‐temperature materials used for manufacturing turbine blades in aero‐engines.During service under combinational impacts of temperature and stress,the SX superalloy may reach its life due to plastic deformation,which normally accompanies time‐dependent microstructural degradation.To reveal this dynamically mechanical response,tensile tests at 1050°C are carried out to record stress‐strain curves at five stain rates as well as creep curves at four applied stresses.Deformed microstructures and defects have been analyzed to understand mechanical behaviors and the underlying mechanism by using advanced scanning electron and scanning transmission electron microscopes.Results show that the de-formation mode of the alloy strongly depends on the strain rates/applied stresses under mechanical loading.The dislocation density inside theγphase is extremely low at all tests,indicating that theγphase is relatively weak and ready to flow at this temperature even at a very fast strain rate.The deformation behavior of theγ′phase is much complicated.At fast strain rates or high applied stresses,the dislocation density in theγ′phase is very high,contributing to high‐stress requirements to deform the material.At slow strain rates or low applied stresses,rafting microstructures develop and the de-formation mode becomes directional coarsening/diffusion‐dominated.Our results de-monstrate a comprehensive understanding of the deformation mechanism of Ni‐based SX superalloys,which may provide lifetime prediction of the mechanical fail-ure,as well as the database for superalloy applications in mechanical systems.

High-performance (K,Na)NbO_(3)-based multilayer piezoelectric ceramic actuators with nickel inner electrodes

Multilayer ceramic actuator(MLCA)has been widely employed in actuators due to the large cumulative displacement under the low driving voltage.In this work,the MLCA devices consisting of a lead-free MnCO_(3-)and CuO-doped 0.96(K_(0.48)Na_(0.52))(Nb_(0.96)Ta_(0.04))O_(3)-0.04CaZrO_(3) piezoelectric ceramics and a base nickel(Ni)metal inner electrode were well co-fired by the two-step sintering process in a reducing atmosphere.The ceramic layer/electrode interface is well-integrated and clearly continuous without distinct interdiffusion and chemical reaction,which is beneficial to the electrical reliability of the MLCA.As a result,the MLCA laminated with nine active ceramic layers obtains an ultrahigh piezoelectric coefficient d_(33) of 3157 pC/N,about 9 times than bulk ceramics.The 0.5 mm-thick MLCA composed of a series of~50μm-thick ceramic layers and~3μm-thick Ni electrodes reaches a high 1.8μm displacement under the low applied voltage of 200 V(the same displacement requires a voltage as high as 3700 V for~1 mm-thick bulk ceramics).The excellent electrical performance and low-cost base electrode reveal that the(K,Na)NbO_(3)(KNN)-based MLCAs are promising lead-free candidate for actuator application.

Dissolution Mechanism of a Zr Rich Structure in a Ni_3Al Base Alloy

In the present research, the dissolution mechanism of a Zr rich structure during annealing of a Ni3Al base alloy containing Cr, Mo, Zr and B, was investigated. The annealing treatments were performed up to 50 h at 900, 1000 and 1100℃. The alloy used in this investigation was produced by vacuum-arc remelting technique. The results show that at the beginning of the process, a mixed interface reaction and local equilibrium （long range diffusion） mechanism controls the dissolution process. After a short time, this mechanism changes and the dissolution mechanism of the Zr rich structure changes to only long range diffusion of Zr element. According to this mechanism, the activation energy of this process is estimated to be about 143.3 kJ.mol-1. Also the phases that contribute to this structure and the transformations that occur at the final steps of solidification of this alloy were introduced. According to the results, at the final step of solidification, a peritectic type reaction occurs in the form of L＋ y→Ni7Zr2 and →-Ni7Zr2 segregates from the melt. Following this transformation, →-Ni7Zr2 eutectic separates from the remaining Zr rich liquid. The solidification process will be terminated by a ternary eutectic reaction in the form of L→y＋Ni5Zr＋Ni7Zr2.

Coarsening Kinetics of γ' Precipitates in Dendritic Regions of a Ni_3 Al Base Alloy

Coarsening behavior of γ＇ precipitates in the dendritic regions of a Ni 3 Al base alloy containing chromium,molybdenum,zirconium and boron was investigated.Annealing treatment was performed up to 50 h at 900,1000 and 1100℃.The alloy was produced by vacuum-arc remelting technique.Results show that coarsening of the γ＇ precipitates in this complex alloy containing high volume fractions of γ＇ phase follows Lifshitz-Slyozov-Wagner（LSW） theory.Coarsening activation energy of the γ＇ precipitates was evaluated to be about 253.5 kJ.mol-1 which shows that the growth phenomenon is controlled by volume diffusion of aluminum.With an innovative approach,diffusion coefficient of the solute element（s） and the interfacial energy between γ＇ precipitates and γ＇（matrix） were estimated at 900,1000 and 1100℃.Accordingly,the interfacial energies at 900,1000 and 1100℃ are 4.49±1.48,2.08±0.69 and 0.98±0.32 mJ.m-2,respectively.Also the diffusivities of solute element（s） at these temperatures are 3.41±1.08,30±9.5 and 145.15±45.85（10-15 m-2.s-1）,respectively.