Using density functional theory with dispersion correction and U-parameter (DFT + U-D3) method, the Cu release process from spinel structure is simulated by stepwise removal of CuO from spinel-structured Cu16Al32O64, forming Cu16-nAl32O64-nwith CuO defects (VCuO)n (n = 1-8). The stepwise formation energies of the Cu16-nAl32O64-n exhibit a complex variation trend with the increasing n, revealing an initial decline from n = 1 to n = 4 and increase with n = 5-7 followed by sharp decrease at n = 8. Interestingly, the stepwise formation energies even become negative (-0.26 eV for n = 4 and-1.62 eV for n = 8, respectively). Hence, the total formation energies of the Cu16-nAl32O64-nsystem demonstrate an increasing trend with two energy reductions at n = 4 and n = 8, respectively. It was also found that the formation of CuO defect induced significant changes in the cationic coordination environment, leading to atomic rearrangement and lattice distortion. As the number of defects increases, the coordination number of some Al atoms decreases from hexa-coordination to lower-coordinations (primarily tetra-coordination, followed by penta-coordination and rarely tri-coordination). The findings of this study are consistent with the experimental data obtained during the sustained release catalysis, validating the dynamic changes in the surface structure during the catalytic process and laying a foundation for further research on the releasing mechanism of Cu-Al spinel.

Owing to its strong corrosion resistance, moderate mechanical properties, and excellent biocompatibility, commercially pure titanium (CP Ti) has been widely applied in the fields of marine sciences, aerospace, and biomedicine. To reduce the trial-and-error production of CP Ti components and optimize the forming processes, an advanced constitutive model for accurate forming simulation of CP Ti was developed in this study based on the non-associated flow rule. The developed non-associated constitutive model can capture the orthotropic flow stress anisotropy, tension-compression strength differential (T-C SD) effect, and planar deformation anisotropy of CP Ti, and it was validated using material characterization data of a hot-rolled CP Ti plate. The developed constitutive model was implemented in Abaqus/Standard via the user subroutine UMAT and achieved an accurate finite element (FE) analysis of the circular cup drawing for the CP Ti sheet. All the material properties considered in the developed constitutive model affect the FE analysis results, which indicate the necessity of considering the orthotropic flow stress anisotropy, T-C SD effect, and in-plane deformation anisotropy during the sheet metal forming simulation of CP Ti.

A series of Ru/CeO2 catalysts were prepared using the deposition precipitation method, and then were fully characterized and evaluated in methanol steam reforming. The results indicated that, besides the target product H2, CH4 was also generated during methanol steam reforming (MSR). The selectivity towards CH4 was governed by reaction conditions (temperature/water-to-methanol ratio) as well as Ru loading. When the reaction temperature was below 320 degrees C, the CH4 selectivity was very low. However, when the temperature exceeded 340 degrees C, the CH4 selectivity increased and continued to rise with the increase of temperature. The influence of the molar ratio of water to methanol was comparatively complex. At a water-to-methanol molar ratio below 1.0, the CH4 selectivity was very low; however, exceeding the ratio above 1.0 resulted in an increase in the CH4 selectivity. Furthermore, an increase in Ru content promotes the formation of non-solid solution Ru species, thereby enhancing CH4 selectivity. Further investigation revealed that CH4 was not formed through the direct transformation of CH3OH, but was rather generated from reaction intermediates with the participation of water. Given that an optimal molar ratio exists for H2 formation, the mechanism by which water participates in the reaction was extremely complex. Based on the research results, the 0.5%Ru/CeO2 catalyst was identified as the optimal choice, showing the highest specific activity. Under a high weight hourly space velocity (WHSV) of 6 h-1, a reaction temperature ranging from 300 to 380 degrees C, and a water-to-methanol molar ratio from 0.96 to 1.2, higher H2 selectivity was obtained.

For sheet metals, anisotropy is a significant property affecting sheet metal forming processes. The anisotropy of sheet metals is caused by the rolling process, and several anisotropic constitutive models have been proposed under the non-associated flow rule to describe the deformation and stress anisotropies of sheet metals independently. However, most of them are based on yield functions that are only identified by the experimental data of orthogonal axes, or yield functions that are applicable to only the plane stress state. In this study, the yld2004-18p yield function, which can be used to analyze the three-dimensional stress state in multiple axes with high accuracy and acceptable identification cost, is used to develop a non-associated constitutive model and subsequently applied to sheet metal forming analysis. Finite element analysis results of circular cup drawing and hole expansion demonstrate the capability of the yld2004-18p-based non-associated constitutive model in more accurately describing both the deformation and stress anisotropies of sheet metals.

The adsorption of CO on different lattice oxygen sites in Cu doped CeO2(111) was studied by DFT method, and the geometrical structure and electronic properties of adsorption systems were analyzed. The results showed that CO interacted with lattice oxygen on the first layer formed CO2. However, when adsorbed on the second layer lattice oxygen, carbonate species were formed with the participation of first layer lattice oxygens, i.e., CO co-adsorbed on first and second layer lattice oxygens.For the second layer adsorption, the absolute CO adsorption energy was big on the Oss nearby Cu. This kind of carbonates was thermodynamically stable, and it was attributed to the facilitation of Cu on CO adsorption, manifested by an electron migration behavior from the C 2p orbitals to the Cu 3d orbitals. However, the absolute CO adsorption energy on the Oss away from Cu was small. Compared to the formation of carbonates, the formation CO2 had very small absolute adsorption energy, suggesting the formed carbonates on second layer was stable.Further, when CO adsorbed on the systems with a carbonate, the absolute CO adsorption energy was significantly smaller than that of the non-carbonated system, indicating that the formation of carbonates inhibited CO oxidation on Cu/CeO2(111). Therefore, the formation of carbonates was unfavorable for CO oxidation reaction on Cu/CeO2(111). The results of this study provide theoretical support for the negative effect of CO2 on ceria-based catalysts.

A series of surface-modified Cu1−xLaxAl2.5 spinel catalysts with La were prepared by using the impregnation method and used in the methanol steam reforming (MSR) for hydrogen production. The interaction between La and the spinel catalyst, along with its effect on the sustained release of copper species, was investigated with the help of XRD, N2 sorption, H2-TPR, and XPS characterization techniques. The results indicate that La modification not only alters the microenvironment of Cu species and enhances the oxygen adsorption, but also promotes the formation of Al–O–La bonds, resulting in a stable interfacial structure. The Cu1−xLaxAl2.5 spinel catalysts can be applied to the MSR reaction without pre-reduction treatment. Under 260 ℃, a water-to-alcohol molar ratio of 2, and a methanol mass space velocity of 2.0 h−1, the optimal catalyst Cu0.9La0.1Al2.5 maintains a stable methanol conversion of approximately 94% during a continuous reaction lasting for 136 h. In comparison with the unmodified catalyst, the catalytic activity of Cu0.9La0.1Al2.5 is 5% higher, in addition to a decreased selectivity to CO by 20%. Further studies reveal that the Cu0.9La0.1Al2.5 catalyst has the lowest Cu sustained release rate and the minimal Cu grain size after prolonged reaction, indicating that La modification plays a crucial role in determining the sustained release rate and the fate of the Cu species.

A series of CuO/CeO2 catalysts with different Cu contents (2 wt %, 1, 0.75, and 0.5 wt %) were prepared by the impregnation method and were characterized by various techniques such as X-ray diffraction, N2-adsorption/desorption, H2-TPR, Raman spectroscopy, and X-ray photoelectron spectroscopy. Moreover, their catalytic performance in CO oxidation was evaluated under both dry and wet conditions. In the absence of water, the T 100 value decreased with Cu contents ranging from 0.5% to 0.75% and then leveled off from 0.75% to 2.0 wt %. However, a different variation trend emerged upon water addition. In the presence of water, the catalyst with 0.75-1.0 wt % Cu exhibited the highest catalytic activity, showing the lowest T 100. These results indicated that excessive Cu was detrimental to CO oxidation under wet conditions but served as a spectator under dry conditions. To explore the possible mechanism, the DFT + U method was employed to investigate the adsorption of water molecules on different systems, including Cu-doped and undoped CeO2. Compared with CeO2 and CeO2-x , Cu-doped systems manifested a greater propensity for adsorbing water molecules, with the potential formation of two hydroxyl groups. It was found that the subsequent CO adsorption could interact with some of the surface lattice oxygens to form CO2, but the absolute value of formation energy was lower as compared to the pure Cu/CeO2(111) surface. The results could be used to account for the negative effect of water on the catalytic oxidation of CO. However, when CO is adsorbed onto the hydroxyl O atom, a formate-like species is formed. As expected, the formate-like species could be decomposed to generate CO2, thereby demonstrating a promoting effect of water, which was evidenced by additional catalytic testing at a high-temperature of 360 degrees C over the 0.75 CuCe catalyst. However, the water promoting effect was not found with the 2CuCe catalyst, demonstrating an obvious loading effect. This article provides foundational data that can be referenced for further research.

Three Ru/CeO2 samples are prepared using the deposition-precipitation method and then ball milled and subsequently calcined at 300 degrees C. It is demonstrated that the ball milling treatment results in a change of Ru valence and a strong interaction with CeO2 to form a Ru-O-Ce solid solution. The CO oxidation rate can be drastically improved with ball milling treatment. Specifically, comparing to 0.5Ru/CeO2, 0.5Ru/CeO2-BM demonstrates a 3-fold increase in activity at low reaction temperatures up to 100 degrees C. The superior activity of the ball-milled catalysts can be well correlated to the increase of oxygen vacancies on the catalyst surface. It is inferred that ball milling treatment is a promising approach to enhance the catalytic efficiency of Ru/CeO2 catalysts, which may provide valuable guidance for improving related catalytic systems.

A series of x/yCuO/NiO-CeO2 catalysts with a constant Cu+Ni molar content and low copper loading of 1 wt% had been prepared by the step-by-step impregnation method and characterized by various techniques (XRD, N-2-adsorption/desorption, HR-TEM, H-2-TPR, Raman and XPS). CO preferential oxidation (CO-PROX) under H-2/CO2-rich conditions had been performed. Experimental results indicated that the catalytic activity of CuO/CeO2 could be enhanced by substituting partial Cu with Ni, and with a Cu/Ni molar ratio of 1/2, the highest catalytic performance was observed. Under the conditions of temperature 130 celcius, space velocity 20266 mL center dot g(cat)(-1)center dot h(-1) and oxygen excess coefficient 1.2, the 1/2CuO/NiO-CeO2 catalyst gave rise to a maximum CO conversion of about 94.8%. The 1/2CuO/NiO-CeO2 catalyst also exhibited good catalytic stability up to 100 h, showing that this catalyst system could be further developed for potential commercial application. Combined with the detailed characterization data, it had been proposed that there was a synergistic interaction among Cu, Ni and CeO2 in the catalyst, generating more oxygen vacancies than the binary CuO/CeO2 and NiO/CeO2 catalysts. With a Cu/Ni molar ratio of 1/2, the formed ternary CuO/NiO-CeO2 catalyst had the highest content of oxygen vacancies, which was believed to play a crucial role in the CO-PROX reaction.

The different metal decorated Cu/CeO 2 catalysts was synthesized by immersion method, and it was found that the formation of Cu/M–O–Ce solid solutions and more Ce 3+ and oxygen vacancies on the surface favored the improvement of catalytic performance.

A series of xMnCu/Ce catalysts with constant low Cu loading of 1 wt% were prepared by the simple impregnation method. The obtained catalysts were characterized by XRD, BET, H2- TPR and XPS, and the preferential oxidation of CO was evaluated in CO2/H2-rich atmo-spheres. It was shown that partial Mn and Cu could be incorporated into the Ceria lattice, forming surface ternary Cu-Mn-Ce oxide solid solutions. At Mn/Cu = 0.6, the catalyst presented strong interaction among Cu, Mn and Ce, had more Ce3+ and Mn4+ at the surface and showed the best catalytic performance, making CO conversion increase of 23.57% at 90 & DEG;C as compared with the Cu/Ce catalyst. For CO-Prox, the highest CO conversion was 94.7% with an oxidation selectivity of 78.9% at 125 & DEG;C. At this temperature, the catalyst revealed stable catalytic performance for a total TOS of 205 h. In addition, with CO/Ar as feed gas, CO conversion was 100%, confirming the negative effects of CO2/H2.& COPY; 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

The adsorption of O2 on Cu/CeO2(111) and the CO oxidation reactivity of the formed oxygen species were studied using the DFT method. The results showed that superoxide species (O2δ-), which directly interacted with Cu, formed when O2 adsorbed on the surface oxygen vacancies, while O2 adsorbed on the subsurface oxygen vacancies gave rise to ozone-like O3δ- species by combining with the nearest surface lattice oxygen (O1). PDOS showed that hybridization of the 2p orbitals between O2 and O1 formed a delocalized π bond, confirming the formation of O3δ-. For O2δ-, electrons on Cu and O1 transferred to O2 while the charge of Ce remained unchanged. However, for O3δ-, the transferred electrons were mainly from O1, and partially from O2, Ce1 and Ce2. It was very interesting that Cu also received a few electrons in the latter case. Compared with CO directly adsorbed on lattice oxygen, the two oxygen species were active for CO oxidation, forming CO2 or carbonates, and higher absolute adsorption energy was obtained with the interaction between CO and O3δ-. The findings of this study provide new insight on the CO oxidation reaction mechanism, facilitating an in-depth understanding of Cu-doped CeO2 catalysts.

采用过饱和浸渍法制备4种大孔Mo-Ni-NH3/γ-Al2O3催化剂,考察了助溶剂种类和用量对活性金属分散性的影响,利用X射线衍射、透射电镜、N2吸附-脱附、H2-程序升温还原、X射线光电子能谱等表征制备催化剂的结构和物种分布,并通过劣质催化裂化柴油加氢精制评价催化剂的活性.结果表明:采用助溶剂三乙醇胺制备的催化剂A40中活性相分散性最好,预硫化后催化剂表面存在大量高分散的MoS2片层晶格条;A40催化剂具有更低还原温度和更高硫化度,高活性金属物种Mo4+占比高达86.46％,高活性NiMoS物种占比为56.3％;在制备的4种催化剂中,A40催化剂的加氢脱硫、加氢脱氮和芳烃饱和活性均最高,对催化裂化柴油的平均脱硫率、脱氮率和芳烃饱和率分别为95.99％,97.48％,65.82％,说明A40催化剂是一种性能良好的加氢催化剂.

以掺杂Y型分子筛的γ-Al2O3为载体,七钼酸铵(AMT)、六次甲基四胺(HMT)为原料,NiCO3?2Ni(OH)2?4H2O为改性助剂,通过共浸渍和程序升温炭化法制备了Mo2C/γ-Al2O3(MCAS)和Ni改性的Ni-Mo2C/γ-Al2O3(MNCAS)催化剂.采用XRD、ICP、N2吸附-脱附、TEM和EDS对其进行了表征,考察了其在逆水气变换反应中的催化性能.结果表明,MNCAS催化剂出现了Ni3Mo3N的特征衍射峰,Ni的加入有效改善了Mo2C的聚集现象,并且该催化剂具有良好的介孔结构.MCAS催化剂对逆水气反应有较高的催化活性,300℃时CO选择性为93.87％,MNCAS-8催化剂〔n(AMT):n(HMT)=1:8,Mo和Ni的理论负载量分别为30％和5％,实际负载量分别为28.52％和4.51％〕倾向于将CO2转化成CH4,在低温段CH4选择性达到84.37％,生成的Ni3Mo3N有利于提高CH4的选择性.

采用水热法合成了Ce0.8Zr0.2O2固溶体,再经浸渍法负载活性组分制备了CuO/Ce0.8Zr0.2O2催化剂,考察了柠檬酸量对CuO/Ce0.8Zr0.2O2催化剂结构、性质及其催化水气变换反应制氢性能的影响.结果表明,不同柠檬酸量制备的CuO/Ce0.8Zr0.2O2催化剂的催化活性主要与Cu比表面积、还原性能及Ce0.8Zr0.2O2固溶体与CuO之间的相互作用有关.其中,柠檬酸浓度为0.04 mol/L所制备的催化剂具有较大的Cu比表面积,较低的CuO还原温度和较强的Ce0.8Zr0.2O2固溶体与CuO之间的相互作用,在水气变换制氢过程中具有较高的CO转化率,表现出了较好的催化活性.在反应温度为320 ℃,水气物质的量比n(H2O)/n(CO) = 2,总气体体积空速GHSV = 6600 h?1时,CO转化率接近热力学平衡值,为96.9％.

The EP (electric potential) signals can be generated during the deformation and fracture process of coal and rock mass. Meanwhile, the EP response is closely related to its stress state and damage evolution, which is expected to be used in monitoring and coal and rock dynamic disaster hazards. Based on this, this paper developed an EP monitoring device for mining to continuously monitor the temporal response characteristics and spatial distribution of coal seam internal EP signals in real time. Further, the experimental tests were carried out, whose results showed that the device has high monitoring sensitivity and little error for the EP signals and can reveal the loading state and damage degree of the coal and rock specimens during the deformation and fracture process. Moreover, the tests and application of EP monitoring were carried out during mining activities in the field. The results showed that the EP signals fluctuate during the coal mining stage and remain relatively stable during the maintenance stage. When the abnormal mining stress or the coal cannon phenomenon occurs, the intensity of EP signals increases rapidly and fluctuates violently, which has precursory response information for the hazards of dynamic disasters. Considering the advantages of sensitive response and nearly non-destructive monitoring, the study results can provide key monitoring equipment and research basis for field testing the EP signals during the mining process, to monitor and forecast the hazards of coal and rock dynamic disasters.

Tension leveling is an important industrial process to eliminate the flatness defects and residual stresses of metal strips to provide high-quality sheet metals for subsequent sheet metal forming. The finite element (FE) method can be applied to elucidate the effects of process parameters on the quality of sheets after tension leveling for various materials. In our previous investigation, an accurate FE model has been established for the elastic–plastic FE analysis of tension leveling. In this study, we further studied the effects of the yield point and plastic anisotropy on tension leveling using the FE model established in our previous investigation. Aiming at improving the accuracy of simulation, a modified constitutive model was developed to describe the anisotropic hardening of materials under cyclic loading. The modified constitutive model was implemented into Abaqus/Standard as a user-defined material subroutine to simulate the development of the anisotropy in materials during tension leveling. The modified model was also applied to the FE analysis of sheet metal forming processes to demonstrate its simulation capability and accuracy.

An anisotropic plasticity model is developed based on the non-associated flow rule with anisotropic hardening. The model combines non-quadratic yield function and quadratic plastic potential function for orthogonal anisotropic sheet metals. The model is also expanded to properly reproduce the cyclic effect during forming processes. The simple formulations can contribute to cost saving in the parameter acquisition process and implementation. The developed model was implemented into the finite element code ABAQUS as a user material subroutine under a general three-dimensional condition. To evaluate the capability of the plasticity model, different loading conditions and prediction of the yield surface were considered. A multi-step rectangular cup drawing process with the AA5182-O and DP600 sheets including draw/re-draw effects was applied to evaluate the performance of capturing complex plastic behavior by finite element simulation. The results show that the anisotropic plasticity model is capable of describing the anisotropic behaviors including anisotropic hardening and cyclic hardening with high accuracy and efficiency.

A new hot rolling & Run Out Table cooling simulator is constructed. The simulator permits continuous collation of process data including in-situ temperature measurement at numerous positions of the strip steel. Tensile properties and microstructural analysis of the hot rolled strip are correlated to the collated process data. A numerical model including phase transformation and latent heat evolution is constructed and calibrated against the experimental data. The resulting numerical model can be used to efficiently predict the optimal process parameters for manufacturing hot rolled strip steels, while the new hot rolling & Run Out Table cooling simulator can be used to efficiently validate the numerical simulation results before up-scaling to the industrial hot mill.