CHINESE JOURNAL OF CATALYSIS
·
2018
·
IF 3.525
Man Yang,Xiaochen Zhao,Yujing Ren,Jia Wang,Nian Lei,Aiqin Wang,Tao Zhang
Selective hydrogenolysis of glycerol to 1,3-propanediol (1,3-PD) is an important yet challenging method for the transformation of biomass into value-added chemicals due to steric hindrance and unfavorable thermodynamics. In previous studies, chemoselective performances were found demanding and sensitive to H 2 pressure. In this regard, we manipulate the chemical/physical characteristics of the catalyst supports via doping Nb into WO x and prepared 1D needle-, 2D flake-, and 3D sphere-stack mesoporous structured Nb-WO x with increased surface acid sites. Moreover, Nb doping can successfully inhibit the over-reduction of active W species during glycerol hydrogenolysis and substantially broaden the optimal H 2 pressure from 1 to 5 MPa. When Nb doping is 2%, supported Pt catalysts showed promising performance for the selective hydrogenolysis of glycerol to 1,3-PD over an unprecedentedly wide H 2 pressure range, which will guarantee better catalyst stability in the long run, as well as expand their applications to other hydrogen-related reactions.
研究领域:
催化化学
·
生物质转化
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2019
·Vol. 30
·期 15
·14424-14429
·
IF 2.195
Kuang Lingtong,Dai Ying,Pei Xinmei,Chen Wen
BaNb x Ti 2–x O 5 (x = 0, 0.002, 0.004, 0.006, 0.008, 0.01) thin films were deposited on the Pt(111)/Ti/SiO 2 /Si substrates using the sol–gel method. The effect of Nb 5+ substitution on the electric properties of BaNb x Ti 2–x O 5 films was investigated. Diffuse phase transition was observed in all the thin films. The relationship between the dielectric constant and temperature of these films showed a wide platform and no frequency dependence. For the film with x = 0.006, an abnormally broadened dielectric platform was obtained in the temperature range of 200–400 °C, and its value fluctuated in the range of 350 ± 10. The research showed that Nb-doped and thermal stress contributed greatly to this abnormally broadened platform of ε(T) curve. The substituting Nb 5+ in BaTi 2 O 5 thin films caused small microscopic composition fluctuation, which enhanced the degree of diffusion phase transition of the films. And the thermal stress on the films caused inhomogeneous polarization of the surface and center of the films, resulting in a change in phase transition behavior. In addition, the BaNb x Ti 2–x O 5 thin films with high dielectric constant at high temperatures were successfully obtained, which were beneficial to the application of BaTi 2 O 5 films under high temperature conditions.
研究领域:
材料科学
·
物理学
✓ 已验证
DOI
高影响因子
Nanoscale Research Letters
·
2017
·Vol. 12
·期 1
·1-7
·
IF 2.833
Zhai Haifa,Liu Hairui,Li Hongjing,Zheng Liuyang,Hu Chunjie,Wang Zhao,Qi Jingjing,Yang Jien
The effects of Li/Nb ratio on the preparation of Li-Nb-O compounds by a hydrothermal method were studied deeply. Li/Nb ratio has a great impact on the formation of LiNbO 3 ; the ratio smaller than 3:1 is beneficial to the formation of LiNbO 3 , while larger than 3:1, forms no LiNbO 3 at all and the morphology and chemical bond of Nb 2 O 5 raw material are totally modified by Li ions. The reason can be attributed to the large content of LiOH, which is beneficial to form Li 3 NbO 4 not LiNbO 3 , and also, even if LiNbO 3 particle locally forms, it is easily dissolved in LiOH solution with strong alkalinity. Pure LiNb 3 O 8 powders are obtained with two absolutely opposite Li/Nb ratios: 8:1 and 1:3; the former shows a unique porous and hollow structure, quite different from the particle aggregation (the latter shows). Compared with Li/Nb = 1:3, the 4.2 times higher photocatalytic performance of LiNb 3 O 8 (Li/Nb = 8:1) are observed and it can be attributed to the unique porous and hollow structure, which provides a high density of active sites for the degradation of MB. Compared to LiNbO 3 , the improved photocatalytic performance of LiNb 3 O 8 can be attributed to its layered structure type with the reduced symmetry enhancing the separation of electrons and holes.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
PubMed
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2018
·
IF 3.779
Xinhua Li,Xin Wen,Huanhuan Zhao,Zongqing Ma,Liming Yu,Chong Li,Chenxi Liu,Qianying Guo,Yongchang Liu
The microstructure and phase evolution in Nb-Al system during MA are systemically studied. The existence of Nb-Al amorphous layer surrounding Nb nano-grains after short-time ball milling was confirmed by the HRTEM observation as well as the crystallization behavior in the annealing experiment. It was also found that after short time milling, only very little Al can enter the crystal lattice of Nb and substitute for Nb, whereas most of Al mainly concentrate in this amorphous layer surrounding Nb nano-grains. What's more, interface thermodynamic analysis and calculation were employed to investigate the phase formation and evolution of this amorphous layer in Nb-Al binary system during MA process. Accordingly, positive driving force (≡-ΔG) definitely exists for the formation of the amorphous layer {NbAl} surrounding Nb nano-grains. Thus, these amorphous layers can form and exist stably in the short-time milled Nb-Al system. With the milling time prolonging, this amorphous layer becomes unstable and can crystallize into Nb(Al) ss solid solution when its thickness increases beyond a critical thickness. The critical thickness of this amorphous layer is also predicted by the interface thermodynamics calculation and the corresponding calculated value (approximately 1.9 nm) is consistent with the observed thickness (about 2.2 nm) by the HRTEM within the error range. More importantly, the solubility of Al in the lattice of Nb can be significantly increased resulting from the crystallization of this amorphous layer {NbAl}. Our work provides a new and rational perspective to well understand the complicated microstructure and phase evolution in various nano-sized systems during MA process.
研究领域:
材料科学
·
物理冶金学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2023
·
IF 22.1
Hao Zhang,Runze Zhang,Wendi Zhang,Bang Gu,Qinghu Tang,Qiue Cao,Wenhao Fang
Constructing functionalized surface for heterogeneous catalysts is vital toward effective conversion of biomass. We show that Pt nanoparticles (ca. 2.1 nm) loaded on Co-Nb bimetallic oxide can efficiently catalyze the aqueous-phase base-free aerobic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid. We ingeniously construct different surface element-distributions over three Co-Nb oxides (Nb@Co, Co&Nb and Co@Nb) with the same bulk composition by changing precipitation sequence of Co and Nb precursors. This strategy allows rationally modulating synergistic interaction and surface acidity of Co-Nb oxides and in return boosts the pristine oxidation activity of loaded-Pt nanoparticles. We use kinetic investigations, comprehensive characterizations, and particularly in situ DRIFT-IR adsorption technique (CO, pyridine and furfural as probe molecules) to unravel the origin of synergistic catalysis. We disclose that Nb 5+ -enriched surface can formulate sufficient Lewis acidic sites and stabilize electron-rich Pt 0 active centers, accelerating the tandem oxidation of HMF and the intermediates. The Co@Nb-Pt catalyst shows the highest productivity of FDCA (25 mmol FDCA mol Pt –1 h –1 ) among all Pt catalysts in the literature and achieves > 99% yield of FDCA at 110 °C and 10 bar of O 2 .
研究领域:
催化化学
·
生物质转化
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
Molecular Catalysis
·
2018
·
IF 0
Sher Ali,Yushi Li,Tianrui Zhang,Syed ul Hasnain Bakhtiar,Xuesong Leng,Zhibin Li,Fulong Yuan,Xiaoyu Niu,Yujun Zhu
Citric acid method was employed to prepare a series of Nb-promoted Fe x -Nb 0 . 5- x -Ce 0.5 ( x = 0.45, 0.4, 0.35) oxides for selective catalytic reduction with NH 3 (NH 3 -SCR) of NO process. The structure, redox ability and reactivity of NH 3 and absorbed NO species on the catalysts were explored by using various characterization techniques such as X-ray diffraction (XRD), temperature program reduction with H 2 (H 2 -TPR), temperature program desorption of NH 3 (NH 3 -TPD), temperature program desorption of NO (NO-TPD), X-ray photoelectron spectroscopy (XPS) and in situ diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS). It was found that the Nb promoted Fe x -Nb 0 . 5- x -Ce 0.5 ( x = 0.45, 0.4, 0.35) oxides catalysts showed outstanding NH 3 -SCR of NO activity, excellent N 2 selectivity and remarkable SO 2 /H 2 O resistance, meanwhile, Fe 0.4 -Nb 0.1 -Ce 0.5 exhibited above 90% NO conversion in the range of 180–400 °C, together with near 100% N 2 selectivity. The characterization results point out that the excellent catalytic performance of Fe 0.4 -Nb 0.1 -Ce 0.5 can be ascribed to the strong interaction among Nb, Fe and Ce oxides. The strong interaction not only increases the BET surface area and redox ability of the catalyst, but also significantly improves the acid amount leading to the enhancement of the adsorption and activation of NH 3 , which is advantage of the reactivity of adsorbed nitrate together with the adsorbed NH 3 species.
研究领域:
催化化学
·
环境科学
✓ 已验证
产品关联
DOI
Nanomaterials
·
2023
·Vol. 13
·期 2
·252
·
IF 5.3
Qi Yuan,Wencai Hu,Tao Wang,Sen Wang,Gaobin Liu,Xueyan Han,Feixiang Guo,Yongheng Fan
In this paper, Nb-doped BaTiO3nanoparticles (BaNb0.47Ti0.53O3) were prepared using an electrochemical method in an alkaline solution, with titanium-niobium alloy as the electrode. The results indicated that under relatively mild conditions (normal temperature and pressure, V < 60 V, I < 5 A), cubic perovskite phase Nb-doped BaTiO3nanoparticles with high crystallinity and uniform distribution can be synthesized. With this increase in alkalinity, the crystallinity of the sample increases, the crystal grain size decreases, and the particles become more equally dispersed. Furthermore, in our study, the average grain size of the nanoparticles was 5–20 nm, and the particles with good crystallinity were obtained at a concentration of 3 mol/L of NaOH. This provides a new idea and method for introducing foreign ions under high alkalinity conditions.Keywords:Nb-BaTiO3;electrochemical synthesis;microstructure;nanoparticles
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
PubMed
高影响因子
FUEL PROCESSING TECHNOLOGY
·
2016
·
IF 3.847
Wei Li,Rui-tang Guo,Shu-xian Wang,Wei-guo Pan,Qi-lin Chen,Ming-yuan Li,Peng Sun,Shu-ming Liu
Heavy metals (such as Zn and Pb) have a deactivation effect on the catalyst for selective catalytic reduction of NO with NH 3 . In this study, it was found that the modification of Mn/TiO 2 catalyst by Nb could greatly enhance its Zn resistance. From the characterization results of BET, XRD, H 2 -TPR, NH 3 -TPD, it may be concluded that the introduction of Nb into Mn/TiO 2 catalyst would lead to its lower crystallinity , more acid sites and higher concentrations of Mn 4 + and surface chemisorbed oxygen. The results of in situ DRIFT study reveal that the NH 3 -SCR reactions over Mn/TiO 2 and Mn-Nb/TiO 2 all obey both the Langmuir-Hinshelwood mechanism and the Eley–Rideal mechanism, and the doping of Nb on Mn/TiO 2 catalyst could promote the adsorption of NH 3 and NOx species on it. All these features make a contribution to the high SCR activity and good Zn resistance of Mn-Nb/TiO 2 catalyst.
研究领域:
催化化学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
OPTICAL MATERIALS
·
2022
·
IF 3.754
Bo Zhang,Jie Luo,Zhi Chen,Yuanshun Xiang,Lu Tang,Hongyi Jiang,Yuanyuan Tian,Shengli Liu
The development of high-quality cathode material is of important value to the research of bifunctional electrochromic energy storage device. Therefore, Nb-doped TiO 2 mesoporous film as the high-performance cathode was prepared via a facile sol-gel technology successfully. The Nb doping content has great effects on the crystallinity and chemical state of TiO 2 films. Compared to the pure TiO 2 film, the optimum Nb-doped TiO 2 film exhibits the excellent optical-electrochemical performance including highest large-rate capability, largest specific capacity (62.4 mAh/g), short switching time (3.4 s/4.5 s) and large transmittance modulation (50.7%). These data indicate that Nb-doped TiO 2 mesoporous films possess the important application prospect.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
JOURNAL OF ELECTROCERAMICS
·
2024
·
IF 1.7
Chen Binbin,Hu Yang,Zhang Huazhang,Chen Wen,Zhou Jing
The fatigue behavior of Bi 0.5 Na 0.4 K 0.1 TiO 3 -based ceramics depends on the polarity. While the non-ergodic relaxor ceramics have large residual polarization but poor fatigue behavior, the ergodic relaxor ceramics have excellent fatigue resistance but tiny residual polarization. Therefore, obtaining ferroelectric ceramics with high residual polarization and excellent fatigue resistance is challenging due to the trade-off between non-ergodic relaxor and ergodic relaxor. Here, we modulate the free energy barrier by doping relaxant Nb to achieve the coexistence of non-ergodic and ergodic relaxor phases. At 0.6% Nb doping, the residual polarization is large at 2 P r = 49.3 µC/cm 2 , increased to 54.23 µC/cm 2 after 10 2 cycles and decreased to 53.04 µC/cm 2 after 10 5 cycles, indicating good fatigue resistance behavior. The large residual polarization is due to the metastable ferroelectric state, while the excellent fatigue resistance may be attributed to the field-induced ferroelectric-relaxor phase transition.
研究领域:
材料科学
·
物理学
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2023
·
IF 7.4
Guoquan Liu,He Zhang,Pengfei Wang,Yi Li,Xueyue Mi,Sihui Zhan
Reducing the poisoning effect of alkaline earth metals over catalysts in industrial fields presents a great challenge to selective catalytic reduction (SCR) of NO x with ammonia. Herein, we successfully introduce sulfates to the surface of supported manganese-based oxides (Nb/MnO 2 -S) for trapping calcium species, and Nb/MnO 2 -S catalyst with superior low-temperature performance and calcium-resistant property still exhibits excellent de-NO x activity in a wide operating temperature window (175–350 °C, over 80 % NO x conversion with a gas hourly space velocity of 60,000 h −1 ) after calcium poisoning. In this case, the addition of sulfates increased the quantity of chemisorbed oxygen on Nb/MnO 2 -S, thus accelerating the redox cycle in NH 3 -SCR reaction. Significantly, compared with calcium-poisoned Nb/MnO 2 , relevant spectroscopy analysis and theoretical calculations further reveal that sulfates species prefer to interact with calcium and release the Nb active sites, which maintains the efficient NH 3 adsorption and preserves a large amount of Brønsted acid sites over calcium-poisoned Nb/MnO 2 -S, thus promoting calcium-resistant performance. This work will provide a general strategy to develop calcium-resistant SCR catalysts with low-temperature activity for industrial applications.
研究领域:
催化化学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
ChemCatChem
·
2022
·Vol. 14
·期 17
·e202200476
·
IF 5.497
Shuangxi Li,Weiwei Hu,Ziqiang Xu,Huijun Yu,Tianwei Lan,Lupeng Han,Dengsong Zhang
Graphical Reaction pathway ? More adsorption of NH 3 /NH 4 + species and the higher reactivity with gaseous NO maintain the process of E−R reaction path, leading to a satisfactory SCR activity of K poisoned NbFeVO x /TiO 2 . Whereas the decreased adsorption and reactivity of NH 3 /NH 4 + and NO x restrains the process of L−H reaction path, thus showing inferior SCR activity of K poisoned FeVO 4 /TiO 2 . FeVO 4 -based catalysts with a wide temperature window and high SO 2 tolerance have attracted increasing attention for the selective catalytic reduction of NO x with NH 3 . However, the alkali-resistance of FeVO 4 -based catalysts is still challenging. In this study, the K-resistance of FeVO 4 /TiO 2 was markedly improved via the Nb modification. It was demonstrated that the adsorption and reactivity of NH 3 /NH 4 + and NO x species on K poisoned FeVO 4 /TiO 2 both decreased, which restrained the process of Langmuir-Hinshelwood reaction path. As a comparison, more adsorption of NH 3 /NH 4 + species and the higher reactivity with gaseous NO maintain the process of Eley-Rideal reaction path, leading to a satisifactory SCR activity. This work demonstrated an effective route to improve alkali-resistance via modulating reactivity and reaction path of adsorbed NH 3 /NH 4 + and NO x species over Nb modified vanadate catalysts, which presented a new point for the development of high-performance alkali-resistant SCR catalysts.
研究领域:
环境科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）