APPLIED CATALYSIS B-ENVIRONMENTAL
·
2017
·
IF 9.446
Wenhui Li,Xiaowa Nie,Xiao Jiang,Anfeng Zhang,Fanshu Ding,Min Liu,Zhongmin Liu,Xinwen Guo,Chunshan Song
Screening of various supports reveals that Co catalysts supported on ZrO 2 and Al 2 O 3 show good initial activity for CO 2 methanation. Co/ZrO 2 and Co/Al 2 O 3 catalysts prepared by impregnation with different metal loadings were further examined comparatively. The 10Co/ZrO 2 catalyst showed high activity with CO 2 conversion of 92.5% and CH 4 selectivity of 99.9% without deactivation after 300 h time on stream (TOS). However, the 10Co/Al 2 O 3 catalyst gave a lower CO 2 conversion of 77.8% which decreased to 38.6% after 300 h TOS. The catalysts were characterized by STEM/EDS (scanning transmission electron microscopy/energy-dispersive X-ray spectroscopy), in situ XRD(X-ray diffractometer), H 2 -TPR(temperature programmed reduction), XPS (X-ray photoelectron spectroscopy), chemisorption of H 2 , CO, CH 4 , CO 2 and NH 3 -TPD (temperature programmed desorption). Re-dispersion of Co species on the ZrO 2 support during reduction by H 2 was observed by STEM/EDS. New Co-Zr phase formed on the Co-ZrO 2 interface was directly observed by TEM for the first time; the Co/ZrO 2 catalyst exhibited high stability with high activity for CO 2 conversion. In situ XRD, H 2 -TPR and XPS results indicate the promoting effect of ZrO 2 on the reduction of Co 3 O 4 to Co metal along with the negative effect of Al 2 O 3 . The oxygen vacancies on the ZrO 2 detected by XPS may help to activate CO 2 and H 2 O and resist deactivation. Co/Al 2 O 3 catalyst deactivates rapidly due to coke deposition and spinel formation.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Advanced Ceramics
·
2018
·Vol. 7
·期 4
·388-391
·
IF 1.605
Lu Youjun,Yuan Zhenxia,Shen Hongfang,Huai Xiaochen,Huang Zhenkun
Zirconium nitride (ZrN) ceramics were prepared via hot pressed sintering (HP) at 1750 °C in N 2 atmosphere with ZrO 2 –Y 2 O 3 as sintering additive. X-ray diffraction was applied to analyze the phase composition of the as-prepared ceramics to study the high temperature phase relation in ZrN–ZrO 2 –Y 2 O 3 ternary system and establish ZrN–ZrO 2 –Y 2 O 3 ternary phase diagrams. The results show that ZrN and tetragonal ZrO 2 (t-ZrO 2 ) solid solution, face-centered cubic ZrO 2 (c-ZrO 2 ) solid solution, body-centered cubic Y 2 O 3 (c-Y 2 O 3 ) solid solution coexist in the system of ZrN–ZrO 2 –Y 2 O 3 .
研究领域:
材料科学
·
陶瓷工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2021
·
IF 5.302
Le Fu,Bo Li,Guofu Xu,Jiwu Huang,Håkan Engqvist,Wei Xia
Thermal stability of nanocrystallites plays an important role in the manufacturing and application of nanocrystalline ceramics/glass-ceramics. This study explores the effects of thermal treatments on the microstructures of two ZrO 2 -SiO 2 nanocrystalline glass-ceramics (NCGCs), an undoped one and a yttria-doped one. The two as-sintered NCGCs were composed of tetragonal (t) and monoclinic (m) ZrO 2 nanocrystallites, and SiO 2 component was amorphous. t-ZrO 2 and m-ZrO 2 nanocrystallites were metastable during thermal treatment. The content of m-ZrO 2 in the undoped ZrO 2 -SiO 2 NCGC first increased after thermal treating at 850 °C for 5 h, then decreased after thermal treating at and above 950 °C. After thermal treating at 1250 °C for 5 h, t-ZrO 2 nanocrystallites experienced a rapid phase transformation during cooling, resulting the formation of 88.6 vol% m-ZrO 2 . Size-driven phase transformation was utilized to explain the metastability of t-ZrO 2 and m-ZrO 2 nanocrystallites. In contrast, the content of m-ZrO 2 in the yttria-doped ZrO 2 -SiO 2 NCGC continuously decreased with the increase of thermal treatment temperature. The addition of yttria improved the phase stability of t-ZrO 2 up to at least 1250 °C. Crystallite size of both t-ZrO 2 and m-ZrO 2 nanocrystallites increased with the increase of thermal treatment temperature in the two NCGCs. The presence of residual thermal stress in the as-sintered NCGCs changed the lattice spacing of t-ZrO 2 and m-ZrO 2 nanocrystallites, and the stress can be released after thermal treatment. Thermal treatment exerts significant influences on the microstructure of ZrO 2 -SiO 2 NCGCs.
研究领域:
材料科学
·
陶瓷学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2016
·
IF 2.758
W.Z. Sun,J.G. Cheng,Z.K. Huang,Y. Jiang,L.E. Wu,L.M. Liu
During investigation of the phase relations in the SiC–ZrO 2 –CaO ternary system, it was revealed that ZrO 2 reacted with SiC and CaO to form ZrC and calcium silicate via a series of solid-state reactions. Because these reactions may provide a new route to reaction-sintering of ZrC ceramics, ZrC/SiC and ZrC/salt composites, the formation process of the ZrC phase was analyzed. Subsolidus phase diagram of the related SiC–SiO 2 –ZrC–ZrO 2 –CaO (Si–Zr–Ca–O–C) quinary system at 1400 °C was presented.
研究领域:
材料科学
·
陶瓷工程
✓ 已验证
产品关联
DOI
高影响因子
ACS Catalysis
·
2021
·
IF 13.084
Yong Xu,Xuchun Wang,Di Yang,Zeyuan Tang,Muhan Cao,Huicheng Hu,Linzhong Wu,Lijia Liu,John McLeod,Haiping Lin,Youyong Li,Yeshayahu Lifshitz,Tsun-Kong Sham,Qiao Zhang
The conversion of light alkanes to olefins (e.g., ethylene, propylene, or butylene) is crucial to the chemical industry. ZrO2 with oxygen vacancies has recently been regarded as a promising catalyst for the direct dehydrogenation of light alkanes. However, the intrinsic mechanism of the effect of oxygen vacancies on catalytic performance has not been completely understood yet, and ZrO2 without promoters generally displays poor activity toward the direct dehydrogenation of light alkanes. In this work, we demonstrate that the oxygen vacancies in ZrO2 can be poisoned by H atoms during the dehydrogenation of light alkanes, and we report a strategy for stabilizing the oxygen vacancies in ZrO2 by Ga2O3. Experimental results and theoretical calculations indicate that ZrO2 with oxygen vacancies is responsible for dehydrogenation, while Ga2O3 prevents the poisoning of oxygen vacancies by dissociated hydrogen atoms which, in the absence of the Ga2O3 component, blocks further dehydrogenation. Consequently, the optimal Zr0.26Ga1 catalyst exhibits superior propane dehydrogenation performance to the industrial Pt–Sn catalyst, the state-of-the-art catalyst for the direct dehydrogenation of light alkanes. We anticipate this work may shed light on both the fundamental research of catalysis and the chemical industry.
研究领域:
催化化学
·
材料科学
·
工业化学
✓ 已验证
产品关联
DOI
高影响因子
Molecular Catalysis
·
2025
·
IF 4.9
Qiuju Qin,Chaolian Zhu,Donghai Mo,Zhengjun Chen,Lihui Dong,Bin Li,Liya Zhou
MnO x exhibits excellent low temperature activity for degradation NO x , but its poor SO 2 tolerance restrains its application. Herein, an in situ construction method for MnO x loading on Mn-doped ZrO 2 carrier with carbon (MnO x /Mn-ZrO 2 -C) derived from Mn(NO 3 ) 2 /UIO-66 by in situ doped pyrolysis–oxidation, in which Mn replaces Zr to modify the electronic structure of the ZrO 2 . The MnO x /Mn-ZrO 2 -C with abundant surface oxygen and acid sites showed excellent activity and better SO 2 resistance. A series of characterization results indicated that Mn doping modulates the electron structure of carrier ZrO 2 and enhances the interactions among MnO x , carbon, and Mn-ZrO 2 , resulting in increasing the electron cloud density around Mn and Zr, and consequently, the Mn and Zr on the MnO x /Mn-ZrO 2 -C exhibit poorer sulfiphilic. These findings emphasize the benefits of utilizing a multipronged effect to fabricate highly active and sulfur-resistant NH 3 -SCR catalysts.
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
CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2021
·
IF 3.171
Xuemei Wu,Minghui Tan,Bing Xu,Shengying Zhao,Qingxiang Ma,Yingluo He,Chunyang Zeng,Guohui Yang,Noritatsu Tsubaki,Yisheng Tan
The effects of crystallite size on the physicochemical properties and surface defects of pure monoclinic ZrO 2 catalysts for isobutene synthesis were studied. We prepared a series of monoclinic ZrO 2 catalysts with different crystallite size by changing calcination temperature and evaluated their catalytic performance for isobutene synthesis from syngas. ZrO 2 with small crystalline size showed higher CO conversion and isobutene selectivity, while samples with large crystalline size preferred to form dimethyl ether (DME) instead of hydrocarbons, much less to isobutene. Oxygen defects (O Defects ) analyzed by X-ray photoelectron spectroscopy (XPS) provided evidence that more O Defects occupied on the surface of ZrO 2 catalysts with smaller crystalline size. Electron paramagnetic resonance (EPR) and ultraviolet–visible diffuse reflectance (UV–vis DRS) confirmed the presence of high concentration of surface defects and Zr 3+ on m -ZrO 2 -5.9 sample, respectively. In situ diffuse reflectance infrared Fourier transform spectroscopy ( in situ DRIFTS) analysis indicated that the adsorption strength of formed formate species on catalyst reduced as the crystalline size decreased. These results suggested that surface defects were responsible for CO activation and further influenced the adsorption strength of surface species, and thus the products distribution changed. This study provides an in-depth insight for active sites regulation of ZrO 2 catalyst in CO hydrogenation reaction.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Energy Chemistry
·
2021
·
IF 9.676
Ziyi Li,Haigang Hao,Jingjing Lu,Chengming Wu,Rui Gao,Jifan Li,Chun-Ling Liu,Wen-Sheng Dong
Here we exquisitely fabricated Cu/ZrO 2 -dp catalysts with plentiful Cu-ZrO 2 interfaces by depositing amorphous ZrO 2 onto Cu nanoparticles for the hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL). With the created plentiful Cu-ZrO 2 interfaces, the optimal catalyst 3Cu/ZrO 2 -dp exhibited exceptional catalytic performance under mild reaction conditions, and achieved the highest GVL mass productivity of 266.0 mmol GVL·h −1 ·g −1 Cu, which was 12.5 and 2.3 times of Cu/ZrO 2 catalysts with equivalent Cu loadings prepared by traditional impregnation (3Cu/ZrO 2 -im) or co-precipitation (3Cu/ZrO 2 -cp). As far as we know, this GVL mass productivity stood at the highest level compared with those obtained using non-noble metal catalysts under similar reaction conditions. By systematic investigation with multiple characterizations, density functional theory (DFT) calculations, and kinetic studies, it was found that interfacial active centers were created at Cu-ZrO 2 interfaces, which contained oxygen vacancies (O v ), negatively charged Cu δ− and partially reduced Zr 3+ . The O v favored the adsorption and activation of LA via its ketone group, while negatively charged Cu δ− was able to enhance heterolysis of H 2 , which resulted in the formation of H + -Cu δ− and Zr 3+ -H − active species via hydrogen spillover. Also, plentiful acid sites, which derived from coordinatively unsaturated and defective Zr species, generated at Cu-ZrO 2 interfaces. With the cooperation of interfacial active centers (Cu δ− -O v -Zr 3+ ) and acid sites, the fabricated 3Cu/ZrO 2 -dp with plentiful Cu-ZrO 2 interfaces achieved excellent catalytic performance for the hydrogenation of LA to GVL. Hence, the synergistic catalysis of Cu-ZrO 2 interfaces provided an effective strategy for designing catalysts with a satisfactory performance for the hydrogenation of LA, which also can be expanded to other hydrodeoxygenation reactions.
研究领域:
催化
·
化学工程
·
材料科学
·
物理化学
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2020
·
IF 10.652
Yi Xia,Jie Shi,Qian Sun,Dan Wang,Xiao-Fei Zeng,Jie-Xin Wang,Jian-Feng Chen
Colloidal nanocrystals can offer exquisite control of physical and chemical properties for technological applications by tuning their sizes, shapes and crystal forms. Herein, a convenient phase-transfer route was presented to controllably prepare transparent dispersions of monodispersed ZrO 2 nanocrystals in an aqueous-organic two-phase medium. By adjusting the surfactants, solvents and basicity, the controllability of crystal forms from monoclinic to tetragonal phases, the particle length from 5 to 20 nm, and the different shapes including spindle, cobblestone, sphere, branch, rod and cube can be achieved. The as-prepared ZrO 2 nanocrystals can be readily dispersed in nonpolar solvents, thereby forming the ultra-highly concentrated (60 wt%), highly stable (>18 months) and highly transparent nanodispersions. Density functional theory (DFT) calculations were further used to elucidate the root causes of underpinning growth mechanisms. This work not merely enriches the methodology of controllable fabrication of monodispersed sub-10 nm ZrO 2 nanocrystals, but also enables a platform to synthesize rare-earth-doped nanophosphors using ZrO 2 as the host matrix. The fluorescent ZrO 2 :Yb 3+ /Er 3+ nanocrystals, which can be easily monodispersed in organic solvents, were also prepared with visible luminescene properties under near-infrared irradiation.
研究领域:
材料科学
·
化学
✓ 已验证
产品关联
DOI
高影响因子
Materials Express
·
2021
·Vol. 11
·期 9
·1594-1601
·
IF 0
Sun Yonggen,Fei Yanhan,Wang Yanchun,Jin Yuhui,Du Lanjun,Cheng Yuansheng,Du Zhiming
ZrO2-5CrMnMo composites were fabricated by ceramic injection molding in this research. The hardness and wear properties of ZrO2 ceramic layer and 5CrMnMo substrate were investigated. Moreover, physical properties and microstructures of ZrO2 ceramic coatings
were studied and the interfaces of composite samples were observed. The results illustrated that the interface was smooth and properly bonded, and it was concluded that the 5CrMnMo substrate ceramic layer could be provided effectively by ZrO2 ceramic coating. Thermal insulation
and thermal shock cycle tests were carried out. The heat insulating property of ZrO2 ceramic coating was remarkable, and even better at a high temperature. The composite samples prepared at 1200 °C did not failed until after more than 68 thermal shocks. The main reasons of limiting
the application of this composites so far were still the physical and thermodynamic mismatch between ceramics and steel. But the composite samples fabricated by ceramic injection molding showed excellent thermal shock resistance and high bonding strength in this work.
研究领域:
材料科学
·
机械工程
✓ 已验证
产品关联
DOI
ACS Applied Nano Materials
·
2019
·
IF 0
Benxue Liu,Min Gao,Xiaochan Liu,Xinfu Zhao,Jing Zhang,Xibin Yi
Compared with single-component aerogels, hybrid aerogels with multiple components possess enhanced properties, especially high thermal stabilities. Thermal stability improvement depends on the mixing between the various components. In the present research, a ZrO2/SiO2 hybrid aerogel was representatively chosen to study the mixing behaviors and resultant thermal stabilities. A series of ZrO2/SiO2 hybrid aerogels were synthesized by using different sol–gel parameters to study shrinkage, nanopore collapse, and crystallization behavior upon heat treatment. The sol–gel hybridization of weakly branched ZrO2 and SiO2 clusters was found to provide maximum mixing of ZrO2/SiO2. The highly mixed hybrid aerogel, with a ratio of 86/14 w/w ZrO2/SiO2, showed the best thermal stability. The thermally stable ZrO2/SiO2 hybrid aerogel, after incorporation into a mullite fiber blanket, showed very low thermal conductivities of 0.026 ± 0.001, 0.037 ± 0.001, and 0.058 ± 0.002 W/(m K) at 600, 800, and 1000 °C, respectively. It was suggested that weakly branched ZrO2 and SiO2 clusters preferred to freely tangle with each other during the preparation procedure, achieving the most highly mixed ZrO2/SiO2 hybrid with the maximum synergistic effect. This hybrid strategy may provide pathways in designing other multiple-component hybrid aerogels.
研究领域:
材料科学
·
纳米技术
✓ 已验证
产品关联
DOI
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2015
·
IF 2.947
Xianqiang Chen,Haiming Qin,Ye Zhang,Jun Jiang,Haochuan Jiang
Gd 3 (Al,Ga) 5 O 12 (GAGG) ceramic is a promising scintillation matrix due to its favorable chemical and physical properties. However, difficulties in the preparation of highly transparent ceramics limit its applications in scintillation detectors. In present work, highly transparent GAGG-based ceramics were prepared via solid state reaction and oxygen sintering method. Ceramics with transmittance of up to 73% at around 560 nm were obtained. This transmittance value is very close to the value of 76% for the equivalent single crystal. Effects of ZrO 2 concentration on the microstructure and optical properties of GAGG-based transparent ceramics were intensively studied. It is found that the addition of ZrO 2 can effectively prohibit grain growth while promoting the removal of residual pores.
研究领域:
材料科学
·
光学工程
✓ 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）