CHEMICAL ENGINEERING SCIENCE
·
2023
·
IF 4.7
Xinyi Chen,Xin Tian,Chaohe Zheng,Haibo Zhao
Propane dehydrogenation is an attractive alternative for propylene production to petroleum-based routes. However, overcoming deactivation and toxicity of catalysts in propane direct dehydrogenation (PDH), and over oxidation in oxidative dehydrogenation (ODHP) remain challenging. Here, a chromium-based catalyst supported on a Ce-Zr solid solution is constructed for chemical looping oxidative propane dehydrogenation (CL-ODHP). A dual modulation of oxygen species by Zr doping was unraveled by characterizations and DFT calculation: the oxygen of surface CrO x was constrained while the oxygen mobility of the Ce-Zr support was promoted. Based on these properties, the interaction between surface CrO x and the support further enables an oxygen “donor–acceptor”, which potentially functions as in situ activation and regeneration of redox CrO x species as well as blockage of non-selective oxygen released from the Ce-Zr support. The optimized material (7.5Cr/Ce 0.8 Zr 0.2 O 2 ) achieves propane conversion up to 50% and propylene yield of 31% at 600 °C, and has the lowest Cr content among previously reported Cr-based catalysts that have comparable performance. These results provide insights for the design of highly active and selective redox catalysts for chemical looping as a reaction engineering strategy for the upgrading of propane dehydrogenation processes.
研究领域:
催化
·
化学工程
·
材料科学
·
表面化学
✓ 已验证
产品关联
DOI
高影响因子
Small
·
2024
·Vol. 20
·期 52
·2408373
·
IF 13
Xiaotong Zhou,Songliang Liu,Huaifang Teng,Kun Ma,Weixin Miao,Xuejing Cui,Xin Zhou,Luhua Jiang
Reasonable construction of high activity and selectivity electrocatalysts is crucial to achieve efficient ethanol oxidation reaction (EOR). However, the oxidation of ethanol tends to produce CO species that poison the active centers of the EOR electrocatalysts. Herein, a unique amorphous CrO x -protected defect-rich ultrafine Pd nanowires (CrO x -Pd NWs) is developed. On the one hand, the CrO x layer can act as a protective layer to maintain the structure of the nanowire. On the other hand, it can play the role of OH regulator to optimize the adsorption energy barrier of intermediate species in Pd nanowire, thereby enhancing the ability of the catalyst to resist CO poisoning. The CrO x -Pd NWs exhibit excellent EOR performance with 3.64 times higher mass activity and 50 mV lower CO electro-oxidation potential than commercial Pd black. The results show that the CrO x layer promotes the dissociation of H 2 O into OH ads , while the CrO x transfers electrons to neighboring Pd atoms optimizing the electronic configuration of Pd, thus selectively oxidizing ethanol to acetate and preventing the formation of toxic * CO. This work provides an effective strategy for the synthesis of nanowire materials with oxide/metal interfaces and offers new ideas for the design of catalysts that can efficiently drive EOR.
研究领域:
材料科学
·
电催化
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CATALYSIS LETTERS
·
2020
·Vol. 151
·期 6
·1755-1765
·
IF 2.482
Meng Fanyu,Zhang Mingjia,Zhou Fayang,Zou Haocheng,Zhu Boming,Zeng Yiqing,Zhang Shule,Zhong Qin
Abstract CrO x /black-TiO 2 catalysts were prepared by ligand-assisted (citric acid, oxalic acid and ethylenediaminetetraacetic acid) impregnation method. These catalysts were characterized in detail by means of X-ray diffraction, Raman, BET, X-ray photoelectron spectroscopy, H 2 and O 2 (NO) temperature programmed reduction or desorption and in-suit DFTIR spectra. The results indicated that ligands assistance was beneficial for CrO x interacted with oxygen vacancies and O–Ti–O structures. Among all the catalysts, CrO x /black-TiO 2 /CA (modified by citric acid) revealed excellent catalytic activity and stability for NO oxidation in the temperature range of 200–450 °C. The characterization results exhibited that the interaction existed between CrO x and oxygen vacancies resulting in more Cr 6+ . Moreover, the strong interaction between CrO x and O–Ti–O was attributed to the modification of carboxylic acid, which increased the content of Cr 3+ and chemical adsorption oxygen. High content of chemical adsorption oxygen promoted the adsorption ability of O 2 , and Cr 6+ enhanced the adsorption capacity of NO. Hence, chemical adsorption oxygen and Cr 6+ synergistically promoted the NO oxidation. Graphic Abstract
研究领域:
催化材料科学
·
环境化学
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Energy Materials
·
2023
·
IF 6.4
Renke Bi,Bing Han,Yijie Shen,Jialong Liu,Zhiyu Wang
Sunlight-driven photocatalytic overall water splitting (OWS) is a promising approach for solar-to-chemical energy conversion. However, its realization with a single photocatalyst by one-step excitation has been extremely limited due to the rapid recombination of photogenerated charges, slow surface redox kinetics, and undesired reverse reactions. Herein, we sought to enhance the OWS performance of SrTiO3 (STO) by exploring the synergistic effects of different kinds of metal/oxide dual cocatalysts. The results show that the Pt/CrOx-STO system had a superior activity, which achieved stoichiometric water splitting with H2/O2 evolution of 1814.17/1020.47 μmol g–1 h–1 under simulated sunlight, without using any sacrificial reagents. The enhanced efficiency can be attributed to the improved interfacial transport of photogenerated charges and the boosted surface kinetics. Importantly, the CrOx layer served as a selective membrane that prevented the O2 diffusion and facilitated H+ transport, while partially covering the highly active site of Pt nanoparticles, thus significantly inhibiting the reverse recombination reaction of H2 and O2. In particular, this dual catalyst system emphasized a low dependence on the properties of the substrate material and is therefore widely applicable and economical. This work demonstrated the potential of the Pt/CrOx dual cocatalyst modification strategy for optimizing photocatalytic OWS, providing a pathway toward selective and sustainable conversion of H2O to H2 and O2.
研究领域:
材料科学
·
可再生能源
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
CATALYSIS TODAY
·
2024
·
IF 5.2
Ruiqi Wu,Ning Liu,Chengna Dai,Gangqiang Yu,Ruinian Xu,Biaohua Chen
The propane oxidation dehydrogenation assisted by CO 2 (CO 2 -ODHP) is currently a hot research topic, not only to meet growing demand of propylene but also to favor the CO 2 neutralization. In present work, a series of CrO x @S1-n-1.0 with different Cr contents (n= 2.2, 3.6 and 4.5 wt%) is synthesized based on a small gas molecule directing synthesis strategy, wherein the gaseous CO of 1.0 MPa was in situ introduced in the synthesis system to regulate the interaction and dispersion of CrO x over silicalite-1 (S1) support. The characterization results of XRD , XPS , H 2 -TPR, and Raman indicate that the CO can affect the oxidation state and dispersion of Cr species. As observed, the Cr species were highly dispersed over CrO x @S1–3.6 %-1.0 (in the form of Cr 6+ valance state), which however would aggregate to generate Cr 2 O 3 nanoparticles over the CrO x @S1–3.6 %-0 a prepared by impregnation method in absence of CO. The activity measurement indicates that the CrO x @S1–3.6 %-1.0 possesses the highest activity by displaying an average propane conversion of 50.4 % and CO 2 conversion of 23.6 % at 600 °C, which surpasses most of the literature reports. The CO 2 -ODHP reaction mechanism was further investigated by in situ DRIFTS , which indicates that dissociated H of propane can react with CO 2 to form formate (-COOH), in turn further reacts with H to produce byproducts CO and H 2 O, and the formate species can also react with the CrO 3 active site to form bicarbonate species (HCO - 3 ). Generally, present work has proposed a small gas molecule directing strategy to adjust the dispersions and chemical states of the loaded guest meals over catalytic support. The study of present work would contribute to other highly efficient catalyst design .
研究领域:
催化化学
·
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2020
·
IF 16.683
Munir Ahmad,Xie Quan,Shuo Chen,Hongtao Yu,Zhenxing Zeng
Metal sulfide photocatalysts have been leading edge for hydrogen evolution reaction (HER) and solar energy conversion due to their suitable electronic and optical properties. The efficiency of these photocatalysts is mostly restricted by slow transfer of photogenerated holes and sluggish water dissociation kinetics. Here, we proposed HER catalyst comprising of Pt-CrO x sites loaded on ZnCdS nanocrystal (ZnCdS/Pt-CrO x ) that employing a redox couple ( OH/OH − ) transport mechanism to efficiently relay of holes in alkaline media. The Pt sites provide optimal hydrogen adsorption energy and CrO x sites support water dissociation, which speed up water dissociation kinetics and leads to a noticeable enhance in HER (21.1 mmol g −1 h −1 ) and phenol degradation. Such efficient activity could be associated to a better mobility of redox couple and fast water dissociation kinetics in alkaline solution. These types of related works open pathways to generate hydrogen from the sea water, largest water source on earth.
研究领域:
材料科学
·
能源化学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2016
·
IF 3.15
Jie Su,Weiyuan Yao,Yue Liu,Zhongbiao Wu
A series of HZSM-5 supported CrO x catalysts at different loadings were prepared by wet impregnation method for catalytic combustion of dichloromethane (DCM) in this paper. The catalytic activity tests indicated that both DCM conversion and product selectivity varied greatly with Cr doping contents. The sample at 2 wt% loading showed the highest DCM conversion, while the selectivity toward CO/CO 2 increased at an elevated CrO x loading. The characterization results revealed that the surface acidity and the chemical states of Cr were strongly affected by the doping content. The surface acidity would decline at an elevated Cr loading owing to the interactions between surface OH groups and chromium ions. And higher surface Cr(VI)/Cr(III) ratios could be observed on the catalysts at lower CrO x doping, leading to the improvement of reducibility. The activity and selectivity of DCM catalytic degradation were found to be highly depended on the balance of surface acidity and redox property. The increased surface acidity could result in the enhancement of dissociated adsorption of DCM, which are beneficial to the catalytic activity. However, higher surface acidity meant lower Cr loading, which might lead the adsorbed intermediates incompletely oxidized and the decrease in CO x selectivity due to the limit redox ability.
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
APPLIED CATALYSIS A-GENERAL
·
2024
·
IF 4.7
Chen Li,Liting Wei,Min Chen,Jiayi Zhang,Yang Yang,Boping Liu,Yulong Jin
CrO x /VO x /TiO 2 -SiO 2 was prepared via solvent-free and conventional wet-impregnation process with ethanol as solvent. The results of ICP-OES, N 2 adsorption-desorption, SEM-EDX, Raman and DR-Uv-vis spectra indicate that well-dispersed Cr and V sites in isolated state were the main species. Bimodal ultra-high molecular weight polyethylene/high-density polyethylene in-reactor blends (UHMWPE/HDPE IRBs) could be synthesized with polymerization activity ＞ 1×10 7 gPE·mol −1 Cr·h −1 . Moreover, the two catalysts displayed similar catalytic behaviors in temperature sensitivity, H 2 response and 1-hexene copolymerization efficiency, and their polymer products also show comparable molecular weight and molecular weight distribution , which implies analogous structures of their well-dispersed active sites. By contrast, the catalyst prepared by wet-impregnation process with water as solvent exhibited poor dispersity, which is reflected by its much lower activity and very different catalytic behaviors and polymer properties when compared with the well-dispersed catalysts. Therefore, the economic and green solvent-free process is promising for preparing highly-active CrO x /VO x /TiO 2 -SiO 2 .
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2022
·
IF 9.136
Xinqian Li,Bo Li,Shuqi Li,Yaping Dong,Dandan Gao,Zhengrong Niu,Wu Li,Haitao Feng
Removing impurities from hexavalent chromium system without secondary pollution is the key to the successful development of green chromate production technology. Here, hydrated chromium oxide CrO x (OH) 3-2x with lamellar cluster microsphere structure was prepared by in-situ hydrothermal method and used to simultaneously adsorb Si (IV) and V (V) in high concentration Cr (VI) solution. In the in-situ hydrothermal process of pH 7, 160 ℃ for 8 h, the Si (IV) and V (V) removal rates of the actual chromate production Na 2 Cr 2 O 7 -Na 2 SiO 3 -NaVO 3 -H 2 O solution can reach 92.27 % and 94.81 %, respectively, which is higher than the ex-situ removal efficiency of Si (IV) (62.88 %) and V (V) (63.16 %) under the same conditions. Further characterization of STEM-elemental mapping, XPS and FT-IR results indicate that during in-situ adsorption, Si (IV) and V (V) are mainly adsorbed on the surface of CrO x (OH) 3-2X adsorbent by interacting with surface hydroxyl groups. More importantly, the simultaneous formation and adsorption of the adsorbent are more conducive to the full utilization of active adsorption sites on the adsorbent surface. After that, CrO x (OH) 3-2x was converted into nano Cr 2 O 3 with a purity of 97.87 % by simple desorption and calcination processes. In addition, the results of UV–vis DRS and SEM show that the residual Si and V elements in Cr 2 O 3 unexpectedly increase the size of the particles to about 300 nm, which redshifts the absorption band of the blue region by 3.3 nm. This results in more red absorption and makes Cr 2 O 3 more yellowish-green and exhibits excellent pigment properties. Thus, the in-situ synthesis, synergistic adsorption and green conversion of trivalent chromium adsorbent provide a promising and sustainable technology for the purification of high concentration Cr (VI) solution that avoids the discharge of Cr (VI) containing slag.
研究领域:
环境科学
·
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
RSC Advances
·
2018
·Vol. 8
·期 7
·3858-3868
·
IF 2.936
Shuohan Yu,Sheng Xu,Bowen Sun,Yiyang Lu,Lulu Li,Weixin Zou,Peng Wang,Fei Gao,Changjin Tang,Lin Dong
Chromium oxide nano-particles with an average diameter of 3 nm covered by amorphous carbon (CrOx/C) were successfully synthesized. The synthesized CrOx/C materials were used for the selective catalytic reduction of NOx by NH3 (NH3-SCR), which shows superb NH3-SCR activity and in particular, satisfactory regeneration ability in the presence of SO2 compared with Mn-based catalysts. The as-prepared catalysts were characterized by XRD, HRTEM, Raman, FTIR, BET, TPD, TPR, XPS and in situ FTIR techniques. The results indicated presence of certain amounts of unstable lattice oxygen exposed on the surface of CrOx nano-particles with an average size of 3 nm in the CrOx/C samples, which led to NO being conveniently oxidized to NO2. The formed NO2 participated in NH3-SCR activity, reacting with catalysts via a “fast NH3-SCR” pathway, which enhanced th NH3-SCR performance of the CrOx/C catalysts. Furthermore, the stable lattice of the CrOx species made the catalyst immune to the sulfation process, which was inferred to be the cause of its superior regeneration ability in the presence of SO2. This study provides a simple way to synthesize stable CrOx nano-particles with active oxygen, and sheds light on designing NH3-SCR catalysts with highly efficient low temperature activity, SO2 tolerance, and regeneration ability.
研究领域:
催化
·
环境工程
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
MATERIALS RESEARCH BULLETIN
·
2018
·
IF 2.873
Wenjie Lin,Weiliang Wu,Jie Bao,Zongtao Liu,Kaifu Qiu,Lun Cai,Zhirong Yao,Youjun Deng,Zongcun Liang,Hui Shen
The dopant-free back contact solar cells are demonstrated based on hole selective contact material, chromium trioxide (CrO x , x < 3) with a low melting point for high stability and high performance. In this contribution, CrO x is first applied in silicon based solar cell as the emitter. Integrating 5 nm CrO x and 2 nm LiF x into solar cell as the emitter and the back surface filed, resulted in a device efficiency of 13.6%. For further improvement, the back contact solar cell reaching an efficiency of 15.8% was fabricated, by implementing the multilayer films of CrO x (5 nm)/Au (4 nm)/ CrO x (5 nm) as the emitter. The formation of Cr(OH) 3 in ambient condition, resulted in a lower work function (4.8 eV) of the CrO x film. Furthermore, the multilayer back contact solar cell demonstrated a high stability due to CrO x covered with 500 nm Ag, when stored in ambient air longer than 170 days.
研究领域:
材料科学
·
光伏技术
·
半导体器件
·
表面工程
·
能源材料
✓ 已验证
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2019
·
IF 3.131
Xiaohai Li,Fanyu Meng,Shule Zhang,Mingjia Zhang,Yiqing Zeng,Qin Zhong
CrO x was loaded on a different amount of polyethylene glycol modified TiO 2 (CrO x /yPEG-TiO 2 ) by impregnation method, successfully utilized in NO oxidation. The structure-property relationships of the catalysts were explored through different characterization techniques including XRD, BET, Raman, XPS, H 2 -TPR, O 2 -TPD, NO-TPD and in situ DRIFTS. The results pointed out that the polyethylene glycol modification could enhance the interaction between CrO x with TiO 2 . Among these CrO x /yPEG-TiO 2 (y = 0, 30, 50, 80) catalysts, the CrO x /50PEG-TiO 2 had the strongest interaction between CrO x with TiO 2 , which resulted in more chemical adsorption oxygen. Meanwhile, CrO x /50PEG-TiO 2 had a certain amount of Cr 6+ . It exhibited the highest catalytic activity due to the synergy between CrO x and chemical adsorption oxygen, which reached 55% at the temperature of 350 °C. Moreover, the CrO x /50PEG-TiO 2 still exhibited wide activity temperature windows of 225–425 °C and good stability.
研究领域:
催化化学
·
环境化学
·
材料科学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）