查找使用阿拉丁产品的科研文献

Ru Single-Atom Decorated Black TiO2 Nanosheets for Efficient Solar-Driven Hydrogen Production

Chunfeng Yuan,Yongli Shen,Chunyu Zhu,Pei Zhu,Fan Yang,Jinghai Liu,Changhua An

Solar-driven hydrogen production is an ideal way to fundamentally solve energy and environmental issues to some extent. TiO2 as a class of promising photocatalysts has attracted intensive attention. However, low light utilization and serious recombination of photo-induced charge carriers lead to a low efficiency. Herein, black TiO2 (B–TiO2) nanosheets have been first synthesized by H2/Ar plasma treatment, onto which Ru single atoms are anchored by dipping RuCl3 solution. X-ray absorption fine spectra reveal that the Ru–O coordination number is ∼5 from the scattering between the Ru center and O atoms of B–TiO2, demonstrating the strong interplay between Ru atoms with TiO2. Density functional theory (DFT) simulations and photoelectrochemical tests clarify that the introduction of Ru single-atoms produces impurity levels, which serves as charge-trapping sites, and facilitates the photo-generated electron separation and transportation. Furthermore, the Gibbs free-energy of the adsorbed H* over RuSAs/B–TiO2 is much closer to zero compared to that of pristine TiO2, thus considerably boosting the photocatalytic performance. The hydrogen evolution over RuSAs/B–TiO2 reaches 17.81 mmol/g/h with an apparent quantum efficiency (AQE) of 21.3% at 365 nm. It is expected that this facile strategy can be employed to fabricate other efficient photocatalysts for new energy production and environmental remediation.

Influence of Ru on the microstructure and performance of WC-Co cemented carbides

Hong Zeng,Wenbin Liu,Chongbin Wei

This study investigated the microstructure and properties of cemented carbides before and after the addition of Ru. The hardness and elastic modulus of the binder phase of Ru-containing cemented carbides were higher, and the hardness at room temperature and high temperature were also high. In particular, the oxidation resistance of Ru-containing cemented carbides was enhanced at high temperatures. Therefore, the solid solution-strengthening effect of the binder phase containing Ru was significant, which was conducive to the improvement of the high-temperature hardness and enhancement of the high-temperature characteristics of the alloy.

Water accelerated activity of Ru NPs in sequential hydrogenation of nitrobenzene to cyclohexylamine

Xiang Li,Xiaomin Ren,Miao Guo,Weijian Li,Qihua Yang

It is difficult to balance the two separate and connected reaction steps in the sequential hydrogenation of nitrobenzene (NB) to cyclohexylamine (CHA) via only tuning the active sites. In this work, we optimize the activity of supported Ru NPs in the one-pot NB hydrogenation to CHA by tuning the surface hydrophobicity of the catalysts and by investigating the solvation effect. The Ru supported on hydrophobic mesoporous silicas is more active than that on hydrophilic mesoporous silicas, which may be attributed to the enrichment effect of the former one for hydrophobic NB. Furthermore, the activity of Ru is significantly promoted with the addition of H 2 O in the reaction system. Systematic studies suggest that the water promotion effect is mainly related with the decreased adsorption strength of NB on Ru surface and the water accelerated H* transfer during the NB hydrogenation process. Our primary results suggest that the modification of the surface properties of the catalysts and the deeper understanding of the solvation effect play an important role in one-pot cascade reactions.

Enhancement of aromatics production via cellulose fast pyrolysis over Ru modified hierarchical zeolites

Jun Zhang,Chengyu Li,Haoran Yuan,Yong Chen

In the present study, Ru modified hierarchical zeolites x Ru-MZSM were developed for cellulose fast pyrolysis . Comprehensive catalyst characterizations including XRD , XPS , N 2 adsorption-desorption, Py-IR and so on, were performed to unveil the essential structural properties. The chemical modification and Ru decoration remarkably regulated the distribution of Brønsted/Lewis acid sites. The presence of RuO x species would supply abundant strong Lewis acid sites for participating catalytic cracking , dehydration, decarbonylation, decarboxylation, cyclization, aromatization, etc., in cooperation with Brønsted acid sites. In-situ generated active Ru 0 centers during cellulose pyrolysis might facilitate the proceeding of deoxygenation , hydride transfer, and dehydrogenation . Among the as-prepared catalysts screened, 2Ru-MZSM was much more efficient in aromatics production from cellulose fast pyrolysis compared to parent ZSM, wherein the total aromatics yield achieved 16.8% at temperature of 650 °C and heating rate of 10 °C/ms with corresponding E value as low as 23.40 kJ/mol. Also, plausible reaction mechanism for x Ru-MZSM involved cellulose fast pyrolysis was proposed in detail.

The dispersed SiO2 microspheres supported Ru catalyst with enhanced activity for ammonia decomposition

Fang Wang,Li-dan Deng,Ze-wei Wu,Kai Ji,Qiao Chen,Xing-mao Jiang

Ru nanoparticles supported on SiO 2 microspheres (Ru/SiO 2 -GUS) were prepared by the glucose-urea-metallic salt method and applied in the decomposition of ammonia. In the glucose-urea-metallic salt method, glucose as the carbon template plays a significant role in the formation of diffusion-beneficial structural properties of Ru/SiO 2 -GUS, and also induceds the modification of the electronic state of Ru. Ru/SiO 2 -GUS exhibited higher catalytic activity compared with the catalyst prepared with the impregnation method. The catalytic performance of Ru/SiO 2 -GUS was further enhanced with the addition of either K or Cs——the addition order and amount strongly affecting the catalytic performance. When the ratio of K/Cs to Ru is 2, the alkali metal (KOH/CsOH) solution is added in the homogeneous solution of glucose, urea, RuCl 3 and the colloidal silica , the promotion effect of K/Cs is the strongest, particularly under lower reaction temperatures. However, the promotion effects of K and Cs are different as reveled by the combined results of H 2 -TPR, XPS and NH 3 -TPSR. More NH 3 can be absorbed on K–Ru/SiO 2 -GUS and the electron density of Ru decreased. By contrast, more metallic Ru formed on Cs–Ru/SiO 2 -GUS, facilitating N 2 recombination.

Mechanisms of Caromatic-C bonds cleavage in lignin over NbOx-supported Ru catalyst

Lin Dong,Jie Xia,Yong Guo,Xiaohui Liu,Haifeng Wang,Yanqin Wang

Efficient and selective cleavage of C aromatic -C linkages in lignin to enhance the productivity of monocyclic aromatic hydrocarbons is an extremely challenging and attractive task. Previously, we reported a Ru/NbOPO 4 catalyst that realized the catalytic cleavage of both interunit C-C and C-O bonds in one-pot lignin conversions [ Chem , 2019, 5, 1521–1536]. However, the roles of NbO x species in the selective C aromatic -C cleavage are not clear and need to be extensively studied. Herein, we focus on the exploration of the catalytic mechanisms of C aromatic -C bond cleavage over NbO x -supported Ru catalyst, by comparing with those of Ru/TiO 2 , Ru/ZrO 2 , and Ru/Al 2 O 3 catalysts. It shows that the Ru/Nb 2 O 5 catalyst exhibits high activity and remarkable selectivity to monocyclic hydrocarbons. A combined diffuse reflectance infrared Fourier Transform spectra (DRIFTS) and density functional theory (DFT) calculation analysis unambiguously confirmed that (i) NbO x not only can strongly adsorb phenylcyclohexane via benzene ring, but also selectively activate C aromatic -C bond between benzene ring and cyclohexane ; (ii) NbO x can promote the protonation of phenylcyclohexane with the assistance of H 3 PO 4 ; and (iii) NbO x can significantly reduce the barrier of C aromatic -C bonds cleavage of the carbocation intermediate (C 6 H 5 (H)C 6 H 11 + ). A detail underlying mechanism has been established, which would have further implications to promote the design of new, high efficient catalysts.

Defect CTF derived Ru-based catalysts for high performance overall water splitting reaction

Xu Gao,Yi-jing Gao,Sui-qin Li,Jun Yang,Gui-lin Zhuang,Sheng-wei Deng,Zi-Hao Yao,Xing Zhong,Zhong-zhe Wei,Jian-guo Wang

Research on water-splitting electrocatalysts is crucial to establishing a solution to the energy crisis. Herein, we report a facile bottom-up strategy for the preparation of high performance supported electrocatalysts for overall water-splitting reaction via a rationally designed defect covalent triazine frameworks (CTFs) support. Specifically, defect CTFs are obtained via binary-precursor polymerization, followed by loading Ru nanoparticles (Ru/D-CTFs-900) with high HER performance at a current density of 10 mA cm −2 . The overpotential is only 17 mV. Calcination of the resultant Ru–RuO 2 /D-CTFs-300 in air, produces excellent OER performance with 190 mV overpotential (at 10 mA cm −2 ). Furthermore, overall water splitting measurements reveal the potential of 1.47 V, which is better than the majority of the reported Ru-based catalysts. Moreover, density functional theory calculation results show that excellent electrocatalytic properties are attributed to the synergistic effect of Ru nanoparticles and carbon support.

Deactivation mechanism and anti-deactivation modification of Ru/TiO2 catalysts for CH3Br oxidation

Lirong Lv,Sheng Wang,Ya Ding,Lei Zhang,Yang Gao,Shudong Wang

Highly Efficient Photocatalytic CO2 Methanation over Ru-Doped TiO2 with Tunable Oxygen Vacancies

Zheyue Li,Di Wu,Wanbing Gong,Jiayi Li,Shuaikang Sang,Hengjie Liu,Ran Long,Yujie Xiong

Solar-driven CO 2 methanation is an imperative and promising approach to relieve the global warming and environmental crisis, yet remains a great challenge due to the low reaction efficiency, unsatisfactory selectivity and poor stability. In this work, we demonstrate a facile and efficient strategy to prepare Ru-doped TiO 2 photocatalyst with tunable oxygen vacancies using the ascorbic acid as a reducing agent for the CO 2 methanation reaction. The optimal Ru-TiO 2 -OV-50 exhibits a remarkable CH 4 production rate of 81.7 mmol g −1 h −1 with a 100% CH 4 selectivity under a 1.5 W cm −2 light illumination, which is significantly higher than commercial Ru/TiO 2 and other reported catalysts. We reveal that the superior photocatalytic CO 2 methanation performance is mainly due to the synergistic effect of Ru doping and TiO 2 with tunable oxygen vacancies. Impressively, the light rather than thermal effect is confirmed as the main influencing factor by experimental studies. In addition, in situ spectroscopic technology is performed to investigate the CO 2 methanation reaction pathway. This work will open an avenue to design and prepare highly efficient photocatalyst with tunable oxygen vacancies for CO 2 conversion and other related applications.

Atomically dispersed Ru on flower-like In2O3 to boost CO2 hydrogenation to methanol

Mengyao Xu,Fei Liu,Shike Liu,Jun Ma,Mengqin Yao,Xiaodan Wang,Jianxin Cao

Metal-based catalysts are prevalent in the CO 2 hydrogenation to methanol owing to their remarkable catalytic activity. Herein, Ru/In 2 O 3 catalysts with different morphologies obtained by doping Ru into In 2 O 3 with irregular, rod-like, and flower-like morphologies are used for catalytic CO 2 hydrogenation to methanol. Results indicate that the flower-like Ru/In 2 O 3 (Ru/In 2 O 3 -F) exhibits higher catalytic performance than Ru/In 2 O 3 with other morphologies, achieving a 12.9% CO 2 conversion, 74.02% methanol selectivity, and 671.36 mg MeOH ·h −1 ·g cat −1 methanol spatiotemporal yield. Furthermore, Ru/In 2 O 3 -F maintains its catalytic stability over 200 h at 5 MPa and 290 °C. The promotional effect mainly stems from the fact that electronic structure of Ru can be effectively adjusted by modulating the morphology of In 2 O 3 . The strong interaction between atomically dispersed Ru and In 2 O 3 -F enhances the structural stability of Ru, inhibiting the agglomeration of the catalyst during the reaction process. Furthermore, density-functional theory calculations reveal that highly dispersed Ru atoms not only perform efficient and rapid electronic gain and loss processes, facilitating the catalytic activation of H 2 into H intermediates. It also enables the generated reactive H to rapidly overflow to the surrounding In sites to participate in CO 2 reduction. These findings provide a theoretical basis for the development of high-performance catalysts for CO 2 hydrogenation.

Selective hydrodeoxygenation of 5-hydroxymethylfurfural to 2,5-dimethylfuran on Ru–MoOx/C catalysts

Yue Yang,Qiying Liu,Dan Li,Jin Tan,Qi Zhang,Chenguang Wang,Longlong Ma

Selective hydrogenation of 5-hydroxymethylfurfural (HMF) has potential application in high quality biofuels. Herein, the catalytic hydrodeoxygenation (HDO) of HMF to 2,5-dimethylfuran (DMF) was investigated using bi-functional Ru–MoOx/C catalyst prepared by initial wetness impregnation. The high dispersion and electronic transfer between Ru and MoOx were demonstrated by a series of characterization techniques. During this HDO process, the synergy effect between metallic Ru and acidic MoOx species in the Ru–MoOx/C catalyst plays an essential role in obtaining maximized target product DMF (79.4%) via effective aldehyde group hydrogenation by Ru followed by dehydration over MoOx. This work also elucidated that DMF production proceeded through two distinct pathways: the 2,5-hydroxymethyl furan intermediate was preferable by the aldehyde group hydrogenation of HMF over the Ru–MoOx/C catalyst. Over MoOx/C catalyst, comparatively, 5-methyl furfural was the key intermediate by direct hydrogenolysis of the hydroxyl group in HMF. This kind of catalyst is stable for the first two runs by maintaining the target product yield. After the third run, the catalyst showed deactivation gradually but could be almost completely recovered after regeneration by H2 reduction.

Selective Hydrogenation of m-Dinitrobenzene to m-Nitroaniline over Ru-SnOx/Al2O3 Catalyst

Haiyang Cheng,Weiwei Lin,Xiaoru Li,Chao Zhang,Fengyu Zhao

Series catalysts of Ru-SnOx/Al2O3with varying SnOxloading of 0–3 wt% were prepared, and their catalytic activity and selectivity have been discussed and compared for the selective hydrogenation ofm-dinitrobenzene (m-DNB) tom-nitroaniline (m-NAN). The Ru-SnOx/Al2O3catalysts were characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and hydrogen temperature-programmed reduction (H2-TPR) and desorption (H2-TPD). Under the modification of SnOx, the reaction activity increased obviously, and the best selectivity tom-NAN reached above 97% at the complete conversion ofm-DNB. With the increasing of the SnOxloading, the amount of active hydrogen adsorption on the surface of the catalyst increased according to the H2-TPD analysis, and the electron transferred from Ru to SnOxspecies, as determined by XPS, inducing an electron-deficient Ru, which is a benefit for the absorption of the nitro group. Therefore, the reaction rate and product selectivity were greatly enhanced. Moreover, the Ru-SnOx/Al2O3catalyst presented high stability: it could be recycled four times without any loss in activity and selectivity.Keywords:Ru catalyst;SnOxdoping;hydrogenation;m-dinitrobenzene;m-nitroaniline;catalyst recycling