查找使用阿拉丁产品的科研文献

Study on the Catalytic Properties of Ru/TiO2 Catalysts for the Catalytic Oxidation of (Chloro)-Aromatics

Wang Jian,Zhao Hainan,Liu Xiaolong,Xu Wenqing,Guo Yangyang,Song Jianfei,Zhu Tingyu

In this work, we presented a detailed evaluation of Ru/TiO 2 (P25) catalysts for the catalytic oxidation of (chloro)-aromatics. The model catalysts were synthesized through wet impregnation. Catalytic evaluations, as well as ICP, BET, XRD and TEM analyses, were conducted. The results indicated that RuO 2 tended to be distributed on the rutile phase of TiO 2 , leading to an inhomogeneous distribution. These Ru/TiO 2 catalysts were very active, especially for chlorobenzene oxidation. The conversions of benzene and chlorobenzene were both suppressed by the introduction of additional water. But the amount of polychlorinated benzenes as by-products was also reduced. However, the activity of the catalyst significantly decreased with an increase in calcination temperature, suggesting that the thermal stability of the catalyst still needed to be improved. Graphical Abstract

Control of metal–support interaction for tunable CO hydrogenation performance over Ru/TiO2 nanocatalysts

Heyun Lin,Wenzhe Zhang,Huachen Shen,Hailing Yu,Yunlei An,Tiejun Lin,Liangshu Zhong

The catalytic behavior of CO hydrogenation can be modulated by metal–support interactions, while the role of the support remains elusive. Herein, we demonstrate that the presence of strong metal–support interactions (SMSI) depends strongly on the crystal phase of TiO2 (rutile or anatase) and the treatment conditions for the TiO2 support, which could critically control the activity and selectivity of Ru-based nanocatalysts for CO hydrogenation. High CO conversion and olefin selectivity were observed for Ru/rutile-TiO2 (Ru/r-TiO2), while catalysts supported by anatase (a-TiO2) showed almost no activity. Characterization confirmed that the SMSI effect could be neglected for Ru/r-TiO2, while it is dominant on Ru/a-TiO2 after reduction at 300 °C, resulting in the coverage of Ru nanoparticles by TiOx overlayers. Such SMSI could be suppressed by H2 treatment of the a-TiO2 support and the catalytic activity of the as-obtained Ru/a-TiO2(H2) can be greatly elevated from almost inactive to >50% CO conversion with >60% olefin selectivity. Further results indicated that the surface reducibility of the TiO2 support determines the SMSI state and catalytic performance of Ru/TiO2 in the CO hydrogenation reaction. This work offers an effective strategy to design efficient catalysts for the FTO reaction by regulating the crystal phase of the support.

Interfacial compatibility critically controls Ru/TiO2 metal-support interaction modes in CO2 hydrogenation

Zhou Jun,Gao Zhe,Xiang Guolei,Zhai Tianyu,Liu Zikai,Zhao Weixin,Liang Xin,Wang Leyu

Supports can widely affect or even dominate the catalytic activity, selectivity, and stability of metal nanoparticles through various metal-support interactions (MSIs). However, underlying principles have not been fully understood yet, because MSIs are influenced by the composition, size, and facet of both metals and supports. Using Ru/TiO 2 supported on rutile and anatase as model catalysts, we demonstrate that metal-support interfacial compatibility can critically control MSI modes and catalytic performances in CO 2 hydrogenation. Annealing Ru/rutile-TiO 2 in air can enhance CO 2 conversion to methane resulting from enhanced interfacial coupling driven by matched lattices of RuO x with rutile-TiO 2 ; annealing Ru/anatase-TiO 2 in air decreases CO 2 conversion and converts the product into CO owing to strong metal-support interaction (SMSI). Although rutile and anatase share the same chemical composition, we show that interfacial compatibility can basically modify metal-support coupling strength, catalyst morphology, surface atomic configuration, MSI mode, and catalytic performances of Ru/TiO 2 in heterogeneous catalysis.

Hydrodeoxygenation of lignin-derived phenolic compounds over Ru/TiO2 catalyst: Effect of TiO2 morphology

Zhuojie Zhong,Junxuan Li,Minyin Jian,Riyang Shu,Zhipeng Tian,Chao Wang,Ying Chen,Ning Shi,Yanxue Wu

Hydrodeoxygenation (HDO) reaction is a necessary refinery process for lignin-derived phenolic compounds to be used as high quality liquid fuels. Catalyst morphology makes a big difference on the HDO performance through changing the properties of metal site and acid site, while the catalytic mechanism is still not very clear. In this work, four kinds of Ru/TiO 2 catalysts with different morphology were prepared by photochemical method and all of them achieved a high Ru metal dispersion. A series of catalyst characterizations were carried out, including XRD, BET, SEM, TEM, H 2 -TPD and NH 3 -TPD, in order to explore the crystal structure, surface property, Ru metal dispersion, hydrogen adsorption capacity as well as acid properties. Results showed that Ru/TNP catalyst possessed a large surface area, an abundance of medium strength acid sites and a good hydrogen adsorption capacity. The HDO performances on lignin-derived phenolic compounds were also compared, in which Ru/TNP catalyst presented the best HDO performance. The guaiacol conversion and the selectivity of cyclohexane product were both close to 100 % at 250 °C under 1 MPa hydrogen pressure. Moreover, the content of hydrocarbons increased from 11.1 % to 60.8 % in the lignin-oil upgrading process.

Conversion of glucose to levulinic acid and upgradation to γ-valerolactone on Ru/TiO2 catalysts

Yubo Liu,Guoqiang Ding,Guoping Zhao,Haohao She,Yulei Zhu,Yong Yang

Combining glucose dehydration and the subsequent hydrogenation in one pot is a preferable approach for process development as such a method allows in situ generation of the reactive intermediate to undergo further reaction without extra energy-intensive separation. Herein, phosphotungstic acid and various types of titania (anatase, rutile, P25) supported Ru-based catalysts were considered as the dehydration and hydrogenation catalysts, respectively. Modulating the different reactant media (N2, H2), various products were obtained with GBL–H2O as the solvent. A considerable yield (42%) of levulinic acid (LA) and γ-valerolactone (GVL) (40%) were obtained in nitrogen and subsequent hydrogen. Ru/TiO2 (rutile) was the favorable hydrogenation catalyst among the three types of Ru/TiO2. Meanwhile, a certain amount of sorbitol (36%) was obtained in pure hydrogen. The hydrogenation of glucose is more likely to occur than the glucose dehydration. The physicochemical properties of the catalysts were characterized by XRD, BET, TPR, STEM and in situ CO/FT-IR, and the results show that well-dispersed Ru particles are located on the rutile crystallites, which facilitated the hydrogenation of LA. A strong metal support interaction (SMSI) was responsible for the various microstructure properties and the different hydrogenation reactivity. This work allows a better understanding of the reaction paths of glucose conversion.

Solvent-Free Hydrogenation of α-Pinene to cis-Pinane by Using Ru/TiO2 Nanocomposite with Strong Acid Sites

Yin Hu,Chen Wei,Ba Mingwei,Xie Xin,Song Weiguo

Abstract Ru/TiO 2 nanocomposite was prepared via loading the active ruthenium species on anatase TiO 2 by a simple hydrothermal approach combined with a sol–gel method. The optimal catalyst with 5.0% of Ru species showed excellent catalytic performance in the solvent-free selective hydrogenation of α-pinene with the conversion of α-pinene and selectivity to cis -pinane of 100.0 and 97.1%, respectively. It has been verified that the superior performance depends on the large amounts of acidic sites induced by HF acid and the SMSI effect between the reducible TiO 2 support and Ru species on its surface. The partial loss of its activity after five hydrogenation cycles should be due to the agglomeration of the catalyst particles and the carbon deposition on the surface. The possible hydrogenation mechanism was also discussed. This work provides an effective approach to develop a highly efficient and recyclable catalyst for the solvent-free selective hydrogenation of α-pinene.

Photo-assisted thermal catalytic CO2 reduction over Ru-TiO2 catalysts

Haodong Zhang,Min Chen,Weiming Qian,Jianghao Zhang,Xueyan Chen,Jinhou Fang,Chi Wang,Changbin Zhang

Photothermal catalysis is a promising technology to convert CO 2 into high value-added products. Here, we show that loading Ru NPs on TiO 2 achieved a remarkable photothermal synergistic effect and the Ru-TiO 2 demonstrated a high efficiency for the photothermal conversion of low CO 2 concentration to CH 4 at the gas-solid interface. The photothermal activity of the Ru-TiO 2 (217.9 µmol/(g·h)) was nearly 6 times higher than pure thermal activity (38.08 µmol/(g·h)), and nearly 20 times than the photocatalytic activity (10.9 µmol/(g·h)). We revealed that the light excitation could drive the generated electrons from TiO 2 to Ru particles, beneficial to CO 2 reduction, while external heating showed no influence on the charge separation of the Ru-TiO 2 . Hence, the photothermal synergy is not a heat-assisted photocatalytic process, but a photo-assisted thermal catalytic process. We finally demonstrated that the CO 2 was firstly converted to CO, and the CO was further hydrogenated to CH 4 . The introduction of light could promote the activation of intermediate CO species at the Ru-Ti interface sites, thus greatly accelerating CO hydrogenation to CH 4 . This work contributes to further understanding of the mechanism of photothermal catalytic CO 2 reduction.

Regulation of Strong Metal-Support Interaction by Alkaline Earth Metal Salts

Guanghao Qiu,Qijun Pei,Yang Yu,Zijun Jing,Jintao Wang,Teng He,Ping Chen

Graphical A strategy for regulating strong metal-support interaction (SMSI) was proposed. The alkaline earth metal salts were doped into a Ru/TiO 2 catalyst, which successfully prevented the migration of TiO 2-x overlayer to Ru nanoparticles via in situ formation of titanates, while the electrons transfer from support to metal nanoparticles was strengthened. The alkaline earth metal salts-doped Ru/TiO 2 catalysts exhibited superior activity in the catalytic hydrogenation of aromatics. Classical strong metal-support interaction (SMSI) is of significant importance to heterogeneous catalysis, where electronic promotion and encapsulation of noble metal by reducible support are two main intrinsic properties of SMSI. However, the excessive encapsulation will inevitably hamper the contact between active sites and reactant, leading to reduced activity in catalysis. Herein, alkaline earth metal salts are employed to depress the encapsulation of Ru nanoparticles in Ru/TiO 2 catalyst in the present study. Thermodynamic calculation, transmission electron microscopy (TEM) and chemisorption results show that the alkaline earth metal salts could successfully prevent the migration of TiO 2-x overlayer to Ru nanoparticles in Ru/TiO 2 catalyst via in situ formation of titanates, resulting in high exposure of active metal. Meanwhile, X-ray photoelectron spectroscopy (XPS) and hydrogen temperature-programmed reduction (H 2 -TPR) results reveal that an even stronger electron donation from the reduced support to Ru nanoparticles is achieved. As a result, the alkaline earth metal salts-doped Ru/TiO 2 catalysts exhibit superior activity in catalytic hydrogenation of aromatics, which is in contrast to the pristine Ru/TiO 2 catalyst that shows negligible activity under the same conditions due to the excess encapsulation of Ru nanoparticles in Ru/TiO 2 catalyst.

Secondary hydrogen spillover enhanced photocatalytic hydrogen evolution activity in Ru/TiO2–GO

Yanfang Nie,Ye Tian,Ni Wang,Yunfan He,Yawen Wang,Yunfang Wang,Rui Li,Lulu Zhang,Jianxin Liu

An effective strategy for enhancing photocatalytic hydrogen evolution reaction (HER) activity is the implementation of the hydrogen spillover effect. Herein, a Ru/TiO2–GO (graphene oxide) catalyst was fabricated by means of simple hydrothermal and ultrasound-assisted techniques. By using the secondary hydrogen spillover process, which involves the transfer of active hydrogen species from Ru to TiO2 and then further to GO, the hydrogen evolution activity of Ru/TiO2–2GO reached 23.9 mmol g−1 h−1, which is 45.2 times and 3.85 times greater than that of TiO2 (0.53 mmol g−1 h−1) and Ru/TiO2 (6.2 mmol g−1 h−1), respectively. Controlled experiments and detailed characterization have revealed that the dispersion of GO on the support provides critical desorption sites for H*, thereby promoting the cleavage of Ti–H bonds. H* undergoes secondary spillover onto GO and desorbs to generate H2, enhancing the photocatalytic HER activity. This study enhances the photocatalytic activity of water splitting for hydrogen production by employing a secondary hydrogen spillover strategy, thereby presenting a novel approach for the design of efficient hydrogen production catalysts.

Switching of CO2 hydrogenation selectivity via chlorine poisoning over Ru/TiO2 catalyst

Zhang Jin,Gao Mengting,Wang Ruiyi,Li Xincheng,Huang Tianfen,Wang Jing,Wang Yunwei,Zheng Zhanfeng

It is fascinating to explore the distribution of CO 2 hydrogenation products regulated by heterogeneous catalysts, as both the chemical state of surface metals and structure of the support itself of the supported catalysts may affect the performance of CO 2 hydrogenation. Herein, the complete switching of CO 2 hydrogenation products from CH 4 to CO can be realized by induction of Cl into Ru/TiO 2 catalyst. Density functional theory (DFT) calculations indicated that Cl ions were mainly located on the Ru metal sites of Ru/TiO 2 catalysts. Bader charge analysis and Ru 3p X-ray photoelectron spectra (XPS) results suggested that electrons transferred from Ru to Cl, resulting in the decrease of electron density of Ru. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) of CO 2 hydrogenation and CO adsorption proved that with the increase of the Cl ion content, the adsorption of CO on the catalyst surface was significantly weakened, and resulted in the high CO selectivity. Our work demonstrates the role of Cl ions in regulating the distribution of CO 2 hydrogenation products, and provides new ideas for regulating other catalytic processes.

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

Ru/TiO2-photocatalysed synthesis of γ-butyrolactone from a furfural derivative under mild conditions

Yang Peng,Haikuan Yang,Ting Zhang,Songsong Zhou,Haiwei Jiang,Yongjie Zheng,Weiran Yang

Synthesis of γ -butyrolactone (GBL) from renewable biomass resources under mild reaction condition with catalysis is attractive but challenging. Herein, we report the photocatalytic oxidation of the biomass-based furfural derivative tetrahydrofurfuryl alcohol (THFAL) to prepare GBL under light irradiation (365 nm) in air at room temperature. Utilising Ru/TiO 2 as the photocatalyst and air as the oxidant, a GBL yield as high as 73 % was achieved. The reaction mechanism was studied rigorously by performing photocatalyst performance evaluation, material characterisation, free-radical quenching reactions and electron spin resonance (ESR). In situ diffuse reflectance infrared Fourier transform spectroscopy was employed to detect intermediate products and elucidate the mechanism at the molecular level. Based on the in-situ monitoring results, we propose a pathway for the oxidation decarbonylation of THFAL to produce CO 2 and GBL.