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Friday, July 22, 2011
More π Please … A Few Recent π-complexation Articles
“No, this trick won't work...How on earth are you ever going to explain in terms of chemistry and physics so important a biological phenomenon as first love?” -- Albert Einstein (German born American Physicist, Nobel Prize for Physics in 1921. 1879-1955)
Here are a few recent π-complexation articles, courtesy of my Google π-complexation alert.You might want to make a note of the fact that they all emanate from China … looks like they’re doing some pretty interesting research.
The China organizations represented are …
·Key Laboratory of Fine Petrochemical Engineering, Changzhou University (http://eng.jpu.edu.cn/), Changzhou 213164, Jiangsu, China
·School of Chemistry and Chemical Engineering, Nantong University (http://english.ntu.edu.cn/), Nantong 226019, Jiangsu, China
·State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemistry and Chemical Engineering, Nanjing University of Technology (http://www.njut.edu.cn/), Nanjing 210009, China
·The State Key Laboratory of Chemical Engineering, East China University of Science and Technology (http://www.ecust.edu.cn/s/2/t/31/main.htm), Shanghai 200237, People’s Republic of China
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Adjusting Host Properties to Promote Cuprous Chloride Dispersion and Adsorptive Desulfurization Sites Formation on SBA-15
Gu-Se He , Lin-Bing Sun , Xue-Lin Song , Xiao-Qin Liu , Yu Yin , and Yu-Chao Wang
Energy Fuels, Just Accepted Manuscript
Publication Date (Web): July 6, 2011
Abstract
Deep desulfurization via -complexation adsorption is a promising method for the purification of transportation fuels. The desulfurization performance of an adsorbent has been proven to strongly depend on the dispersion extent of adsorption active species. In this paper, we reported a strategy to promote the dispersion of active species CuCl on mesoporous silica SBA-15 by incorporating alumina. By use of such a strategy, properties of the host SBA-15 were successfully adjusted. The enhancement of host-guest interaction and the improvement of surface hydrophilicity were realized simultaneously. Furthermore, the solid state ion exchange between CuCl and formed Brönsted acid sites (H+) was observed, which leads to the generation of isolated cuprous species. As a result, the dispersion of guest CuCl on the host was efficiently promoted. We also demonstrated that the obtained material, CuCl supported on SBA-15 incorporated with 10 wt% of alumina, can capture 0.240 mmol∙g−1 thiophene, which is obviously higher than that over CuCl/SBA-15 (0.167 mmol∙g−1). Our materials may provide potential candidate for application in adsorptive desulfurization.
Isolated Cu(I) sites supported on β-cyclodextrin: an efficient π-complexation adsorbent for thiophene capture
Xue-Lin Song, Lin-Bing Sun, Gu-Se He and Xiao-Qin Liu
Chem. Commun., 2011, 47, 650-652
A novel π-complexation adsorbent is fabricated by grafting Cu(I)-containing molecule precursors onto β-cyclodextrin. The adsorbent provides a molecular-level dispersion of Cu(I), which is particularly beneficial to the adsorptive removal of aromatic sulfur thiophene, and is impossible to be realized through the conventional thermal method.
Adsorptive Desulfurization by Copper Species within Confined Space
Wen-Hang Tian, Lin-Bing Sun, Xue-Lin Song, Xiao-Qin Liu*, Yu Yin, and Gu-Se He
State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemistry and Chemical Engineering, Nanjing University of Technology, Nanjing 210009, China
Copper species were incorporated into SBA-15 by solid-state grinding precursor with as-prepared mesoporous silica (SPA). The obtained materials (CuAS) were well-characterized by XRD, TEM, N2 adsorption, H2-TPR, IR, and TG and compared with the material derived from calcined SBA-15 (CuCS). Surprisingly, CuO up to 6.7 mmol·g−1 can be highly dispersed on SBA-15 by use of SPA strategy. Such CuO forms a smooth layer coated on the internal walls of SBA-15, which contributes to the spatial order and results in less-blocked mesopores. However, the aggregation of CuO takes place in CuCS material containing 6.7 mmol·g−1 copper, which generates large CuO particles of 21.4 nm outside the mesopores. We reveal that the high dispersion extent of CuO is ascribed to the abundant silanols, as well as the confined space between template and silica walls provided by as-prepared SBA-15. The SPA strategy allows template removal and precursor conversion in one step, avoids the repeated calcination in conventional modification process, and saves time and energy. We also demonstrate that the CuAS material after autoreduction exhibits much better adsorptive desulfurization capacity than CuCS. Moreover, the adsorption capacity of regenerated adsorbent can be recovered completely.
This work mainly involved the investigation of the adsorption of thiophene on Pt/Ag-supported activated carbons (ACs) prepared by ultrasonic-assisted impregnation (UI). The adsorption capacity of thiophene over the ACs studied followed the order of Pt/Ag/AC-UI > Ag/AC-UI > Ag/AC > AC > Pt/AC. Pt ions can promote the reaction between the soft acid Ag(I) and the soft base thiophene. These sorbents were characterized by X-ray diffraction (XRD), sorption of nitrogen (BET), and thermal analysis.
Highly Active and Selective Nickel-Platinum Catalyst for the Low Temperature Hydrogenation of Maleic Anhydride to Succinic Anhydride and Synthesis of Succinic Acid at 40 °C
Source: Catalysis Letters, Volume 141, Number 4, April 2011 , pp. 565-571(7)
Abstract:
PtNi bimetallic and Ni monometallic catalysts supported on HY-Al2O3, HX-Al2O3, ZSM-5-Al2O3, USY-Al2O3, Beta-Al2O3 and Al2O3 were prepared and evaluated for the hydrogenation of maleic anhydride in the temperature range of 40-150 °C. Results from flow reactor studies showed that supports strongly affected the catalytic properties of different bimetallic and monometallic catalysts. The results showed that the HY-Al2O3 support exhibited the highest activity and selectivity. Using NiPt/Al2O3-HY catalyst and performing the reaction, it was possible to carry out the lowest reaction temperature ever carried at 100% conversion. Adding a small amount of Pt (0.5) to the Ni (5%)/Al2O3-HY catalyst that is effective for increasing the selectivity and activity. We also found that PtNi is an efficient catalyst for the one-pot conversion of maleic acid into succinic acid with 100% conversion at 40 °C.
Hydrogenation activity was found to correlate to the extent of PtNi bimetallic bond formation, as characterized by the analysis of XRD and TPR.
Affiliations: 1: The State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai, 200237, China 2: The State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai, 200237, China,
A series of Cu-containing mesoporous MCM-48 molecular sieves (Cu-MCM-48) were prepared by the direct synthesis method and used as the adsorbents for desulfurization of model fuel. The samples were characterized by X-ray power diffraction, N2 adsorption–desorption isotherms, Brunauer–Emmett–Teller specific surface area, transmission electron microscopy, inductively coupled plasma atomic emission spectrometry, and X-ray photoelectron spectroscopy. The results show that the Cu-MCM-48 adsorbent with a copper content up to 10 wt % can still retain the uniform mesoporous framework of MCM-48. The proposed direct synthesis method gives better Cu dispersion and a higher content of active component Cu+ in the support than the conventional incipient impregnation method. As a result, the desulfurization performance of these adsorbents is enhanced. The adsorption behaviors of thiophene on these molecular sieves were measured at 20 °C, and their adsorption capacities follow the order 10Cu-MCM-48 > 5Cu-MCM-48 > 10Cu/MCM-48 (synthesized by the incipient impregnation method) > 20Cu-MCM-48. The adsorption isotherms for thiophene fit the Langmuir model well.
Adsorbents based on metal ion-exchanged Y zeolites (with single Cu and Ce or the combined Cu−Ce) were prepared. Then, the adsorptive desulfurization properties of the adsorbents were studied by a batch method at ambient conditions through model fuels, which were the iso-octane solution of sulfur compounds, and, in some cases, with a small quantity of toluene. The results show that CuCeY not only has the high sulfur adsorption capacity similar to CuIY but also has the high selectivity for sulfur compounds similar to CeIVY. Inductively coupled plasma−atomic emission spectrometer (ICP−AES) and X-ray photoelectron spectroscopy (XPS) studies indicate that Ce can not only use the surface of zeolite effectively and disperse at the geometric position, which is unfavorable to Cu, but also accelerate the conversion of Cu2+ to Cu+ and enhance the concentration of Cu+ on the surface of the adsorbent. Therefore, CuCeY exhibits an excellent sulfur adsorption performance. The saturated CuCeY can be regenerated with a solvent consisting of 30 wt % toluene and 70 wt % iso-octane. In addition, about 90% of the sulfur adsorption capacity is recovered after regeneration.
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