Xn:Harmful;95-57-8Relevant articles and documents
Pd supported on boron-doped mesoporous carbon as highly active catalyst for liquid phase catalytic hydrodechlorination of 2,4-dichlorophenol
Zhou, Juan,Wu, Ke,Wang, Wenjuan,Xu, Zhaoyi,Wan, Haiqin,Zheng, Shourong
, p. 336 - 343 (2014)
Palladium catalysts supported on both ordered mesoporous carbon (CMK-3) and boron-doped mesoporous carbon (B-CMK-3) were synthesized via the complexing-reduction method. These catalysts were characterized using X-ray diffraction, N2 adsorption-desorption, transmission electron microscopy, and X-ray photoelectron spectroscopy, and their catalytic performance was examined for the liquid phase catalytic hydrodechlorination (HDC) of 2,4-dichlorophenol. Characterization results showed that for B-CMK-3 boron was introduced into the framework of the mesoporous carbon. Pd supported on B-CMK-3 had a smaller average Pd particle size and higher Pd 2+/Pd0 ratio than that on CMK-3, although B-CMK-3 had slightly lower surface area and pore volume than CMK-3. For Pd/B-CMK-3, increasing Pd loading led to an increase in Pd particle size and a decrease in Pd2+/Pd0 ratio. The liquid phase catalytic HDC of 2,4-dichlorophenol over Pd/B-CMK-3 followed the Langmuir-Hinshelwood model, and the catalytic reaction proceeded in both stepwise and concerted pathways. The initial reaction rates of Pd(2.7)/B-CMK-3 and Pd(2.6)/CMK-3 were 0.608 and 0.207 M gCat-1 h-1, respectively, reflecting a much higher catalytic activity of Pd/B-CMK-3 than that of Pd/CMK-3. For Pd/B-CMK-3, increasing Pd loading from 1.6 to 2.7 wt.% led to an increase in the initial rate from 0.260 to 0.608 M gCat-1 h-1, but further increase of the loading to 3.9 wt.% resulted in a slight decrease in the catalytic activity.
Enhanced catalytic hydrodechlorination of 2,4-dichlorophenol over Pd catalysts supported on nitrogen-doped graphene
Zhou, Juan,Chen, Quanyuan,Han, Yuxiang,Zheng, Shourong
, p. 91363 - 91371 (2015)
Pd catalysts supported on graphene and N-doped graphene (GN-1, GN-2 and GN-3) with varied N-doping amounts were prepared using the deposition-precipitation method, and liquid phase catalytic hydrodechlorination (HDC) of 2,4-dichlorophenol (2,4-DCP) was investigated over these catalysts. The catalysts were characterized by X-ray diffraction, elementary analysis, N2 adsorption-desorption isotherms, transmission electron microscopy, and X-ray photoelectron spectroscopy. Characterization results showed that graphene could be successfully doped by N using the heat treatment method with melamine as precursor, and N doping amounts were determined to be 5.7, 8.6 and 11.3% for GN-1, GN-2 and GN-3, respectively. Additionally, Pd2+/Pd0 ratios and Pd dispersions in the Pd/GN catalysts were much higher than those in Pd/graphene. For a similar Pd loading, the Pd dispersion of Pd/GN first increased and then decreased with the increase of N-doping amount, and the highest Pd dispersion was observed on Pd(2.9)/GN-2. Accordingly, GN supported Pd catalysts exhibited much higher catalytic activities than Pd/graphene, the catalytic reaction first increased and then decreased slightly in activity with the increase of nitrogen doping amount, and the highest activity was identified on Pd(2.9)/GN-2. Moreover, the dechlorination of 2,4-DCP over supported Pd catalysts proceeded via both a stepwise and concerted pathway, and the concerted pathway became predominant upon N doping.
Imidazolium-urea low transition temperature mixtures for the UHP-promoted oxidation of boron compounds
Martos, Mario,Pastor, Isidro M.
, (2022/01/03)
Different carboxy-functionalized imidazolium salts have been considered as components of low transition temperature mixtures (LTTMs) in combination with urea. Among them, a novel LTTM based on 1-(methoxycarbonyl)methyl-3-methylimidazolium chloride and urea has been prepared and characterized by differential scanning calorimetry throughout its entire composition range. This LTTM has been employed for the oxidation of boron reagents using urea-hydrogen peroxide adduct (UHP) as the oxidizer, thus avoiding the use of aqueous H2O2, which is dangerous to handle. This metal-free protocol affords the corresponding alcohols in good to quantitative yields in up to 5 mmol scale without the need of further purification. The broad composition range of the LTTM allows for the reaction to be carried out up to three consecutive times with a single imidazolium salt loading offering remarkable sustainability with an E-factor of 7.9, which can be reduced to 3.2 by the threefold reuse of the system.
A mild desilylation of phenolic tert-butyldimethylsilyl ethers using in situ generated tetraethylammonium superoxide
Pandey, Surabhi,Shukla, Ajay K.,Raghuvanshi, Raghvendra S.
, p. 809 - 811 (2021/07/16)
Desilylation of phenolic tert-butyldimethylsilyl ethers has been achieved under the mild reaction conditions of in situ generated tetraethylammonium superoxide, at room temperature. (Figure presented.).
