Heteroatom Bridging Strategy in Carbon-Based Catalysts for Enhanced Oxidative Desulfurization Performance

Author(s):  
Peiwen Wu ◽  
Yang Sun ◽  
Linlin Chen ◽  
Qingdong Jia ◽  
Jing He ◽  
...  
Catalysts ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1239
Author(s):  
Fernanda F. Roman ◽  
Jose L. Díaz de Tuesta ◽  
Adrián M. T. Silva ◽  
Joaquim L. Faria ◽  
Helder T. Gomes

Sulfur (S) and nitrogen (N) are elements naturally found in petroleum-based fuels. S- and N-based compounds in liquid fuels are associated with a series of health and environmental issues. Thus, legislation has become stricter worldwide regarding their content and related emissions. Traditional treatment systems (namely hydrodesulfurization and hydrodenitrogenation) fail to achieve the desired levels of S and N contents in fuels without compromising combustion parameters. Thus, oxidative treatments (oxidative desulfurization–ODS, and oxidative denitrogenation-ODN) are emerging as alternatives to producing ultra-low-sulfur and nitrogen fuels. This paper presents a thorough review of ODS and ODN processes applying carbon-based materials, either in hybrid forms or as catalysts on their own. Focus is brought to the role of the carbonaceous structure in oxidative treatments. Furthermore, a special section related to the use of amphiphilic carbon-based catalysts, which have some advantages related to a closer interaction with the oily and aqueous phases, is discussed.


Author(s):  
B. K. Kirchoff ◽  
L.F. Allard ◽  
W.C. Bigelow

In attempting to use the SEM to investigate the transition from the vegetative to the floral state in oat (Avena sativa L.) it was discovered that the procedures of fixation and critical point drying (CPD), and fresh tissue examination of the specimens gave unsatisfactory results. In most cases, by using these techniques, cells of the tissue were collapsed or otherwise visibly distorted. Figure 1 shows the results of fixation with 4.5% formaldehyde-gluteraldehyde followed by CPD. Almost all cellular detail has been obscured by the resulting shrinkage distortions. The larger cracks seen on the left of the picture may be due to dissection damage, rather than CPD. The results of observation of fresh tissue are seen in Fig. 2. Although there is a substantial improvement over CPD, some cell collapse still occurs.Due to these difficulties, it was decided to experiment with cold stage techniques. The specimens to be observed were dissected out and attached to the sample stub using a carbon based conductive paint in acetone.


2020 ◽  
Author(s):  
Idoia Hita ◽  
Tomas Cordero-Lanzac ◽  
Francisco J. Garcia-Mateos ◽  
Jose Rodriguez-Mirasol ◽  
Tomas Cordero ◽  
...  

2020 ◽  
Author(s):  
Idoia Hita ◽  
Tomas Cordero-Lanzac ◽  
Francisco J. Garcia-Mateos ◽  
Jose Rodriguez-Mirasol ◽  
Tomas Cordero ◽  
...  

2019 ◽  
Author(s):  
Zhen Liu ◽  
Xiaohan Li ◽  
Tian Zeng ◽  
Keary Engle

A substrate-directed enantioselective <i>anti</i>-carboboration reaction of alkenes has been developed, wherein a carbon based nucleophile and a boron moiety are installed across the C=C bond through a 5- or 6-membered palladacycle intermediate. The reaction is promoted by a palladium(II) catalyst and a mondentate oxzazoline ligand. A range of enantioenriched secondary alkylboronate products were obtained with moderate to high enantioselectivity that could be further upgraded by recrystallization. This work represents a new method to synthesize versatile and valuable alkylboronate building blocks. Building on an earlier mechanistic proposal by Peng, He, and Chen, a revised model is proposed to account for the stereoconvergent nature of this transformation.


Sign in / Sign up

Export Citation Format

Share Document