Oxidation of soot takes place inside and on the surface of its constituent primary particles at a rate that depends on temperature, T, and O2 concentration. Even though accurate oxidation kinetics ...are essential in both industrial uses and environmental impact of soot, they are often derived neglecting internal particle oxidation and the structure of such soot agglomerates. Here, the detailed evolution of the fractal-like agglomerate soot mass, m, and mobility diameter, dm, during both internal and surface oxidation is determined by a moving sectional model. The model predictions are in excellent agreement with oxidation data of mature ethylene soot dm for T = 900–1200 K. The oxidation mode index, a, given by the ratio of the characteristic O2 reaction and diffusion times is used to quantify the contributions of internal and surface oxidation of soot. At low Τ (e.g., < 1100 K), O2 diffuses into the primary particles and reacts with bulk soot, hardly altering the dm and yielding a > 3. As T increases, surface oxidation becomes dominant, decreasing both dm and a. The common assumption that soot agglomerates are spheres underestimates their dm up to 50 % during oxidation. Coupling this detailed moving sectional model with soot mobility size distributions can yield realistic soot oxidation rates. Accounting for soot morphology and internal oxidation shows that the classic NSC rate increasingly underestimates (by 3–7 times) the oxidation rate of soot (from ethylene and toluene flames) with decreasing temperature (900–1800 K) and/or oxygen concentration (0.2–21 vol %).
The front cover artwork for Issue 04/2016 is provided by the Korea Institute of Machinery and Materials and Chosun University. The image shows a novel reaction pathway for the reduction of metal ...oxide under electric discharge conditions where activated intermediate species desorb without further surface reaction and react with gas‐phase radicals. See the Communication itself at http://dx.doi.org/10.1002/cctc.201500865.
“The secret of faster and safer reduction lies in the generation of energetic gas‐phase radicals” This and more about the story behind the research featured on the front cover can be found in this issue's Cover Profile. Read the full text of the corresponding research at http://dx.doi.org/10.1002/cctc.201500865.
A domino palladium-catalyzed recombinant gamma-isomerization and reverse Wacker oxidation of gamma-vinyl-gamma-butyrolactone has been explored. The strategy has been used in the stereoselective ...synthesis of (+)-trans-, (-)- and (+)-disparlures. The synthesis was achieved in seven to eight steps from D-glucono-delta-lactone with overall yields of 19.3, 20.7 and 22.6%, respectively.
A de novo tandem benzylic oxidative dihydroxylation of alpha-vinyl- and alpha-alkenylbenzyl alcohols has been developed to give alpha,beta-dihydroxypropiophenones ...(=2,3-dihydroxy-1-phenylpropan-1-ones) and alpha,beta-dihydroxyalkyl phenones. This method was shown to be substrate-selective and specific for the oxidation of benzylic alcohols.
Display omitted
•Cu(Ⅱ) stearate evokes both homo- and heterogenous catalytic oxidation of heavy oil.•In-situ formed CuO nanoparticles improves the formation rate and quality of fuel.•Cu(Ⅱ) stearate ...changes dependence of Eα vs α (lower values, far less fluctuation)•Energy barrier is significantly reduced and reactions continuity is enhanced.•Cu(Ⅱ) stearate has a great potential in improving the efficiency of ISC.
In this study, copper (Ⅱ) stearate was proposed as oil-soluble catalysts for catalyzing heavy oil oxidation in in-situ combustion (ISC) process to improve the efficiency of ISC for heavy oil recovery. Its catalytic mechanism and kinetics were deeply investigated by joint use of TG-FTIR, autoclave experiments, FESEM-EDX, and XPS, etc., together with isoconversional kinetic methods. We find that the addition of copper (Ⅱ) stearate initiated both efficient homogenous and heterogenous catalytic oxidation/combustion process of heavy oil. In low-temperature range, copper (Ⅱ) stearate (before its full decomposition) played a homogenous catalytic role in low temperature oxidation (LTO), and in high-temperature range, in-situ formed CuO nanoparticles (after the full decomposition of copper (Ⅱ) stearate) played a heterogenous catalytic role in the formation and combustion process of fuel (coke-like residues) in fuel deposition (FD) and high temperature oxidation (HTO) stages. Specifically, the addition of copper (Ⅱ) stearate significantly reduced the values of Eα of all reaction stages (LTO, FD, and HTO), especially at the later stage of LTO, FD and the beginning of HTO (the maximum values of Eα were decreased from about 500–600 KJ/mol to 300–400 KJ/mol), decreased the energy required to overcome reaction barriers, and improved the formation rate and quality of coke-like residues, which thus promotes the formation of coke-like residues and their combustion a more continuous process. Such a superior catalytic effect makes copper (Ⅱ) stearate have a great potential in improving efficiency of ISC process for heavy oil recovery.
alpha-Hydrogen-substituted nitroxyl radicals are of considerable interest as catalysts for oxidation and polymerization, but are usually inherently unstable. We report herein the catalytic activity ...of a new family of stable iso-azaphenalene (IAPNO) alpha-hydrogen nitroxyl radicals in the copper/bipyridine/N-methylimidazole co-catalyzed aerobic oxidation of alcohols. The nitroxyl radical Mes/TIPSO-IAPNO (TIPSO=triisopropyloxy, IAPNO=isoazaphenalene N-oxyl) displays higher activity than TEMPO in the oxidation of benzylic and allylic alcohols. Alkyl, benzyl, allyl, and propargyl alcohols are oxidized with yields up to 96%. The readily prepared nitroxyl catalysts are recovered in 75-90% yield after purification of the reaction mixture and are recycled.
•Summary of the performance and mechanism of different NO oxidation modes.•Current situation and prospect of different NO oxidation modes in industry.•Deep oxidation of NO, improvement of oxidant ...utilization and expansion of reaction temperature range are the research emphases.•The influence of complex flue gas components is the focus of future research.•Sulfur resistance and water resistanceof catalysts are still the thorny problems.
Due to the increasingly strict emission standards of NOx on various industries, many traditional flue gas treatment methods have been gradually improved. Except for selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR) methods to remove NOx from flue gas, theoxidation method is paying more attention to NOx removal now because of the potential to simultaneously remove multiple pollutants from flue gas. This paper summarizes the efficiency, reaction conditions, effect factors, and reaction mechanism of NO oxidation from the aspects of liquid-phase oxidation, gas-phase oxidation, plasma technology, and catalytic oxidation. The effects of free radicals and active components of catalysts on NO oxidation and the combination of various oxidation methods are discussed in detail. The advantages and disadvantages of different oxidation methods are summarized, and the suggestions for future research on NO oxidation are put forward at the end. The review on the NO removal by oxidation methods can provide new ideas for future studies on the NO removal from flue gas.
Graphical abstract
Display omitted
Despite the large number of disparate approaches for the direct selective partial oxidation of methane, none of them has translated into an industrial process. The oxidation of methane to methanol is ...a difficult, but intriguing and rewarding, task as it has the potential to eliminate the prevalent natural gas flaring by providing novel routes to its valorization. This Review considers the synthesis of methanol and methanol derivatives from methane by homogeneous and heterogeneous pathways. By establishing the severe limitations related to the direct catalytic synthesis of methanol from methane, we highlight the vastly superior performance of systems which produce methanol derivatives or incorporate specific measures, such as the use of multicomponent catalysts to stabilize methanol. We thereby identify methanol protection as being indispensable for future research on homogeneous and heterogeneous catalysis.
Being selective: The selective oxidation of methane to methanol in high yield is currently elusive, but when accomplished it could redefine the petrochemical industry. This Review illustrates the homogeneous and heterogeneous catalytic routes for this process and discerns the most promising approaches with the potential to conquer the challenge.
Single-atom catalysts (SACs) have emerged as efficient materials in the elimination of aqueous organic contaminants; however, the origin of high activity of SACs still remains elusive. Herein, we ...identify an 8.1-fold catalytic specific activity (reaction rate constant normalized to catalyst’s specific surface area and dosage) enhancement that can be fulfilled with a single-atom iron catalyst (SA-Fe-NC) prepared via a cascade anchoring method compared to the iron nanoparticle-loaded catalyst, resulting in one of the most active currently known catalysts in peroxymonosulfate (PMS) conversion for organic pollutant oxidation. Experimental data and theoretical results unraveled that the high-activity origin of the SA-Fe-NC stems from the Fe–pyridinic N4 moiety, which dramatically increases active sites by not only creating the electron-rich Fe single atom as the catalytic site but also producing electron-poor carbon atoms neighboring pyridinic N as binding sites for PMS activation including synchronous PMS reduction and oxidation together with dissolved oxygen reduction. Moreover, the SA-Fe-NC exhibits excellent stability and applicability to realistic industrial wastewater remediation. This work offers a novel yet reasonable interpretation for why a small amount of iron in the SA-Fe-NC can deliver extremely superior specific activity in PMS activation and develops a promising catalytic oxidation system toward actual environmental cleanup.
![Domino Recombinant [gamma]-...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/1434-193X/small "Domino Recombinant [gamma]-Isomerization and Reverse Wacker Oxidation of [gamma]-Vinyl-[gamma]-butyrolactone: Synthesis of (+)-trans-, (-)- and (+)-Disparlures")
