Olefins In Presence Research Articles

Investigation of bionano additives in red algae Cyanidioschyzon merolae ultrasonified MgO/MWCNT catalyzed biodiesel in optimized engine performance

Renewable energy research is burgeoning with the anticipation of finding neat liquid fuel. Ultra sonification assisted biodiesel was derived from red algae Cyanidioschyzon merolae, with biodiesel yield of 98.9%. The results of GC MS of the prepared biodiesel showed higher concentration of methyl palmitate, methyl oleate, and stearate. This composition is appreciable, as this plays significance in desirable pour & cloud point properties. NMR spectrum revealed the ester linkages, presence of olefins, and α methyl position in olefins. Mixture of 30 wt% of biodiesel in diesel exhibited work efficiency, and also exhibited low pour point and, lower viscosity values. CeO2 and Fe2O3 nano particles were bio reduced, and were added as nano additive in biodiesel. 1:1 ratio of CeO2 and Fe2O3 added to biodiesel maximised the combustion ability of fuel owing to the oxygen storage capacity of CeO2. Further, this combination produced a satisfactory calorific value. Imbalanced ratios disrupted the catalytic and oxygen storage effects, reduced the overall energy release and calorific value of the biodiesel blend. Pour point and cetane number value of biodiesel blend ultrasonifacted with 1:1 mass ratio of Fe2O3 and CeO2 was observed to be around −7 °C and 53 °C respectively, and was better than other compositions. 1:1 mass ratio of NPS blended with 30 wt% BD in diesel showed tremendous increase in brake thermal efficiency, torque, and power. HC, NOX, and SOX emissions were reduced by 42.8%, 19.3%, and 57% respectively with 1:1 Fe2O3 and CeO2 mixed biodiesel blend. CeO2 favourably improved the oxygen storage capacity of the fuel, whereas Fe2O3 showed decrease in formation of gums and sediments in biodiesel.

Chromatographic Analysis of the Chemical Composition of Exhaust Gas Samples from Urban Two-Wheeled Vehicles

The subject of the article was the chemical analysis of gasoline and exhaust gas samples taken from an urban two-wheeled vehicle. The main aim of the work was to identify chemical compounds emitted by a group of urban two-wheeled vehicles depending on the engine’s operating parameters. First, engine operating parameters and driving parameters of three urban two-wheeled vehicles were measured in real operating conditions. Based on the averaged results, engine operating points were determined for exhaust gas samples that were collected into Tedlar bags. The exhaust gas composition of individual chemical substances obtained in the chromatographic separation process were subjected to a detailed analysis relating the engine operating point with their emission rate, with each individual component being assessed in terms of its impact on human health. The obtained qualitative analysis results indicated the presence of alkenes, alkanes, aliphatic aldehydes, and aromatic and cyclic hydrocarbons (cycloalkanes) in the tested samples. The experiments provided a variety of conclusions relating to the operating parameters of a two-wheeler engine. Qualitative assessment of exhaust samples showed that a two-wheeled vehicle was characterized by the most varying composition of BTX aromatic hydrocarbons derivatives, which are particularly dangerous to human health and life. Therefore, the authors suggest that in the future, approval procedures regarding toxic emissions should be extended to include chromatographic tests. The presented results are an extension of previous studies on toxic emissions from urban two-wheeled vehicles in real operating conditions that were published in other journals.

Selective Adsorptive Desulfurization with Alkaline-Earth Metal-Modified Zeolites in Oil in the Presence of Olefin

Selective Adsorptive Desulfurization with Alkaline-Earth Metal-Modified Zeolites in Oil in the Presence of Olefin

Ruthenium, rhodium and iridium complexes of a silyl-substituted N-heterocyclic carbene ligand and their catalytic performance in hydrosilylation of terminal alkynes

Herein, [Ru(NHC)(p-cymene)Cl2] (3) and [MCl(NHC)(cod)] (M=Rh (4) or Ir (5)) (cod=1,5‒cyclooctadiene) complexes of a silyl‒substituted N-heterocyclic carbene ligand (NHC) have been prepared by the transmetalation reaction between Ag‒NHC (2) and corresponding starting metal compound. The characterization of the complexes has been completed by NMR spectroscopy and elemental analyses. Solid state structures of Ag- (2) and Rh-NHC (4) have also been determined by single crystal X-ray analysis. [RhCl(NHC)(CO)2] type bis-carbonyl complex (6) has also been prepared and CO stretching frequencies pointed the strong σ‒donor ability of the silyl-substituted NHC. The catalytic activity of all complexes have been examined in hydrosilylation of terminal alkynes. Among the complexes, Ir-NHC has been found out as active catalyst with around 90% conversion and β‒(Z) selectivity at room temperature. Further studies revealed that this complex is able to maintain its stability in catalytic reaction conditions, chemoselective to alkynes in the presence of alkenes, and operable in scale-up reactions. In contrast, bis-carbonyl Rh-NHC performed 82% β‒(Z) selectivity with full conversion of alkyne in first 4 h of reaction, but when reaction time was extended to 24 h, almost all β‒(Z) vinylsilane isomerised to thermodynamically more stable β‒(E).

Highly Chemoselective Zn+2 -Catalyzed Hydrosilylation of Alkynes.

Hydrosilylation of C=C double and C≡C triple bonds is one of the most widely used processes in organosilicon chemistry, mostly catalyzed by Pt-based complexes. Herein, the synthesis of a dicationic Zn+2 -based complex with a tripodal tris(2-pyridylmethyl)amine (TPA) ligand is reported which was found to be a highly chemoselective catalyst for hydrosilylation reactions of alkynes. Mechanistic studies revealed that unlike typical Zn-catalyzed hydrosilylation reactions where the key step is the activation of the Si-H bond, this system catalyzes the hydrosilylation reaction through the activation of C≡C triple bonds, which presumably is the reason for its high chemoselectivity. Remarkably, the hydrosilylation of alkynes could be performed in the presence of alkenes and other functional groups that remained intact in this reaction.

Application of response surface methodology for the modelling and optimisation of bio-oil yield via intermediate pyrolysis process of sugarcane bagasse

ABSTRACT The search for renewable resources has grown globally as a result of the harmful effects of fossil fuel use on the environment, such as global warming and acid rain. Biomass fuels do not contribute to the accumulation of carbon dioxide in the atmosphere. This study utilised response surface methodology for the optimisation of pyrolysis process parameters (temperature, heating rate, reaction time, nitrogen flow rate, and particle size) at five levels of experimental runs to enhance bio-oil production from the intermediate pyrolysis of sugarcane bagasse. The bio-oil yield increased continuously with an increase in T (320–520°C) and H (7.5–12.5°C/min) due to complete pyrolysis, while a decrease in bio-oil was noticed at a T (520–720°C) and H (22.5–27.5°C/min) due to secondary cracking such as thermal cracking, repolymerisation and recondensation that might enhance the yield of NCG and biochar. The optimum bio-oil yield (46.7 wt%) was achieved at a temperature, reaction time, heating rate, nitrogen flow rate, and particle size of 493.7°C, 15.5 min, 24.5°C/min, 225 cm3/min, and 0.1 mm, respectively. Results showed that the predicted data closely correlated with the experimental data (p < 0.05, R2 = 0.9891). Hence, the model is suitable and can accurately predict the experimental data. The presence of alkene, alcohol, and ester makes the bio-oil applicable for energy generation to power heavy equipment, ships, compressor, and boilers. Likewise, the presence of by-products such as oleic acids, methyl ester, 9,17-octadecdienal, and 9,12-octadecadienoyl chloride makes it suitable as fuel for high-speed diesel engines, powering heavy machines, vehicle locomotion, marine equipment, mining types of machinery, and manufacturing industries.

Taming Bromine Azide for Use in Organic Solvents─Radical Bromoazidations and Alcohol Oxidations.

The formation of bromine azide from the bisazidobromate(I) anion or alternatively from Zhdankin's reagent, using a phosphonium bromide salt as a common starting point, is reported. After homolytic cleavage in the presence of alkenes or alcohols either 1,2-functionalization or alternatively the selective oxidation of secondary alcohols in the presence of primary alcohols occur. The scopes and limitations of the use of BrN3 are covered.

Synthesis of deep eutectic solvents based on triethylamine and organic acids and their application in fuel oil denitrogenation: A theoretical and experimental study

In this work, three deep eutectic solvents (DESs) triethylamine/formic acid ([Et3N/FA]), triethylamine/acetic acid ([Et3N/PA]), triethylamine/propionic acid ([Et3N/AA]) were synthesized and were used for extractive denitrogenation of model oil. Among them [Et3N/PA] exhibited reasonably high extraction efficiency for both indole and quinolone. Structure optimization, electrostatic potential analysis and reduced density gradient analysis were performed to explore the synthesis mechanism of DESs and extractive denitrogenation mechanism by DESs taking [Et3N/PA] as a representative. The structure of [Et3N/PA] were characterized by FTIR and NMR. Results indicate that both strong hydrogen bond and van der Waals are the majorforcefor DESs synthesis. Both hydrogen bonds and van der Waals are responsible for indole removal, while only van der Waals is responsible for quinolone removal. The effect of factors on extraction efficiency was also investigated and results indicate that [Et3N]/[PA] has the advantages of short equilibrium time, ability to deal with fuel oils with a wide range of nitrogen contents, excellent performance near room temperature. The presence of olefins and aromatics in fuel oil has negligible negative influence on the extraction efficiency of indole and quinolone. Furthermore, [Et3N/PA] exhibits excellent regeneration performance. Consequently, [Et3N/PA] is a promising extractant for fuel oil denitrogenation.

Photoredox Activation of Anhydrides for the Solvent‐Controlled Switchable Synthesis of gem ‐Difluoro Compounds**

Photoredox Activation of Anhydrides for the Solvent‐Controlled Switchable Synthesis of <i>gem</i> ‐Difluoro Compounds**

Photoredox Activation of Anhydrides for the Solvent-Controlled Switchable Synthesis of gem-Difluoro Compounds.

The incorporation of the gem-difluoromethylene (CF2 ) group into organic frameworks is highly sought due to the influence of this unit on the physicochemical and pharmacological properties of molecules. Herein we report an operationally simple, mild, and switchable protocol to access various gem-difluoro compounds that employs chlorodifloroacetic anhydride (CDFAA) as a low-cost and versatile fluoroalkylating reagent. Detailed mechanistic studies revealed that electron-transfer photocatalysis triggers mesolytic cleavage of a C-Cl bond generating a gem-difluoroalkyl radical. In the presence of alkene, this radical species acts as a unique intermediate that, under solvent-controlled reaction conditions, delivers a wide range of gem-difluorinated γ-lactams, γ-lactones, and promotes oxy-perfluoroalkylation. These protocols are flow- and batch-scalable, possess excellent chemo- and regioselectivity, and can be used for the late-stage diversification of complex molecules.

Piperazine/Alkene-Containing Phosphoramide Oligomer for the Intumescent Flame Retardation of EPDM Rubber

Ethylene propylene diene monomer (EPDM) rubber is highly flammable, facing potential fire hazard when it is used as electric cable sheaths, automobile parts, etc. In this work, aiming to reduce fire hazard of EPDM rubber, a piperazine/alkene-containing phosphoramide oligomer poly (2-butene-1,4-dione piperazine fumaroyl phenylphosphonate) (PPFPP) was synthesized and used as charring agent to fabricate intumescent flame retardant with ammonium polyphosphate (APP). When 20 wt% APP/PPFPP (weight ratio: 3:1) was incorporated into EPDM, the flame-retarded EPDM achieved the UL-94 V-0 rating and the limiting oxygen index (LOI) of 27.0%, significantly superior to flame-retarded EPDM consisting of controlled flame retardant PPSPP without alkene and PPFA without phenyl phosphine. In cone calorimeter test, flame retardant consisting of 6.25 wt% PPFPP and 18.75 wt% APP strongly reduced the peak of heat release rate (PHRR) and the peak of smoke production rate (PSPR) of EDPM, diminished approximately by 72% and 60%, respectively. In the case of meeting flame retardancy, mechanical property of flame-retarded EPDM maintained at a high level. Different measurements confirmed that the flame-retardant mechanism of PPFPP is attributed to two aspects. The first one is ascribed to the char-forming action of PPFPP in the presence of alkene and piperazine, playing a barrier role in condensed phase; the second one is due to the gaseous action of phenyl phosphine groups originating from the pyrolysis of PPFPP. In summary, the combination of piperazine and alkene with phenyl phosphine may fabricate an efficient charring agent for the intumescent flame retardation for EPDM.

Greener extraction‐chemical modification‐polymerization pipeline of vernolic acid from Ethiopian ironweed plant

AbstractEpoxidized oils are commonly used in the plastics industry as additives in the formulation of polyvinyl chloride (PVC) and as monomers in the coating industry. They are produced from petrochemical feedstocks or by chemical epoxidation of natural oils. Currently, the synthesis processes of these materials are expensive, utilize volatile organic solvents and hazardous oxidants, which are unfavorable for the environment. There is a need to find natural epoxidized oils. Vernonia galamensis (ironweed) is a plant found in abundance in Ethiopia with no commercial value, but its seeds contain 40 wt% epoxide rich triglycerides. V. galamensis oil contains up to 80 wt% of vernolic acid (VA), a mono‐unsaturated fatty acid with an additional epoxide functionality. The presence of alkene and epoxide(oxirane) groups offers excellent opportunities to synthesize new building blocks for polymerisations. Here, we report a green and efficient extraction methodology (up to 80% of extraction‐efficiency) of the triglyceride vernonia oil from V. galamensis using supercritical carbon dioxide (scCO2). We then report the synthesis of a series of polymerisable monomers (conversion in monomers 64%–99%) based on the VA obtained from the saponification process. Finally, the novel monomers are polymerized into different polymers through polycondensation using a mixture of metal‐based and enzyme catalysts.

Olefin Metathesis Catalysts Generated In Situ from Molybdenum(VI)-Oxo Complexes by Tuning Pendant Ligands.

Tailored molybdenum(VI)‐oxo complexes of the form MoOCl2(OR)2(OEt2) catalyse olefin metathesis upon reaction with an organosilicon reducing agent at 70 °C, in the presence of olefins. While this reactivity parallels what has recently been observed for the corresponding classical heterogeneous catalysts based on supported metal oxide under similar conditions, the well‐defined nature of our starting molecular systems allows us to understand the influence of structural, spectroscopic and electronic characteristics of the catalytic precursor on the initiation and catalytic proficiency of the final species. The catalytic performances of the pre‐catalysts are determined by the highly electron withdrawing (σ‐donation) character of alkoxide ligands, OtBuF9 being the best. This activity correlates with both the 95Mo chemical shift and the reduction potential that follows the same trend: OtBuF9>OtBuF6>OtBuF3.

Metal-Free Direct C-H Functionalization of Quinoxalin-2(1H)-Ones to Produce 3-Vinylated Quinoxalin-2(1H)-Ones in the Presence of Alkenes.

A novel and efficient C3-H vinylation reaction with quinoxalin-2(1H)-one as the substrate, in the presence of alkenes, under metal-free conditions, is reported herein. The reaction leads to the formation of new carbon–carbon bonds that exhibit moderate to good reactivities. The vinylation of quinoxalin-2(1H)-ones, in the presence of alkenes, is an attractive process that can be potentially utilized to produce biologically active 3-vinylated quinoxalin-2(1H)-ones.

Aqueous Polyphenol Semi-Purified Fractions from Galls of Quercus infectoria Increase ALP Activity and Mineralisation of hFOB 1.19 Cells

The galls of Quercus infectoria (QI) have been reported to possess numerous medicinal values and give a positive effect on bone metabolism. This study investigated the effects of semi-purified fractions of QI gall extract on the proliferation, alkaline phosphatase (ALP) activity, and mineralisation of human foetal osteoblast cell line (hFOB1.19). The semi-purified fractions (fraction A and B) were prepared by column chromatography methods. MTT assay was used to measure cell proliferation activity to obtain half maximal concentration (EC50) of the cells treated with fraction A (phenolic components and contained amide), fraction B (phenolic components with the presence of alkene), and pamidronate (drug control). The most potent or lowest EC50 was further used to measure ALP activity in the treated and untreated cells at day 1, 3, 7, 10, and 14 by ELISA. Cell mineralisation was determined by von Kossa staining for phosphate depositions and Alizarin Red S staining for calcium depositions. The EC50 values for fraction A and B were 8.86 and 9.92 μg/mL, respectively, which showed a greater effect compared to the pamidronate (15.27 μg/mL). The ALPactivity of both fractions in the treated cells were also greater compared to the two control groups (cells treated with pamidronate and untreated cells), starting from day 3 onwards. The calcium depositions appeared as red spots, while phosphate depositions appeared as black spots. Interestingly, the calcium depositions of cells treated with both fractions were higher than those of the two control groups. In conclusion, semi-purified fractions of QI gall extract enhanced proliferation, improved mineralisation, and increased ALP activity of hFOB 1.19 cells.

Fouling tendency of bitumen visbreaking products

In this work, the fouling behaviour of thermally processed bitumen products obtained by visbreaking was studied. The feedstock was prepared by blending raw oil sands bitumen with 15 vol% hydrotreated light oil (HLO). The visbreaking products obtained at different pitch (525 °C + fraction) conversions were characterized and tested for fouling tendency. Test results showed that the fouling tendency linearly increased with total olefin content in visbreaking products. To further investigate the separate contributions of olefins and asphaltenes to fouling tendency, a selected visbreaking product was distilled into an olefin-rich 280 °C − fraction and a “heavy” 280 °C + fraction to avoid the loss of lighter fractions during the deasphalting process. To minimize the effect of interactions between olefins and asphaltenes on the fouling tendency, the 280 °C − fraction was hydrotreated and the 280 °C + fraction deasphalted. The deasphalted samples with different olefin contents and the hydrotreated samples with different asphaltene contents were obtained by blending the processed 280 °C − and 280 °C + fractions. Test results showed that deasphalting significantly reduced the fouling tendency of the visbreaking product. In the presence of olefins, asphaltenes have a significant effect on the fouling tendency of thermally processed products, whereas in the absence of olefins, the impact of asphaltenes on fouling tendency was limited. Similarly, olefins have a limited effect on the fouling tendency of visbreaking product in the absence of asphaltenes.

Catalytic Chemoselective Sulfimidation with an Electrophilic [CoIII (TAML)]- -Nitrene Radical Complex*.

The cobalt species PPh4[CoIII(TAMLred)] is a competent and stable catalyst for the sulfimidation of (aryl)(alkyl)‐substituted sulfides with iminoiodinanes, reaching turnover numbers up to 900 and turnover frequencies of 640 min−1 under mild and aerobic conditions. The sulfimidation proceeds in a highly chemoselective manner, even in the presence of alkenes or weak C−H bonds, as supported by inter‐ and intramolecular competition experiments. Functionalization of the sulfide substituent with various electron‐donating and electron‐withdrawing arenes and several alkyl, benzyl and vinyl fragments is tolerated, with up to quantitative product yields. Sulfimidation of phenyl allyl sulfide led to [2,3]‐sigmatropic rearrangement of the initially formed sulfimide species to afford the corresponding N‐allyl‐S‐phenyl‐thiohydroxylamines as attractive products. Mechanistic studies suggest that the actual nitrene transfer to the sulfide proceeds via (previously characterized) electrophilic nitrene radical intermediates that afford the sulfimide products via electronically asynchronous transition states, in which SET from the sulfide to the nitrene radical complex precedes N−S bond formation in a single concerted process.

Thermal and clinker‐catalyzed pyrolyses of polystyrene waste using the Portland cement solid‐base catalyst

AbstractPolystyrene is a nondegradable lightweight foamy substance that easily blows from landfills into drains and waterways. This material creates litter and water pollution and harms the wildlife who mistakenly eat it. This study investigated a cost‐effective pyrolysis approach for catalytic conversion of waste polystyrene into useful oil and gas products. The Portland cement was used as a solid base to catalyze the pyrolysis reaction for improving the product yield, lowering the reaction temperature and shortening the reaction time. Optimum reaction conditions were investigated by varying the process temperature, process time, and amount of the catalyst. The catalytic conversion of polystyrene into oil was measured about 94.98% at 400°C. In noncatalytic conversion experiments, same conversion efficiency was achieved at 600°C, which is significantly higher than the catalytic conversion. Catalytic pyrolysis produced oil with major part of volatile fractions and 42.14% styrene. The thermal pyrolysis produced oil with high styrene content (63.17%). Overall, styrene content of oil product was lower than the reported values in the literature. The noncatalytic pyrolysis produced nonreactive gases toward the copper‐I solution while catalytic pyrolysis produced highly reactive gases. The presence of olefins and acetylene in gaseous form confirmed the presence of hydrogen in the product.

Impact of the Carbene Derivative Charge on the Decomposition Rates of Hoveyda-Grubbs-like Metathesis Catalysts.

Hoveyda–Grubbs metathesis catalysts undergo a relatively fast decomposition in the presence of olefins. Using a computational density functional theory approach, we show that positively charged derivatives of N-heterocyclic carbenes have little impact on the degradation/deactivation rates of such catalysts with respect to neutral carbenes. On the other hand, the hypothetical anionic Hoveyda–Grubbs-like catalysts are predicted to less likely undergo degradation in the presence of the olefin, while being as active as standard, neutral Hoveyda–Grubbs catalysts.

Influence of hydrocarbons on hydrogen chloride removal from refinery off-gas by zeolite NaY derived from rice husks

The removal of gaseous hydrochloric acid (HCl) in refineries and petrochemical plants is essential to prevent potential catalyst poisoning, equipment corrosion, and several associated public health and environmental hazards when the acid contaminates the hydrogen–hydrocarbon feedstock. In the present work, the effect of alkanes, alkenes, and liquid aromatic hydrocarbons on the removal of HCl from refinery off-gas using zeolite NaY was evaluated. Zeolite NaY was synthesized from rice husks via a hydrothermal route. Adsorbent characterization analyses such as XRD, SEM-EDS, FT-IR, BET and particle size distribution were employed. Fixed-bed experiments were operated under feed condition of 600 ppm HCl and gas hourly space velocity of 640 mL/h·cm3. Gaseous HCl was combined with H2, H2-alkanes and H2-alkenes to simulate the main components of refinery-off gas. Experimental breakthrough curves were used to determine the adsorption capacities of zeolite NaY pellets at breakthrough and saturation. HCl removal by fresh zeolite NaY was inhibited by light alkanes but improved in the presence of alkenes. The adsorption capacity at breakthrough for fresh zeolite with combined hydrogen and light alkenes was measured at 0.1507 g/g. In the presence of aromatics, significant reduction in adsorption capacities to 0.1247, 0.1379 and 0.1437 g/g were obtained for adsorbents subjected to H2, H2-alkanes and H2-alkenes respectively. Zeolite NaY consistently showed higher performance for HCl removal in the presence of H2 feed mixed with light hydrocarbons compared with a commercial adsorbent.