Absence Of Catalyst Research Articles

Chemical oxidation of arsenic in the environment and its application in remediation: A mini review

Arsenic (As) contamination in soil and water poses a serious threat to the ecosystem health and human beings, and is of widespread concern. The main As species found in soil and water are arsenite As(III) and arsenate As(V). Because As(III) is more toxic and often more mobile than As(V), many remediation strategies aim to oxidize As(III) to As(V). In the environment, the reduction of As(V) under anaerobic conditions is mainly mediated by microorganisms, but the oxidation of As(III) under aerobic conditions can be mediated primarily by chemical processes. This article first reviews the existing knowledge on chemical oxidation of As(III) in the environment, with an emphasis on the roles of iron (Fe) and manganese (Mn) oxides. The application of Fe and Mn oxides for the remediation of As-contaminated soil and water is then summarized. The oxidation of As(III) by oxygen is very slow in the absence of catalysts. Many Mn oxides, on the other hand, can efficiently oxidize As(III). Although the oxidation of As(III) by Fe(III) is also slow, this process can be accelerated by light or Fe(II). Iron and Mn oxides are widely used for the remediation of As-contaminated soil and water, with Fe oxides generally acting as absorbents while Mn oxides as oxidants. To better understand and regulate As transformation and transport in the environment, further study is needed on the mechanisms and influencing factors of As(III) oxidation by Fe and Mn oxides, and the development of innovative methods and materials based on Fe and Mn oxides are desired.

Obtaining phthalate substituted post-consumer polyethylene terephthalate and its isothermal crystallization

Objects. Due to the polymer waste accumulation, the search for new directions for their utilization is urgent. Chemical recycling methods are of considerable interest, which allow one to obtain the original monomers or change the compositions of the copolymers. From the point of view of building a circular economy, a promising material is polyethylene terephthalate (PET), on the basis of which amorphous copolyesters can be obtained. The study aimed to analyze the simultaneous glycolysis and interchain exchange reactions of PET in the presence of the oligoethylene phthalate modifier with hydroxyl end groups and the study of isothermal crystallization of poly(ethylene phthalate-co-terephthalates) with different phthalate contents obtained in this way.Methods. Oligoethylene phthalate is synthesized by polycondensation. Poly(ethylene phthalateco-terephthalates) were obtained by the interaction of post-consumer PET with oligoethylene phthalate. The composition of the oligomer and copolymers was confirmed using Fourier-transform infrared spectroscopy, thermal characteristics and crystallization half-times were determined by differential scanning calorimetry.Results. In this work, the use of the post-consumer PET chemical recycling process, aimed at obtaining copolyesters under the influence of small modifier amounts was proposed. The process consisted in carrying out the combined interchain exchange and degradation with a complex oligoester different from PET. Poly(ethylene phthalate-co-terephthalate) copolymers were obtained via reaction of post-consumer poly(ethylene terephthalate) flakes and synthesized oligoethylene phthalate resin in the melt phase in the absence of catalyst. The effect of phthalate concentration in polymer on the isothermal crystallization of phthalate substituted poly(ethylene terephthalate) was estimated.Conclusions. The hypothesis about the possibility of using an oligoester modifier to obtain the PET-based copolymer at the high rate and without reducing the molecular weight to values characteristic of a monomer or oligomer has been confirmed. The process can be used to obtain random copolyesters based on post-consumer PET. The phthalate unit concentration increase is followed by decrease in the glass transition temperature, temperature and heat of fusion, and increase in crystallization half-times. Phthalate has a better ability to retard PET crystallization than 2-methyl-1,3-propanediol or furandicarboxylic acid, but is inferior to some of the other modifiers known.

Chiral probe for mass spectrometric identification and quantitation of levodropropizine and its enantiomer, dextrodropropizine.

Acyl chlorides react rapidly with hydroxyl and amino groups in the absence of catalysts and therefore hold great promise for chiral mass spectrometry. Herein, a tandem mass spectrometry method based on derivatization with (-)-camphanic acid chloride as a simple chiral probe was developed for the highly sensitive detection and quantitation of levodropropizine and its enantiomer, namely, dextrodropropizine. The diastereomeric derivatization products were quantified based on the relative abundances of their fragment ions produced upon collision-induced dissociation in positive-ion mode. The reactive site was elucidated using nuclear magnetic resonance spectroscopy and two-dimensional total correlation spectroscopy, and the reaction mechanism was proved by stoichiometry studies. The degree of isomer recognition was investigated at different collision energies and determined as Rchiral ≈1.5. Thus, this study gives the way to the mass spectrometric identification and quantitation of levodropropizine and its enantiomer, and the developed method represents a new and practical technique for rapid and sensitive determination and quality control of enantiomers of chiral drugs.

Catalytic hydrothermal liquefaction of sewage sludge: Effect of metal support heterogeneous catalysts on products distribution

Industrial wastes and natural mixed oxide materials were evaluated as inexpensive heterogeneous catalysts supports for catalytic hydrothermal liquefaction (HTL) of biomass. In this study, Palygorskite (ATP) clay, a hydrated magnesium aluminosilicate clay mineral supported metal catalysts (Co, Mo and Co–Mo/ATP) and Al2O3 supported (Co, Mo, Co–Mo/Al2O3) catalysts were examined for the sewage sludge (SS) hydrothermal liquefaction (HTL). The highest biocrude yield of 34.2 wt% was obtained with Co–Mo/ATP bimetal catalyst. Biocrude characterization revealed that significantly different families of molecules were formed in the presence and absence of catalysts, implying that the main role of the catalyst is to promote rates of thermal reactions, leading to biocrude production. The improved catalytic HTL performance with Co–Mo metal catalyst as attributed to the synergistic effects of both metal sites present on catalyst surfaces. The main components of bio-oil were phenols, N-containing compounds and hydrocarbons, and the increased selectivity to hydrocarbons with Co–Mo/ATP was observed. Maximum yield of aromatic hydrocarbon (20% observed in case of HTL with metal supported ATP catalyst. presence of Co–Mo metal catalysts promoted the deoxygenating by reduction of oxygen in the form of carbon dioxide or water. The distribution of biocrude samples indicates that most compounds in biocrude were light-weighted and had low boiling points. There were more light-weight compounds in biocrude by adding catalyst.

Origin of enantioselectivity and product-distribution control in isocyanide-based multicomponent reaction catalysed by chiral N, N'-dioxide-Mg(II) complex

Reaction mechanism and key factors controlling the stereo- and product-selectivity in isocyanide-based multicomponent reactions (MCRs) of alkylidene malonate and HN3 mediated by chiral N, N'-dioxide-Mg(II) catalyst were studied at the B3LYP-D3(BJ)/6-311G(d,p)//B3LYP-D3(BJ)/def2-SVP(SMD, CH2Cl2) theoretical level. Both three- and four-component reactions carried out via the same chiral-controlling step, with the energy barrier of 29.4 kcal mol−1 in the absence of catalyst. Two kinds of tetrazoles were formed via the construction of five-membered rings through two-stage one-step pathway, followed by carbanion protonation via intramolecular H-shift process. The non-catalytic MCRs were difficult to occur because of high energy barriers of 39.9–52.5 kcal mol−1 in the rate-determining step (RDS). A hexacoordinate-Mg(II) species formed by coordinating alkylidene malonate to Mg2+ center in bidentate fashion accelerated the formation of tetrazole ring via stepwise mechanism. The significant steric hindrance of cyclohexyl group in alkylidene malonate as well as the o-iPr group in the catalyst induced isocyanide to attack from the si-face of alkylidene malonate in the chiral-controlling step, affording predominantly S-configuration products in the two kinds of MCRs. The nucleophilicity of reactants (i.e., isocyanide and HN3) (not the electrophilicity of zwitterionic intermediate) as well as weak π-π interaction of the naphthyl rings in the second CC bonding transition state played important roles to control the distribution of the two kinds of tetrazoles. Isocyanide with high nucleophilicity was preferably trapped by the zwitterionic intermediate to proceed the four-component reaction. In contrast, the isocyanide with electron-withdrawing group exhibited better reactivity in three-component reaction.

Investigation of catalytic potential of sodium dodecyl sulfate stabilized silver nanoparticles for the degradation of methyl orange dye

Sodium dodecyl sulfate (SDS) was employed as a stabilizing agent for the preparation of Ag-NPs while using AgNO3 salt as a source of silver ions and sodium borohydride as a reducing agent in an aqueous medium. Synthesized sodium dodecyl sulfate stabilized silver nanoparticles (Sd@Ag-NPs) were extensively characterized by FTIR, UV–Vis spectroscopy, SEM, XRD and DLS analysis. After that, Sd@Ag-NPs particles were employed as an active catalyst for the reduction of methyl orange (MO) and Rhodamine B (Rh-B) dyes. At first, reduction of MO was carried out in the presence of a catalyst and an excessive amount of NaBH4 in water medium. Reduction of MO was completed in 21 min while the value of apparent rate constant (kapp) was found as 0.385 min −1. Reduction of Rh-B was completed in 15 min with the value of kapp found as 0.131 min−1. Controlled reactions were also performed for the reduction of MO in the absence of catalyst and in the absence of NaBH4 to check the kinetic feasibility of the reaction as well as to check either the decrease in absorbance value was due to the adsorptive action of Sd@Ag-NPs or its working as a catalyst. It was concluded that MO reduction was completed in feasible time in the presence of catalyst. The activity of 9 months old catalyst was slightly decreased as compared to the freshly prepared catalyst for the reduction of MO under same reaction conditions. It was also concluded that Sd@Ag-NPs catalyst successfully degraded the MO dye in the presence of another toxic dye Rh-B in a feasible time. It indicates that our reported Sd@Ag-NPs catalyst can simultaneously reduce the mixture of dyes.

Rubbery Polyhydroxyesters based on Polyethylene Glycol Diglycidyl Ether: Reaction and Vitrimer-like Behavior Catalyzed by Tin Octoate

Background: Polyhydroxyesters prepared from epoxy and organic acids are vitrimers that can rearrange their topology from exchange reactions enhanced by catalysts, forming crosslinked net-works that can be deformed and remolded. Objectives: In this work, the curing kinetics and thermal properties of polyhydroxyesters vitrimers based on polyethylene glycol diglycidyl ether (PEGDGE), citric acid (CA), and sebacic acid (SA) in the presence and absence of tin octoate (Sn(Oct)2) were investigated. Methods: Differential scanning calorimetry (DSC) non-isothermal experiments and Ozawa models were used for the curing kinetic studies, and thermogravimetry analysis (TGA) and thermomechanical analyses (TMA) were employed to investigate the thermal behavior of the networks. Results: The highest curing enthalpy of these exothermic reactions was observed in the binary system PEGDGE:CA without catalyst (326 J/g). The addition of Sn increases the reaction enthalpy for formu-lations with SA and decreases it for formulations rich in CA. The lowest activation energy was shown for the formulation PEGDGE:CA = 3:2 containing 1 mol% of Sn (56 kJ/mol). The polyhydroxyesters presented Tg ranging from -24 to -48 °C, and the Tg decreased when the proportion of SA was in-creased in the formulation. The thermal stability was increased when the SA content increased and de-creased when the content of Sn increased from 1 to 5 mol%. Conclusion: Esterification of PEGDGE and organic acids (SA and CA) occurs even in the absence of catalyst, producing rubbery polyesters, but the use of Sn(Oct)2 decreases the curing time. Ternary net-works of polyhydroxyesters containing Sn showed a discontinuity in the thermal expansion around 180°C attributed to exchange reactions, similarly to what was theorized for this class of vitrimer material.

Visible Light Mediated, Catalyst Free, One-Pot Convenient Synthesis of Dihydropyridines

: A simple, efficient and green protocol has been developed for the synthesis of polysubstituted dihydropyridines via one-pot, four-component reaction of aldehydes, arylamines, dialkyl acetylenedicarboxylate, and malononitrile. The reaction was proceeded at room temperature in the absence of catalyst in aqueous ethyl lactate under visible light irradiation. The main advantages of the present approach are mild reaction condition, high yield, no column chromatography, clean reaction profile, environmentally friendly and sustainable from the economic point of view

Coupled adsorption-catalytic reduction of permanganate on Co–Al-layered double hydroxide for dye removal

Permanganate (MnO4−) ions were catalytically reduced to MnO2 by water molecules after adsorption on the surface of carbonate intercalated Co–Al-LDH. This reaction was very slow under experimental conditions in the absence of catalyst and was catalyzed by Co–Al-LDH and Co(II) ion had a key role in this process in the pH range of 2.8–13. But, at pH = 14, MnO4− ions reacted with Co(II) ion of adsorbent and produced Co(III). At all pHs, adsorption sites of Co–Al-LDH for MnO4− ions were Co–OH groups. These adsorption sites were located in micropores and mesopores of Co–Al-LDH and were called MI and ME adsorption sites, respectively. MnO4− ions were adsorbed on both adsorption sites in neutral aqueous solutions and only on ME sites at other pHs. Adsorption experiments were carried out at different temperatures, ionic strengths, pHs and initial adsorbate concentrations. Co–Al-LDH acted as a superadsorbent for MnO4− ions and maximum adsorption capacity was 347.9 mg g−1 (2.2 mmol g−1) in neutral aqueous solution at 318 K. The adsorption binding constants and thermodynamic parameters of adsorption of MnO4− ions on Co–Al-LDH were analyzed by ARIAN (adsorption isotherm regional analysis) model. This model determined the boundaries of adsorption of MnO4− ions on Co–Al-LDH under different conditions and showed that this process was endothermic in regions I and II of its isotherms in neutral solution and at pH = 13. This process obeyed ARIAN–Hinshelwood mechanism and water molecules in the pH range of 2.8–13 and hydroxide ions at pH = 14 participated as nucleophile reagents. Reaction in the pH range of 2.8–13 was as follows2MnO4−+ H2O →2MnO2(ad)+32O2+2OH− and at pH = 14 was as2MnO4−+2Co(II)–OH+H2O→2Co(III)–OH+2MnO2ad+32O2+2OH−This adsorbent was used for selective separation of permanganate from cationic safranin O and methylene blue dyes. However, it could not separate anionic methyl orange dye from MnO4− ions.This work further successfully demonstrated an approach to recycle the used Co–Al-LDH using a reducing agent.

Asymmetric α‐Allylation of Glycinate with Switched Chemoselectivity Enabled by Customized Bifunctional Pyridoxal Catalysts

AbstractOwing to the strong nucleophilicity of the NH2 group, free‐NH2 glycinates react with MBH acetates to usually deliver N‐allylated products even in the absence of catalysts. Without protection of the NH2 group, chiral pyridoxal catalysts bearing an amide side chain at the C3 position of the naphthyl ring switched the chemoselectivity of the glycinates from intrinsic N‐allylation to α‐C allylation. The reaction formed chiral multisubstituted glutamic acid esters as SN2′–SN2′ products in good yields with excellent stereoselectivity (up to 86 % yield, >20 : 1 dr, 97 % ee). As compared to pyridoxal catalysts bearing an amide side arm at the C2 position, the pyridoxals in this study have a bigger catalytic cavity to enable effective activation of larger electrophiles, such as MBH acetates and related intermediates. The reaction is proposed to proceed via a cooperative bifunctional catalysis pathway, which accounts for the high level of diastereo‐ and enantiocontrol of the pyridoxal catalysts.

Asymmetric α-Allylation of Glycinate with Switched Chemoselectivity Enabled by Customized Bifunctional Pyridoxal Catalysts.

Owing to the strong nucleophilicity of the NH2 group, free-NH2 glycinates react with MBH acetates to usually deliver N-allylated products even in the absence of catalysts. Without protection of the NH2 group, chiral pyridoxal catalysts bearing an amide side chain at the C3 position of the naphthyl ring switched the chemoselectivity of the glycinates from intrinsic N-allylation to α-C allylation. The reaction formed chiral multisubstituted glutamic acid esters as SN 2'-SN 2' products in good yields with excellent stereoselectivity (up to 86 % yield, >20 : 1 dr, 97 % ee). As compared to pyridoxal catalysts bearing an amide side arm at the C2 position, the pyridoxals in this study have a bigger catalytic cavity to enable effective activation of larger electrophiles, such as MBH acetates and related intermediates. The reaction is proposed to proceed via a cooperative bifunctional catalysis pathway, which accounts for the high level of diastereo- and enantiocontrol of the pyridoxal catalysts.

Upgrade of heavy crude oil via aquathermolysis over several types of catalysts

A solid NaY zeolite catalyst was synthesized from raw materials using a hydrothermal method. The NH4Y and HY forms of the catalyst were then prepared using multistage ion-exchange and calcination processes, respectively. Cobalt and Zinc as transition metals were loaded into the HY structure through impregnation method. The synthesized Zn/HY and Co/HY zeolites along with ZnO and CoO nanoparticles were all used as catalysts for aquathermolysis. The catalysts were characterized using X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy-energy-dispersive X-ray spectroscopy, and Brunauer-Emmett-Teller surface area and pore volume analysis. A stainless-steel autoclave operated at 45 bar and 250 °C for 24 h was employed for upgrading heavy crude oil samples extracted from the East Baghdad oilfield using toluene as the hydrogen donor. The reaction products were analyzed by evaluating the changes in their viscosity, API gravity, density, pour point, and flash point. The results indicated that the efficiency of the catalysts decreased as follows: Zn/HY zeolite > Co/HY zeolite > nano CoO > nano ZnO > HY zeolite > in the presence of the hydrogen donor only = in the absence of catalysts or the hydrogen donor. The decrease in the S-content of the products was also evaluated. The results indicated that the efficiency of the catalysts decreased as follows: Co/HY zeolite > Zn/HY zeolite > nano CoO > nano ZnO > HY zeolite > in the presence of the hydrogen donor only > in the absence of catalysts or the hydrogen donor. The S-content of the products obtained over the Co/HY zeolite catalyst decreased the most (by 65.63%). Moreover, the viscosity of the crude oil obtained over the Zn/HY zeolite catalyst decreased the most (by 63.69%).

C-Methylation Of Organic Substrates. A Comprehensive Overview. Part IVa. Methylating Agents Other Than Methane, Methanol, and Methyl Metals

: C-Methylation of organic substrates was accomplished with a number of methylating agents other than methane, methanol, and methyl metals. They include methyl halides (MeX, X = I, Br, Cl, F), methyl-containing halogenated reagents, methyl peroxides, dimethyl carbonate (DMC), dimethylsulfoxide (DMSO), N,N-dimethyl formamide (DMF), diazomethane, formate salts, trioxane, CO/H2, CO2/H2, and dimethyl ether (DME). Under particular conditions, some methyl- containing molecules such as polymethylbenzenes, methylhydrazine, tris(diethylamino) sulfonium difluorotrimethylsilicate, methyl tosylate, long-chain alkyl alcohols, and acetic acid unexpectedly C-methylated a variety of organic substrates. A few cases of C-methylation were only reported to occur in the absence of catalysts. Otherwise, transition metal complexes as catalysts in conjunction with specific ligands and bases were ubiquitously present in most C-methylation reactions. Of the reactions, Suzuki-Miyaura-type cross-coupling remained of paramount importance in making 11CH3-bearing positron emission tomography tracers (PETs), one of the best applications of such methylation. Methylation proceeded at C(aromatic)-X, C(sp3)-X C(sp2)-X, and C(sp)-X of substrates (X = H, halogen). Ortho-methylation was regioselectively observed with aromatic substrates when they bear moieties such as pyridyl, pyrimidyl, amide, and imine functionalities, which were accordingly coined ‘ortho-directing groups’.

Visible Light-Emitting Diode Light-Driven Aerial Oxidation of Aldehydes under Catalyst and Solvent-Free Conditions

Background: Green and sustainable method for the oxidation of aldehydes into acids is now in demand as carboxylic acids are important and versatile intermediates. In this context, visible LED light-promoted aerial oxidation can be efficient and greener protocol. Objective: Herein, we have demonstrated a visible LED light-promoted efficient and greener protocol for the aerial oxidation of aromatic aldehydes into corresponding acids in the absence of any additives, base, catalyst, and oxidant. Methods: The oxidation of aromatic aldehydes was irradiated by an LED light at room temperature under an open atmosphere, monitored by TLC. The rate of oxidation was also monitored using different LED lights by UV-Vis studies. The products were purified by column chromatography using silica gel, and the mixture of ethyl acetate/petroleum ether as an eluting solvent and the pure products were confirmed by their melting point determination and NMR spectroscopic analysis. Results: The aldehydes were successfully converted into corresponding acids with good isolated yields (60-90 %) by this protocol, where blue LED light (l ~ 490 nm) was found to be the best choice. Conclusion: The present protocol of aerial oxidation of aromatic aldehydes into corresponding acids under visible LED light has been carried out in the absence of catalyst, oxidant, base, and any other additives. The higher isolated yields, no byproduct formation, and neat reaction conditions are the major advantages of the protocol.

A Study of the Pyrolysis Products of Kraft Lignin

In order to valorize lignin wastes to produce useful aromatic compounds, the thermal degradation pyrolysis of Kraft lignin in the absence of catalysts has been investigated at 350, 450, and 550 °C. The high content of sulfur in the fresh sample led to the formation of S-containing compounds in products whose evolution in the gas phase was monitored through GC-MS analysis. Pyrolytic gas is rich in CH4, CO, CO2, and H2S with the presence of other sulfur compounds in smaller amounts (i.e., CH3SH, CH3-S-CH3, SO2, COS, and CS2). Biochar morphology and elemental composition have been investigated by means of SEM and EDX. The carbon content reaches ~90% after pyrolysis at 550 °C, while the oxygen content showed a decreasing trend with increasing temperature. From GC-MS analysis, bio-oil resulted rich in alkyl-alkoxy phenols, together with (alkyl)dihydroxy benzenes and minor amounts of hydrocarbons and sulfur compounds. NaOH/H2O and EtOH/H2O extraction were performed with the aim of extracting phenolic-like compounds. Sodium hydroxide solution allowed a better but still incomplete extraction of phenolic compounds, leaving a bio-oil richer in sulfur.

Catalytic Oxidative Desulfurization of Model Diesel Using TBHP-DMF System

Hydrodesulfurization (HDS) technique is no longer applicable in achieving ultra-low sulfur diesel because of high operational cost, high operating temperature and low efficiency. Due to these disadvantage, catalytic oxidative desulfurization (Cat-ODS) has been introduced as a new technique in achieving ultra-low sulfur diesel. The performance of the Fe catalyst was investigated in Cat-ODS of model diesel using terbutyl hydroperoxide (TBHP) as oxidant and dimethylformamide (DMF) as an extracting solvent. The physicochemical analysis of this catalyst was accomplished using several characterization techniques such as BET, EDX and HRTEM. It posseses high surface area of 226 m2g-1 with small particle sizes in the range of 6-7 nm and less metal leaching. Under optimize condition, about 90% of sulfur was removed from model diesel. In the absence of catalyst, only about less than 80% of organosulfur compounds were removed. The Cat-ODS system showed the promising technology to be compliment with hydrodesulfurization (HDS) to produce low sulfur diesel.

One-Pot Synthesis of Dihydroxyindeno[1,2-d]Imidazoles and Naphthoquinone Substituted Indandione and Oxindole Derivatives

A series of potentially bioactive compounds having either indole or indene frameworks such as dihydroindenone and indolinone derivatives were synthesized in good to high yields by one-pot, multi-component reaction of various amines, trichloroacetonitrile, ninhydrin or isatin, and 2-hydroxy-1,4-naphthoquinone. The present method offers desirable advantages including mild conditions, absence of catalyst, simple workup procedure, and easy purification process with no chromatographic technique.

Catalytic pyrolysis of coconut oil with Ni/SBA-15 for the production of bio jet fuel.

Catalytic pyrolysis of vegetable oil is one of the potential routes to convert oil to drop-in biofuels, known as renewable hydrocarbons. In this paper, we explored catalytic pyrolysis of coconut oil using SBA-15 impregnated with Ni in proportions of 1% to 5% to produce sustainable aviation fuel. The catalysts were synthesized, calcined and then characterized by XRD, FTIR, SEM, and EDS. In order to better understand the behavior of this process, thermal and kinetic studies were carried out by thermogravimetry. The TG curves of vegetable oil with (10%) and without catalysts were obtained at heating rates of 5, 15 and 20 °C min−1, in the temperature range between 30 and 600 °C. The kinetic parameters were calculated by the Ozawa–Flynn–Wall (OFW) and Kissinger–Akahira–Sunose (KAS) methods. In the kinetic study, lower heat rates promoted higher conversions and the KAS model suits the process. The results calculated for the OC sample using the two kinetic models showed an increase in the Ea energy as the conversion progressed to a certain point. Catalytic pyrolysis experiments were performed in a one-stage tubular reactor at 500 °C with a catalyst loading of 10 wt% on the basis of mass of oil. The catalyst with 5% Ni showed greater presence of hydrocarbons and greater formation of water, indicating that the deoxygenation process occurred through decarbonylation. With this, the present study was successful in the development of methodologies for obtaining hydrocarbons with a composition close to that of drop-in fuels, compared to the process carried out with vegetable oil in the absence of catalysts.

Stepwise Pyrolysis by LBCR Downstream to Enhance of Gasoline Fraction of Liquid Fuel from MMSW

Pyrolysis is one of the thermal cracking methods to convert hydrocarbon to liquid fuel. The quantity and quality of the process are dependent on several condition including temperature, reaction time, catalyst, and the type of reactor. Meanwhile, a gasoline fraction was maximum product to be considered in the pyrolisis process. Therefore, this study aims to increase the gasoline fraction in liquid fuel using stepwise pyrolysis with a long bed catalytic reactor downstream (LBCR). The LBCR downstream was equipped with the top and bottom outlet and the fed source was mixed municipal solid waste (MMSW). The activated natural dolomite at 500°C was used to allow the repetition of the secondary cracking. Also, the reactor temperature was setup at around 200°C–300°C and the pyrolizer was 400°C. To analyze the gasoline fraction and physical properties of liquid fuel, Gas Chromatography-Mass Spectroscopy (GC-MS) and ASTM standard were employed. The experimental results showed there was a significant increase in the gasoline fraction of liquid fuels compared to using direct catalytic cracking and absence of catalysts. By using a LBCR at 250°C, the liquid fuel obtained at top outlet (TO) and bottom outlet (BO) have 84.08 and 56.94 percent peak area of gasoline fraction (C5--C12), respectively. The average value (TO and BO) of the fraction at 250°C by LBCR was 70.51 percent peak area and it was increased by about 93.6% and 51.14% compared to without catalyst and direct catalytic, respectively. Furthermore, pyrolytic liquid oils were found to have kinematic viscosity of 2.979 and 0.789 cSt, density of 0.781 and 0.782 g/cm3, and flash point

Biodiesel soot combustion: Analysis of the soot-catalyst contact in different experimental conditions

To simulate the oxidation of Biodiesel soot in a catalyzed Diesel Particulate Filter, oxidation experiments of undoped or Na-doped model soot were performed in the presence of Pt-Pd/Al2O3 under Temperature Programmed Oxidation and different carbon-catalyst configurations. Loose or tight contact was simulated by mixing soot and catalyst either with a spatula or in a mortar. Samples were characterized by Flame Atomic Adsorption Spectroscopy, Inductively Coupled Plasma-Optical Emission Spectroscopy, N2-physisorption, X-ray Photoelectron Spectroscopy, Raman Spectroscopy and Transmission Electron Microscopy coupled with Energy Dispersive X-Ray. The results showed that reducing the carbon granulometry led to an enhancement of the reactivity under NO2, due to the external combustion mechanism of carbon crystallite. In the absence of catalysts, no impact of the granulometry was observed under a flue gas containing NO and O2. A better catalyst efficiency was obtained when the carbon-catalyst contact was increased. In tight contact, a mechanism where NO2 can react adsorbed on a metallic site with a carbon site was proposed. In the presence of water, a simple addition of the catalytic activity of both water and Pt-Pd/Al2O3 catalyst impact on carbon oxidation was observed. The use of Biodiesel, simulated by Na-doped model soot, led to a significant increase in the catalyst efficiency in loose contact. Thus, a second mechanism was proposed, assuming that the doped sites play the role of NO2-reservoir and carrier between catalyst and carbon sites.