Oxidation Of Paraffins Research Articles

Decarbonizing Petrochemical Processes: Contribution and Perspectives of the Selective Oxidation of C1–C3 Paraffins

In this perspective, we present an overview of the most relevant advances in the selective oxidation of light paraffins to contribute to the petrochemical decarbonization processes. An analysis of the catalysts reported for methane to chemicals focusing the attention on the oxidative coupling, the dehydroaromatization, the oxidation to formaldehyde, and, more particularly, the direct oxidation to methanol is done. For ethane, the examination is centered on the catalysts investigated for the oxidative dehydrogenation to ethylene, the ammoxidation to acetonitrile, and the partial oxidation to acetic acid. Finally, in the case of propane, the scrutiny is focused on the oxidative dehydrogenation to propylene, the selective oxidation to acrolein and acrylic acid, and the ammoxidation to acrylonitrile. The main challenges to face on the catalyst design and process development are pointed out.

Comprehensive characterization of sooting butane jet flames, Part 1: Soot, soot-precursor, and reaction zone

The present work examines the effect of Reynolds number (Re) on n-butane jet flames, ranging from laminar to turbulent regime (Re=2100 to 21,500). n-butane is chosen since it can represent the oxidation of larger paraffins contained in practical fuels. Several quantities are measured, and various data analysis approaches are employed. Soot volume fraction (fv) was measured using a laser-induced incandescence technique, whereas polycyclic aromatic hydrocarbons (PAH) and reaction zone (OH) were imaged using laser-induced fluorescence (LIF) tool. The mean and instantaneous images of OH, PAH, and soot volume fraction are examined. The reaction zone is the least affected by the turbulence, while the PAH-LIF signal is moderately affected. A strong effect of turbulence is observed on the soot concentration and intermittency. Soot and PAH concentration decreased with Re due to reduced residence time, increased strain rate, and likely increase in a scalar dissipation rate. In the turbulent regime, fv decreases with PAH at a sharper rate, possibly due to reduced local time scales associated with turbulent eddies. Soot structure complexity is quantified through a fractal dimension (Df). Df increased with Re; however, in a turbulent regime Df becomes insensitive to Re. A semi-global correlation between fv and sheet thickness is also analyzed. A power-law trend is noted in the fv vs. thickness plot. Coefficients of power-fit are found to be Re-dependent. Additionally, the local correlation between fv and sheet thickness is examined, which revealed a non-monotonic trend. fv peaks at a preferred soot sheet thickness. These analysis-derived insights can contribute towards the understanding of soot-turbulence interaction. Furthermore, the reported database will facilitate the validation of soot chemistry models intended for practical fuels.

Processing of High-Paraffinic vacuum residues by thermocatalytic methods to obtain bitumen

This work was conducted to discover ways of processing high-paraffin oil residues using thermochemical processes to obtain binders. The principal purpose of such treatment of high-paraffinic residues is in the thermocatalytic process which consists of dehydroesterification via oxidation of paraffins which increase bitumen’s low-temperature stability (Fraass breaking point). Thus the n-alkanes, via our thermocatalytic process, can form several carbonyl compounds and oxidised compounds (such as alcohols, carboxylic acids, etc.). The thermocatalytic process of petroleum’s raw materials in our research carried out in two stages, including the catalytic process, as well as the thermal oxidation by air-blowing process. In this study, we used a biturox reactor. We evaluated the content of paraffin with GOST 33139 and low-field nuclear magnetic resonance (1H LF-NMR) relaxometry in high-paraffinic vacuum residues, and after our thermocatalytic process in the obtained product. Moreover, in order to ensure the reliability of results obtained through the processing of vacuum residues as well as the obtained product, various physicochemical methods were used. These investigation methods include SARA fractionation, Fourier-transform infrared spectroscopy, electron paramagnetic resonance (EPR), and VNII NP analysis. Furthermore, the colloidal structures were studied using the Gaestel and Asphaltene Index. The tests were carried out to determine the bitumen’s quality under the Russian interstate standard GOST 33133-2014 and the European standard EN 12591.

Effect of stearates on the thermal oxidation process of paraffin

Thermal reaction process of paraffin/stearate mixtures was studied by thermogravimetric–differential scanning calorimetry–Fourier transform infrared spectroscopy (TG–DSC–FTIR) simultaneous experiments under argon and oxygen atmospheres, and the thermal reaction kinetics were estimated through the non-isothermal measurements and model-free isoconversional methods. The results show that all stearates except for magnesium stearate have a positive effect on the oxidation of paraffin at lower temperature, but only cobalt stearate plays a positive effect during the whole oxidation process; the oxidation of paraffin/cobalt stearate mixture could be divided into three stages, and cobalt stearate could decrease the oxidation reaction temperature of paraffin obviously concerning the first stage; however, the catalytic effects could not be improved markedly by adding more cobalt stearate; the increase in activation energy (Ea) with the increase of cobalt stearate may be attributed to the adsorption catalysis system of the oxidation process.

Oxidation of ultralene and paraffin due to radiation damage after exposure to soft X-rays probed by FTIR microspectroscopy and X-ray fluorescence.

Radiation damage upon soft X-ray exposure is an important issue to be considered in soft X-ray microscopy. The work presented here is part of a more extended study on the topic and focuses on the effects of soft X-rays on paraffin, a common embedding medium for soft-tissues, and on ultralene and Si3N4 windows as sample supports. Our studies suggest that the sample environment indeed plays an important role in the radiation damage process and therefore should be carefully taken into account for the analysis and interpretation of new data. The radiation damage effects were followed over time using a combination of Fourier transform infrared (FTIR) microspectroscopy and X-ray fluorescence (XRF), and it was demonstrated that, for higher doses, an oxidation of both embedding medium and ultralene substrate takes place after the irradiated sample is exposed to air. This oxidation is reflected in a clear increase of C=O and O-H infrared bands and on the XRF oxygen maps, correlated with a decrease of the aliphatic infrared signal. The results also show that the oxidation process may affect quantitative evaluation of light element concentrations.

Thermal reaction characteristics of paraffin in the presence of combustion catalysts

Paraffin fuels are regarded to be the best solid fuel of hybrid rocket motor due to the high regression rate, low cost, and environment friendly products. However, the regression rate of the fuels still cannot completely meet the requirement of the motor. Catocene, copper chromite, and cobalt stearate have been used as the combustion catalysts in this study, where the simultaneous TG-FTIR-MS and TG experiments at different heating rates were carried to investigate the thermal behavior of paraffin and paraffin/combustion catalysts mixtures. The results showed that both paraffin and the mixtures could decompose or be oxidized into gases products almost completely, with the main decomposition product of C2H6 and oxidation products of C2H4O, CO, CO2, and H2O. There was only one stage for both decomposition and oxidation of paraffin, and the kinetic model of decomposition process are close to two-dimensional diffusion (D2 model); cobalt stearate favored the decomposition of paraffin owing to the higher pre-exponential factor and the lower activation energy, whereas only copper chromite played an obvious positive role in both oxidation and regression rate of paraffin.

Пионеры синтеза ионообменных материалов. 120 лет со дня рождения Александра Борисовича Даванкова (1899-1971)

Представлена история создания отечественных ионообменников с конца 1930 гг. по начало 1970 гг. на основе анализа работ лаборатории ионитов МХТИ им. Д.И. Менделеева. Представлена биография Александра Борисовича Даванкова – одного из отечественных пионеров ионного обмена, а также ранее неизвестные факты биографий и научные работы некоторых ученых, внесших заметный вклад в данную область. Впервые проанализированы ключевые публикации и патенты этого периода с историко-научной точки зрения.

Thermal oxidation reaction of paraffin with O2 and N2O under different pressures

Thermal reaction of paraffin with oxidizers could provide valuable information concerning the regression rate and combustion efficiency of paraffin-based fuels. In this paper, thermogravimetric–differential scanning calorimetry experiments were carried out for paraffin under O2 and N2O atmosphere, and the thermal reaction kinetics of paraffin under different pressures of O2 and N2O was estimated through the non-isothermal measurements and model-free isoconversional methods. The results show that the oxidation of paraffin under O2 and N2O atmosphere represents the multistage reaction process; the obtained activation energy (E a) is much close by using different model-free isoconversional methods, and paraffin is easier to be oxidized under O2 because of the lower E a and lower reaction temperature; Pressure plays a positive effect on the oxidation of paraffin, especially under O2 atmosphere.

Synthesis of thermally stable metal substituted hydroxy apatites for the selective oxidation of light paraffins

Hydroxyapatite and a series of hydroxyapatite-type compounds containing Co, Fe or Sr were synthesized by co-precipitation and characterized by ICP-OES, BET, IR, Raman spectroscopy, powder and in-situ XRD, SEM, TEM, TPR, TPD and TGA. In-situ XRD and TGA studies indicate that the materials are able to maintain their structure at temperatures reaching 900 °C. The TPD data indicated that acidic sites of varying strengths were present in all the three hydroxyapatites. From SEM, the surface of the materials consisted of an agglomeration of irregular plate-like particles. The catalytic activity of the compounds was investigated in the oxidation of n- pentane and n- hexane. The conversion of the feed and composition of the products were largely influenced by changes in the temperature and flow rates. For n -pentane, the products consisted of lower hydrocarbons and oxygenated compounds, carbon oxides and very small amounts 1,3-pentadiene, furan and furfural. Low conversions of n- hexane were obtained for all the tested catalysts and selective products were the hexene isomers and some aromatics. KEY WORDS : Hydroxyapatite, Selective oxidation of n -pentane and n -hexane, Characterization, Oxygenates, Olefins Bull. Chem. Soc. Ethiop. 2013 , 27(1), 57-68. DOI: http://dx.doi.org/10.4314/bcse.v27i1.6

ChemInform Abstract: The Role of the Geometric Factor in the Selective Oxidation of Lower Paraffins at VPO Catalysts

For the most widely published oxidation of n-butane at vanadium-phosphorus catalysts it was shown that the geometric factor plays a deciding role in the formation of the selective oxidation products. The mechanism proposed for the transformation of the paraffin at the [100] plane of the vanadyl pyrophosphate, which takes account of the geometry of the molecule being oxidized, explains the observed experimental facts, i.e., the increase in the oxidation rate with increase in the effective negative charge at the oxygen atoms of the catalyst, the positive effect of the hyperstoichiometric phosphorus on the selectivity of oxidation, the increased selectivity of oxidation with the introduction of additives that form phosphates, and the difference in the characteristics and mechanism of the oxidation of a paraffin and C4 olefins. On the basis of the proposed mechanism suggestions are made about possible paths for the transofrmation of C2−C6 paraffins at VPO catalysts and the factors that could affect the selectivity of these processes. A number of the suggestions were confirmed by the author's own investigations and by published investigations.

Study on Kinetics of Paraffin-Catalyzed Oxidation Reaction

Special wax was obtained by liquid-phase oxidation of paraffin by air in the presence of catalyst under atmosphere pressure. The oxidation reaction was carried out in a glass bubble reactor at 150–170°C, with 0.02 g of catalyst and a reaction time of 8 h. The kinetics and mechanism of the catalytic reaction were investigated and the kinetic models were developed. The contrast time method was employed to estimate the reaction order. The calculation results show that the first step of the reaction model obeys the first reaction order rule. Based on the assumption of first reaction order, the activation energy of the reaction model was obtained, thus providing reliable kinetic data for the theoretical analysis of special wax synthesis.

The selective oxidative activation of light alkanes. From supported vanadia to multicomponent bulk V-containing catalysts

V-containing materials have been proposed as active and selective catalysts in the selective oxidative transformation of C2–C4 alkanes to the corresponding olefins, oxygenates and nitriles. Although vanadium ions are generally assumed as the active sites in the oxidative activation of short chain alkanes, the coordination, the oxidation state and the environment of V atoms strongly influence both the catalytic activity and the nature of the reaction products. A comparative study on the catalytic behaviour of V-containing catalysts, i.e. metal vanadates, supported vanadium oxides, V-containing microporous/mesoporous materials and multicomponent bulk Mo–V–Te(Sb)–Nb mixed metal oxides, on the alkane oxidation is presented. The influence of the structure (including the V-coordination and V-environment) and the physico-chemical properties (especially redox and acid–base characteristics) of the catalysts on their behaviour in the selective oxidation of paraffins and alkenes is discussed.

Scanning calorimetry and thermogravimetry in analysis of petroleum systems. Determination of the component composition

The possibility of qualitative analysis of heavy hydrocarbon mixtures by differential scanning calorimetry (DSC) and quantitative analysis combined with thermogravimetry (TG) was demonstrated. In experimental conditions that ensure complete oxidation of the sample on heating, successive oxidation and evaporation of paraffins, light and heavy aromatics, and naphthenes, resins, asphaltenes, and carbenes take place. Crudes of different classes (waxy, naphthene-paraffin, naphthene bases) and geological age were investigated. Methods of qualitative and quantitative analysis by TG-DSC are reported.

The properties of hydrocarbon-oxidizing bacteria isolated from the oilfields of Tatarstan, western Siberia, and Vietnam

Eleven strains of hydrocarbon-oxidizing bacteria, isolated from oilfields, representing the genera Rhodococcus, Gordonia, Dietzia, and Pseudomonas, were characterized as mesophiles and neutrophiles. Rhodococci were halotolerant microorganisms growing in a media containing up to 15% NaCl. All the strains oxidized n-alkanes of crude oil. An influence of the cultivation temperatures (28 or 45 degrees C) and organic supplements on the degradation of C12-C30 n-alkanes in oxidized oil by two bacterial strains of the genus Pseudomonas was shown. The introduction of acetate, propionate, butyrate, ethanol, and sucrose led mainly to the decreased oxidation of petroleum paraffins. At certain cultivation temperatures, the addition of volatile fatty acid salts increased the content of individual n-alkanes in oxidized vs. crude oil.

Production of Acetic Acid by Oxidation of Butane with Air Under High Pressure

Acetic acid can be prepared by oxidation of paraffin, naphtha, and by direct reaction between methanol and carbon monoxide. In this work acetic acid was prepared by direct oxidation of butane with air for the first time. The optimum selectivity was obtained at 110–120○C and 60 atm in the presence of Cobalt acetate as a catalyst. A laboratory scale experimental high-pressure reactor was constructed. Results from experimental work were promising.

Factors affecting the efficiency of Nafion-based catalytic membranes in the selective oxidation of light paraffins mediated by the Fenton system

The partial oxidation of propane to oxygenates (isopropanol, n-propanol, propionic aldehyde and acetone) is attained in a multifunctional three phase catalytic membrane reactor (3PCMR) operating under mild conditions (TR, 80–120°C; PR, 140kPa). A comparative testing of different Nafion-based catalytic membranes mediated by Fe2+/H2O2 Fenton system has been carried out. The influences of textural and compositional properties and acid functionality on the catalytic performance of the Nafion membranes are outlined. The enhancing effect of the partial heterogenisation of the Fenton system on reaction rate and H2O2 yield is discussed.

Partial oxidation of light paraffins to synthesis gas in short contact-time reactors

The reaction pathways of ethane and propane partial oxidation to synthesis gas were investigated over a Pt/γ-Al 2O 3 and a Rh/α-Al 2O 3 catalyst. An annular reactor was used for this purpose at high space velocities and at temperatures below 700 °C in order to avoid homogeneous reactions. Under fuel-rich conditions, the Pt-based catalyst produced CO and H 2 at high temperatures (>550 °C), while CO 2 and H 2O were the only reaction products at lower temperatures. The formation of CO and H 2 was consistent with direct oxidation reactions, since contact time had no effect on the product distribution, and secondary reactions (steam and dry reforming) showed negligible activity. The Rh/Al 2O 3 catalyst was also active and selective in the partial oxidation of light hydrocarbons, but in this case the production of hydrogen and CO was strongly dependent on contact time, and steam reforming was important even at short contact times. It was concluded that, over rhodium, both direct and indirect routes were probably involved in the formation of CO and H 2. The main difference between the two noble metals thus seemed to be that Pt mainly produced CO and H 2 by means of O 2 (direct routes), while over Rh the light paraffins were converted to CO and H 2 by means of O 2 and H 2O (direct+indirect routes). This could explain the remarkably different behavior of the two systems when tested in high temperature autothermal reactors ( T>700 °C). Under adiabatic conditions, the partial oxidation of light paraffins led to large amounts of gas-phase olefinic products over Pt, whereas high selectivities to synthesis gas were found over Rh. The mechanistic results suggest that this different behavior could be due to the varying capability of Pt and Rh surface reactions to compete with homogeneous reactions.

Transition metal modified lacunary heteropoly compounds as catalysts for oxidation of light paraffins

Lacunary tungstophosphoric heteropoly compounds (HPW 11) of Keggin structure modified with transition metal ions (Fe 2+, Fe 3+ and Mn 2+) were applied as catalysts for oxydehydrogenation (ODH) of propane. The activity of iron modified HPW 11 was unstable in the reaction under investigation. High activity and selectivity for oxydehydrogenation reaction were achieved as a result of modification of heteropoly compounds with excess of manganese ions. Thermal treatment (400–500 °C) of HPW 11, modified with excess of manganese ions, resulted in the formation of a very active oxide like system. Lacunary heteropoly compounds play the role of a precursor for the formation of catalysts active for ODH. Stoichiometric HPW 11 containing Mn 2+ in the Keggin structure showed rather low activity.

The influence of some additives on the lubricating properties of semi-synthetic ester oils

This article presents research on the lubricating properties of semi-synthetic oils, made as compositions of mineral oil and esters. The esters were synthesized from acid substrates from the oxidation of paraffins. The last non-seizure load (Pn), the weld point (Pz), the load wear index (Ih), and the limiting wear load (Goz) were measured, and the effects of additives or mixtures of additives were investigated by their effects on these parameters. It was found that the efficiency of the additives depended on their chemical characteristics and concentration, and also on the chemical nature of the ester component of the semi-synthetic oils.

Oxidative dehydrogenation of light paraffins in novel short contact time reactors. Experimental and theoretical investigation

A previous study on the selective oxidation of propane over a commercial Pt/Al 2O 3 catalyst is herein extended to the oxidative dehydrogenation (ODH) of ethane. ODH tests were performed in an annular reactor, wherein catalytic experiments could be performed at varying temperatures on a wider operating field than that characteristic of autothermal reactors; besides, gas-phase experiments were performed for comparison. Together with the results of a theoretical analysis on homogeneous ethane oxidative pyrolysis, the bulk of data indicated that the high-temperature production of ethylene observed in the presence of the catalyst could be well explained by the single contribution of gas-phase radical reactions. The catalyst was proved to be active, instead, in the non-selective oxidation of paraffins to CO x . Further tests in an insulated millisecond contact time reactor demonstrated that the catalytic combustion reactions could be exploited to ignite the gas-phase reactions; comparison with the simulations of a purely homogeneous adiabatic reactor showed that at the highest temperatures the observed ethylene yields were close to the maximum obtainable values.