MICROBIAL. TRANSFORMATION AND BIODEGRADATION OF CALOTROPIS PROCERA LATEX TOWARDS OBTAINING VALUE ADDED CHEMICALS,PHARMACEUTICALS AND FUELS

ABSTRACT

The latex of Calotropia arocera (Ait.) R.Br., (a potential petrocrop) may be exploited to obtain fuels and chemicals. This latex has been subjected to microbial action with Sphaerotilus aeruginosa, Sphaerotilus natans, Streptococcus sp.. Escherichia coli. Penicllllum expanaum and Mucor Sp. with an aim to find out a biochemical route way to obtain fuels and chemicals. The treated latex was extracted with hexane, chloroform and methanol separately. The extracts obtained were analysed using 13CNMR and ¹HNMR spectral techniques to understand the chemical dynamics of biotransformation of latex components. Microbial action was found to degrade, biotransform, oxidise, dehydrogenate and dearomatize the chemical components of the latex. S. aeruginosa and streptococcus sp were found to be the potential candidates for the microbial degradation of latex. Latex mainly contains triterterpenoid, steroid etc. compounds. These acyclic and naphthenic type of compounds are stabler and relatively less reactive compounds. Hydrotreatment of such compounds by thermal degradation would require drastic conditions. The complex degradation reactions at high temperature (under pressure) would be slower. Microbial treatment renders the latex (;and compounds present therein) as reactive substrates or feedstocks close for hydrotreatment for obtaining value added and premium products. These products may include value added chemicals, fuels and pharmaceuticals etc. in the long run. Microbial treatments may reduce the heat panalty of the hydrogen treatment etc. process. This may also make the rates of the hydrotreatment etc. reactions faster to afford the continuous processes in the long run     

Degradation of alkyl radicals via C-C bond dissociation: Kinetic parameters and transition state geometry

Experimental data on the gas-phase degradation of alkyl radicals of the type R¹CHR²C^?H₂ → CHR² = CH₂ + R^?1 were rationalized in terms of the method of crossing parabolas. The parameters characterizing the degradation were calculated. The semiempirical algorithm for the calculation of the geometric parameters of the transition state of methyl radical addition to olefins is extended over the reactions of degradation of alkyl radicals. The kinetic (activation energy) and geometric (interatomic distances in the transition state) parameters of the reaction were calculated for the degradation of alkyl radicals of various structures. For the degradation reactions involving the detachment of the methyl radical, a linear correlation between the transition-state interatomic distance r ^#(C…C) and the enthalpy of the reaction ΔH _e was revealed: r ^#(C…C) × 10¹⁰/m = 2.37 ? 1.19 × 10^?2 ΔH _e/kJ mol^?1. A similar relationship is observed for the ethylene elimination reactions: r ^#(C…C) × 10¹⁰/m = 2.40 ? 1.46 × 10^?2ΔH _e/kJ mol^?1. The enthalpies, activation energies, and transition-state interatomic distances for the degradation of alkyl radicals involving H^? and C^?H₃ detachment are compared.     

Stability tests of TNAZ — thermal and shock impact

Abstract

Two types of tests were performed on 1,3,3-trinitroazetidine. (A) Analyses were made of decomposition products generated from gaseous TNAZ when kept in stainless steel or Pyrex containers at various temperatures (< 240°C) for up to 24 hours. (B) Evidence for evaporation of the compound or the appearance of NO₂ was sought when thin layers of solid TNAZ (initially at R.T.) were impacted by shock-waves, in an Ar or Ar/O₂ medium. The step functions of the pressure/temperature increments had rise times well below microseconds. The pressure jumps ranged from 2–10 atm, and the associated temperature jumps varied from 550 to 2500K. In all these tests the elevated pressure/temperature conditions lasted for 1.5 ms. Finally, shock-waves were impacted on a well packed cavity (3/16″ thick; 3/8″ diameter) filled with powdered TNAZ to a depth of 1/8″. Under these relatively mild perturbations no detectable evaporation or decomposition was observed.     

Some Ab initio MO studies relevant to the thermal decomposition of TNT

Abstract

Ab initio molecular orbital calculations in a variety of basis sets and including electron correlation have been used to examine the energetics of the channel for TNT decomposition involving intramolecular hydrogen transfer. Calculations both for the model system, 1-nitropropene, and for TNT itself, are reported. These studies pay particular attention to the determination of the transition state for these reactions. It is shown that model systems have considerable value in such studies, as do semiempirical methods. The calculated barrier for intramolecular hydrogen transfer in TNT is found to be close to the measured activation energy for the induction reaction.     

Kinetic parameters and geometry of the transition state of decarboxylation reactions of carboxyl and formyl radicals

Experimental data on the degradation of carboxyl radicals RCO ₂ ^. → R^. + CO₂ (where R is an alkyl or aryl) and formyl radicals ROC^.O → R^. + CO₂ (where R is an alkyl or aryl) in the liquid phase were analyzed in terms of the method of crossing parabolas. The kinetic parameters that characterize this decomposition were calculated. Using the density functional theory, the transition state was calculated for the reaction of methyl radical addition to CO₂ at the C and O atoms. A semiempirical algorithm was developed for the calculation of the geometric parameters of the transition state for decomposition reactions of carboxyl and formyl radicals and the reverse addition reactions of R^. with CO₂. The kinetic (activation energies and rate constants) and geometric (interatomic distances in the transition state) reaction parameters were calculated for 37 degradation reactions of various formyl and carboxyl radicals. The activation energies and geometric parameters of the transition state were calculated for the alternative addition reactions of R^. to CO₂:R^. + CO₂ → RCO ₂ ^. (where R is an alkyl or aryl) and R^. + CO₂ → ROC^.O (where R is an alkyl or aryl). A linear correlation between the interatomic distance r ^#(C...C) (or r ^#(C...O)) in the transition state and the reaction enthalpy ΔH _e was found for the degradation reactions of carboxyl and formyl radicals (at br _e = const). The enthalpies, activation energies, and interatomic distances in the transition state for the degradation of carboxyl and formyl radicals and their formation were compared.     

Degradation of alkyl radicals via C-H bond dissociation: Kinetic parameters and transition state geometry

Experimental data on the decomposition of alkyl radicals in the gas phase of the type RCH₂C^.H₂ → RCH=CH₂ + H^. were analyzed in terms of the method of crossing parabolas. The parameters characterizing such decomposition were calculated. The activation energy E _e0 for the thermoneutral degradation reaction was shown to depend on the radical structure. The degradation of the radicals RCH₂C^.H₂, CH₂=CRC^.H₂, PhC^.HCH₂R, and CH₂=C^.CH₂R is characterized by E _e0 = 81.6, 85.9, 85.9, and 115.2 kJ mol^?1, respectively. The semiempirical algorithm for calculation of geometric parameters of the transition state for reactions of hydrogen atom addition to olefins was extended to the degradation reactions of alkyl, aminoalkyl, and ketyl radicals. The kinetic (activation energies) and geometric (interatomic distances in the transition state) reaction parameters were calculated for the decomposition reactions of various alkyl, alkylaromatic, aminoalkyl, and ketyl radicals.     

Oxidative desulfurization of 4,6-dimethyldibenzothiophene in a two impinging streams spray reactor

Oxidative desulfurization of 4,6-dimethyldibenzothiophene was performed in a two impinging streams spray reactor (TIS-SR) using H₂O₂ and phosphotungstic acid as oxidant and catalyst, respectively. The reaction was optimized using response surface methodology. The reaction constant of a pseudo first order rate based on the dynamic data obtained for the optimal operation conditions was calculated to be 9.45 × 10^?4 s^?1. It is about one order of magnitude larger than the one calculated for a conventional ideal stirred batch reactor at the same reaction conditions (1.03 × 10^?4 s^?1). Accordingly, ODS reaction rate may be substantially enhanced using TIS-SR.     

Oxidation of alcohols involving two types of peroxyl radicals

Liquid-phase oxidation of alcohols (R¹R²CHOH) occurs as a chain reaction involving two peroxyl radicals, namely, R¹R²C(OH)O ₂ ^· and HO ₂ ^· . Using the model of crossing parabolas, the activation energy and the rate constant were calculated for the reactions of α-hydroperoxyl radicals with four alcohols. A kinetic analysis of this reaction as a two-center chain process in which two peroxyl radicals that differ in reactivity (R¹R²C(OH)O ₂ ^· and HO ₂ ^· ) participate in chain propagation was performed. The relative amounts of the peroxyl radicals and their contribution to chain propagation under different oxidation conditions (temperature, alcohol concentration) were calculated for the oxidation of four alcohols: ethanol, 2-propanol, cyclohexanol, and α-phenylethanol. A change in the ratio between radicals due to the accumulation of a carbonyl compound and the fast addition of hydroperoxyl radicals to the carbonyl group during alcohol oxidation was considered and its effect on the chain propagation step in the oxidation reaction was discussed.     

X-RAY DIFFRACTION USED TO MEASURE LEVELS OF SP2 AND SP3 CARBON IN FOSSIL FUELS: A MICROCOSM OF THE 1990'S,WORKING HARDER AND GETTING LESS

ABSTRACT

The proposition that a diffraction peak can be “far too intense to be caused by amorphous scattering and far too broad to be caused by conventional diffraction” is analyzed and found to be in error. Theoretically, Debye peaks arising from intermolecular interference in liquids and conventional Bragg peaks are part of a continuum. Experimentally, with respect to the “(002)” peak in benzenoid materials, not all aromatic carbons need contribute to an intermolecular interference peak, so that determinations of sp² or sp³ carbon abundance based on analysis of only the “(002)” peak are necessarily flawed. As a separate but related matter, journal citation trends of relevance to the court case Gordon and Breach v. AIP are analyzed     

Kinetics and Selectivity of Asphaltene Thermal Cracking,Thermal Hydrocracking,and Catalytic Hydrocracking

Abstract

A pentane-insoluble asphaltene was processed by thermal cracking, thermal hydrocracking, and catalytic hydrocracking in a microbatch reactor at 430°C. The experimental data of asphaltene conversion fit second-order kinetics adequately to give the apparent rate constants of 1.704 × 10^?2, 2.435 × 10^?2, and 9.360 × 10^?2 wt frac^?1 min^?1 for the above three cracking processes, respectively. A three-lump kinetic model is proposed and solved to obtain rate constants of parallel reactions of asphaltenes to produce liquid oil (k₁) and gas + coke (k₃) and a consecutive reaction from liquid to gas + coke (k₂). The value of k₁ is 1.697 × 10^?2, 2.430 × 10^?2, and 9.355 × 10^?2 wt frac^?1 min^?1; k₂ is 3.605 × 10^?2, 2.426 × 10^?2, and 6.347 × 10^?3 min^?1; and k₃ is 6.934 × 10^?5, 5.416 × 10^?5, and 4.803 × 10^?5 wt frac^?1 min^?1 for asphaltenes thermal cracking, thermal hydrocracking, and catalytic hydrocracking, respectively. Analysis of selectivity shows that the catalytic hydrocracking process provides the highest liquid production, and the coking process provides the highest coke formation, as expected. An induction period of coke formation was found to increase from thermal cracking to thermal hydrocracking to catalytic hydrocracking process.     

Spectrophotometric determination of erbium using kojic acid dye in different rare earth concentrates

A sensitive and selective spectrophotometric method was studied for the determination of erbium (Er) with kojic acid dye (koj) and cetylpyridinium chloride (CPC) as a cationic surfactant from Egyptian monazite and xenotime concentrates using third derivative spectrophotometry. The calibration curve was linear from 1 to 150?µg/mL erbium. The influence of various parameters and reaction conditions for optimum complex formation were investigated. The relative standard deviation for determination of 1?µg/mL erbium was found to be 1.5 after 5 repeated determinations with percentage error for Er determination from monazite and xenotime concentrates 6.4% and 4.48% respectively. The molar absorptivity of conventional and third derivative spectrum were 0.14?×?10³?M^?1?cm^?1 and 0.13?×?10³?M^?1?cm^?1 respectively and the detection limit was 1?µg/mL.     

Kinetics of desulfurization by electrochemical oxidation in an emulsifying electrolyte

Diesel with S content 624.4 µg/g was directly used, and a constant current of 500 mA was proposed in this work. Emulsification as an enhancement method was used to enhance the interphase mass transfer. After emulsifying electrochemical oxidation–extraction, the sulfur content of diesel decreased to 8.1 µg/g and the desulfurization efficiency reached 98.71 %. On comparingwith the non-emulsifying electrochemical oxidation–extraction, it has a highly efficient deep desulfurization.

The analysis also found that the effect of emulsion and non-emulsion extraction desulfurization process on electrochemical oxidation has great difference under the same operating conditions, and parameters such as the order, reaction rate and activation energy of the two kinds of oxidation desulfurization reaction were studied. The results showed the oxidative desulfurization reaction is the first reaction. When the temperature reached T₂, the oxidation rate constant of the emulsion/non-emulsion system was 0.0199 min^?1 and 0.0179 min^?1, respectively. When the temperature reached T₁, the oxidation rate constant of the emulsion/non-emulsion system was 0.0375 min^?1 and 0.0346 min^?1, respectively. According to Arrhenius' law, the apparent activation energy of sulfur compounds in the raw oil is E_a (emulsion) = 6.9783 kJ/mol and E_a (non-emulsion) = 9.1826 kJ/mol, respectively.     

Effect of small concentrations of water on ethylbenzene oxidation with molecular oxygen catalyzed by iron(II, III) acetylacetonate complexes with 18-crown-6

The catalytic effects of small amounts of water (～10^?3 mol/l) added to the ethylbenzene oxidation reaction with molecular oxygen catalyzed by the system {Fe(III)(acac)₃ + 18-crown-6 (18C6)} were revealed. An increase in the reaction rate was observed, and the direction of the oxidation reaction changed. In the presence of the catalytic system {Fe(III)(acac)₃ (5.0 × 10^?3 mol/l) + 18C6 (5.0 × 10^?3 mol/l) + H₂O (3.7 × 10^?3 mol/l}, the main product at early stages of ethylbenzene oxidation is acetophenone, rather than α-phenylethyl hydroperoxide produced in the case of catalysis by the system {Fe(III)(acac)₃ (5.0 × 10^?3 mol/l) + 18C6 (5.0 × 10^?3 mol/l)} (in the absence of water admixture). A method is proposed to evaluate the activity of forming in situ (Fe(II)(acac)₂) _x (18C6) _y (H₂O) _n complexes at microstages of chain initiation (O₂ activation) and propagation (Ct+RO ₂ ^· ) involving the catalyst, which determine the rate and selectivity of oxidation. A possible “dioxygenase-like” mechanism of conversion of iron complexes with 18C6 in the presence of activating H₂O admixtures is discussed.     

Reductive dimerization and oligomerization of alcohols,ketones, and aldehydes to hydrocarbons on a promoted,fused iron catalyst

A new reductive dimerization and oligomerization reaction of (C₅ and C₆) cycloalkanols and cycloalkanones, benzaldehyde, and benzyl alcohol to hydrocarbons containing as many, or more, carbon atoms as the reactant oxygenated compound on a promoted, fused iron catalyst proceeds at a temperature of 250–350°C, a hydrogen pressure of 0.1–1 MPa, a specific feed rate of oxygenated reagent of 80–320 g h^?1kg^?1Ct, and a hydrogen space velocity of 1 × 10³ to 20 × 10³ h^?1. Possible reaction mechanisms have been considered.     

The influence of nature of the anion in tetraalkylammonium salts on the crystallization of zeolite beta

The influence of the nature of anion X in the tetraethylammonium salt [N(C₂H₅)₄]X on the selectivity of the formation zeolite beta in the SiO₂-Al₂O₃-Na₂O-[N(C₂H₅)₄]X-H₂O system under hydrothermal conditions without seed crystals was studied. It was shown that the test anions can be arranged in the following series in terms of the preferential formation of zeolite beta: F^?, SO ₄ ^2? , PO ₄ ^3? , (CH₂COO) ₂ ^2? > HCOO^? > (COO) ₂ ^2? , CH₃COO^? ? Cl^? ～ NO ₃ ^? ? Br^? ? I^? ? ClO ₄ ^? . In particular, the fluoride and the anions of polybasic acids facilitate the formation of zeolite, whereas perchlorate, bromide, and iodide ions inhibit its formation. The experiments showed that anions facilitating the formation of zeolite beta make it possible to synthesize zeolite within the same broad range of chemical composition of the reaction mixture as in the case of [N(C₂H₅)₄]OH. The reveled classification of anions into groups coincides with their categorization by Samoilov into anions with positive and negative hydration.     

Hydroalkylation of benzene and ethylbenzene over metal-containing zeolite catalysts

The hydroalkylation reaction of benzene and ethylbenzene over BEA zeolites with a Si/Al ratio of 9–190, MOR with Si/Al = 48, and MFI with Si/Al = 25 containing ruthenium, rhodium, platinum, or palladium was studied, as well as over the Ru/BEA zeolites with Si/Al = 42 doped with a second metal: nickel, cobalt, or rhodium. The catalytic experiments were conducted under flow conditions in the temperature range 130–190°C, a pressure of 1 MPa, a feed weight hourly space velocity of 2–64 h^?1, and a stoichiometric reactant ratio. It was shown that the main reaction routes are the complete hydrogenation of benzene and ethylbenzene yielding cyclohexane and ethylcyclohexane, respectively; hydroalkylation yielding cyclohexylbenzene, para- and meta-ethylcyclohexylbenzenes, and diethylcyclohexylbenzenes; and alkylation resulting in dicyclohexylbenzenes and ethyldicyclohexylbenzenes. The ruthenium-promoted (1 wt %) zeolite BEA with Si/Al = 42 displayed the highest activity and selectivity in the benzene and ethylbenzene hydroalkylation reactions. Doping of the catalyst with cobalt and rhodium did not improve its catalytic properties, presumably, owing to the fact that the dopant metals largely occur in the cationic form according to the IR data for adsorbed CO. An admixture of nickel (0.5 wt %) to the catalyst increases the catalyst operation stability without reducing the yield of ethylcy-clohexy lbenzenes.     

The thermal decomposition of basic lead styphnate RD 1349 at its ignition temperature

Abstract

Basic lead styphnate RD 1349 forms the primary explosive component of several high temperature fuzehead formulations and percussion primers. A study of its thermal decomposition under controlled conditions near its ignition temperature (521–525 K) shows that it decomposes very rapidly, following a second order autocatalytic rate law. The kinetics of this reaction are initially controlled by the ‘‘nucleation of reactive molecules'’occurring on the crystal surfaces or glide planes, by the growth of these nuclei as the reaction proceeds and, in the rate determining step, by their subsequent reaction in the bulk of the material. The rate determining step in this reaction follows Arrhenius kinetics with an activation energy of 197 kJ mol^?1 and pre-exponential log₁₀ A (s^?1) = 17.9.     

Synthesis,interface activity and oil flooding experiment with an authentic sandstone microscopic model of cationic gemini surfactant

In this work, a series of cationic gemini surfactants with different hydrophobic tails were prepared and characterized by element analysis, IR spectra, and ¹H NMR spectra. The influencing factors of physic-chemical properties of these surfactants were carefully studied. The critical micelle concentration (CMC) of all the surfactants ranged from 3.87 × 10^?4 mol L^?1 to 8.97 × 10^?4 mol L^?1 and the values (γ_cmc) also ranged from 28.62 mN m^?1 to 34.07 mN m^?1 at CMC level by surface tension experiments. The consequences of the oil/water interface tension experiments indicated that all these prepared surfactants could lower oil/water interface tension to ultra-low with the combination of Na₂CO₃. C₁₂-2-C₁₂, and C₁₄-2-C₁₄ were chosen as the representative to evaluate the displacement efficiency in the oil flooding experiments using authentic sandstone microscopic model. The results showed that these surfactants could effectively improve the displacement efficiency by 10–20%.     

Study on product distribution and catalytic performance of ZSM-5 in methanol conversion to gasoline-range hydrocarbons (MTHC)

Precise product distribution data is very important for kinetic modeling of chemical reactions and chemical reactor design. In this work, H-ZSM-5 catalyst was hydrothermally synthesized and characterization tests including XRD, XRF, BET, and NH₃-TPD revealed its physicochemical properties. Then, methanol conversion into hydrocarbons over ZSM-5 was investigated with WHSV of 4 h^?1 at reaction temperature 410°C. Product distribution result indicated that C₃-C₅⁺ and C₂⁼-C₄⁼ were the major products in gaseous phase, and in liquid phase xylenes, three methyl benzene and C₁₀⁺ aromatics were the main components. It was also observed that the synthesized ZSM-5 had good performance in the methanol to hydrocarbons process and gave rise to highest activity (100%) during 10 h of operation approximately.     

Synthesis of mixed polynitroorthocarbonates and related derivatives

Abstract

Tris(polynitroalkoxy)chloromethanes (chloroorthoformates), a new class of compounds, are prepared by the chlorination of tris(polynitroalkoxy)methyl disulfides. The chloroorthoformates are reactive intermediates, which with alcohols give mixed 1:3 and 1:1:2 orthocarbonates. Additional derivatives are obtained with nucleophiles such as F^?, N₃ ^?, CN^?, and 2-imidazolidone.