Monocyclic Aromatics Research Articles

Correlations among thermophysical properties, ignition quality, volatility, chemical composition, and kinematic viscosity of petroleum distillates

Thermophysical measurements and Raman spectroscopy were utilized to investigate 17 hydrocarbon distillates derived from Canadian oil sands in this work. Thermal lens and optical interferometer techniques were used to determine the thermal diffusivity (D) and temperature coefficient of the refractive index (dn/dT), respectively. It was found that D and dn/dT are closely correlated with the cetane numbers, distillation temperatures, monocyclic aromatics contents, and kinematic viscosities of the fuels. Raman spectra yielded information on the chemical compositions of the distillates, with aromatic contents proving to be particularly relevant. Multivariate analysis elucidated the relationships among the samples, their properties according to ASTM analyses, and the influence of composition on D and dn/dT.

Incorporation of paper sludge in clay brick formulation: Ten years of industrial experience

The large amounts of sewage sludge (11million tonnes in Europe in 2005) produced in paper manufacturing plants require the introduction of recycling and/or alternative recovery solutions to minimize the amounts of generated waste, such as its use in soil remediation or in the cement industry. A feasible alternative to valorize that waste is the use of paper sludge as raw material in the production of structural ceramic or clay bricks.Previous studies tried to incorporate sewage sludge from different sources into ceramic matrices, unfortunately with little success in the final result for most types of sludge. However, those experiments carried out using as additive sludge from the paper industry succeeded in producing a material suitable for the red ceramic industry.In this paper, binary mixtures of clay and paper sludge under different formulations were produced and their physico-chemical properties were studied. Increasing the paper sludge content in the clay mixture provides the material with improved properties regarding its thermal and acoustic insulation, but in turn it decreases its mechanical strength. However, this fragility of the material is compensated by an increased ductility. Regarding metal leaching, the studied ceramics have no environmental restrictions as far as their use as building material is concerned, as the obtained results were virtually identical to those for the blank samples (100% clay). Results showed that the presence of dichloromethane (373.2μgm−3) and propanone (61.2μgm−3) in the samples with added sludge was relatively relevant with respect to concentrations in samples made of 100% clay. All monocyclic aromatics detected showed a concentration level far below their odor threshold. In general, thus, it can be concluded that volatile organic compound (VOC) emissions during firing of the new ceramic material do not involve any particular problem. Finally, the experience obtained after more than 10years of industrial production of this new mixed ceramic product was also analyzed. This analysis allowed confirmation that clay brick production with incorporation of paper sludge waste is a feasible solution from a technical point of view. As a key outcome, this fact has helped the reduction in a large proportion the amount of sludge produced by the Spanish paper industry ending up in landfills.

Isolation and characterization of humic substances‐degrading bacteria from the subarctic Alaska grasslands

Humic substances (HS), an important fraction of soil organic carbon, are distributed widely throughout cold environments. A total of cold-adapted 122 bacterial strains were isolated from 66 Alaska grassland soil samples based on their ability to grow on humic acids (HA), a main fraction of HS, as a carbon and energy source. These isolates were identified based on 16S rRNA gene sequencing, with class Bacilli (79.5%) and γ-Proteobacteria (17.1%) comprising the largest groups. Among them, 45 strains, mainly Paenibacillus (27 strains) and Pseudomonas (15 strains), were selected for further screening. Two strains (Pseudomonas sp. PAMC 26793 and Paenibacillus sp. PAMC 26794) most efficiently degraded HA, but showed significant differences in their ability to grow on various monocyclic aromatics, which are putative degradative metabolites of HS. Fourier transform infrared spectra also showed substantial but different changes in HA chemical structure after incubation with each strain. Gel permeation chromatography demonstrated that depolymerization and polymerization of HA occurred during HS degradation by these newly isolated microbes.

Catalytic pyrolysis of microalgae for production of aromatics and ammonia

We report an economically- and environmentally-promising microalgae biorefinery pathway, which uses catalytic pyrolysis with HZSM-5 catalyst to convert whole microalgae into aromatic hydrocarbons. This process produces valuable petrochemicals and ammonia, the latter of which can be recycled as a fertilizer for microalgae cultivation. We tested samples of lipid-lean green microalgae, Chlorella vulgaris, at various reaction temperatures and catalyst loads. We also tested samples of lignocellulosic biomass, red oak, for comparison. Our results demonstrated that catalytic pyrolysis of microalgae produces better aromatic yields and better aromatic distributions than catalytic pyrolysis of red oak. The maximum carbon yield of aromatics from microalgae was 24%, while that from red oak was 16.7%. Moreover, catalytic pyrolysis of microalgae produced more monocyclic aromatics than were produced by catalytic pyrolysis of lignocellulosic biomass. Microalgae present many advantages as a feedstock for biofuel. With the promise catalytic pyrolysis offers for solving some of microalgae's disadvantages, microalgae biorefineries move one step closer to economic and environmental feasibility.

Influence of Solution Thermal and Structural History on the Nucleation of m-Hydroxybenzoic Acid Polymorphs

Influence of Solution Thermal and Structural History on the Nucleation of <i>m</i>-Hydroxybenzoic Acid Polymorphs

Naphthenic ring opening of perhydrophenanthrene over zeolite catalysts

AbstractExperiments of perhydrophenanthrene cracking over zeolite catalysts were conducted in a small fixed fluidized bed (FFB) unit. Effects of Y and ZSM-5 zeolite catalysts, temperature and catalyst/oil ratio on naphthenic ring opening reactions of perhydrophenanthrene were examined. The results show that products from naphthenic ring opening reactions of perhydrophenanthrene over zeolite catalysts are monocyclic or dicyclic cycloparaffin (cyclohexane, decalin), which is further converted into isoparaffin (2-methylpenptane, methyl hexane) by side chain breaking, or into monocyclic aromatics (benzene, C1–4 alkyl benzene) by hydrogen transfer, or into dicyclic aromatics (tetrahydronaphthalene, naphthalene, alkyl naphthalene) by deep hydrogen transfer. Products from dehydrogenation condensation reactions of perhydrophenanthrene are polycyclic aromatics with more than 3 rings (phenanthrenes, pyrenes) and coke. Due to the influence of naphthenic diffusion and adsorption on catalysts, selectivity of the naphthenic ring opening reaction is higher over Y catalyst than that over ZSM-5 catalyst. The relative ratio of naphthenic ring opening reactions to dehydrogenation condensation reactions, abbreviated as s(NRO)/s(DHC), is higher over Y catalyst than that over ZSM-5 catalyst. At the weight hourly space velocity of 10 h−1, temperature of 475–550°C, catalyst/oil mass ratio of 3.0–9.0, reactions of bimolecular hydrogen transfer and dehydrogenation condensation became stronger, and selectivity of the products from naphthenic ring opening reactions decreases with the rising of temperature or catalyst/oil ratio over Y catalyst.

A first step towards identification of tannin-derived black carbon: Conventional pyrolysis (Py–GC–MS) and thermally assisted hydrolysis and methylation (THM–GC–MS) of charred condensed tannins

Tannins account for a significant proportion of plant biomass and are likely to contribute to the residues formed by incomplete biomass combustion (black carbon, BC). Nonetheless, the molecular properties of thermally modified tannins have not been investigated in laboratory charring experiments. We applied conventional analytical pyrolysis–gas chromatography–mass spectrometry (Py–GC–MS) and thermally assisted hydrolysis and methylation (THM–GC–MS) to investigate the effects of heat treatment with a muffle furnace on the properties of condensed tannins (CT) from Corsican pine (Pinus nigra) needles. Py–GC–MS showed a decrease in the relative abundance of the 1,2,3-trihydroxybenzenes (pyrogallols) at ⩾300°C and of the dihydroxybenzenes (mainly catechols) at ⩾350°C due to dehydroxylation of the CT B ring. Further dehydroxylation led to formation of monohydroxybenzenes (phenols), which showed a strong enrichment between 350 and 400°C and, at higher temperatures, to a series of monocyclic and polycyclic aromatics [benzene, alkyl benzenes and polycondensed aromatic hydrocarbons (PAHs)]. Degradation of the A ring could not be recognized via Py–GC–MS, probably because of the poor chromatographic behavior of 1,3,5-trihydroxybenzenes (phloroglucinols). The progressive dehydroxylation and eventual polycondensation of the CT B ring was corroborated using THM–GC–MS. In addition, with THM–GC–MS the thermal rearrangement of CT A rings at 300°C and higher was inferred from the relative abundance of 1,3,5-trimethoxybenzenes (methylated phloroglucinol derivatives). These compounds were observed at moderate/high temperature (up to 450°C) and can not be produced from THM of lignin, suggesting that they may be markers of CT in natural BC samples.

Optimizing the aromatic yield and distribution from catalytic fast pyrolysis of biomass over ZSM-5

The conversion of glucose, furan and maple wood has been investigated over different types of ZSM-5 catalyst in semi-batch and fixed-bed reactors. The aromatic yield from glucose conversion goes through a maximum as a function of the framework silica-to-alumina ratio (SAR) of ZSM-5 with an optimum at SAR=30. This suggests that the concentration of acid sites inside the zeolite is critical for maximizing aromatic yield. Creating hierarchical mesopores within the zeolite slightly increased of coke formation and decreased the formation of the monocyclic aromatics. Mesoporous ZSM-5 was also observed to favor the production of larger alkylated monoaromatics. The selective removal of external acid sites from the ZSM-5 catalysts only slightly increased the catalyst activity but also decreased the selectivity to the desired aromatic products.

Production of green aromatics and olefins by catalytic fast pyrolysis of wood sawdust

Catalytic fast pyrolysis of pine wood sawdust and furan (a model biomass compound) with ZSM-5 based catalysts was studied with three different reactors: a bench scale bubbling fluidized bed reactor, a fixed bed reactor and a semi-batch pyroprobe reactor. The highest aromatic yield from sawdust of 14% carbon in the fluidized bed reactor was obtained at low biomass weight hourly space velocities (less than 0.5 h−1) and high temperature (600 °C). Olefins (primarily ethylene and propylene) were also produced with a carbon yield of 5.4% carbon. The biomass weight hourly space velocity and the reactor temperature can be used to control both aromatic yield and selectivity. At low biomass WHSV the more valuable monocyclic aromatics are produced and the formation of less valuable polycyclic aromatics is inhibited. Lowering the reaction temperature also results in more valuable monocyclic aromatics. The olefins produced during the reaction can be recycled to the reactor to produce additional aromatics. Propylene is more reactive than ethylene. Co-feeding propylene to the reactor results in a higher aromatic yield in both continuous reactors and higher conversion of the intermediate furan in the fixed bed reactor. When olefins are recycled aromatic yields from wood of 20% carbon can be obtained. After ten reaction–regeneration cycles there were metal impurities deposited on the catalyst, however, the acid sites on the zeolite are not affected. Of the three reactors tested the batch pyroprobe reactor yielded the most aromatics, however, the aromatic product is largely naphthalene. The continuous reactors produce less naphthalene and the sum of aromatics plus olefin products is higher than the pyroprobe reactor.

Recent Advances of Bismuth(III) Salts in Organic Chemistry: Application to the Synthesis of Aliphatics, Alicyclics, Aromatics, Amino Acids and Peptides, Terpenes and Steroids of Pharmaceutical Interest

In this review recent uses of the inexpensive and commercially available bismuth(III) salts in organic chemistry will be highlighted. Their application to the development of new processes or synthetic routes that lead to compounds of pharmaceutical interest will be matter of discussion. It will focus on bismuth(III) salt-mediated reactions involving the preparation of non-heterocyclic compounds such as aliphatics and alicyclics, monocyclic and polycyclic aromatics, amino acids and peptides, terpenes and steroids.

Offline LC‐GC×GC in combination with rapid‐scanning quadrupole mass spectrometry

The present research is focused on the offline combination of normal-phase LC to double-oven GC x GC-quadrupole MS. Initially, a diesel sample was subjected to automated LC x GC in order to define the elution windows of four fractions, viz., saturated hydrocarbons, monocyclic aromatics, dicyclic aromatics, tri- + tetracyclic aromatics; each fraction was collected exploiting the LC system in a further analysis and subjected to large-volume-injection-GC x GC analysis using an apolar-polar column combination. The GC x GC operational conditions were tuned in relation to the specific separation requirements of each heart-cut. The main benefits of what can be defined as offline LC-GC x GC were: (i) the high first-dimension LC selectivity; (ii) the injection of high sample amounts in the GC x GC system, enabling the detection and quantification of a series of low-amount diesel constituents; (iii) improved GC x GC operational conditions for each heart-cut with respect to direct GC x GC.

Hydraulic, water quality, and isotopic characterization of Late Cretaceous-Tertiary Ardley coal waters in a key test-well, Pembina-Warburg exploration area, Alberta, Canada

Abstract A detailed evaluation of the hydraulic parameters and formation fluids of a key test-well completed in the uppermost Ardley coal was undertaken in the Pembina-Warburg exploration area, Alberta Basin, Alberta, Canada. The testing method isolated the target coal zone from the overlying Paskapoo Formation with an intermediate casing set in the coal. Measurements showed a build-up of fluid (water) pressure within the coal to approximately 1,470 kPa. Detailed hydrogeological testing showed that the permeability of the coal is clearly less than 5 mD and likely on the order of 1 mD. Formation waters sampled during the drawdown and build-up phases were Na-HCO3 type with salinities of approximately 1,920 mg/L TDS (calculated). Sodium and chloride concentrations were approximately 835 and 250 mg/L, respectively. Detailed analyses of the formation waters showed that dissolved and total trace metal concentrations fall within Canadian drinking water quality standards with the exception of iron and manganese. Organic compounds including monocyclic aromatics (Benzene, Toluene, Ethyl-benzene, Xylene, BTEX) were not detected, with the exception of trace toluene concentrations. Anomalously high bicarbonate concentrations of up to 1650 mg/L (δ13CDIC +22.50 ‰) and dissolved methane concentrations of up to 36 mg/L (δ13CCH4 −48.32 ‰) point to the presence of secondary biogenic gas. Formation waters are non-tritiated; δ18O and δ2H values plot along the local groundwater line for Edmonton, Alberta indicating a meteoric origin. Data from the test-well suggest that depressurization (i.e., diversion of fluids) of the coal zone is necessary for gas production. If depressurization is contained to within the coalbeds, relatively small quantities of produced fluids would be anticipated. Although most of the groundwater for consumption within the immediate area of the test well is obtained from shallower parts of the flow systems in the uppermost parts of the Paskapoo Formation, under the current regulatory framework a Preliminary Groundwater Assessment as defined by the Alberta Environment and the EUB (2004) would be necessary prior to diversion.

Thermodynamic and transport behaviour of binary liquid mixtures of benzyl alcohol with monocyclic aromatics at 303.15 K

This paper presents densities, ρ, ultrasonic speeds, u, viscosities, η, and refractive indices, n, of pure benzyl alcohol (BA), benzene (B), chlorobenzene (CB), benzonitrile (BN), nitrobenzene (NB), and their binary liquid mixtures, with BA as a common component, over the whole composition range at 303.15 K. The excess molar volumes, V E, deviations in isentropic compressibility, Δ k s, viscosity, Δ η, ultrasonic speed, Δ u, and in refractive index, Δ n, were calculated from the experimental data. The apparent molar volumes, V ϕ,2, and apparent molar isentropic compressibilities, K ϕ,2, of B, CB, BN and NB in BA were also calculated. The values of V ϕ,2 and K ϕ,2 were used to estimate the partial molar volumes, V¯ ϕ,2 0, and partial molar isentropic compressibilities, K¯ ϕ,2 0, of B, CB, BN and NB in BA at infinite dilution. The variations of these parameters with composition of the mixtures suggest that the interaction between BA and B/CB/BN/NB molecules follow the sequence: B < CB < BN < NB. Apart from using density data for the calculation of V E, excess molar volumes have also been estimated by using Flory's statistical theory. The results show that Flory's theory predicts V E well for the mixture with least interaction between the component molecules while it shows large deviation for the mixture showing highest interaction.

Synthesis of Vicinal Diols from Various Arenes with a Heterocyclic, Amino or Carboxyl Group by Using Recombinant Escherichia coli Cells Expressing Evolved Biphenyl Dioxygenase and Dihydrodiol Dehydrogenase Genes.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Hazardous substances in separately collected grey- and blackwater from ordinary Swedish households

The objective of this paper is to present the mass flows of a number of selected hazardous substances in raw, separate grey- and blackwater from ordinary Swedish households. The Vibyasen housing area was selected for the investigation since its wastewater system has separate flows for grey- and blackwater. Due to the high analytical costs, a limited number of hazardous substances had to be selected and the number of samples restricted. The greywater flow was manually measured and the samples were collected at set time intervals. The blackwater samples were randomly collected from a blackwater tank. A total of 105 selected hazardous substances were measured in both fractions. Of the 24 elements (Ca, Fe, K, Mg, Na, S, Al, Ag, As, Ba, Bi, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Pt, Sb, Sn, Te, Zn) measured in both fractions, 22 were detected in the greywater and 23 in the blackwater. 81 organic substances were selected and measured in both fractions (nonylphenol- and octylphenol ethoxylates, brominated flame-retardants, organotin compounds, PAH, PCB, phthalates, monocyclic aromatics, and triclosan). 46 organic substances were found in greywater and 26 in blackwater. PCB was the only group found in neither grey- nor blackwater. The greywater flow fluctuated, with a specific average flow of 66 L per person and day. The composition of blackwater also fluctuated, with shifting proportions of urine, faeces, and flush water. The specific average blackwater flow was 28.5 L per person and day. The mixture of substances in separate wastewater fractions from Swedish households was too complex to exactly distinguish their specific sources.

Synthesis of vicinal diols from various arenes with a heterocyclic, amino or carboxyl group by using recombinant Escherichia coli cells expressing evolved biphenyl dioxygenase and dihydrodiol dehydrogenase genes

Various aromatic molecules, in which heterocycles are linked with a phenyl or benzyl group, were converted to their respective 2,3-diols (catechols) in the benzene ring by growing cell reactions using recombinant Escherichia coli, which expressed the evolved biphenyl dioxygenase [ bphA (2072)] genes and the subsequent bacterial dihydrodiol dehydrogenase ( bphB) gene. These vicinal diol products showed strong in vitro inhibitory activity against the lipid peroxidation induced by free radicals and strong scavenging activity towards DPPH radicals. The vicinal diols were also synthesized from ionized monocyclic aromatics incorporating an amino or carboxyl group.

FT-Raman and photoacoustic infrared spectroscopy of syncrude light gas oil distillation fractions

FT-Raman and photoacoustic (PA) infrared spectra of 12 distillation fractions derived from Syncrude light gas oil (LGO), which has a boiling range from 195 to 343 °C, were analyzed in detail in this study. In the fingerprint region (200–1800 cm −1) most of the information is obtained from the FT-Raman spectra, which display 36 bands that are assignable to various alkyl or aryl functional groups. Monocyclic, bicyclic and tricyclic aromatics in the 12 fractions were also characterized using Raman bands in this region. The corresponding section of the infrared spectra is much simpler, displaying a relatively small number of bands due to either aromatic or aliphatic CH n ( n=1, 2 or 3) groups. The CH stretching region in both FT-Raman and PA infrared spectra of the LGO distillation fractions was curve-fitted according to procedures established in previous investigations of Syncrude samples with various boiling ranges. The PA spectra of the LGO fractions were also analyzed using an accepted integration strategy that requires no a priori assumptions with regard to the number of constituent bands or their shapes. The curve-fitting results show that the frequencies of the 11 Raman and eight infrared bands used to model the aliphatic (∼2775–3000 cm −1) parts of the respective spectra decrease systematically as the median boiling points of the LGO fractions increase. These band positions are consistent with those determined in earlier studies of other distillation fractions. Both curve fitting and integration show that the abundance of CH 2 groups increases at the expense of CH 3 groups as the boiling points of the fractions increase within the LGO region.

FT-Raman and photoacoustic infrared spectroscopy of Syncrude heavy gas oil distillation fractions

FT-Raman and photoacoustic (PA) infrared spectra of six distillation fractions derived from Syncrude heavy gas oil (HGO), which has a boiling range from 343 to 524 °C, were analyzed in detail in this study. Most of the information on the fingerprint region (200–1800 cm −1) is provided by the FT-Raman spectra, which display approximately 30 bands that are assignable to functional groups in alkanes or aromatics. Monocyclic, bicyclic and tricyclic aromatics in the six fractions were also monitored using bands in this region. The CH stretching region in both the FT-Raman and PA infrared spectra of the HGO distillation fractions was analyzed according to a curve-fitting algorithm used in previous investigations of samples with lower boiling points. The PA spectra of the HGO fractions were also analyzed by integration. The curve-fitting results show that the frequencies of the 11 Raman and 8 infrared bands used to model the aliphatic (∼2775–3000 cm −1) parts of the respective spectra are approximately constant across the entire HGO boiling range. These band positions are consistent with the results obtained in earlier studies of other distillation fractions obtained from Syncrude sweet blend. Both curve-fitting and integration show that the respective proportions of CH 2 and CH 3 groups do not vary significantly within the HGO region.

Dimerization of cyclopentadienyl radical to produce naphthalene

An improved polycyclic aromatic hydrocarbon (PAH) model is developed to predict the decomposition of indene and the formation of large PAHs under pyrolytic conditions. This model is developed based on experimental study of pyrolytic kinetics of indene in a flow reactor at low and atmospheric pressures (30 and 760 Torr) by using synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). A general map of PAH growth is presented according to the observations in this study and those in literature. Indene dissociates via indanyl forming mono-cyclic aromatics and small intermediates, while its dominant decomposition product is indenyl. As a resonantly stabilized radical, indenyl serves as a platform molecule in PAH growth process which links small unsaturated hydrocarbons and mono-aromatic species to multi-cyclic ones. Reactions of indenyl radical are proposed to form commonly studied and recently observed PAHs. Rate constants of these reactions are evaluated by analyzing literature data of rate constant measurements, quantum chemical calculations and analogy to cyclopentadienyl radical. The main PAH formation pathways are the bi-molecular addition reactions of indenyl radical with indene and a series of intermediates, forming C10C18 and larger PAHs. Meanwhile, radical chain reactions provide huge passage for PAH growth form one resonantly stabilized radical (RSR) to larger ones. Particular contribution has been found from the reactions of RSRs that have five-member ring in their molecular structures, such as fluorenyl, benz-indenyl, cyclopenta-phenanthrenyl and benzo-fluorenyl.

Flavonoids in seed and root exudates of Lotus pedunculatus and their biotransformation by Mesorhizobium loti

Analysis of the flavonoid content of seed and root exudates of Lotus pedunculatus was undertaken using multiple coupled analytical techniques: capillary zone electrophoresis coupled to a UV spectral array detector (CZE‐UV), high performance thin‐layer chromatography with densitometry (HPTLC‐UV) and gas chromatography with mass spectrometry (GC‐MS). These procedures provided separation, identification and structural confirmation of the previously unidentified flavonoids in this plant's seed and root exudates and were particularly applicable to samples from a small seeded legume. Catechin, naringenin, kaempferol, quercetin aglycone and 3 different glycosides of quercetin were detected in seed exudate. Sterile root exudates contained catechin, naringenin and quercetin in addition to apigenin, kaempferol and other flavones and flavanones for which partial identifications were obtained. When sterile root exudate was incubated with Mesorhizobiumloti, changes in its flavonoid content were detected. Analysis of bacterial cells after incubation revealed the presence of quercetin, kaempferol and one other flavone. The monocyclic aromatics protocatechuic acid and phloroglucinol were detected in both the incubated root exudate and its bacterial cells.