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1.
ChemSusChem ; 2021 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-33492767

RESUMO

Recycling multilayer plastic packaging is challenging due to its intrinsic compositional heterogeneity. A promising route to increase recycling rates for these materials is delamination, which allows recycling the polymers separately. Yet, this process is not well understood on a fundamental level. This study aimed to obtain first principles-based insights of the delamination mechanism of multilayer flexible packaging film (MFPF) with carboxylic acids. Delamination of MFPFs was described through a model based on Fick's first law of diffusion and first-order dissolution kinetics of polyurethane adhesives. The model was experimentally tested on 5 different MFPFs at different temperatures (50-75 °C), formic acid concentrations (50-100 vol %), and solid/liquid (S/L) ratios (0.005, 0.025, and 0.12 g mL-1 ). Under the studied conditions the model proved to successfully estimate the delamination time of MFPF with the average Theil's Inequality Coefficient (TIC) value of 0.14. Essential for scaling-up delamination processes is the possibility to use high S/L ratios as the solubility of the adhesive is rarely limiting.

2.
Waste Manag ; 120: 290-302, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33333467

RESUMO

Household packaging waste sorting facilities consist of complex networks of processes to separate diverse waste streams. These facilities are a key first step to re-enter materials into the recycling chain. However, so far there are no general methods to predict the performance of such sorting facilities, i.e. how efficiently the heterogeneous packaging waste is sorted into fractions with value for further recycling. In this paper, a model of the material flow in a sorting facility is presented, which allows changing the incoming waste composition, split factors on the sorting units as well as the setup of the sorting facility. The performance of the sorting facility is judged based on the purity of the output material (grade) and the recovery of the input material. A validation of the model was performed via a case study on Belgian post-consumer packaging waste with a selection of typical waste items that can be found in this stream. Moreover, the model was used to predict the possible sorting qualities of future Belgian post-consumer packaging waste after an extension of the allowed waste packaging items in the waste stream. Finally, a sensitivity analysis was performed on the split factors, which are a key data source in the model. Overall, the developed model is flexible and able to predict the performance of packaging waste sorting facilities as well as support waste management and design for recycling decisions, including future design of packaging, to ensure proper sorting and separation.


Assuntos
Eliminação de Resíduos , Gerenciamento de Resíduos , Fenômenos Físicos , Plásticos , Embalagem de Produtos , Reciclagem
3.
Waste Manag ; 2020 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-33139193

RESUMO

Mechanical recycling is to date the most commonly applied recycling technology. However, mechanical recycling of post-consumer plastics still faces many challenges, such as the presence of odorous constituents. Accordingly, recycling industry is looking for cost-effective solutions to improve the current washing efficiencies. However, scientific literature and basic understanding of deodorization processes are still scarce, which impedes efficient industrial optimization. Therefore, this study aims to obtain more fundamental insights in the deodorization mechanisms of plastic films in different washing media such as water, detergent, caustic soda, and ethyl acetate as organic solvent. The removal efficiencies of 19 odor components with a wide range of physicochemical properties were quantified via GC-MS analysis. The results revealed that deodorization depends on various factors such as temperature and physicochemical properties as polarity, volatility, and molecular weight of the odor components and the washing media. It was shown that polar washing media are less efficient compared to apolar media or media containing a detergent, achieving efficiencies of around 50% and 90%, respectively. The desorption processes can be accurately modeled by the isotherm model of Fritz-Schlunder in combination with a reversible first order kinetic model for the deodorization kinetics. Aspen Plus® process simulations of a water-based washing process reveal that at least 60% fresh water is needed to avoid saturation of the medium and undesired (re-)adsorption of odor components onto the plastics, which results in a substantial ecological footprint.

4.
Environ Sci Technol ; 54(20): 13282-13293, 2020 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-32985869

RESUMO

Plastic packaging typically consists of a mixture of polymers and contains a whole range of components, such as paper, organic residue, halogens, and metals, which pose problems during recycling. Nevertheless, until today, limited detailed data are available on the full polymer composition of plastic packaging waste taking into account the separable packaging parts present in a certain waste stream, nor on their quantitative levels of (elemental) impurities. This paper therefore presents an unprecedented in-depth analysis of the polymer and elemental composition, including C, H, N, S, O, metals, and halogens, of commonly generated plastic packaging waste streams in European sorting facilities. Various analytical techniques are applied, including Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), polarized optical microscopy, ion chromatography, and inductively coupled plasma optical emission spectrometry (ICP-OES), on more than 100 different plastic packaging products, which are all separated into their different packaging subcomponents (e.g., a bottle into the bottle itself, the cap, and the label). Our results show that certain waste streams consist of mixtures of up to nine different polymers and contain various elements of the periodic table, in particular metals such as Ca, Al, Na, Zn, and Fe and halogens like Cl and F, occurring in concentrations between 1 and 3000 ppm. As discussed in the paper, both polymer and elemental impurities impede in many cases closed-loop recycling and require advanced pretreatment steps, increasing the overall recycling cost.

5.
Polymers (Basel) ; 12(8)2020 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-32727004

RESUMO

Chemical or feedstock recycling of poly(methyl methacrylate) (PMMA) by thermal degradation is an important societal challenge to enable polymer circularity. The annual PMMA world production capacity is over 2.4 × 106 tons, but currently only 3.0 × 104 tons are collected and recycled in Europe each year. Despite the rather simple chemical structure of MMA, a debate still exists on the possible PMMA degradation mechanisms and only basic batch and continuous reactor technologies have been developed, without significant knowledge of the decomposition chemistry or the multiphase nature of the reaction mixture. It is demonstrated in this review that it is essential to link PMMA thermochemical recycling with the PMMA synthesis as certain structural defects from the synthesis step are affecting the nature and relevance of the subsequent degradation reaction mechanisms. Here, random fission plays a key role, specifically for PMMA made by anionic polymerization. It is further highlighted that kinetic modeling tools are useful to further unravel the dominant PMMA degradation mechanisms. A novel distinction is made between global conversion or average chain length models, on the one hand, and elementary reaction step-based models on the other hand. It is put forward that only by the dedicated development of the latter models, the temporal evolution of degradation product spectra under specific chemical recycling conditions will become possible, making reactor design no longer an art but a science.

6.
Waste Manag ; 104: 148-182, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31978833

RESUMO

Additives are ubiquitously used in plastics to improve their functionality. However, they are not always desirable in their 'second life' and are a major bottleneck for chemical recycling. Although research on extraction techniques for efficient removal of additives is increasing, it resembles much like uncharted territory due to the broad variety of additives, plastics and removal techniques. Today solvent-based additive extraction techniques, solid-liquid extraction and dissolution-precipitation, are considered to be the most promising techniques to remove additives. This review focuses on the assessment of these techniques by making a link between literature and physicochemical principles such as diffusion and Hansen solubility theory. From a technical point of view, dissolution-precipitation is preferred to remove a broad spectrum of additives because diffusion limitations affect the solid-liquid extraction recoveries. Novel techniques such as accelerated solvent extraction (ASE) are promising for finding the balance between these two processes. Because of limited studies on the economic and environmental feasibility of extraction methods, this review also includes a basic economic and environmental assessment of two extreme cases for the extraction of additives. According to this assessment, the feasibility of additives removal depends strongly on the type of additive and plastic and also on the extraction conditions. In the best-case scenario at least 70% of solvent recovery is required to extract plasticizers from polyvinyl chloride (PVC) via dissolution-precipitation with tetrahydrofuran (THF), while solid-liquid extraction of phenolic antioxidants and a fatty acid amide slip agents from polypropylene (PP) with dichloromethane (DCM) can be economically viable even without intensive solvent recovery.


Assuntos
Plásticos , Reciclagem , Plastificantes , Cloreto de Polivinila , Solventes
7.
Materials (Basel) ; 12(16)2019 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-31405103

RESUMO

Low-coking reactor material technologies are key for improving the performance and sustainability of steam crackers. In an attempt to appraise the coking performance of an alternative Ti-base alloy during ethane steam cracking, an experimental study was performed in a jet stirred reactor under industrially relevant conditions using thermogravimetry (Tgasphase = 1173 K, Ptot = 0.1 MPa, XC2H6 = 70%, and dilution δ = 0.33 kgH2O/kgHC). Initially, a typical pretreatment used for Fe-Ni-Cr alloys was utilized and compared with a pretreatment at increased temperature, aiming at better surface oxidation and thus suppressing coke formation. The results revealed a decrease in coking rates upon high temperature pretreatment of the Ti-base alloy, however, its coking performance was significantly worse compared to the typically used Fe-Ni-Cr alloys, and carbon oxides formation increased by a factor of 30 or more. Moreover, the analyzed coupons showed crack propagation after coking/decoking and cooling down to ambient temperature. Scanning electron microscopy combined with energy-dispersive X-ray spectroscopy indicated that the prompt and unsystematic oxidation of the surface and bulk caused observable crack initiation and propagation due to alloy brittleness. Hence, the tested Ti-base alloy cannot be considered an industrially noteworthy steam cracking reactor alloy.

8.
Science ; 364(6442): 734-735, 2019 05 24.
Artigo em Inglês | MEDLINE | ID: mdl-31123123
9.
Chem Commun (Camb) ; 55(44): 6245-6248, 2019 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-31086889

RESUMO

By using flexible metal organic frameworks such as MIL-53(Al), the selective uptake of 4-methylguaiacol was achieved from a simulated bio-oil (40 wt%). Similar high uptake capacity of phenolics (27 wt%) was observed from a real pyrolysis bio-oil, with good selectivity towards a variety of phenolics, e.g. guaiacol, 4-methylguaiacol and catechol.


Assuntos
Estruturas Metalorgânicas/química , Fenóis/isolamento & purificação , Óleos Vegetais/química , Polifenóis/química , Temperatura Alta
10.
ChemSusChem ; 12(15): 3642-3653, 2019 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-31081279

RESUMO

Twelve new quaternary ammonium sophorolipids with long alkyl chains on the nitrogen atom were synthesized starting from oleic and petroselinic acid-based sophorolipids. These novel derivatives were evaluated for their antimicrobial activity against selected Gram-negative and Gram-positive bacteria and their transfection efficacies on three different eukaryotic cell lines in vitro as good activities were demonstrated for previously synthesized derivatives. Self-assembly properties were also evaluated. All compounds proved to possess antimicrobial and transfection properties, and trends could be observed based on the length of the nitrogen substituent and the total length of the sophorolipid tail. Moreover, all long-chain quaternary ammonium sophorolipids form micelles, which proved to be a prerequisite to induce antimicrobial activity and transfection capacity. These results are promising for future healthcare applications of long-chained quaternary ammonium sophorolipids.


Assuntos
Anti-Infecciosos/química , Lipídeos/química , Compostos de Amônio Quaternário/química , Transfecção , Anti-Infecciosos/farmacologia , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Micelas , Testes de Sensibilidade Microbiana , Compostos de Amônio Quaternário/farmacologia , Relação Estrutura-Atividade
11.
Comput Struct Biotechnol J ; 17: 599-610, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31080566

RESUMO

Genetic engineering is a powerful tool to steer bio-oil composition towards the production of speciality chemicals such as guaiacols, syringols, phenols, and vanillin through well-defined biomass feedstocks. Our previous work demonstrated the effects of lignin biosynthesis gene modification on the pyrolysis vapour compositions obtained from wood derived from greenhouse-grown poplars. In this study, field-grown poplars downregulated in the genes encoding CINNAMYL ALCOHOL DEHYDROGENASE (CAD), CAFFEIC ACID O-METHYLTRANSFERASE (COMT) and CAFFEOYL-CoA O-METHYLTRANSFERASE (CCoAOMT), and their corresponding wild type were pyrolysed in a Py-GC/MS. This work aims at capturing the effects of downregulation of the three enzymes on bio-oil composition using principal component analysis (PCA). 3,5-methoxytoluene, vanillin, coniferyl alcohol, 4-vinyl guaiacol, syringol, syringaldehyde, and guaiacol are the determining factors in the PCA analysis that are the substantially affected by COMT, CAD and CCoAOMT enzyme downregulation. COMT and CAD downregulated transgenic lines proved to be statistically different from the wild type because of a substantial difference in S and G lignin units. The sCAD line lead to a significant drop (nearly 51%) in S-lignin derived compounds, while CCoAOMT downregulation affected the least (7-11%). Further, removal of extractives via pretreatment enhanced the statistical differences among the CAD transgenic lines and its wild type. On the other hand, COMT downregulation caused 2-fold reduction in S-derived compounds compared to G-derived compounds. This study manifests the applicability of PCA analysis in tracking the biological changes in biomass (poplar in this case) and their effects on pyrolysis-oil compositions.

12.
J Phys Chem B ; 123(17): 3841-3858, 2019 05 02.
Artigo em Inglês | MEDLINE | ID: mdl-31002250

RESUMO

Conventional head-chain but also more exotic divalent, Gemini, or bolaform amphiphiles have in common well-defined hydrophilic and hydrophobic blocks with often a predictable self-assembly behavior. However, new categories of amphiphiles, such as microbial biosurfactants, challenge such conventional understanding because of the poorly defined boundaries between the hydrophilic and hydrophobic portions. Microbial glycolipids, such as sophorolipids, rhamnolipids, or cellobioselipids, interesting biodegradable, nontoxic, alternatives to synthetic surfactants, all represent interesting examples of atypical amphiphiles with partially predictable self-assembly properties. However, their limited molecular diversity strongly limits their application potential. For this reason, we used them as ready-made platform to prepare a whole class of new derivatives. In particular, a broad range of amino derivatives of sophorolipid biosurfactant was recently prepared with the goal of producing biobased antimicrobial and transfection agents, of which the efficiency strongly depends on their molecular structure and unpredictable self-assembly behavior. The new compounds contain a set of asymmetrical and symmetrical bolaamphiphiles, the latter with three or four hydrophilic centers, divalent amphiphiles with asymmetric polar headgroups and even Y-shaped amphiphiles, bearing two sophorose groups connected to one nitrogen atom. In this contribution, we employ small-angle X-ray scattering to establish a relationship between their peculiar molecular structures and the self-assembly properties in water. We find that all divalent and Y-shaped compounds form micelles, of which the hydrophilic shell is composed of a bulky sophorose-C x( x = 8,11)-amine moiety, with aggregation numbers between 30 and 100. On the contrary, most symmetrical and asymmetrical bolaamphiphiles display poor self-assembly properties, generally showing aggregation numbers below 20, especially in the presence of either short spacers or large spacers containing hydrophilic centers.


Assuntos
Ácidos Oleicos/química , Tensoativos/química , Interações Hidrofóbicas e Hidrofílicas , Estrutura Molecular , Ácidos Oleicos/síntese química , Tensoativos/síntese química
13.
ChemSusChem ; 12(6): 1256-1266, 2019 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-30810285

RESUMO

The capping formate anions of the metal-organic framework (MOF) zirconium benzene-1,3,5-tricarboxylate (MOF-808) were removed by a solvent exchange procedure, resulting in a formate-free MOF-808 sample containing "geminal" defects consisting of six coordinatively unsaturated sites (CUSs) on each of the Zr6 nodes. Adsorption experiments with this material showed that the uptake of 4-methylguaiacol from a bio-oil mixture was proportional to the number of defects and amounted to one mole adsorbed per mole of zirconium. The selective uptake behavior of MOF-808 towards phenolic compounds was further evident from competitive adsorption experiments between furfuryl alcohol and 4-methylguaiacol as well as from the excellent (20 wt % for phenolic compounds and <7 wt % for other compounds) uptake performance for real bio-oil mixtures containing a large concentration and diversity of molecules.

14.
Materials (Basel) ; 11(10)2018 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-30287759

RESUMO

The service time of an industrial cracker is strongly dependent on the long-term coking behavior and microstructure stability of the reactor coil alloy. Super alloys are known to withstand temperatures up to even 1400 K. In this work, several commercially available alloys have been first exposed to a long term oxidation at 1423 K for 500 h, so-called metallurgic aging. Subsequently, their coking behavior was evaluated in situ in a thermogravimetric setup under ethane steam cracking conditions (Tgasphase = 1173 K, Ptot = 0.1 MPa, XC2H6 = 70%, continuous addition of 41 ppmw S/HC of DMDS, dilution δ = 0.33 kgH2O/kgHC) and compared with their unaged coking behavior. The tested samples were also examined using scanning electron microscopy and energy diffractive X-ray for surface and cross-section analysis. The alloys characterized by increased Cr-Ni content or the addition of Al showed improved stability against bulk oxidation and anti-coking behavior after application of metallurgic aging due to the formation of more stable oxides on the top surface.

15.
J Cheminform ; 10(1): 11, 2018 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-29524042

RESUMO

Both the automated generation of reaction networks and the automated prediction of synthetic trees require, in one way or another, the definition of possible transformations a molecule can undergo. One way of doing this is by using reaction templates. In view of the expanding amount of known reactions, it has become more and more difficult to envision all possible transformations that could occur in a studied system. Nonetheless, most reaction network generation tools rely on user-defined reaction templates. Not only does this limit the amount of chemistry that can be accounted for in the reaction networks, it also confines the wide-spread use of the tools by a broad public. In retrosynthetic analysis, the quality of the analysis depends on what percentage of the known chemistry is accounted for. Using databases to identify templates is therefore crucial in this respect. For this purpose, an algorithm has been developed to extract reaction templates from various types of chemical databases. Some databases such as the Kyoto Encyclopedia for Genes and Genomes and RMG do not report an atom-atom mapping (AAM) for the reactions. This makes the extraction of a template non-straightforward. If no mapping is available, it is calculated by the Reaction Decoder Tool (RDT). With a correct AAM-either calculated by RDT or specified-the algorithm consistently extracts a correct template for a wide variety of reactions, both elementary and non-elementary. The developed algorithm is a first step towards data-driven generation of synthetic trees or reaction networks, and a greater accessibility for non-expert users.

16.
Phys Chem Chem Phys ; 20(16): 10877-10894, 2018 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-29517772

RESUMO

A set of group additivity values for intramolecular hydrogen abstraction reactions of alkanes, alkenes and alkynes is reported. Calculating 448 reaction rate coefficients at the CBS-QB3 level of theory for 1-2 up to 1-7 hydrogen shift reactions allowed the estimation of ΔGAV° values for 270 groups. The influence of substituents on (1) the attacking radical, (2) the attacked carbon atom, and (3) the carbon chain between the attacking and attacked reactive atom has been systematically studied. Substituents have been varied between hydrogen atoms and sp3, sp2 and sp hybridized carbon atoms. It has been assumed that substituents further away from the reactive atoms or their connecting carbon chain have negligible influences on the kinetics. This group additivity model is applicable to a wide variety of reactions in the 300-1800 K temperature range. Correlations for tunneling coefficients have been generated which are complementary to the ΔGAV°'s to obtain accurate rate coefficients without the need for imaginary frequencies or electronic energies of activation. These correlations depend on the temperature and activation energy of the exothermic step. The group additivity model has been successfully applied to a test set of reactions also calculated at the CBS-QB3 level of theory. A mean absolute deviation of 1.18 to 1.71 has been achieved showing a good overall accuracy of the model.

17.
Chemosphere ; 200: 561-568, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29505928

RESUMO

Selected sophorolipid quaternary ammonium salts (SQAS), being a new class of modified biosurfactants, were studied in this work for the first time with regard to their biodegradability and fate in the environment. It was made to find whether environment-friendly bioproducts like biosurfactants are still safe to the environment after their chemical modification. The susceptibility of these SQAS for biodegradation was estimated together with the evaluation of their influence on activated sludge microorganisms. Additionally, the mechanisms of removal of the SQAS from wastewater and from the aquatic environment, were analysed. The evaluated SQAS were potentially biodegradable, although none of them could be classified as readily biodegradable. The biodegradation degrees after 28 days ranged from 4 to 42%, dependent on the SQAS tested, i.e. below the required OECD 301D Closed Bottle Test level of 60%. Simultaneously, the analysis of the mass spectra revealed the presence of the breakdown products of each SQAS studied. Biodegradation was preceded by sorption of the SQAS on sludge particles, which occurred to be a main mechanism of the removal of these newly synthesized biosurfactants from wastewater. The mean degree of sorption calculated on the basis of SQAS determination was from 75 to 96%, dependent on the studied SQAS. The presence of SQAS in wastewater did not deteriorate the operation of the activated sludge system, although the products of the SQAS biodegradation remained in the liquid phase and might contribute to the increase of COD of the effluent to be introduced to the environment.


Assuntos
Bactérias/metabolismo , Compostos de Amônio Quaternário/metabolismo , Tensoativos/metabolismo , Poluentes Químicos da Água/metabolismo , Biodegradação Ambiental , Esgotos/química , Esgotos/microbiologia , Águas Residuárias/química , Águas Residuárias/microbiologia
18.
J Chromatogr A ; 1509: 102-113, 2017 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-28648258

RESUMO

An improved method for on-line measurement of sulfur containing compounds in complex matrices is presented. The on-line system consists of a specifically designed sampling system connected to a comprehensive two-dimensional gas chromatograph (GC×GC) equipped with two capillary columns (Rtx®-1 PONA×SGE BPX50), a flame ionization detector (FID) and a sulfur chemiluminescence detector (SCD). The result is an unprecedented sensitivity down to ppm level (1 ppm-w) for various sulfur containing compounds in very complex hydrocarbon matrices. In addition to the GC×GC-SCD, the low molecular weight sulfur containing compounds such as hydrogen sulfide (H2S) and carbonyl sulfide (COS) can be analyzed using a thermal conductivity detector of a so-called refinery gas analyzer (RGA). The methodology was extensively tested on a continuous flow pilot plant for steam cracking, in which quantification of sulfur containing compounds in the reactor effluent was carried out using 3-chlorothiophene as internal standard. The GC×GC-FID/-SCD settings were optimized for ppm analysis of sulfur compounds in olefin-rich (ethylene- and propylene-rich) hydrocarbon matrices produced by steam cracking of petroleum feedstocks. Besides that is primarily used for analysis of the hydrocarbon matrix, FID of the GC×GC-FID/-SCD set-up serves to double check the amount of added sulfur internal standard which is crucial for a proper quantification of sulfur compounds. When vacuum gas oil containing 780 ppm-w of elemental sulfur in the form of benzothiophenes and dibenzothiophenes is subjected to steam cracking, the sulfur balance was closed, with 75% of the sulfur contained in the feed is converted to hydrogen sulfide, 13% to alkyl homologues of thiophene while the remaining 12% is present in the form of alkyl homologues of benzothiophenes. The methodology can be applied for many other conversion processes which use sulfur containing feeds such as hydrocracking, catalytic cracking, kerogen evolution, bio-waste pyrolysis, supercritical water treatment, etc.


Assuntos
Automação/métodos , Cromatografia Gasosa/métodos , Ionização de Chama/métodos , Hidrocarbonetos/química , Compostos de Enxofre/química , Catálise , Petróleo/análise
19.
ACS Sustain Chem Eng ; 4(9): 4974-4985, 2016 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-27668136

RESUMO

Fast pyrolysis bio-oils are feasible energy carriers and a potential source of chemicals. Detailed characterization of bio-oils is essential to further develop its potential use. In this study, quantitative 13C nuclear magnetic resonance (13C NMR) combined with comprehensive two-dimensional gas chromatography (GC × GC) was used to characterize fast pyrolysis bio-oils originated from pinewood, wheat straw, and rapeseed cake. The combination of both techniques provided new information on the chemical composition of bio-oils for further upgrading. 13C NMR analysis indicated that pinewood-based bio-oil contained mostly methoxy/hydroxyl (≈30%) and carbohydrate (≈27%) carbons; wheat straw bio-oil showed to have high amount of alkyl (≈35%) and aromatic (≈30%) carbons, while rapeseed cake-based bio-oil had great portions of alkyl carbons (≈82%). More than 200 compounds were identified and quantified using GC × GC coupled to a flame ionization detector (FID) and a time of flight mass spectrometer (TOF-MS). Nonaromatics were the most abundant and comprised about 50% of the total mass of compounds identified and quantified via GC × GC. In addition, this analytical approach allowed the quantification of high value-added phenolic compounds, as well as of low molecular weight carboxylic acids and aldehydes, which exacerbate the unstable and corrosive character of the bio-oil.

20.
J Vis Exp ; (114)2016 08 05.
Artigo em Inglês | MEDLINE | ID: mdl-27583700

RESUMO

The shift to heavy crude oils and the use of alternative fossil resources such as shale oil are a challenge for the petrochemical industry. The composition of heavy crude oils and shale oils varies substantially depending on the origin of the mixture. In particular they contain an increased amount of nitrogen containing compounds compared to the conventionally used sweet crude oils. As nitrogen compounds have an influence on the operation of thermal processes occurring in coker units and steam crackers, and as some species are considered as environmentally hazardous, a detailed analysis of the reactions involving nitrogen containing compounds under pyrolysis conditions provides valuable information. Therefore a novel method has been developed and validated with a feedstock containing a high nitrogen content, i.e., a shale oil. First, the feed was characterized offline by comprehensive two-dimensional gas chromatography (GC × GC) coupled with a nitrogen chemiluminescence detector (NCD). In a second step the on-line analysis method was developed and tested on a steam cracking pilot plant by feeding pyridine dissolved in heptane. The former being a representative compound for one of the most abundant classes of compounds present in shale oil. The composition of the reactor effluent was determined via an in-house developed automated sampling system followed by immediate injection of the sample on a GC × GC coupled with a time-of-flight mass spectrometer (TOF-MS), flame ionization detector (FID) and NCD. A novel method for quantitative analysis of nitrogen containing compounds using NCD and 2-chloropyridine as an internal standard has been developed and demonstrated.


Assuntos
Cromatografia Gasosa/métodos , Hidrocarbonetos/análise , Medições Luminescentes/métodos , Espectrometria de Massas/métodos , Compostos de Nitrogênio/análise , Ionização de Chama/métodos , Petróleo/análise , Piridinas/química
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