Wyniki wyszukiwania - Biblioteka Nauki

1

Niobia supported on silica as a catalyst for Biodiesel production from waste oil

100%

Tesser R. , Vitiello R. , Carotenuto G. , Garcia Sancho C. , Vergara A. , Maireles Torres P. J. , Li C. , Di Serio M.

Catalysis for Sustainable Energy

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2014

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tom 1

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nr 1

EN

The activity and stability of niobia supported on silica catalyst have been tested in continuous micro-pilot reactors, for biodiesel production starting from acid vegetable oils. A catalyst was prepared by the impregnation of silica pellets with a loading of 12% of Nb and was extensively characterized. The activity of this catalyst in both esterification and transesterification was tested in a continuous micro-pilot laboratory plant in which acid oil was fed (FFA 10% w/w) at a temperature of 220°C and at a pressure of 60 bar. The niobia based catalyst resulted in a very active catalyst in both esterification (FFA conversion = 95-90%) and transesterification reactions (FAME yield = 80-90%), and the activity remained quite constant for more than 100 h on stream. Notwithstanding this stability, a non-negligible leaching phenomena has been detected, in the case of long-time continuous runs, as the Nb concentration on the spent catalyst resulted lower than that on the fresh one. The obtained result confirms that the leaching of the active specie is one of the most strong problem in heterogeneous catalysis for biodiesel production.

2

Screening of lipase carriers for reactions in water, biphasic and pure organic solvent systems

100%

Hrydziuszko Z. , Dmytryk A. , Majewska P. , Szymańska K. , Liesiene J. , Jarzębski A. , Bryjak J.

Acta Biochimica Polonica

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2014

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tom 61

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nr 1

1-6

EN

In bioprocesses lipases are typically used in immobilized form, irrespective of type of reaction systems, to ensure an even distribution of catalysts in water restricted media and/or to facilitate separation and reuse. In these studies we report on the selection of appropriate enzyme-carrier preparation for hydrolysis reaction in aqueous and biphasic systems and transesterification in organic solvent. For this Candida rugosa lipase was bound by adsorption or covalent attachment onto various carriers to give 24 preparations. Selection of proper preparation was based on reactivity, thermal stability (4 h at 60°C), possibility of drying and operational stability in 17-23 successive batch processes of 4-nitrophenyl palmitate hydrolysis in water. Activity of preparations varied from 20 to 5100 U∙mL-1 but the most stable preparations were those of moderate activity: bound by adsorption or covalent attachment to NH2-Kieselgel or acrylic carrier (retained activity over 90%). Selected preparations were used for hydrolysis of ethyl (1-butyryloxyethyl)-phenylphosphinate in biphasic system, and, after drying, in ethyl (1-hydroxyethyl)-phenyl-phosphinate transesterification. In this study operational stability was the principal criterion of selection. In water system, lipase covalently bound to NH2-Kieselgel was the best - preserved 50% of initial activity in consecutive batch processes. In biphasic system and lipase covalently bound to acrylic and NH2-Kieselgel the values were 90 or 77%, respectively, whereas in organic solvent, when lipase was immobilized on NH2-Kieselgel by adsorption, it was 50%. Thus, NH2-Kieselgel appears to be an universal matrix for investigated lipase immobilization and can be used in all reaction systems.

3

On the utilization of the glycerin fraction - a side product of biofuel production from vegetable oils

100%

Sulewski M. , Urbaniak W. , Wasiak W.

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2010

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tom Vol. 12, nr 1

57-66

EN

The glyceric fraction, forming as a side product in the process of production of biodiesel from plant oils, does not consist, how it results from many popular papers, of practically glycerine only but is a complex mixture of many substances, including toxic ones, and the glycerine content does not usually exceed 50%. In this paper the results of research on the influence of the kind of raw material, the quantity and kind of catalyst and the conditions of transesterification process on the quantity and composition of glyceric fraction.

PL

Frakcja glicerynowa powstająca jako produkt uboczny w procesie produkcji biopaliw z olejów roślinnych nie składa się, jak to wynika z wielu popularnych opracowań, praktycznie wyłącznie z gliceryny, lecz jest złożoną mieszaniną wielu substancji, także toksycznych, a zawartość gliceryny z reguły nie przekracza 50 %. W pracy przedstawiono wyniki badań wpływu rodzaju surowca, ilości i rodzaju katalizatora oraz warunków prowadzenia procesu transestryfikacji na ilość i skład frakcji glicerynowej.

4

Biorefineries - from biofuels to the chemicalization of agricultural products

88%

Kijeński J.

Polish Journal of Chemical Technology

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2007

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tom 9

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nr 3

42-45

EN

The recent research into the viable economy in sustainable energy from renewable sources has prompted a review into the potentials of Polish-oriented raw material sources as a catalyst for technological advance, product diversification and consumer satisfaction. The elongation of the process chain in vegetable (rape seed, potato), alcohol additives and glycerin processing has been found to drastically improve energy balances for the short processing methods adopted presently and can make Poland self sustainable in the future.

5

Kinetics of Enantiomerically Enriched Synthesis of Solketal Esters Using Native and SBA-15 supported P. Fluorescens Lipase

88%

Zniszczoł A. , Szymańska K. , Kocurek J. , Bryjak J. , Walczak K. , Jarzębski A.

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nr 2

6

Simulation and sensitivity analysis for biodiesel production in a reactive distillation column

75%

Agarwal M. , Singh K. , Chaurasia S. P.

Polish Journal of Chemical Technology

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2012

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tom 14

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nr 3

59-65

EN

The conventional process for biodiesel production by transesterification is still expensive due to a need of high excess of alcohol required and its recovery by distillation. The use of a reactive distillation process can reduce the amount of alcohol in the feed stream as it works on a simultaneous reaction and separation. In the present study, a mathematical model has been developed for biodiesel production from triglycerides in a reactive distillation column, which has been validated with the reported data and CHEMCAD results. The effects of process parameters such as methanol to oil feed ratio, feed temperature, and reaction time have been investigated. The sensitivity analysis shows that yield of ester increases with methanol to oil ratio and number of stages, however, it decreases with fl ow rate. The MATLAB simulated results show that methanol to oil molar ratio of 5:1 produces 90% (by wt.) of methyl ester in a residence time of 4.7 minutes.

7

Structure and mechanical properties of biodegradable copolyesters and blends based on poly (butylenes terephthalate)

75%

Kiersnowski A. , Szymczak S. , Serwadczak M. , Szustakiewicz K. , Pisula W. , Pigłowski J.

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2009

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tom Vol. 53, nr 3

223-229

EN

The contribution presents results of the research on biodegradable systems based on poly(butylcnc tcrcphthalatc) (PBT) either melt-blended or copolymerizcd with poly( 1,4-butylene succinate) (PTMS) or poly(e-caprolactonc) (PCL). Syntheses of copolycsters were carried out in a twin-screw extruder using of dibutyltin dilaurate as a catalyst. DSC results indicated that the blends were phase-separated systems while copolymcrs were semicrystallinc homogenous materials. The x-ray diffraction was used to study the molecular and supramolecular structure of blends and copolycsters. The results of structural investigation were then correlated with mechanical properties and biodegradability of the obtained materials.

8

Chemiczno-technologiczne aspekty procesu transestryfikacji olejów roślinnych i tłuszczów małocząsteczkowymi alkoholami, głównie alkoholem metylowym

63%

Matyschok H.

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2001

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tom Nr 10

267-277

PL

Przedstawiono i omówiono dotychczasowy stan badań i rozwiązań przemysłowych w dziedzinie alkoholizy naturalnych triglicerydów malocząsteczkowymi alkoholami. Przedyskutowano wpływ najważniejszych parametrów na przebieg tego procesu i sposoby wydzielania produktów. Omawiana transestryfikacja zachodzi jako szereg egzotermicznych, odwracalnych reakcji następczo—równoległych. Jej katalizatorami są zarówno substancje o charakterze kwasowym, jak i zasadowym. Z uwagi na aktywność katalityczną najkorzystniej jest prowadzić tą reakcje wobec wodorotlenków metali alkalicznych gwarantujących szybki jej przebieg już w temperaturze pokojowej przy możliwości prowadzenia procesu tak sposobem okresowym, jak też ciągłym. Zastosowanie KOH zamiast NaOH sprawia, że proces jest całkowicie bezodpadowy.

EN

Presented and discussed are the hitherto state of investigations and industrial solutions in the area of alcoholyse of natural triglycerides using low-molecular alcohols. In particular, the effect of most important parameters on the course of the process, and ways of separating the products, are presented. The transesterification runs as a series of exothermic, reversible sequent-parallel reactions. Its catalysts are both acid and basic substances. With regard to catalytic activity, the reaction is most useful to be run in the presence of alkali metal hydroxides enabling its rapid course at room temperature, both periodically or continuously. The use of KOH instead of NaOH the process being completely wasteless.

9

Badanie reakcji transestryfikacji oleju rzepakowego metanolem na katalizatorach heterogenicznych

63%

Żmudzińska-Żurek B. , Grzywacz-Wątroba J.

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2012

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tom R. 68, nr 5

306-312

PL

W pracy przedstawiono wyniki badań reakcji transestryfikacji oleju rzepakowego metanolem prowadzonej w obecności katalizatorów heterogenicznych: KOH/Al2O3, K2CO3/Al2O3, KOH/MgO, K2CO3/MgO, K2CO3/SiO2. Określono wpływ rodzaju aktywnej fazy katalizatora, rodzaju nośnika oraz zawartości katalizatora i ilości jego fazy aktywnej na przebieg procesu transestryfikacji. Porównano efektywność użytych w pracy katalizatorów heterogenicznych i homogenicznych o takiej samej ilości substancji aktywnej w katalizatorze.

EN

The paper presents the transesterification of canola oil with methanol in the presence of heterogeneous catalysts: KOH/Al2O3, K2CO3/Al2O3, KOH/MgO, K2CO3/MgO, K2CO3/SiO2. The effects of the active catalytical phase and carrier types as well as active phase content on the transesterification process are described. The efficiency of heterogeneous and homogeneous catalysts with the same content of active substance used in the present work is compared.

10

Homo-and copolymerization of aliphatic cyclic carbonates with suppression of transesterification

63%

Socka M. , Duda A.

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2009

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tom Vol. 53, nr 2

187-193

EN

The ring-opening polymerization (ROP) of cyclic carbonates initiated with chiral Al-alkoxides that bear stcrically demanding ligands provides sufficient control of molar mass, macromolecular architecture and end groups of the resulting (co)polymers. The present paper reports that this kind of control takes place also in the cyclic carbonates (trimethylene carbonate (TMC) and 2,2-dimethyltrimcthylene carbonate (DTC)) homopolymerization and their copolymcrization with L,L-lactide (LA). This is in contrast to previous, reported attempts of cyclic carbonates polymerization proceeding on the achiral active species. Thus, in the properly chosen conditions di- and mutiblock copolymers could be obtained by starting the polycarbonate blocks growth with the living poly(L,L-lactide) (PLA). Namely, application of a bulky, Schiffs base derivative: (5)-(+)-2,2'-[l,r-binaphtyl- 2,2'diylbis-(nitrylomethilidyne)]-diphenolate at the aluminum alkoxidc active species (SBOiAl-O/Pr) results in a suppression of the segmental exchange involving polycarbonates and PLA blocks and eventually leads to the corresponding well-defined di- and triblock copolymers formation.

11

Mathematical modelling of enzymatic transesterification of mandelic acid with vinyl acetate

63%

Dąbkowska K. , Szewczyk K.

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2007

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tom Vol. 28, z. 3

795-802

EN

Racemic mandelic acid was resolved by transesterification with vinyl acetate catalysed by Pseudo-monas cepacia lipase. A high enantiomeric excess (>99%) of both unreacted substrate and acylated product was obtained at 25 C degrees using diisopropyl ether as the reaction medium. The Ping-Pong Bi-Bi mechanism and second order kinetics have been used to model the reaction rate. The best estimation has been obtained for the Ping-Pong Bi-Bi model without inhibition. Values of kinetic parameters were estimated.

PL

Przeprowadzono efektywny, kinetyczny rozdział enancjomerów kwasu migdałowego na drodze transestryfikacji octanem winylu, katalizowanej przez lipazę z Pseudomonas cepacia. Prowadząc reakcję w środowisku eteru diizopropylowego w 25 stopni C, uzyskano duży nadmiar enancjomeryczny (>99%) zarówno substratu, jak i produktu reakcji. Do opisu przebiegu reakcji zastosowano model reakcji drugiego rzędu oraz model Ping-Pong. Najlepszą zgodność obliczeń modelowych z danymi doświadczalnymi uzyskano dla modelu Bi-Bi Ping-Pong bez inhibicji żadnym z reagentów.

12

Transesterification of postfrying oils and utilization of the glycerol phase

51%

Perkowska M. , Łuczak J. , Sawicki J. , Hupka J.

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2006

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tom Vol. 8, nr 3

132-134

EN

Methyl esters synthesis using spent frying oils and subsequent utilization of the glycerol phase have been described. Potassium hydroxide (basic transesterification) at 25°C and sulfuric acid (acidic transesterification) at 60 °C were used. The conditions of the transesterification reaction which affect the yield and purity of the product esters, including the oil quality (acid number, peroxide number), were considered. It was found that dipper thermal oil degradation during frying resulted in FAME of inferior calorific value. The glycerol fraction from methanolysis was purified and used for the production of triacetin with the 76% yield.

13

Surface-active properties of CMC and xylan esters produced by transesterification with MERO

51%

Tomanova V.

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2006

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tom R. 103, z. 7-Ś

81-88

EN

In this paper is presented a new method of preparation of polymeric surfactants from carboxymethylcellulose (CMC) and 4-O-glucuronoxylan (XY) under microwave irradiation. Partial hydrophobizations of CMC and XY were performed by transesterification method with methyl ester of vegetable oil (MERO) in homogeneous solvent systems under various reaction conditions to optimalize the preparation of water-soluble products having surface-active properties. The obtained esters were characterized by FTIR spectrometry. Their surface-active properties were tested. Most of the tested derivatives lowered surface tension of water and gave emulsions of the oil/water type with excellent emulsifying efficiency comparable to the commercial emulsifier Tween 20.

PL

W niniejszym artykule przedstawiono nową metodę otrzymywania polimerowych związków powierzchniowo czynnych na bazie karboksymetylocelulozy (CMC) i 4-O-glukoranoksylanu (XY) w polu promieniowania mikrofalowego. Transestryfikacja CMC i XY zachodziła w rozpuszczalniku (DMF) w obecności estrów metylowych zawartych w oleju MERO. Struktura otrzymanych estrów została określona metodą FTIR. Przeprowadzono również badania określające aktywność powierzchniową otrzymanych związków. Dla większości próbek zaobserwowano obniżenie napięcia powierzchniowego. Ponadto wykazano, że otrzymane związki mają podobne właściwości do powszechnie stosowanego emulgatora Tweed 20 i mogą być stosowane jako środki powierzchniowo czynne w procesie wytwarzania emulsji typu olej/woda.

14

Cykliczne węglany w syntezie oligowęglanodioli metodą polireakcji stopniowej

51%

Rokicki G. , Piotrowska A. , Kowalczyk T. , Kozakiewicz J.

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2001

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tom T. 46, nr 7-8

483-493

PL

Przedstawiono wpływ warunków prowadzenia polikondensacji węglanu propylenu z 1,6-heksanodioIem lub 1,10-dekanodiolem (tabela 1) na budowę chemiczną powstających oligowęglanodioli. Wykazano, że użycie węglanu propylenu jako źródła wiązań węglanowych (w odróżnieniu od stosowania węglanu etylenu) oraz wykorzystanie H-heksanu jako czynnika azeotropującego 1,2-propanodiol, który stanowi produkt uboczny transestryfikacji, prowadzi do produktów nie-zawierających, praktycznie biorąc, fragmentów poi i eterowych. Do analizy budowy otrzymanych oligomerów węglanowych zastosowano spektrometrię masową MALDI TOF oraz spektroskopię 'H- i I3C-NMR (rys. 1-9). Zbadano wpływ rodzaju katalizatora [K2CO3, Bu^SnO, stearynian cyny (II)] na przebieg omawianego procesu. Najlepszym katalizatorem transestryfikacji był Bu2SnO, którego stosowanie prowadzi do oligomerów węglanowych zakończonych wyłącznie grupami hydroksylowymi; mogą one znaleźć zastosowanie jako poliole do wytwarzania poliuretanów odpornych na hydrolizę i utlenianie.

EN

The chemical structure of resulting oligocarbonate diols was studied in relation to catalyst type and experimental conditions of the polyesterification of propylene carbonate with 1,6-hexanediol or 1,10-decanediol (Table 1). Unlike ethylene carbonate, propylene carbonate employed as a source of carbonate linkages and n-hexane vised as an azeotroping agent to entrain a 1,2-propane glycol by-product from the reaction medium, afforded products containing practically no polyether moieties. The structure of the resulting carbonate oligomers was studied by MALDI TOF mass spectrometry and ^H and 13C NMR spectroscopies (Figs. 1-9). Of the transesterification catalysts examined, viz., K2CO3, Bu2SnO and tin(II) stearate, Bu2SnO proved to be the best, providing the oligomers terminated exclusively with hydroxyl groups. Such oligomers can be used as polyols to make polyurethanes that are resistant to hydrolysis and oxidation.

15

Wpływ reakcji transestryfikacji na stopień mieszalności układów polimerowych PEN/PC

51%

Woźniak-Braszak A. , Jurga J. , Baranowski M. , Szostak M. , Jurga K.

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2007

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tom Nr 4

287-292

PL

Celem przedstawionej pracy jest badanie własności fizycznych i mechanicznych nowego kompozytu polimerowego otrzymanego w wyniku mieszania dwóch polimerów poli(naftalenianu etylenu) PEN i poliwęglanu PC w obecności i bez kompatybitizatora. Zastosowano kompatybiliza-tor o nazwie Samarium acetylacetonate hydrate [CH3COCH=C(O-)-CH3SxH3O, którego rola jest ułatwienie mieszalności dwóch niemieszalnych polimerów. Przy właściwym doborze składników wyjściowych zachodzi reakcja transestryfikacji polegająca na wyparciu cząsteczki alkoholu z estru przez cząsteczkę innego alkoholu. Produktem tej reakcji jest nowy kompozyt.

EN

DSC and DMTA techniques are used to get detailed information on the chain dynamics and the scale of blends miscibility, which influence their mechanical and physical properties. Two series of blends with changing weight ratio of homopoiymers were prepared by injection moulding using the Engcl machine ES 80/25 HLS, one with the compatibilizer (Samarium acetyiacetonate hydrate SMAC) and the second one without it. The obtained results show that PEN/PC blends at room temperature are immiscible. At the 563 K temperature between molten homopoiymers of PEN and PQ a reaction, known as transesterifkation takes place, which indicates that the miscibility of the two polymers occurred. The initial heterogeneous system becomes a single phase by decreasing blends differences between the two coexisting phases. The degree of transesterification is higher for the blends with the compatibilizer. It means that the compatibilizer improved the PEN/PC blends compatibility.

16

Zastosowanie biotransformacji w syntezie optycznie czynnych laktonów

44%

Gładkowski W.

|

2009

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tom [Z] 63, 5-6

361-389

EN

Compounds with lactone moiety exhibit many biological acitivities (for example antimicrobial, antifeedant, cytostatic). One of the most attractive methods to obtain optically active lactones are regio- and stereoselective biotransformations. These together with mild reaction conditions are the main advantages of the processes compared to chemical synthesis of lactones. In this review examples of such biotransformations are presented. The lactones may be obtained via direct biotransformation of substrate or in chemoenzymatic synthesis. In the second case the enzymatic step is the key one, leading to optically pure or enriched intermediate which is further transformed into desired, optically active product. As the products of direct biotransformation, lactones can be formed from fatty acids like ricinoleic or vernolic acid [1, 2], aromatic compounds (benzoic acid, mandelic acid, catechol) [3] as well as in the result of lactonization of epoxyesters by enzymatic systems of fungi or plants. In the last case the biocalysts is the apple pulp or Jerusalem artichoke pulp [4-6]. Hydrolysis of amides and nitriles is also applied to the synthesis of lactones. Especially useful in this regard are microorganisms, which exhibit both enzymatic activities [7-9]. Microbial reduction of carbonyl group in ketoesters or ketoacids is also very useful method. The reduction may occur in ? or ? position, leading to ?- or ?-hydroxyacids which cyclize to the corresponding lactones [10-13]. Reduction of carbonyl group in ?-position is the first step of a synthesis of lactones with 7- or 8-membered rings [14-16]. The application of hydrolysis or transesterification processes catalyzed by hydrolytic enzymes, mainly lipases from Pseudomonas sp., also leads to enzymatically enriched lactones. The substrates may be ?-ketoesters, ?-hydroxyamides, meso-diols or meso-diesters [10, 17-19]. Among the oxidation reaction the most known is Baeyer-Villiger reaction in which cyclic ketones are directly oxidized to the lactones by enzymes called Baeyer-Villiger monooxygenases (BVMO) [20]. The reaction is highly regioselective and can be applied to the production of unsaturated lactones [23]. In this area of research genetically modified strains of Escherichia coli are applied [21, 24], although the wild strains are also used, for example to the production of ?-caprolactone from cyclohexanone [22]. Another reaction catalyzed by oxidoreductases is the oxidation of hydroxyl group to carbonyl or carboxyl one [25-27]. In this first case horse liver alcohol dehydrogenase (HLADH) found application in the oxidation of meso-diols to lactones. The ability of different fungal strains to the regioselective hydroxylation of unactivated carbon atom found an application to the synthesis of lactones with eudesmane and germacrane systems [28-30]. Resolution of racemates is an alternative strategy used to the synthesis of lactones in optically pure forms. This aim can be achieved by enzymatic cleavage of lactone ring catalyzed by lactonases. These enzymes of microbial origin belong to esterases and are often induced during the growth of microorganisms on cyclic ketones as the carbon sources [31, 32, 34]. Enzymatic resolution of pantolactone by lactonase from Fusarium oxysporum is an example of industrial biotransformation [33]. Lipases can also be applied to the enantioselective hydrolysis of lactone ring [35-37]. The other functional groups present in the molecule can also be converted during the resolution of racemic lactones [39-44]. The examples are hydrolysis of acetoxylactones or esterification of hydroxylactones.