The Influence Of Flow Dynamics And Temperature On The Content And Conversion Of Fatty Acids In Sunflower Oil Hydrogenation

Sunflower oil („DIJAMANT“-oil factory in Zrenjanin-Republic of Serbia) was hydrogenated using commercial nickel (Ni) catalyst, PRICATTM 9910, in a 1 liter double jacket reactor, Series 5100 (Parr Instrument). The pocess was conducted at four different temperatures (120, 130, 140 and 150 °C) and three different agitation velocities (800, 1200 and 1600 rpm). In all cases, partial pressure of hydrogen was 0.202 MPa, agitation velocity was 1200 rpm, and catalyst concentration was 0.03 wt. % (compared to Ni). In the analysis of the influence of flow dynamics, temperature was constant 140 °C, and other parameters were the same as in the case of the temperature effect analysis. The hydrogenation activity of the catalyst was monitored through the decrease of refractive index and hydrogen consumption. During the process of hydrogenation, partially hydrogenated sunflower oil was sampled at specified time intervals, and gas-chromatography analysis of the samples collected gave the results representing the content of fatty acids at different time intervals. We used the data on the content of fatty acids to determine the iodine value and the number of double bonds, as well as to interpret and determine cis/trans selectivity in certain hydrogenation conditions. Moreover, the correlations among the iodine value, refractive index and hydrogen consumption were established. The reaction rate constants were obtained based on fatty acid content in partially hydrogenated oil and further studied for the investigation of possible reaction pathways. A set of ordinary differential equations corresponding to the investigated model was solved numerically by the Gear's algorithm. Commercial catalyst PRICATTM 9910 exhibited the highest activity at hydrogenation temperature 150 °C, i.e. the time to reach the desired iodine value was 30 minutes, while at the lowest hydrogenation temperature that time was 80 minutes. The dependences among the iodine value, the index of refraction and hydrogen consumption exhibited a high level of correlation, and therefore can be used in the similar processes. Already in this paper the dependence between the iodine number and the refraction index was used for the determination of the iodine value in the case of the analysis of the flow dynamics effect, with the results showing a high level of agreement with experimental data. It was found, that cis selectivity decreased by increasing the temperature, i.e. more iso-trans isomers were obtained, and cis selectivity was the highest at 120 °C as a result. Moreover, the changes in hydrogenation temperature also affected the number of the reaction pathways, in such manner that the number of reaction pathways was greater at lower temperatures. However, at higher temperatures (particularly at 150 °C) the reaction pathways were mainly directed towards C18:1-trans isomers formation, which becomes saturated further in the hydrogenation process (C18:0). When changing the agitation velocity, it was observed that the catalyst activity is higehr at higher agitation velocities, i.e. the time to reach the desired iodine value was shorter (being 80 minutes for 800 rpm, 50 minutes for 1200 rpm, and 60 minutes for 1600 rpm). Hence, the increase in the agitation velocity also increases the volumetric liquid-side mass transfer coefficient (kLa), which also reduces the hydrogenation time and results in the formation of tdesired products. However, the increase of agitation velocity has certain limitations, because significantly higher agitation velocities result in the impacts similar to those occurring at lower agitation velocities. This refers primarily to the drop in the volumetric liquid-side mass transfer coefficient (kLa), due to the possible formation of vortices. Votices lead to intense circular movement of the whole mass of the liquid, without mixing particular elements.Hidrogenovanje suncokretovog ulja („DIJAMANT“-fabrika ulja u Zrenjaninu-Republika Srbija) izvođeno je primjenom komercijalnog nikl (Ni) katalizatora, PRICATTM 9910 u reaktoru zapremine jedan litar sa dvostrukim zidom, Series 5100 (Parr Instrument). Proces je vođen na četiri različite temperature (120, 130, 140 i 150 °C) i tri različite brzine miješanja (800, 1200 i 1600 ob∙min-1). U svim slučajevima parcijalni pritisak vodonika bio je 0,2 MPa, brzina miješanja je iznosila 1200 ob∙min-1, a koncentracija katalizatora 0,03 mas. % u odnosu na Ni. Kod analize uticaja dinamike strujanja temperatura je bila konstantna i iznosila je 140 °C, a ostali parametri su bili kao i u slučaju ispitivanja uticaja temperaure. U radu je analiziran uticaj temperature i dinamike strujanja na aktivnost i selektivnosti katalizatora, kao i na nastajanje trans i zasićenih masnih kiselina. Aktivnost katalizatora tokom hidrogenovanja praćena je padom indeksa refrakcije i potrošnjom vodonika. Uzorkovanja parcijalno hidrogenovanog sucokretovog ulja vršena su u određenim vremenskim intervalima, a gasno-hromatografskom analizom navedenih uzoraka dobijeni su rezultati koji se odnose na sadržaj masnih kiselina tokom procesa hidrogenovanja. Podaci o sadržaju su nam poslužili da dođemo do vrijednosti jodnog broja, broja dvostrukih veza, ali su nam poslužili i za tumačenje i određivanje cis/trans selektivnost za određene uslove hidrogenovanja. Ustanovljene su zavisnosti između jodnog broja, indeksa refrakcije i potrošnje vodonika. Konstante brzine hemijske reakcije su takođe dobijene iz sadržaja masnih kiselina parcijalno hidrogenovanog suncokretovog ulja i poslužile su za ispitivanje mogućih reakcionih puteva. Kinetika i mehanizmi koji su u radu razvijeni i testirani, imali su za cilj da pokažu na koji način će se promjena operativnih uslova odraziti na promjenu reakcionih puteva. Grupa običnih diferencijalnih jednačina, koja je odgovarala analiziranom modelu, riješena je numerički primjenom Gear-ovog algoritma. Katalizator PRICATTM 9910 je pokazao najveću aktivnost na temperaturi hidrogenovanja od 150 °C, tj. vrijeme za dostizanje željenog jodnog broja bilo je najkraće i iznosilo je oko 30 minuta, dok je za najnižu temperaturu hidrogenovanja (120 °C) to vrijeme iznosilo oko 80 minuta. Zavisnosti između jodnog broja, indeksa refrakcije i potrošnje vodonika dale su visok stepen korelacije, pa su time otvorile mogućnost ka njihovoj primjeni u procesima slične prirode. Još u ovom radu zavisnost jodnog broja od indeksa refrakcije je primjenjena za računanje jodnog broja u slučaju analize uticaja dinamike strujanja, pri čemu su dobijena veoma dobra slaganja sa eksperimentalnim podacima. Utvrđeno je da cis selektivnost opada sa porastom temperature,odnosno nastaje više izo-trans-oleinskih oblika masnih kiselina, pa je na temperaturi od 120 °C cis-selektivnost bila najviše izražena. Takođe, promjena temperature hidrogenovanja se takođe odrazila i na broj reakcionih puteva, tako da je na nižim temperaturama broj reakcionih puteva veći, nego na višim temperaturama. Međutim, na višim temperaturama (posebno na 150 °C) reakcioni putevi su uglavnom usmjereni ka stvaranju C18:1-trans izomera koji u daljem procesu hidrogenovanja prelazi u zasićen oblik (C18:0). Kod promjene brzine miješanja uočeno je da je aktivnost katalizatora veća pri većim brzinama miješanja, odnosno vrijeme potrebno za dostizanje željenog jodnog broja je kraće (za 800 ob∙min-1 je 80 min, 1200 ob∙min-1 je 50 min, a za 1600 ob∙min-1 je 60 min). Dakle, povećanjem brzine miješanja povećava se koeficijent prenos mase u tečnoj fazi (kLa), pa samim tim i brzina reakcije hidrogenovanja postaje veća, što naravno pored toga što skraćuje vrijeme hidrogenovanja, vodi i ka stvaranju željenih proizvoda hidrogenovanja. Međutim, povećanje brzine miješanja takođe ima određena ograničenja, jer pri znatno većim brzinama miješanja dolazi do sličnih uticaja koji se manifestuju pri nižim brzinama miješanja. Prvenstveno se misli na pad koeficijenta prenosa mase usljed stvaranja vrtloga koji dovode do intenzivnog kružnog kretanja cijele mase tečnosti, bez miješanja pojedinih elemenata

Heat Utilization of Distiller Liquor by using the High Temperature Heat Pump

Proces proizvodnje kalcinisane sode, kao tipičan primjer procesa bazne hemijske industrije, je veliki potrošač energije a naročito toplotne energije. Pored toga, proces proizvodnje kalcinisane sode je i veliki rasipnik te energije. Najveći gubici toplotne energije se ostvaruju sa otpadnim tokom, destiler lužinom. Iz postrojenja proizvodnje kalcinisane sode kapaciteta 1000 t/dan nastaje destiler lužina, kao otpadni tok, u količini od 424646,0 kg/h (ili 370,2 m3/h). Ova količina destiler lužine je baza za sintezu i analizu procesa korišćenja njene toplote. Mogućnost korištenja toplote destiler lu¬žine manifestuje se na nekoliko načina: u proizvodnji kalcijum-hlorida, ako takva postoji, u postrojenju regenaracije amonijaka ako nema proizvodnje kalcijum-hlorida, za zagrijavanje voda u toplotnim šemama termocentrala i kotlovnica. Još jedna od mogućnosti korištenja toplote destiler lužine jeste i primjena visokotemperaturnih pumpi koje koriste niskotemperaturne energetske i industrijske otpadne tokove, kakav je i destiler lužina, što je i prikazano u ovom radu. Nakon detaljnih istraživanja i uz korišćenje visokotemperaturnih toplotnih pumpi (HTHP), predlaže se kao osnovna mogućnost korišćenja toplote destiler lužine, tj. korišćenje te rekuperisane toplote u sistemima daljinskog grijanja. Ovaj osnovni postupak se sastoji iz dva stupnja: adijabatskog isparavanja destiler lužine, smanjenjem temperature od 95 °C na 68,5 °C i prenošenjem adekvatnog dijela toplote na vodu i adijabatskog isparavanja destiler lužine, smanjenjem temperature sa 68,5 °C na 41,4 °C i prenošenjem adekvatnog dijela toplote na vodu. Ključne riječi: destiler lužina, visokotemperturne toplotne pumpe, kalcinisana soda, energetska efikasnost, količina toplote

Verification of McCabe-Thiele method and determination of basic parameters of distillation by using software packages MATLAB and ChemCAD for separating of mixture n-heptanen-octane

This paper shows the verification of the graphic McCabe-Thiele method for separating the mixture n-heptane-n-octane. Verification of McCabe-Thiele method was performed by analytical calculations system and applying SHORTCUT methods for calculation of distillation in ChemCAD. Also, the program designed in MATLAB allows calculation of important parameters such as the minimum reflux, working reflux ratio, the theoretical number of theoretical plates, the supply of the stage, certain value, which depend largely on the reflux and the number of theoretical plates required for the separation. The paper describes the graphic dependence of parameters of interst for light volatile components, in this case n-heptane, in the supply of the mixture. At the same time, calculation was conducted for the rigorous separation condition, which demands separation of 99%, and for less rigorous separation condition, with separation of 95%.

Calcium oxide on coal fly ash cancrinite-type zeolite as a catalyst for biodiesel production

This paper discloses the synthesis of new supported catalyst in which the main components of the catalyst, catalyst support and active component, derived from waste material, and its catalytic properties tested in the reaction of the production of biodiesel. Cancrinite-type zeolite catalyst support was synthesized from coal fly ash using hydrothermal technique with NaOH as the activation reagent in a rotating PTFE autoclave reactor. The active component, CaO, was derived from waste chicken eggshells by calcination at 900 °C. Supported catalytic material was synthesized by impregnation. The content of CaO in the prepared catalysts was varied from 5 to 20 wt%. The catalysts were characterized using XRD, FT-IR, SEM, N2-physisorption, and Hg-porosimetry. The methanolysis of sunflower oil was carried out in a batch reactor at 60 °C, with methanol to oil molar ratio of 12:1, and catalyst concentration of 4 wt.%. The fatty acid methyl ester content (% FAME) was analyzed using HPLC method. Structural information related to phase identification and vibration of chemical bonds in molecular units indicates that a multiphase zeolitic structure was obtained. The structure of cancrinite-type zeolite was found to be dominantly present. It was found that the catalyst impregnated with 20% of CaO gave the highest FAME percentage of 96.46 for the reaction time of 2 h

Rare-Earth/Manganese Oxide-Based Composites Materials for Electrochemical Oxygen Reduction Reaction

The main objective of this research was a systematic development of advanced micro/nanostructured materials based on the most used metal-oxides for ORR and metal-oxides with an extremely low-loading of Pt for comparison. Hybrid composites compared were: MnO2, La2O3, mixed lanthanum manganese oxides (LMO), and mixed lanthanum manganese oxides with reduced platinum load (LMO-Pt). The influence of the reduced amount of noble metal, as well as single oxide activity toward ORR, was analyzed. The complete electrochemical performance of the hybrid materials has been performed by means of CV, LSV, and EIS. It was shown that all synthesized catalytic materials were ORR-active with noticeable reduction currents in O2 saturated 0.1 M KOH. The ORR behavior indicated that the La2O3 electrode has a different mechanism than the other tested electrode materials (MnO2, LMO, and LMO-Pt). The EIS results have revealed that the ORR reaction is of a mixed character, being electrochemically and diffusion controlled. Even more, diffusion is of mixed character due to transport of O2 molecules and the chemical reaction of oxygen reduction. O2 diffusion was shown to be the dominant process for MnO2, LMO, and LMO-Pt electrolytic materials, while chemical reaction is the dominant process for La2O3 electrolytic materials

Modelovanje destilacionih kolona

As a distillation is one of the most important operations in the chemical industry, and distillation columns are very specific and important equipment, during the analysis and modelling of such systems necessary is to pay special attention. This paper can be divided into two parts, first part of this paper refers to modelling, calculation and analysis of the binary mixtures, and the second part of the paper refers to the dimensioning of the distillation column. Binary mixture was analyzed in the paper are benzene-toluene, ethylbenzene-styrene, N-heptane-N-oktane, trichlorethylene-tetrachlorethylene. In calculations of a binary mixture, special emphasis is placed on the applications of the graphic McCabe-Thiele method for determining of the number of theoretical stages for separating the above mixture and evaluate the behaviour of these mixture under different condition of separation. Vrification of McCabe-Thiele's method is performed by using analythical calculations of distillation as well as using the SHORTCUT method for calculation of distillations in ChemCAD. The special contribution of this paper is based on the design of program in MATLAB, which allows calculation of very importrant parameters such as the minimum reflux ratio, reflux ratio, number of theoretical stages, the place of feed stage and certain parameters which depend of reflux ratio and number of theoretical stages required for the separation. The second part of this paper refers to the sizing of distillation columns for the separation of the analyzed systems. In the sizing process, special attention was paid to the sizing of sieve and valve trays. For sieve, trays were carried out the detailed calculation “tray by tray” for all analyzed systems, while for valve trays was carried out the calculation for two trays, for the all examined mixtures., one tray for rectifying section and one tray from stripping section. In this paper, analysis of distillation columns is based on the determination of the basic dimension of the columns (active and total area of trays and area of downcomer and diameter of columns) and the assessment of basic hydraulic parameters (% of flooding, removal, pressure drop). The calculation of the above parameters of distillation columns was carried out analytically, by using the Excel, as well as by using of strict procedures of TOWER method in ChemCAD. In this way, and for the first and second part of the paper were compared the results obtained by using different calculation methods and performed various dependencies that largely describe distillation and distillation columns for the analyzed types of mixtures and set condition of separation.Kako je destilacija jedna od veoma važnih operacija u hemijskoj industiji, a destilacione kolone veoma specifični i važni uređaji, potrebno je posvetiti posebnu pažnju pri analizi i modelovanju ovakvih sistema. Ovaj rad se može podijeliti u dva dijela, prvi dio rada se odnosi na modelovanje, proračune i analizu binarnih smjesa, a drugi dio rada se odnosi na dimenzionisanje destilacionih kolona. Binarne smjese koje su analizirane u ovom radu su: benzen-toluen, etilbenzen-stiren, N-heptan-N-oktan i trihloretilen-tetrahloretilen. Pri proračunavanju navedenih binarnih smjesa poseban akcenat je stavljen na primjenu grafičke McCabe-Thiele-ove metode, za određivanje broja teorijskih podova potrebnih za razdvajanje navedenih smjesa i procjenu ponašanja navedenih smjesa pri različitim uslovima razdvajanja. Provjera McCabe-Thiele-ove metode vršena je analitičkim proračunima sistema za destilaciju, kao i primjenom SHORTCUT metode za proračune destilacije u ChemCAD-u. Poseban doprinos ovog rada zasniva se na osmišljanju programa u MATLAB-u, koji omogućava izračunavanje veoma važnih parametara u destilaciji poput minimalnog refluksnog odnosa, radnog reflusknog odnosa, broja teorijskih podova, mjesta napojnog poda, određenih veličina koje u velikoj mjeri zavise od refluksa i broja teorijskih podova potrebnih za razdvajanje. Drugi dio rada odnosi se na dimenzionisanje destilacionih kolona za razdvajanje analiziranih sistema. U postupku dimenzionisanja posebna pažnja je posvećena dimenzionisanju sitastih i ventilskih podova. Za sitaste podove je vršen detaljan proračun, „pod po pod“ za sve analizirane sisteme, dok je za ventilske podove vršen proračun za po dva poda, jedan iz zone rektifikacije i jedan iz zone stripovanja, za sva četiri analizirana sistema. Analiza destilacionih kolona u ovom radu je zasnovana na određivanju osnovnih dimenzija kolone (aktivne i ukupne površine podova i površine preliva i dijametra kolone) i procjeni osnovnih hidrauličkih parametara (% plavljenja, odnošenja, pada pritiska). Proračun svih navedenih parametara destilacionih kolona je vršen analitičkim proračunom, primjenom Excel-a, kao i primjenom strogog postupka dimenzionisanja TOWER metodom u ChemCAD-u. Na ovaj način su i za prvi i za drugi dio rada izršena poređenja dobijenih rezultata primjenom različitih metoda proračuna i izvedene razne zavisnosti koje u velikoj mjeri opisuju destilaciju i destilacione kolone za analiziranu vrstu sistema i za postavljene uslove razdvajanja

Najnovija saznanja o upotrebi prirodnih zeolita i zeolitnih katalizatora baziranih na otpadu za proizvodnju biodizela

Considering the current world crisis and definite future energy challenges, biomass-to-fuel transformation is increasingly becoming important both to the policy makers and to the industry. In this perspective, the valorisation of oils and fats via transesterification/esteri fication reaction is an attractive method for producing biodiesel with qualities suitable for diesel engines. The recent interest indicated a significant shift to industrial waste valorisation as another approach for achieving process eco-efficiency. In this respect, the use of zeolite based catalysts for the production of biofuels is reviewed here, with a special emphasis on the utilization of waste raw materials following the principles of green chemistry and sustainable development. Zeolites are interesting due to their outstanding catalytic properties, including the presence of intrinsic acid sites, simple loading of base sites, shape-selectivity, and high thermal stability. Neat zeolites or modified by the loading of active species are classified into several groups following their origin. For each group, the most relevant recent results reported in the literature are reviewed together with some critical considerations on the catalyst effectiveness, stability, reusability, and economy of synthesis. As an important part required for understanding and optimization of the biodiesel production process, the mechanisms of the reaction were discussed in detail. Finally, key perspective directions for further research studies were carefully identified and elaborated.Imajući u vidu trenutnu svetsku krizu kao i buduće energetske izazove, transformacija biomase u goriva ponovo dobija veliku pažnju zakonodavaca i industrije. Znajući ovo, valorizacija ulja i masnoća putem reakcija transesterifikacije/esterifikacije postaje atraktivan metod za proizvodnju kvalitetnog biodizela pogodnog za postojeće dizel motore. Veliko interesovanje naučnika ukazuje na značajan pomak ka valorizaciji industrijskog otpada kao još jednom pristupu za razvoj ekološki efikasnih procesa. U tom smislu, ovaj rad predstavlja pregled upotrebe zeolitnih katalizatora za dobijanje biogoriva, sa posebnim akcentom na upotrebu otpadnih sirovina u skladu sa principima zelene hemije i održivog razvoja. Zeolitni materijali su veoma pogodni zbog svojih izvanrednih katalitičkih svojstava, uključujući intrinsičke kisele centre, jednostavno nanošenje baznih centara, strukturnu selektivnost i veliku termičku stabilnost. Čisti zeoliti, ili modifikovani nanošenjem aktivnih centara, klasifikovani su u nekoliko grupa u ovom radu u skladu sa njihovim poreklom. Za svaku od različitih grupa zeolita, najrelevantniji skorašnji literaturni rezultati predstavljeni su zajedno sa kritičkim razmatranjem efikasnosti katalizatora, stabilnosti, mogućnosti ponovne upotrebe i ekonomičnosti njihove sinteze. Kao važan deo neophodan za razumevanje i optimizaciju procesa, detaljno su razmotreni mehanizmi reakcije. Na kraju, pažljivo su identifikovani i obrazloženi ključni perspektivni pravci za dalja istraživanja