Browsing by Author "Karinen, Reetta"

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1-Butanol dehydration in microchannel reactor: Kinetics and reactor modelling
(2015) Khan, Y.; Marin, M.; Karinen, Reetta; Lehtonen, Juha; Kanervo, Jaana
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
3D simulations of a microchannel reactor with diffusion inside the catalyst layer for 1-butanol dehydration reaction in gas phase
(2016-12-01) Khan, Yaseen; Marin, Minna; Karinen, Reetta; Lehtonen, Juha
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
3D and a 2D-axisymmetric models in COMSOL Multiphysics® environment were developed to address modeling strategies to optimize the performance of wall-coated microstructured reactors operated to study gas-phase reactions under isothermal conditions. The kinetics for 1-butanol dehydration reaction was derived in our previously published research. Typically ideal models are used for modelling bulk flow in the free channel with diffusion–reaction at the surface of the layer. However in order to solve the system non-idealities, we used non-ideal models to simulate the flow field inside the free channel and diffusion–reaction in the catalyst coating. The obtained results from the 3D and 2D-axisymmetric models developed in COMSOL Multiphysics® were compared mainly with 2D-PFR-type model developed in MATLAB®. The one-way coupling between the fluid flow and transport of the components revealed that flow field non-idealities effect the performance predictions for the system. The performance and efficiency of the washcoat catalyst in microstructured reactors can be improved by controlling the thickness of the catalyst layer. As a conclusion, to optimize the performance of microstructured reactors the effect of reactor flow field must also be considered besides, the other key operational parameters such as global residence time, reaction conditions and catalyst layer thickness.
Acidity characterisation of zeolites for glycerol aromatisation with temperature-programmed desorption
(2024-01-23) Järvinen, Ellen
Kemian tekniikan korkeakoulu | Master's thesis
Zeolites are among the most industrially significant solid acid catalysts. Effective and accessible methods for analysing the acidity of solid materials are critical for zeolite-related catalyst research, as the acidity characterisation elucidates the relationship between the properties and the catalytic activity of the material. The temperature-programmed desorption (TPD) of basic probe molecules is a widely reported method for characterising the acidity of solids. Automated TPD instruments requiring little operator input are available commercially, which makes the method particularly accessible for routine acidity characterisation. Typical probe molecules used in the analysis of zeolites with TPD include ammonia (NH3) and isopropylamine (IPAm). This work implemented a NH3-TPD and an IPAm-TPD method for determining the total acidity and the Brønsted acidity of zeolitic samples respectively. This work also compared NH3-TPD and IPAm-TPD as acidity characterisation methods for zeolites. The theory part of this work covered the principles of zeolite catalysts and TPD and examined previously reported NH3-TPD and IPAm-TPD methods. In the experimental part, a NH3-TPD and an IPAm-TPD method were developed, and sample materials intended for glycerol aromatisation were characterised with the developed NH3-TPD and IPAm-TPD methods. The NH3-TPD and IPAm-TPD methods developed in this work produced TPD profiles that corresponded well to descriptions of zeolite NH3-TPD and IPAm-TPD profiles available in literature. Out of the tested materials, only the Zn-modified zeolite sample produced an abnormal IPAm-TPD profile. The total acidity and Brønsted acidity results calculated from the TPD data were logical with respect to the theoretical acidity of the studied materials. As an exception, the IPAm-TPD analysis of the γ-Al2O3 reference sample yielded a higher value for Brønsted acidity than expected. This was suspected to be due to Brønsted acid sites associated with impurities. The relative standard deviation of both the total and Brønsted acidity results was 4% in the repeat tests.
Aqueous-phase reforming of Fischer-Tropsch alcohols over nickel-based catalysts to produce hydrogen: Product distribution and reaction pathways
(2018-10-25) Coronado, Irene; Pitínová, Martina; Karinen, Reetta; Reinikainen, Matti; Puurunen, Riikka L.; Lehtonen, Juha
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Catalytic aqueous-phase reforming (APR) can be applied to process the organic compounds in the water fractions derived from the Fischer-Tropsch (FT) synthesis. This work aimed at finding an active nickel-based catalyst to convert organic compounds typically found in FT-derived waters, such as alcohols, into hydrogen. In addition, this work aimed at proposing potential reaction pathways that explain the product distribution resulting from the APR of C1–C3 alcohols. Solutions with 5% mass fraction of either methanol, ethanol, propan-1-ol or propan-2-ol in water were processed in APR at 230 °C and 3.2 MPa over different nickel-based catalysts in a continuous packed-bed reactor. Methanol was successfully reformed into hydrogen and carbon monoxide with conversions up to 60%. The conversion of C2–C3 alcohols achieved values in the range of 12% to 55%. The results obtained in the APR of C2–C3 alcohols suggest that in addition to reforming to hydrogen and carbon monoxide, the alcohols underwent dehydrogenation and decarbonylation. The most stable catalyst, nickel-copper supported on ceria-zirconia, reached feedstock conversions between 20% and 60% and high hydrogen selectivity. Monometallic nickel supported on ceria-zirconia catalysts reached higher H2 yields; however, the yield of side products, such as alkanes, was also higher over the monometallic catalysts. Accordingly, ceria-zirconia nickel-based supported catalysts constitute suitable candidates to process the alcohols in the water fractions derived from the FT synthesis.
Atomic Layer Deposition of Zinc Oxide on Mesoporous Zirconia Using Zinc(II) Acetylacetonate and Air
(2023-10-10) Yim, Jihong; Haimi, Eero; Mäntymäki, Miia; Kärkäs, Ville; Bes, René; Arandia Gutierrez, Aitor; Meinander, Kristoffer; Brüner, Philipp; Grehl, Thomas; Gell, Lars; Viinikainen, Tiia; Honkala, Karoliina; Huotari, Simo; Karinen, Reetta; Putkonen, Matti; Puurunen, Riikka L.
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
The self-terminating chemistry of atomic layer deposition (ALD) ideally enables the growth of homogeneously distributed materials on the atomic scale. This study investigates the ALD of zinc oxide (ZnO) on mesoporous zirconium oxide (ZrO2) using zinc acetylacetonate [Zn(acac)2] and synthetic air in a fixed-bed powder ALD reactor. A broad variety of methods, including thermogravimetry analysis, scanning electron microscopy with energy-dispersive X-ray spectroscopy, low-energy ion scattering, X-ray absorption near-edge structure, X-ray photoelectron spectroscopy, in-situ diffuse reflectance infrared Fourier transform spectroscopy-mass spectrometry, and density functional theory calculations, were used to analyze the reactant and the resulting samples. The factors affecting the zinc loading (wt %) on ZrO2 were investigated by varying the ALD reaction temperature (160-240 °C), the calcination temperature of zirconium oxide (400-1000 °C), and the ALD cycle number (up to three). The studied process showed self-terminating behavior with the areal number density of zinc of approximately two atoms per square nanometer per cycle. Zinc was distributed throughout ZrO2. After the Zn(acac)2 reaction, acac ligands were removed using synthetic air at 500 °C. In the following cycles, already-deposited ZnO acted as nuclei for further ZnO growth. This study demonstrates the potential of Zn(acac)2 as an ALD reactant and provides an initial understanding of ZnO growth via ALD on high surface area porous particles as an example for catalytic applications.
Biopohjaisten pyrolyysiöljyjen tuotanto ja käyttö
(2021-05-24) Henriksson, Antti
Kemiantekniikan korkeakoulu | Bachelor's thesis
Biopolttoaineiden valmistus ja katalyyttien elinkaari
(2023-12-20) Jänkävaara, Julia
Kemiantekniikan korkeakoulu | Bachelor's thesis
Carbon dioxide methanation over hydrotalcite-based nickel catalysts
(2017-06-13) Agbaba Sener, Özgül
Kemian tekniikan korkeakoulu | Master's thesis
Global warming and energy shortage have driven modern society to search for alternative and sustainable energy sources to replace with the fossil fuels. Innovative solutions are required for mitigating CO2 emissions to the atmosphere and storing H2 due to the intermittency of the renewable energy sources. With this thesis, it is possible to cover both of these concerns at the same time while utilizing CO2 to produce CH4 as a synthetic fuel that could also be transported into already existing infrastructures or as a chemical compound that could store H2. Hydrotalcite-based nickel catalysts were synthesized via various techniques such as wet impregnation, co-precipitation and sol-gel with different nickel contents utilising a one-pot synthesis approach. The main approach of utilizing catalysts was with the washcoating of the newly synthesized catalysts inside the reactor tubes with a diameter of 4 mm and a length of 17.5 cm. Catalytic performance of the catalysts was investigated for the hydrogenation of carbon dioxide under atmospheric pressure in a temperature range of 250-500oC. These synthesized catalysts were compared with a Ni/Al2O3 catalyst, which was prepared as a benchmark, in terms of CO2 conversion-to-CH4. Additionally, throughout this thesis, the effect of many parameters to the performance of the catalysts had been studied, including but not limited to, nickel content, GHSV, catalyst amount, reduction temperature and the addition of Ce as well as Zr. Furthermore, the stability of the catalysts was investigated through long-term tests. The CO2 methanation was already initiated below 220oC (XCO2=10.2 %, SCO2=98.4 %) which was ~100oC lower than that over Ni/Al2O3 and reached 80% conversion of CO2 at 300oC with 99.9 % selectivity of CH4 on 15 w% Ni/Mg/Al HT by co-precipitation method. When further increment in the temperature, at 350oC a complete conversion (99.5 %) of CO2 was achieved with ~100 % of CH4 selectivity. The catalysts were also utilised as packed-beds, among those 5 w% Ni/Mg/Al HT by sol-gel showed the highest activity at 300oC, 95.0% conversion of CO2 with 99.8% CH4 selectivity. The performance of the catalysts reduced with an increase in GHSV, while enhanced catalytic activity results obtained in the presence of excess amount of H2 in the feeding gas mixture. Furthermore, additional catalyst amount which was assured by repeating washcoating cycles significantly improved the activity results. Finally, long-term tests proved a good stability of the catalysts. This superior performance of hydrotalcite-based nickel catalysts could decrease the reaction temperature of CO2 methanation to lower temperatures and replace the usage of expensive Ru-based catalysts and conventional Ni catalysts supported on various oxides.
Catalyst deactívation in aqueous phase reforming induced by a phase change of gamma-Al₂O₃-catalyst support
(2012) Vikla, Anna Kaisa
School of Chemical Engineering | Master's thesis
Aqueous phase reforming (APR) is an efficient way to convert dilute biomass streams to hydrogen. The process is operated at elevated pressures in order to keep hot water in a liquid phase (e.g. T=225-450°C, p=2.9-25 MPa). Heterogeneous catalysts, especially Pt/y-Al₂O₃, have been reported to be active and selective catalyst for the conversion of biomass based oxygenates to hydrogen with APR. However, maintaining catalysts stability in hot pressurized water is challenging. It has been reported by several researchers that the phase of the y-Al₂O₃ support changes to boehmite (AlOOH) during APR resulting in decrease in the support surface area and changes in acidity. Furthermore, the active metals on the support surface lose their surface area due to sintering, resulting in changes in the catalyst performance. However, there are contradictory explanations in the literature about how the phase change alters the catalysts properties and in turn the performance. In this study the deactivation of Pt/y-Al₂O₃ catalyst in APR of ethylene glycol (EG) was studied. Pt/y-Al₂O₃ and Pt/AlOOH catalysts with similar particle size were prepared. Their properties, such as surface area, support structure and acidity, and activity in APR of EG were compared. Based on the results the y-Al₂O₃-support loses it acidity during APR due to the phase change. Acidity is required to bind the metals on the surface. After loss of the acidity, Pt particles are detached from the support surface and they create larger Pt clusters due to coalescence. This results in catalysts deactivation due to loss of active metal surface area.
Catalytic upgrading of lignin
(2015-08-25) Garza Treviño, Ricardo
Kemian tekniikan korkeakoulu | Master's thesis
In the broadest vision to contribute to sustainability, with focus on the use of lignin as a sustainable source for the production of chemicals, experiments were performed to find which chemicals may potentially be produced from isolated (organosolv-extracted) lignin through its decomposition by hydrodeoxygenation, as well as to describe the properties and composition of the product as a whole. Catalyst screening was implemented to evaluate the optimal catalyst to obtain low molecular weight organic compounds. The catalyst screening results of the light bio-oil reaction product fraction showed lowest molecular weights for the experiment involving the Pd/C 3% catalyst with values of 363.4 g/mol of number average and 583.9 g/mol of weight average, as well as fraction of light (monomers and dimers) compounds of 24.1%. The experiment involving the Pd/Al2O3 5% showed the highest molecular weights and lowest light compounds fraction. Regarding the gas product, the experiment involving the Pd/Al2O3 5% catalyst exhibited a considerably high amount of methane, and a considerably low amount of hydrogen concentration compared to the other experiments. In regards to the mass balance of the product streams excluding the gas phase, the Pd/Al2O3 5% catalyst showed the highest amount of light bio-oil, however, also the highest amount of char. On the other hand, the lowest amounts of both light bio-oil and char belonged to the experiment involving the Pd/C 3% catalyst. GC-MS analysis was performed to identify 24 small molecular weight compounds. The most representative compounds for the experiments involving the Pd/C 3%, ZrO2, and Pd/Al2O3 5% catalysts were 4-propylsyiringol, trans-4-propenylsyringol, and dihydrosinapyl alcohol, respectively.
Coking of steam reforming catalysts in biomass gasification conditions
(2012) Kaisalo, Noora
School of Chemical Engineering | Master's thesis
In the literature part of this master thesis, the coking problem in catalytic hot gas cleaning of biomass gasification gas is discussed. The feed, catalyst, temperature and pressure affect coking. Increasing H₂O/C ratio decreases coking rate, whereas the effect of sulfur is not clear. The unsaturated and aromatic compounds in the feed form coke easily. Nickel catalysts tend to coke more than noble metal catalysts. Smaller nickel crystal size decreases coking rate. The support affects the dispersion of active metal and thus also the crystal size. In addition, acid sites on the support increase coking of the catalyst. Different coke types were reviewed and special attention was paid to whisker coke because of its destructive nature. In the experimental part of this master thesis, coking of three different catalysts is studied using simulated biomass gasification gas. The experiments were carried out in a pressurized plug flow reactor at different temperatures at pressure of 4 bar (a). A reactor with four catalyst compartments was used. The catalysts used were two nickel catalysts and one noble metal catalyst. In addition, SiC and Al₂O were used as inerts. Experiments were carried out with two different water concentrations in the gas. Experiments with 100 ppm of H₂S in the feed were performed to see the effect of sulfur on coking. The coked catalysts were inspected with microscope and characterized by TPO and elemental analysis. The thermodynamic equilibrium limit for coking was calculated by HSC program and the experimental results were compared to thermodynamic calculations.
Competitive Hydrodeoxygenation and Hydrodenitrogenation Reactions in the Hydrotreatment of Fatty Acid and Amine Mixtures
(2023-10) Verkama, Emma; Auvinen, Paavo; Albersberger, Sylvia; Tiitta, Marja; Karinen, Reetta; Puurunen, Riikka L.
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Understanding how hydrotreating oxygen-containing compounds together with nitrogen-containing compounds affects the reactivity and selectivity is relevant for processing renewable feedstocks. In this work, competitive hydrodeoxygenation (HDO) and hydrodenitrogenation (HDN) reactions were studied by co-hydrotreating palmitic acid (C16 acid) and tetradecylamine (C14 amine) over a Pt/ZrO2 catalyst in a batch reactor. HDO proceeded faster than HDN in the studied system, and the deoxygenation reactions were found to have an inhibitory effect on HDN. Co-hydrotreating the C16 acid and the C14 amine expanded the reaction network from the individual HDO and HDN networks and changed the prevailing reaction pathways, initially in favor of oxygen removal. The formation of heavy secondary amides and amines through condensation reactions became increasingly favored as the share of C16 acid in the feed increased. For a given conversion level, the condensation product selectivity was observed to increase as the reaction temperature was decreased, whereas increasing the reaction temperature promoted the formation of the desired paraffins. This work described the ease of HDO compared to HDN, the role of condensation reactions in the co-hydrotreating reaction network, and the inhibitory effect on HDN thereof.
Conversion of furfural to 2-methylfuran over CuNi catalysts supported on biobased carbon foams
(2021-05-01) Varila, Toni; Mäkelä, Eveliina; Kupila, Riikka; Romar, Henrik; Hu, Tao; Karinen, Reetta; Puurunen, Riikka; Lassi, Ulla
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
In this study, carbon foams prepared from the by-products of the Finnish forest industry, such as tannic acid and pine bark extracts, were examined as supports for 5/5% Cu/Ni catalysts in the hydrotreatment of furfural to 2-methylfuran (MF). Experiments were conducted in a batch reactor at 503 K and 40 bar H2. Prior to metal impregnation, the carbon foam from tannic acid was activated with steam (S1), and the carbon foam from pine bark extracts was activated with ZnCl2 (S2) and washed with acids (HNO3 or H2SO4). For comparison, a spruce-based activated carbon (AC) catalyst and two commercial AC catalysts as references were investigated. Compressive strength of the foam S2 was 30 times greater than that of S1. The highest MF selectivity of the foam-supported catalysts was 48 % (S2, washed with HNO3) at a conversion of 91 %. According to the results, carbon foams prepared from pine bark extracts can be applied as catalyst supports.
Dieselkäyttöisten ajoneuvojen pakokaasujen puhdistus
(2021-05-18) Kostiander, Niilo
Kemiantekniikan korkeakoulu | Bachelor's thesis
E-metanolin valmistusprosessit
(2024-05-11) Ollila, Saara
Kemiantekniikan korkeakoulu | Bachelor's thesis
Tämän kandidaatintyön tavoitteena oli tutkia e-metanolin valmistusprosesseja. Työssä keskityttiin nimenomaan valmistusprosesseihin, joita e-metanolin valmistus vaatii. Tällaisia prosesseja ovat itse metanolisynteesin lisäksi myös hiilidioksidin talteenotto ja vihreän vedyn valmistus. Tehtiin myös katsaus e-metanolin valmistusteknologian nykytilanteeseen sekä tulevaisuuden mahdollisuuksiin. Selvitettiin, onko olemassa jo valmiita e-metanolilaitoksia tai kehitteillä olevia laitoksia. Selvitettiin, onko e-metanoli valmis kaupallistettavaksi. Tulokseksi saatiin, että e-metanolin valmistusteknologia on kehittynyt siihen vaiheeseen, että e-metanolia voidaan valmistaa jo teollisessa mittakaavassa. Tuotantokustannukset ovat kuitenkin edelleen niin korkeat, että e-metanoli ei ole kilpailukykyinen konventionaalisen metanolin kanssa. Fossiilisesti valmistettujen polttoaineiden kustannusten oletetaan kuitenkin nousevan tulevaisuudessa etenkin hiilidioksidin päästöhyvitysten takia, jolloin sähköpolttoaineista tulee kilpailukykyisempiä. E-metanolin lisäksi myös muut sähköpolttoaineet tulevat yleistymään tulevaisuudessa. Maailmalla on jo muutamia toimivia e-metanolilaitoksia ja Suomeen on kaavailtu useita laitoksia, joiden odotetaan aloittavan toiminta vielä 2020-luvulla.
Effect of impurities on hydrogenation of CO2
(2016-10-31) Henriksson, Fanny
Kemian tekniikan korkeakoulu | Master's thesis
The literature survey of this thesis deals with capture and separation technologies for CO2, impurities found in industrial CO2 streams and impurity effect on CO2 hydrogenation catalysts. In addition, impurities originating from CO2 separation have been discussed. The experimental part studied the effect of impurities on four different CO2 hydrogenation catalysts by temperature programmed desorption (TPD) and reaction tests in a fixed bed plug flow reactor (PFR). The catalysts studied were two in-house Fe-based FT catalysts (one impregnated and one precipitated), a commercial Ni-based methanation catalyst and a commercial Cu-based methanol synthesis catalyst. Special emphasis was given to studying the effects of monoethanolamine (MEA), a commonly used absorbent for CO2 separation, and hydrogen sulphide (H2S) on the catalysts. MEA was chosen due to a lack of earlier research on the effects of MEA on catalytic processes, while H2S was chosen as it is a typical catalyst poison and a common impurity in separated CO2. Furthermore, previous researches studying the effect of H2S on catalytic processes have been rather contradictory. The effect of MEA was studied by pulse reaction experiments in the TPD apparatus with a constant H2 flow by pulsing CO2 and following the formation of methane. During poisoning experiments, the concentration of MEA in the carrier gas was approximately 570 ppm. Interestingly, the CH4 formation increased after MEA poisoning for precipitated in-house catalyst 100Fe/4.6Si/2.0Cu/1.5K (atomic ratio composition) and commercial CuO/ZnO catalyst. The reason for increase in CH4 formation is proposed to be a modification in selectivity of the catalysts caused by MEA and its degradation products. For the other studied catalysts, the formation of CH4 was drastically decreased during MEA poisoning without catalyst recovery. For the precipitated in-house catalyst 5Fe/5Mn/Al2O3 (weight ratio composition), the formation of CH4 was decreased by 61% without catalyst recovery. It is suggested that MEA’s degradation products, e.g. NOx, oxidizes the active carbide sites on the catalyst to inactive magnetite. The effect of H2S on catalysts was studied in TPD and reaction tests in PFR. However, the TPD tests were only indicative and thus the PFR tests were considered to be more reliable. The CuO/ZnO catalyst maintained its activity surprisingly well. After 60 ppm H2S poisoning the catalyst recovered almost completely (initial conversion 17.5% compared to 15.6% during recovery). However, during the poisonings the selectivity of CO was increased on the expense of methanol. The impregnated Fe catalyst deactivated completely at 30 ppm, while the precipitated Fe catalyst recovered from 1 ppm H2S, but deactivated completely at 60 ppm. However, the selectivity of the catalyst remained unaffected.
Etherification of some C8-alkenes to fuel ethers
(2002-05-17) Karinen, Reetta
Doctoral dissertation (article-based)
Tertiary ethers are formed in a reaction between alcohols and alkenes. They are used in gasoline to enhance its burning and to reduce harmful exhaust emissions. They also have high octane rating, which is beneficial for gasoline blending. Regulations in regard to fuel composition and exhaust emissions are tightening and new, cleaner burning high octane gasoline components are of wide interest. This work concerns the etherification of C8-alkenes. Several C8-alkenes were screened for their reactivity. Study of the properties of the resulting ethers showed that some of them are potential for gasoline blending. 2,4,4-Trimethyl pentenes were chosen for more detailed study in view of the availability of the feed stock in industrial scale and the promising properties of the resulting ether. The reactivity of 2,4,4-trimethyl pentenes was tested with various alcohols. The marked effect of the alcohol on the reaction rate was attributed primarily to the polarity of the alcohol, which affects the adsorption of the components and the catalyst. Compared with the ethers currently in commercial production, the C8-alkenes are etherified rather slowly. A new catalyst was sought to enhance the reaction rate. Traditionally, etherification is catalysed by strong cation exchange resin beads, such as Amberlyst resins, but a novel fibrous Smopex-101 catalyst was found to be more active in the etherification of 2,4,4-trimethyl pentenes with methanol, evidently because diffusional limitations were less. A kinetic model was developed for the etherification of 2,4,4-trimethyl pentenes with methanol for purposes of reactor design. Kinetic experiments were performed with Smopex-101 as catalyst. Before the kinetic studies, thermodynamic parameters were derived for the etherification reactions and for the isomerisation reaction between 2,4,4-trimethyl-1-pentene and 2,4,4-trimethyl-2-pentene. The results of the kinetic modelling indicated that the adsorption of the alkenes was minor. The best models to describe the data were the Langmuir-Hinshelwood type model where the adsorption of alkenes is assumed to be negligible compared to other reactive components and the Eley-Rideal type model where alkenes are not adsorbed. Adsorption behaviour was different on the fibrous catalyst than on the ion exchange resins: ether was better adsorbed than alcohol on the fibrous catalyst, whereas alcohol is known to better adsorb than ether on the traditional ion exchange resin catalyst. The better adsorption of ether on the fibrous catalyst was attributed to the greater hydrophobicity of this catalyst.
Fractionation and characterization of renewable paraffinic solvents
(2013) Sinthavarayan, Kanokporn
School of Chemical Engineering | Master's thesis
Furfural Hydrotreatment Applying Isopropanol as a Solvent: The Case of Acetone Formation
(2017-11-01) Jaatinen, Salla; Karinen, Reetta
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
In this study, acetone formation was investigated as a side reaction in furfural hydrotreatment applying isopropanol as a solvent. Acetone formation was observed to depend strongly on the metal and metal loading of catalysts as copper, nickel, and iron catalysts supported on activated carbon were studied. Furfural has an important role in acetone formation: the initial formation rate for acetone was high as long as furfural reacted further. After furfural was consumed the acetone formation decelerated except with the catalysts including iron. Two formation mechanisms were derived: first mechanism includes direct and transfer hydrogenation of furfural and isopropanol dehydrogenation, as mechanism two consists only of isopropanol dehydrogenation. Another novel discovery of the study was the confirmation of the formation mechanism for 2-methylfuran through transfer hydrogenation of furfuryl alcohol in the experiments. In conclusion, the acetone formation as a side product was observed significant and could not be totally prevented.
Glyserolin aromatisointi
(2024-12-22) Hellämäki, Lauri
Kemiantekniikan korkeakoulu | Bachelor's thesis
Tämän kandidaattityön tarkoitus on tutkia biodieselin valmistuksessa syntyvän glyserolin soveltuvuutta aromaattien lähtöaineeksi sekä vertailla erilaisia tapoja saada glyserolista aromaatteja. Työ on toteutettu kirjallisuustutkielmana. Biodieselin valmistuksessa syntyy valtava määrä glyserolia, joka aiheuttaa markk-noille ylitarjonnan. Glyserolin hinta romahtaa ja siitä aiheutuu taloudellisia sekä logistisia ongelmia tuottajille. Tarkoitus on tutkia glyserolin jatkojalostamista arvokkaiksi aromaateiksi, joka edistäisi biodieselin valmistusta monin tavoin. Glyserolin aromatisointi tapahtuu HZSM5 zeoliitin avulla, jolla pystytään tuottamaan BTX-aromaatteja oikeilla reaktio olosuhteilla. Reaktio on monimutkainen eikä vielä valmis laajaan tuotantoon erilaisten ongelmien takia. Suurimpana ongelmana on katalyytin deaktivoitumien koskaantumisen vuoksi. Deaktivoitumiseen on etsitty erilaisia ratkaisuja, joilla pystytään hidastamaan deaktivoitumista ja näin pidentämään katalyytin elinikää.