Electron Microscopy | Materials Science | Materials Characterisation | Catalytic Biomass Conversion for Renewable Chemicals and Fuels | Hydrogenation, Oxidation, Hydrolysis and Dehydration | Green Chemistry | Metal Nanoparticles | Porous Materials | Catalysts Synthesis and Characterization | Positive, Hardworking, Communicative, Resourceful and Hands On
Tato diplomova praca sa zaobera deoxygenaciou rastlinných olejov na NiMoalumina katalyzatoroch. V... more Tato diplomova praca sa zaobera deoxygenaciou rastlinných olejov na NiMoalumina katalyzatoroch. V prvej casti su charakterizovane Ni-, Mo- a NiMo-alumina katalyzatory. Katalyzatory su charakterizovane XRF (chemicke zloženie), XRD (krystalickosť), BET (specifický povrch), SEM (morfologia), SEM-EDX (homogenita povrchovej distribucie Ni a Mo castic) a UV-Vis DRS (distribucia Ni a Mo castic). V druhej casti su popisane tri efekty, ktore by mohli hrať doležitu ulohu vzhľadom k aktivite NiMo-alumina katalyzatorov. Je to uloha distribucie Ni, použitie mesoporeznej aluminy namiesto konvencnej komercnej aluminy a porovnanie NiMo-alumina katalyzatorov pripravených v laboratornych podmienkach s priemyslovými NiMoalumina katalyzatormi.
This thesis is focused on NiMo-alumina catalysts for application in (i) hydrodeoxygenation of rap... more This thesis is focused on NiMo-alumina catalysts for application in (i) hydrodeoxygenation of rapeseed oil as a feasible way to produce diesel-like fuels from renewable feedstocks and (ii) for hydrodesulfurization of 4,6-dimethyldibenzothiophene as a model compound for sulfur removal from vehicular fuels. The main aim was to elucidate structural parameters of these catalysts and to connect these properties with their catalytic performance. This should reveal structure-activity relationships, which could deepen the knowledge about hydrotreating catalysts and improve their optimization for particular applications. The thesis consists of 1 review on the topic (book chapter), 3 original research papers and results of so far unpublished work, which are presented as an introduction to hydrotreating and deoxygenation catalysis and discussion of the results. The main point of our investigation was the determination of structural changes in NiMo-alumina catalysts. Promoter and support effect...
The contribution deals with the synthesis of hexagonal mesoporous silica containing aluminum, sil... more The contribution deals with the synthesis of hexagonal mesoporous silica containing aluminum, silica and titanium. Catalytic performance of vanadium species supported on hexagonal mesoporous silica containing aluminum, silica and titanium was compared in the oxidative dehydrogenation of ethane. The supports and the vanadium based catalysts were characterized by using of UV- Vis DR spectroscopy, N 2 -isotherm, SEM and X-ray diffraction.
A comparative environmental life cycle assessment of using low-value wheat straw to produce high ... more A comparative environmental life cycle assessment of using low-value wheat straw to produce high value biosurfactants using a novel biorefinery, compared to those produced from palm and wheat, is reported.
The application of microwave irradiation in the transformation of biomass has been receiving part... more The application of microwave irradiation in the transformation of biomass has been receiving particular interest in recent years due to the use of polar media in such processes and it is now well-known that for biomass conversion, and particularly for lignocellulose hydrolysis, microwave irradiation can dramatically increase reaction rates with no negative consequences on product selectivity. However, it is only in the last ten years that the utilisation of microwaves has been coupled with catalysis aiming towards valorising biomass components or their derivatives via a range of reactions where high selectivity is required in addition to enhanced conversions. The reduced reaction times and superior yields are particularly attractive as they might facilitate the transition towards flow reactors and intensified production. As a consequence, several reports now describe the catalytic transformation of biomass derivatives via hydrogenation, oxidation, dehydration, esterification and transesterification using microwaves. Clearly, this technology has a huge potential for biomass conversion towards chemicals and fuels and will be an important tool within the biorefinery toolkit. The aim of this chapter is to give the reader an overview of the exciting scientific work carried out to date where microwave reactors and catalysis are combined in the transformation of biomass and its derivatives to higher value molecules and products.
ABSTRACT The diploma thesis is focused on the deoxygenation of vegetable oils on MoNialumina cata... more ABSTRACT The diploma thesis is focused on the deoxygenation of vegetable oils on MoNialumina catalysts. In the first part, Ni-, Mo- and NiMo-alumina catalysts are characterized. The catalysts are characterized by XRF (chemical composition), XRD (crystallinity), BET (specific surface area), SEM (morphology), SEM-EDX (homogeneity of the surface distribution of Ni and Mo species) and UV-Vis DRS (distribution of metal species). In the second part, the activity of NiMo-alumina catalysts in the deoxygenation of the vegetable oils is described. There are described three effects, which appeared to be important with respect to the final activity of NiMoalumina catalysts. It is the role of Ni distribution, the use of mesoporous alumina support instead of the commercial one and the comparison of NiMo-alumina catalysts prepared at the laboratory and the industrial NiMo-alumina catalysts.
This critical review examines recent scientific and patent literature in the application of micro... more This critical review examines recent scientific and patent literature in the application of microwave reactors for catalytic transformation of biomass and biomass-derived molecules with a particular emphasis on heterogeneous catalysis. Several recent reports highlight dramatic reductions in reaction time and even superior selectivity when microwaves are used. However, there are still many controversies and unexplained effects in this area that deserve attention. We critically review the available sources attempting to establish trends and elucidate the actual status of this area of research. Additionally, where possible, we discuss the potential for scale-up and commercial utilization of microwaves and impediments that currently hold back their implementation. This critical review aims at highlighting the opportunity of combining catalysis with microwave technology for biomass conversion but also to stimulate the reader to generate future understanding of the influence of the microwaves in catalytic processes in general.
Green, inexpensive, and robust copper-based heterogeneous catalysts achieve 100 % conversion and ... more Green, inexpensive, and robust copper-based heterogeneous catalysts achieve 100 % conversion and 99 % selectivity in the conversion of furfural to furfuryl alcohol when using cyclopentyl-methyl ether as green solvent and microwave reactors at low H2 pressures and mild temperatures. The utilization of pressurized microwave reactors produces a 3–4 fold increase in conversion and an unexpected enhancement in selectivity as compared to the reaction carried out at the same conditions using conventional autoclave reactors. The enhancement in catalytic rate produced by microwave irradiation is temperature dependent. This work highlights that using microwave irradiation in the catalytic hydrogenation of biomass-derived compounds is a very strong tool for biomass upgrade that offers immense potential in a large number of transformations where it could be a determining factor for commercial exploitation.
Abstract Despite the high amount of scientific work dedicated to the gold nanoparticles in cataly... more Abstract Despite the high amount of scientific work dedicated to the gold nanoparticles in catalysis, most of the research has been performed utilising supported nanoparticles obtained by traditional impregnation of gold salts onto a support, co-precipitation or deposition-precipitation methods which do not benefit from the recent advances in nanotechnologies. Only more recently, gold catalyst scientists have been exploiting the potential of preforming the metal nanoparticles in a colloidal suspension before immobilisation with great results in terms of catalytic activity and the morphology control of mono- and bimetallic catalysts. On the other hand, the last decade has seen the emergence of more advanced control in gold metal nanoparticle synthesis, resulting in a variety of anisotropic gold nanoparticles with easily accessible new morphologies that offer control over the coordination of surface atoms and the optical properties of the nanoparticles (tunable plasmon band) with immense relevance for catalysis. Such morphologies include nanorods, nanostars, nanoflowers, dendritic nanostructures or polyhedral nanoparticles to mention a few. In addition to highlighting newly developed methods and properties of anisotropic gold nanoparticles, in this review we examine the emerging literature that clearly indicates the often superior catalytic performance and amazing potential of these nanoparticles to transform the field of heterogeneous catalysis by gold by offering potentially higher catalytic performance, control over exposed active sites, robustness and tunability for thermal-, electro- and photocatalysis.
Methylbenzenes are among the most important organic chemicals today and, among them, p-xylene des... more Methylbenzenes are among the most important organic chemicals today and, among them, p-xylene deserves particular attention because of its production volume and its application in the manufacture of polyethylene terephthalate (PET). There is great interest in producing this commodity chemical more sustainably from biomass sources, particularly driven by manufacturers willing to produce more sustainable synthetic fibres and PET bottles for beverages. A renewable source for p-xylene would allow achieving this goal with minimal disruption to existing processes for PET production. Despite the fact that recently some routes to renewable p-xylene have been identified, there is no clear consensus on their feasibility or implications. We have critically reviewed the current state-of-the-art with focus on catalytic routes and possible outlook for commercialisation. Pathways to obtain p-xylene from a biomass-derived route include methanol-to-aromatics (MTA), ethanol dehydration, ethylene dimerization, furan cycloaddition or catalytic fast pyrolysis and hydrotreating of lignin. Some of the processes identified suggest near-future possibilities, but also more speculative or longer-term sources for synthesis of p-xylene are highlighted.
This work aims to develop a rapid and efficient strategy for preparing supported metal catalysts ... more This work aims to develop a rapid and efficient strategy for preparing supported metal catalysts for catalytic applications. The sonication-assisted reduction-precipitation method was employed to prepare the heterogeneous mono- and bi-metallic catalysts for photocatalytic degradation of methyl orange (MO) and preferential oxidation (PROX) of CO in H2-rich gas. In general, there are three advantages for the sonication-assisted method as compared with the conventional methods, including high dispersion of metal nanoparticles on the catalyst support, the much higher deposition efficiency (DE) than those of the deposition-precipitation (DP) and co-precipitation (CP) methods, and the very fast preparation, which only lasts 10-20s for the deposition. In the AuPd/TiO2 catalysts series, the AuPd(3:1)/TiO2 catalyst is the most active for MO photocatalytic degradation; while for PROX reaction, Ru/TiO2, Au-Cu/SBA-15 and Pt/γ-Al2O3 catalysts are very active, and the last one showed high stabili...
Tato diplomova praca sa zaobera deoxygenaciou rastlinných olejov na NiMoalumina katalyzatoroch. V... more Tato diplomova praca sa zaobera deoxygenaciou rastlinných olejov na NiMoalumina katalyzatoroch. V prvej casti su charakterizovane Ni-, Mo- a NiMo-alumina katalyzatory. Katalyzatory su charakterizovane XRF (chemicke zloženie), XRD (krystalickosť), BET (specifický povrch), SEM (morfologia), SEM-EDX (homogenita povrchovej distribucie Ni a Mo castic) a UV-Vis DRS (distribucia Ni a Mo castic). V druhej casti su popisane tri efekty, ktore by mohli hrať doležitu ulohu vzhľadom k aktivite NiMo-alumina katalyzatorov. Je to uloha distribucie Ni, použitie mesoporeznej aluminy namiesto konvencnej komercnej aluminy a porovnanie NiMo-alumina katalyzatorov pripravených v laboratornych podmienkach s priemyslovými NiMoalumina katalyzatormi.
This thesis is focused on NiMo-alumina catalysts for application in (i) hydrodeoxygenation of rap... more This thesis is focused on NiMo-alumina catalysts for application in (i) hydrodeoxygenation of rapeseed oil as a feasible way to produce diesel-like fuels from renewable feedstocks and (ii) for hydrodesulfurization of 4,6-dimethyldibenzothiophene as a model compound for sulfur removal from vehicular fuels. The main aim was to elucidate structural parameters of these catalysts and to connect these properties with their catalytic performance. This should reveal structure-activity relationships, which could deepen the knowledge about hydrotreating catalysts and improve their optimization for particular applications. The thesis consists of 1 review on the topic (book chapter), 3 original research papers and results of so far unpublished work, which are presented as an introduction to hydrotreating and deoxygenation catalysis and discussion of the results. The main point of our investigation was the determination of structural changes in NiMo-alumina catalysts. Promoter and support effect...
The contribution deals with the synthesis of hexagonal mesoporous silica containing aluminum, sil... more The contribution deals with the synthesis of hexagonal mesoporous silica containing aluminum, silica and titanium. Catalytic performance of vanadium species supported on hexagonal mesoporous silica containing aluminum, silica and titanium was compared in the oxidative dehydrogenation of ethane. The supports and the vanadium based catalysts were characterized by using of UV- Vis DR spectroscopy, N 2 -isotherm, SEM and X-ray diffraction.
A comparative environmental life cycle assessment of using low-value wheat straw to produce high ... more A comparative environmental life cycle assessment of using low-value wheat straw to produce high value biosurfactants using a novel biorefinery, compared to those produced from palm and wheat, is reported.
The application of microwave irradiation in the transformation of biomass has been receiving part... more The application of microwave irradiation in the transformation of biomass has been receiving particular interest in recent years due to the use of polar media in such processes and it is now well-known that for biomass conversion, and particularly for lignocellulose hydrolysis, microwave irradiation can dramatically increase reaction rates with no negative consequences on product selectivity. However, it is only in the last ten years that the utilisation of microwaves has been coupled with catalysis aiming towards valorising biomass components or their derivatives via a range of reactions where high selectivity is required in addition to enhanced conversions. The reduced reaction times and superior yields are particularly attractive as they might facilitate the transition towards flow reactors and intensified production. As a consequence, several reports now describe the catalytic transformation of biomass derivatives via hydrogenation, oxidation, dehydration, esterification and transesterification using microwaves. Clearly, this technology has a huge potential for biomass conversion towards chemicals and fuels and will be an important tool within the biorefinery toolkit. The aim of this chapter is to give the reader an overview of the exciting scientific work carried out to date where microwave reactors and catalysis are combined in the transformation of biomass and its derivatives to higher value molecules and products.
ABSTRACT The diploma thesis is focused on the deoxygenation of vegetable oils on MoNialumina cata... more ABSTRACT The diploma thesis is focused on the deoxygenation of vegetable oils on MoNialumina catalysts. In the first part, Ni-, Mo- and NiMo-alumina catalysts are characterized. The catalysts are characterized by XRF (chemical composition), XRD (crystallinity), BET (specific surface area), SEM (morphology), SEM-EDX (homogeneity of the surface distribution of Ni and Mo species) and UV-Vis DRS (distribution of metal species). In the second part, the activity of NiMo-alumina catalysts in the deoxygenation of the vegetable oils is described. There are described three effects, which appeared to be important with respect to the final activity of NiMoalumina catalysts. It is the role of Ni distribution, the use of mesoporous alumina support instead of the commercial one and the comparison of NiMo-alumina catalysts prepared at the laboratory and the industrial NiMo-alumina catalysts.
This critical review examines recent scientific and patent literature in the application of micro... more This critical review examines recent scientific and patent literature in the application of microwave reactors for catalytic transformation of biomass and biomass-derived molecules with a particular emphasis on heterogeneous catalysis. Several recent reports highlight dramatic reductions in reaction time and even superior selectivity when microwaves are used. However, there are still many controversies and unexplained effects in this area that deserve attention. We critically review the available sources attempting to establish trends and elucidate the actual status of this area of research. Additionally, where possible, we discuss the potential for scale-up and commercial utilization of microwaves and impediments that currently hold back their implementation. This critical review aims at highlighting the opportunity of combining catalysis with microwave technology for biomass conversion but also to stimulate the reader to generate future understanding of the influence of the microwaves in catalytic processes in general.
Green, inexpensive, and robust copper-based heterogeneous catalysts achieve 100 % conversion and ... more Green, inexpensive, and robust copper-based heterogeneous catalysts achieve 100 % conversion and 99 % selectivity in the conversion of furfural to furfuryl alcohol when using cyclopentyl-methyl ether as green solvent and microwave reactors at low H2 pressures and mild temperatures. The utilization of pressurized microwave reactors produces a 3–4 fold increase in conversion and an unexpected enhancement in selectivity as compared to the reaction carried out at the same conditions using conventional autoclave reactors. The enhancement in catalytic rate produced by microwave irradiation is temperature dependent. This work highlights that using microwave irradiation in the catalytic hydrogenation of biomass-derived compounds is a very strong tool for biomass upgrade that offers immense potential in a large number of transformations where it could be a determining factor for commercial exploitation.
Abstract Despite the high amount of scientific work dedicated to the gold nanoparticles in cataly... more Abstract Despite the high amount of scientific work dedicated to the gold nanoparticles in catalysis, most of the research has been performed utilising supported nanoparticles obtained by traditional impregnation of gold salts onto a support, co-precipitation or deposition-precipitation methods which do not benefit from the recent advances in nanotechnologies. Only more recently, gold catalyst scientists have been exploiting the potential of preforming the metal nanoparticles in a colloidal suspension before immobilisation with great results in terms of catalytic activity and the morphology control of mono- and bimetallic catalysts. On the other hand, the last decade has seen the emergence of more advanced control in gold metal nanoparticle synthesis, resulting in a variety of anisotropic gold nanoparticles with easily accessible new morphologies that offer control over the coordination of surface atoms and the optical properties of the nanoparticles (tunable plasmon band) with immense relevance for catalysis. Such morphologies include nanorods, nanostars, nanoflowers, dendritic nanostructures or polyhedral nanoparticles to mention a few. In addition to highlighting newly developed methods and properties of anisotropic gold nanoparticles, in this review we examine the emerging literature that clearly indicates the often superior catalytic performance and amazing potential of these nanoparticles to transform the field of heterogeneous catalysis by gold by offering potentially higher catalytic performance, control over exposed active sites, robustness and tunability for thermal-, electro- and photocatalysis.
Methylbenzenes are among the most important organic chemicals today and, among them, p-xylene des... more Methylbenzenes are among the most important organic chemicals today and, among them, p-xylene deserves particular attention because of its production volume and its application in the manufacture of polyethylene terephthalate (PET). There is great interest in producing this commodity chemical more sustainably from biomass sources, particularly driven by manufacturers willing to produce more sustainable synthetic fibres and PET bottles for beverages. A renewable source for p-xylene would allow achieving this goal with minimal disruption to existing processes for PET production. Despite the fact that recently some routes to renewable p-xylene have been identified, there is no clear consensus on their feasibility or implications. We have critically reviewed the current state-of-the-art with focus on catalytic routes and possible outlook for commercialisation. Pathways to obtain p-xylene from a biomass-derived route include methanol-to-aromatics (MTA), ethanol dehydration, ethylene dimerization, furan cycloaddition or catalytic fast pyrolysis and hydrotreating of lignin. Some of the processes identified suggest near-future possibilities, but also more speculative or longer-term sources for synthesis of p-xylene are highlighted.
This work aims to develop a rapid and efficient strategy for preparing supported metal catalysts ... more This work aims to develop a rapid and efficient strategy for preparing supported metal catalysts for catalytic applications. The sonication-assisted reduction-precipitation method was employed to prepare the heterogeneous mono- and bi-metallic catalysts for photocatalytic degradation of methyl orange (MO) and preferential oxidation (PROX) of CO in H2-rich gas. In general, there are three advantages for the sonication-assisted method as compared with the conventional methods, including high dispersion of metal nanoparticles on the catalyst support, the much higher deposition efficiency (DE) than those of the deposition-precipitation (DP) and co-precipitation (CP) methods, and the very fast preparation, which only lasts 10-20s for the deposition. In the AuPd/TiO2 catalysts series, the AuPd(3:1)/TiO2 catalyst is the most active for MO photocatalytic degradation; while for PROX reaction, Ru/TiO2, Au-Cu/SBA-15 and Pt/γ-Al2O3 catalysts are very active, and the last one showed high stabili...
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