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The major lactiferous ducts of the human breast branch out and end at terminal ductal lobular units (TDLUs). Despite their functional and clinical importance, the three-dimensional (3D) architecture of TDLUs has remained undetermined. Our quantitative and volumetric imaging of healthy human breast tissue demonstrates that highly branched TDLUs, which exhibit increased proliferation, are uncommon in the resting tissue regardless of donor age, parity, or hormonal contraception. Overall, TDLUs have a consistent shape and branch parameters, and they contain a main subtree that dominates in bifurcation events and exhibits a more duct-like keratin expression pattern. Simulation of TDLU branching morphogenesis in three dimensions suggests that evolutionarily conserved mechanisms regulate mammary gland branching in humans and mice despite their anatomical differences. In all, our data provide structural insight into 3D anatomy and branching of the human breast and exemplify the power of volumetric imaging in gaining a deeper understanding of breast biology. [Display omitted] • Breast terminal ductal lobular unit (TDLU) branching varies regardless of age or parity • TDLUs have a main branch that dominates in bifurcations and has duct-like features • Highly branched TDLUs proliferate more and may contain more S100A4+ stromal cells • Human and mouse mammary glands appear to branch by the same principles Paavolainen, Peurla et al. studied intact terminal ductal lobular unit (TDLU) structures to quantitatively assess the branching morphology of the human breast in three dimensions. The study provides a framework for investigating the role of TDLU architecture and cell-type-specific anatomical niches in breast homeostasis and malignant progression. [ABSTRACT FROM AUTHOR]

Algae as a raw material are highly important, since algae have high growth rates and are rich in lipids, proteins, and carotenoids. Direct saponification of alga with an ethanolic solution of KOH or NaOH followed by extraction was investigated and the composition of different fractions was studied by several physico-chemical methods, such as gas- and liquid chromatography, Fourier transform infrared analysis, scanning and transmission electron microscopy, organic elemental analysis, and thermogravimetric analysis. Direct saponification of Chlorella sp. was demonstrated with detailed analysis of different products, such as lipids, proteins, carotenoids and carbohydrates. The yield of lipids and the unsaponifiable fraction was independent on the type and concentration of alkali in direct saponification of green alga Chlorella sp. Proteins were mainly in the solid residue remaining after saponification. Protein content in the solid residue decreased with increasing alkali concentration and the solid residue. The main fatty acids were oleic and linoleic acids. Lutein and β-carotene were the main carotenoids in Chlorella sp. Sugars and large part of proteins remained in the polar fraction after separation of lipid and carotenoids. [ABSTRACT FROM AUTHOR]

• Isoeugenol hydrodeoxygenation was studied over Ni-SBA-15 and Ni-SZ-SBA-15 with sulfated ZrO 2. • 75% yield of propylcyclohexane was obtained over a non acidic Ni-SBA-15. • Ni particles in Ni-SBA-15 (size 20 nm) were mainly located outside SBA-15 promoting HDO. • Ni particles in Ni-SZ-SBA-15 were partially inside the SBA-15 structure, leading a very low HDO activity. • The kinetic model was developed for HDO of isoeugenol based on the proposed reaction network. Hydrodeoxygenation (HDO) of isoeugenol has been investigated over Ni-SBA-15 and Ni-SZ-SBA-15 containing sulfated ZrO 2 with Si/Zr molar ratio of 8.4. The catalysts were prepared via incipient wetness method and characterized by N 2 adsorption, AAS, TPR, X-ray diffraction (XRD), thermal gravimetric/differential thermal analyses (TG-DTA), organic elemental analysis, pyridine adsorption-desorption with Fourier-transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). The results revealed that 75% yield of propylcyclohexane was obtained over a non acidic Ni-SBA-15 in isoeugenol HDO at 300 °C under 3 MPa H 2 using dodecane as a solvent. Ni-SZ-SBA-15 gave only very low HDO activity, which is explained by location of the acid sites both inside and outside SBA-15, whereas nickel particles were partially located inside the SBA-15 structure. On the other hand Ni particles in Ni-SBA-15 with the size of 20 nm were located outside SBA-15 promoting HDO. The kinetic model was developed for HDO of isoeugenol based on the proposed reaction network, which took into account formation of intermediate products as well as oligomers. The developed kinetic model was capable of describing well the experimental data with the degree of explanation equal to 91%. The activation energy for hydrogenation of propylcyclohexene and for demethoxylation of dihydroeugenol to 4-propylphenol are equal to 92 kJ/mol and 62 kJ/mol, respectively. [ABSTRACT FROM AUTHOR]

In the present work, the formulation and performance of the silica-aluminosilicate-based composites were studied for catalytic conversion of sugars to levulinic acid. Tailoring the acidity, surface area and the porosity of the catalysts were the main goal of the work. The acidities of the catalysts were provided by ZSM-5 zeolite and were modulated by microwave assisted solid state ion-exchange with copper. The high surface area and porosity of the catalysts were guaranteed by mesopores silica type HMS. The composites of HMS and CuZSM-5 with different contents of 30%, 50%, 60% and 70% were synthesized and the morphological and textural features and acidity of the materials were assessed using XRD, EDX, SEM, TEM, N 2 -physisorption, and FTIR, FTIR with pyridine and NH 3 -TPD. CuZ(60%)@H composite acted as the best catalyst with production of 45% yield and 30% yield of LA from glucose and cellulose conversion, respectively. High surface area, large pore size and volume of HMS in the best composite structure favored mass transfer of the substrates and products and higher performance of the catalyst especially in cellulose hydrolysis. In addition, tuned and balanced concentration, strength and type of CuZSM-5 acidity in the composite promoted the desired pathway, favored formation of levulinic acid and suppressed humins formation. [Display omitted] • Ion-exchanged CuZSM5 with optimum acidity for sugars conversion to levulinic acid. • HMS with high surface area and suitable porosity for facile cellulose mass transfer. • The composite of CuZSM5 and HMS with suitable acidity and porosity. • CuZ(60%)@H composite as a promising catalyst for sugars conversion to levulinic acid. [ABSTRACT FROM AUTHOR]

Formic acid is one of the key components in green chemistry being involved in energy storage, production of chemical intermediates and fuel components. Therefore the knowledge of its stability is of crucial importance and a systematic study of its decomposition is needed. The kinetics of formic acid decomposition to hydrogen and carbon dioxide was investigated in a laboratory-scale fixed bed reactor at 150–225 °C and atmospheric pressure. Palladium nanoparticles deposited on porous active carbon Sibunit were used as the heterogeneous catalyst. The catalyst was characterized by nitrogen physisorption and high-resolution transmission electron microscopy. The average palladium nanoparticle size was 5–6 nm. The impacts of mass transfer resistance and formic acid dimerization were negligible under the reaction conditions. Prolonged experiments revealed that the catalyst had a good stability. Hydrogen and carbon dioxide were the absolutely dominant reaction products, whereas the amounts of carbon monoxide and water were negligible. The experimental data were described with three kinetic models: first order kinetics, two-step adsorption-reaction model and multistep adsorption-decomposition model of formic acid. The multistep model gave the best description of the data. [Display omitted] • Formic acid is very important molecule in large-scale production, biomass conversion and energy storage • Catalytic decomposition of formic acid was studied from kinetic, mass transfer and reactor perspectives • A model for the decomposition process in a fixed bed reactor was developed • The model gave a good description of experimental data [ABSTRACT FROM AUTHOR]

• A clear impact of the precursor on physico-chemical properties of solution impregnated Ni in zeolite 5A and 13X was shown. • Significant differences were also observed in activity and selectivity of the prepared catalysts in CO 2 methanation. • Besides the choice of precursor, the calcination temperature also influenced clearly the performance of the catalysts. • Detailed catalyst characterization was performed. • 13X was concluded to be the superior support and nickel citrate was the best precursor. Zeolite 13X and 5A supported Ni catalysts were synthesized for CO 2 methanation using the evaporation impregnation method. The influence of using different Ni precursors (nitrate, citrate, and acetate) as well as calcination temperatures on the catalyst properties and performance were investigated. XRD, SEM-EDX, TEM, STEM-EDX, N 2 physisorption, H 2- TPR, TPD-NH 3 and TG/DTA were used for detailed characterization of the catalysts. The parent structure of the zeolites did not change during catalyst synthesis. Using nickel citrate and acetate resulted in smaller NiO particle size compared to nitrate. STEM-EDX results showed that all the Ni-precursor complexes entered more efficiently the 13X zeolite structure, which is mainly due to steric hindrance resulting from the smaller pore size of 5A. Methanation experiments revealed that the 13X catalysts synthesized using nickel citrate (5% Ni) displayed clearly higher activity, compared to the catalysts synthesized using nickel nitrate or nickel acetate. A 79% conversion at 320 °C was obtained with 100% selectivity towards CH 4 and the catalyst showed excellent stability during 200 h testing. Overall, it can be concluded that the Ni precursor significantly influences the physico-chemical characteristics and catalytic properties of Ni 13X and Ni 5A zeolite catalysts in CO 2 methanation: complex size and pore size matter. [ABSTRACT FROM AUTHOR]

Five different support materials were modified with 5 wt.% Cu, using an evaporation impregnation method. The synthesized CuCl 2 /γ-Al 2 O 3 , CuCl 2 /TiO 2 (Hombikat), CuCl 2 /TiO 2 (Alfa Aesar), CuCl 2 /SiO 2 and CuCl 2 /H-Beta-25 materials were characterized by nitrogen physisorption, X-ray powder diffraction, scanning electron microscopy, energy dispersive Xray microanalysis, transmission electron microscopy, Fourier transform infrared spectroscopy and CO 2 -temperature programmed desorption. The physical-chemical characterization was correlated with catalytic activity, stability and selectivity in the ethylene oxychlorination. It was found that γ-Al 2 O 3 and TiO 2 support materials demonstrate very good activity and 1,2dichloroethane selectivity compare to other catalysts. Zeolite H-Beta-25 and SiO 2 support materials proved to be unusable for this reaction. [ABSTRACT FROM AUTHOR]

Stearoyl ethanolamine was synthesized by amidation of stearic acid with ethanolamine in solventless conditions. Iron containing heterogeneous catalysts supported on SiO 2 , Al 2 O 3 , Beta (BEA), ZSM-12 (MTW) and Ferrierite (FER) were used in this work. Sn-modified Ferrierite and H-Ferrierite were also studied for comparison. Fe-modified catalysts synthesized using solid state ion-exchange and evaporation impregnation methods, were thoroughly characterized with X-ray powder diffraction, scanning electron microscope, FTIR with pyridine, nitrogen adsorption, energy dispersive X-ray microanalysis and Mössbauer spectroscopy. The highest conversion was obtained with Fe-H-FER-20 at 140 °C in 1 h giving 61% conversion and 98% selectivity towards the desired amide. The catalytic performance in terms of turnover frequency per mole of iron was achieved with the catalyst exhibiting the largest amount of Fe 3+ species, optimum acidity and a relatively low Brønsted to Lewis acid site ratio. [ABSTRACT FROM AUTHOR]

Kinetics in the hydrodeoxygenation of stearic acid was investigated over Ni-γ-Al 2 O 3 catalyst. The main variables were catalyst prereduction mode, reaction atmosphere and hydrogen pressure in the total pressure range of 7–30 bar. The results revealed that high conversion, 99% in 360 min and high selectivity to heptadecane, 97% were achieved at 300 °C under 30 bar total pressure. The yield of an intermediate hydrogenation product, stearyl alcohol increased with increasing hydrogen pressure as expected. Higher reaction rates and conversion levels were also achieved with the prereduced catalyst and carrying out the reaction in the presence of hydrogen. As a comparison to stearic acid, hydrodeoxygenation of tall oil fatty acids, an industrial feedstock was successfully demonstrated with Ni-γ-Al 2 O 3 under the same conditions. A kinetic model including the pressure effect was derived and applied for data with Ni-γ-Al 2 O 3 as well as for Pd/C, Ni-H-Y-80 and Ni/SiO 2 catalysts. The model described well the kinetic data. [ABSTRACT FROM AUTHOR]

Sn–Al-Beta zeolite was prepared through a hydrothermal method and further modified by alkali and alkaline earth (e.g. Sr and Ba) metals not practically altering the textural properties of the catalyst. The catalytic materials were tested in glucose transformation to methyl lactate in a batch reactor at 180 °C allowing to correlate catalytic activity and selectivity with the strength and type of acid sites. The results showed that by suppressing the Brønsted acidity of the modified catalyst with different promoters the yield of methyl lactate can be increased from ca. 20% to over 50%. Modification of Sn-Beta zeolite by alkali and alkaline earth (e.g. Sr and Ba) metals not practically altering the textural properties of the catalyst was essential for catalytic properties. The yield of methyl lactate can be increased from ca. 20% to over 50% by suppressing the Brønsted acidity of the modified catalyst with different promoters. [Display omitted] • Modification of Sn-Beta zeolite with alkali and alkaline earth (e.g. Sr and Ba) metals. • Glucose transformations to methyl lactate over these catalysts. • Catalytic activity and selectivity correlated with the strength and type of acid sites. • Suppressing Brønsted acidity increased methyl lactate yield from ca. 30% to over 50%. [ABSTRACT FROM AUTHOR]

• Higher activity of smaller gold nanoparticles (AuNPs) towards glucose and xylose hydrogenation and oxidation was observed. • Higher extent of HER observed with xylose solution compared to glucose when moving towards more negative potentials (in-situ FTIR-ATR). Electrocatalytic conversion of hemicellulose-derived glucose and xylose presents a sustainable approach to utilize renewable energy (e.g. solar, wind) to produce value-added chemicals. In this work, the electrochemical hydrogenation and oxidation of glucose and xylose at ambient conditions were studied using dispersed, mesoporous Sibunit Carbon (SC)-supported Au nanocatalysts (SC/AuNPs) with different cluster sizes (4.4 nm, 5.9 nm, 10-30 nm), providing novel results on the cluster size - activity relation. For the electrocatalytic hydrogenation (ECH) of glucose and xylose into sorbitol and xylitol, respectively, higher conversion rates were obtained when more negative potentials were applied. This indicates that the hydrogenation reaction proceeds concurrently with hydrogen evolution reaction (HER). SC/AuNPs with smaller Au clusters were more active towards glucose or xylose ECH at all potentials applied. The selectivity (Faradaic efficiency) increased towards more negative potentials for glucose ECH but followed an opposite trend for xylose ECH. Analysis using in-situ FTIR-ATR spectroscopy showed that water adsorption which leads to HER, was more extensive in xylose solution than in glucose solution at lower potentials. This would indicate greater inhibition of xylose ECH than glucose ECH at more negative potentials. The electrocatalytic oxidation (ECO) of glucose and xylose to gluconic acid and xylonic acid, respectively, was observed to occur at -0.05, +0.3, and +0.4 V (vs Ag/AgCl) using the present electrocatalytic set up. Constant-potential electrolysis at these potentials showed differences in ECO rate depending on the applied potential and average Au cluster size. The highest glucose and xylose ECO rate was obtained for the SC/AuNPs with the smallest average Au cluster size (4.4 nm) at +0.3 V. Constant-potential electrolysis of the sugars at +0.3 V using this catalyst resulted in 42 % yield of gluconic acid and 32 % yield of xylonic acid in 6 hours, both with a very low Au loading of 0.08 % wt.. These results show the strong influence of Au cluster size on the catalytic activities of SC/AuNPs toward sugar ECH or ECO. [Display omitted] [ABSTRACT FROM AUTHOR]

• Microreactor channels were coated with Au/γ-Al 2 O 3 catalyst. • The presence of active gold nanoparticles was confirmed. • Selective oxidation of methanol, ethanol, propanol and butanol was successfully conducted and modelled mathematically. • The role of intrawashcoat diffusion in the catalyst layer was revealed. Selective oxidation of methanol, ethanol, 1-propanol and 1-butanol to corresponding aldehydes was performed in a microreactor in the presence of a Au/γ-Al 2 O 3 coated catalyst. Nanoparticle size distribution, acidity, specific surface area and the average pore size as well as uniformity and thickness of the coating layer were evaluated with relevant characterization techniques. The experiments were designed to reveal the effect of temperature, residence time and oxygen-to-alcohol ratio on both alcohol conversion and product distribution. Stability and repeatability of the coating procedure was successfully demonstrated. To describe the reaction kinetics, plausible kinetic equations were implemented in a pseudo-homogeneous plug flow model, which turned out to be an adequate approximation to describe the flow pattern in the microreactor. Non-linear regression analysis enabled the determination of the rate and adsorption parameters included in the kinetic model. An advanced kinetic and mass transfer model was developed to reveal the impact of the diffusion inside the catalytic washcoat layer, confirming that molecular diffusion is not a limiting factor for alcohol oxidation in the microreactor. [ABSTRACT FROM AUTHOR]

• Different AuNPs size distribution among CF/AuNPs catalysts resulting from different pre-treatment methods of the CF support (chemical and thermal pre-treatment) prior to Au deposition. • Higher reaction rates of glucose and xylose toward ECH over a CF/AuNPs catalyst than polycrystalline Au. • Variation of ECSA-normalized ECH activity and Faradaic Efficiency (FE) of CF/AuNPs catalysts depending on the catalyst Au cluster size. Recent evidences have shown catalyst structure sensitivity of electrocatalytic hydrogenation (ECH) of organic molecules in aqueous phase. In this study, ECH of glucose and xylose was investigated using gold nanoparticles (AuNPs) on activated carbon fiber (CF) support as catalyst. CF supported AuNPs catalysts (CF/AuNPs) were synthesized by deposition-precipitation method and were characterized by physicochemical (SEM, TEM, XRD, N 2 physisorption, ICP-OES) and electrochemical methods. Chemical or thermal pre-treatment of CF prior to Au deposition resulted in different AuNPs size distributions. The activity towards glucose or xylose ECH were observed to be dependent on the particle size of AuNPs and the applied potential. Compared to a polycrystalline Au catalyst, higher reaction rates for glucose and xylose ECH were observed for a CF/AuNPs catalyst with a higher surface area. This indicates that the activity of Au towards glucose and xylose ECH is dependent on the surface area and particle size, and particle size control can be achieved by simple chemical or thermal pretreatment of the catalyst support. [Display omitted] [ABSTRACT FROM AUTHOR]

One-pot continuous synthesis of menthols both from citronellal and citral was investigated over 5 wt% Ni supported on H-Beta-38-sepiolite composite catalyst at 60–70 °C under 10–29 bar hydrogen pressure. A relatively high menthols yield of 53% and 49% and stereoselectivity to menthol of 71–76% and 72–74% were obtained from citronellal and citral respectively at the contact time 4.2 min, 70 °C and 20 bar. Citral conversion noticeably decreased with time-on-stream under 10 and 15 bar of hydrogen pressure accompanied by accumulation of citronellal, the primary hydrogenation product of citral, practically not affecting selectivity to menthol. A substantial amount of defuctionalization products observed during citral conversion, especially at the beginning of the reaction (ca. 1 h), indicated that all intermediates could contribute to formation of menthanes. Ni/H-Beta-38-sepiolite composite material prepared by extrusion was characterized by TEM, SEM, XPS, XRD, ICP-OES, N 2 physisorption and FTIR techniques to perceive the interrelation between the physico-chemical and catalytic properties. [Display omitted] • one-pot continuous synthesis of menthols from citronellal and citral. • 5 wt% Ni supported on H-Beta-38-sepiolite composite catalyst. • menthols yield of 53% and 49% from citronellal and citral. • stereoselectivity to menthol ca. 70–75%. [ABSTRACT FROM AUTHOR]

Four clay materials, namely, bentonite, bleaching earth, attapulgite and sepiolite, were shaped into the cylindrical body by extrusion. Clays were characterized in depth by TEM, SEM-EDX, N 2 physisorption, pyridine FTIR, pH measurements, contact angle measurements, 27Al MAS NMR, and the crush test. Catalytic properties were investigated in the citronellal cyclization as a model reaction. The reaction was performed in the trickle-bed reactor at 70 °C, 10 bar of Ar with 0.086 M initial citronellal concentration in cyclohexane. The best results were obtained over attapulgite with isopulegols yield of 24% and stereoselectivity to the desired isopulegol isomer of 61%. Attapulgite had the highest meso-to-micropore volume ratio, the highest basicity, a low Brønsted-to-Lewis acid sites ratio, and the lowest amount of Brønsted acid sites compared to other extrudates. In addition, same clay exhibited the highest mechanical strength of extrudates. [Display omitted] • Extrusion of bentonite, attapulgite and sepiolite and detailed characterization. • citronellal cyclization as a model reaction in trickle-bed at 70 °C. • Over attapulgite selectivity to isopulegols of 92%. • Catalytic behavior linked to the micro-to-mesopore volume ratio, basicity, Brønsted-to-Lewis acid sites ratio. [ABSTRACT FROM AUTHOR]

The present work is focused on the improvement of an effective approach to tailor the acidity of silica alumina composite. SBA-15 was selected based on high surface area, uniform porosity and large mesopores. Modification of SBA-15 was performed to improve both Lewis and Brønsted acidities and hence catalyst activity. Therefore, introduction of alumina as a co-catalyst was carried out to enhance Lewis acid sites through its incorporation into the silica network. Evaporation impregnation method was evaluated for incorporation of aluminium to SBA-15 and materials with different SiO 2 /Al 2 O 3 ratios were prepared. Acidity and morphological features of the materials were assessed using XRD, EDX, SEM, TEM, N 2 -physisorption, 27Al MAS-NMR and FTIR with pyridine. Brønsted acidity was attained by the introduction of sulfonic acid groups in the final catalyst via the post-synthesis grafting method. Therefore, the balanced Lewis and Brønsted acidities and proper porosity of modified SBA-15 led to its efficient performance in the conversion of glucose as a biomass-based model component to levulinic acid. [Display omitted] • Acid sites modification of siliceous-based mesoporous material (SBA-15). • Alumina introduction as Lewis acid sites by evaporation impregnation technique. • Sulfonic acid groups incorporation as Brønsted acid sites by post-grafting method. • Obtaining the balanced acidity for biomass-based glucose transformation to levulinic acid. [ABSTRACT FROM AUTHOR]

• Heterogeneous catalysts for ethene and diethyl ether formation from ethanol were screened. • The role of active sites in the product distribution was revealed. • Very precise kinetic data were produced in a microreactor device. • It was demonstrated that microreactors are strong tools in the study of gas-phase kinetics and catalyst stability. Dehydration and etherification of bio-ethanol was studied in a microreactor using γ-alumina, H-Beta-38 and Sn-Beta-38 as catalysts. An extensive series of kinetic experiments was carried out in the microreactor device operating at ambient pressure and temperatures 225–325 °C. The H-Beta-38 catalyst coated microplates exhibited the highest production rate of ethene. While the fresh H-Beta-38 catalyst allowed complete conversion of ethanol and 98% selectivity towards ethene, the catalyst deactivated significantly with time-on-stream. Diethyl ether was the dominating co-product, whereas trace amounts of acetaldehyde were detected in the experiments. Based on the kinetic studies, thermodynamic analysis and catalyst characterization results obtained with SEM-EDX, TEM, nitrogen physisorption, FTIR-Pyridine and white light confocal microscopy, a surface reaction mechanism was proposed. The fundamental hypothesis of the reaction mechanism was the co-existence of two kinds of active sites on the catalyst surface, namely the Brønsted sites promoting dehydration and the Lewis sites responsible for etherification. The Brønsted sites deactivate, whereas the Lewis sites are more stable, which leads to a shift of the product distribution during long-term experiments, from ethene to diethyl ether. The rate equations were implemented in the microreactor model. The kinetic and adsorption parameters included in the model were estimated by non-linear regression analysis. The experimental data were satisfactorily described by the proposed mechanism. The work demonstrated that microreactors are strong tools in the determination of catalytic kinetics and catalyst durability. [ABSTRACT FROM AUTHOR]

Hexadecane hydrocracking was investigated over bifunctional Ru-containing micro- and mesoporous USY zeolites at 250°C under 45 bar in the presence of hydrogen in a batch reactor. A comparative study was performed using the Ru-free zeolites in the protonic form. The highest yield of jet-fuel products, C 9 - C 15 , being 26% at 71% conversion, was obtained with 2.5 wt% Ru deposited on a hierarchical micro-mesoporous USY zeolite, e.g. a material possessing secondary porosity, where a superior combination of acidity and mesoporosity was created by treatment of the parent zeolite with aqueous sodium hydroxide and tetrapropylammonium hydroxide. [ABSTRACT FROM AUTHOR]

[Display omitted] •Mono- and bi-metallic Ru and Ni loaded 13X and 5A catalysts were synthesized and characterized. •Ni was able to enter the pores of 13X, in the other case, 5A, an egg shell type structure was formed. •The morphology of the catalyst influenced significantly the selectivity. High conversion of CO 2 and selectivity to CH 4 were obtained, clear differences were observed depending on support and loading. Zeolites 13X and 5A were modified with nickel and/or ruthenium for CO 2 methanation. The catalysts were prepared by evaporation impregnation and XRD, SEM-EDX, TEM, STEM-EDX, nitrogen physisorption, H 2 -TPR and NH 3 -TPD were used to characterize the physico-chemical properties of the catalysts. The physico-chemical characterization results show that the zeolites structure did not change after the Ni, Ru modification, however. Ni was able to enter the pores of 13X, in the other case, 5A, an egg shell type structure was formed. Methanation experiments were performed in a lab scale fixed bed reactor system, the results showed that the mono-metallic catalysts out-performed the bi-metallic ones with Ni being the more active. One of the factors influencing the performance of the bi-metallic catalysts was the difficulty to obtain good dispersion when both metals were used. Also the morphology of the catalyst significantly influenced the selectivity. The catalysts with lower weak acidity benefit for getting a higher activity. The single metal catalysts 2.5 %Ru13X and 5%Ni13X showed good catalytic stability with around 97 % CH 4 selectivity at 360 °C, with no catalyst deactivation during the 200 h catalyst stability test. [ABSTRACT FROM AUTHOR]

Synthesis of Beta zeolite catalysts was carried out using two different methods. The influence of such parameters as synthesis time and temperature, gel composition and gel ripening on the physico-chemical and catalytic properties of Beta zeolite catalysts was studied. A range of analytical methods was applied in this work including scanning and transmission electron microscopies, energy dispersive X-ray spectroscopy, X-ray powder diffraction, nuclear magnetic resonance spectroscopy – 27A1-MAS-NMR and 29Si-MAS-NMR, nitrogen physisorption, Fourier transform infrared spectroscopy and inductively coupled plasma optical emission spectrometry. The sodium forms of Beta zeolites were transformed to the proton forms H-Beta by ion-exchange using aqueous solutions of NH 4 NO 3 and thereafter evaluated in Prins cyclization of (−)-isopulegol with benzaldehyde. The best catalyst synthesized at 150 °C in the rotation mode for 17 h possessing an optimal combination of morphological and structural properties as well as concentration of acid sites demonstrated high (−)-isopulegol conversion (93%) along with high selectivity to the desired product (79%). Image 1 • Influence of the synthesis parameters on properties of Beta zeolites. • Characterization of synthesized Beta zeolites by several methods. • Evaluation of activity in Prins cyclization of (−)-isopulegol with benzaldehyde. • Comparison of synthesized zeolites with a commercial beta zeolite. • High conversion and selectivity to the desired product. [ABSTRACT FROM AUTHOR]