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Heterogeneous catalytic oxidative dehydrogenative processes for N-heterocycles are presented, which enable waste-minimized (additive-, oxidant-, base-free), efficient cyclisations/couplings via transition metal oxide–Bi(iii) cooperative catalysis.

Although using supported noble-metal catalysts for CO2 hydrogenation is an effective solution due to their excellent catalytic properties, metal oxide supports themselves can exhibit good activity ...

The feasibility of indium introduction into the hydrocalumite group of layered double hydroxides (LDHs) was investigated for the first time. Mechanochemical and co-precipitation techniques were applied in the syntheses. During the development of preparation, a yet unknown CaIn chloride-hydroxide solid side-product was found and synthesized in phase-pure state. The as-prepared materials were characterized by X-ray diffractometry, Fourier-transform infrared, Raman, and UV–Vis diffuse reflectance spectroscopies. Their thermal behavior was mapped up to 900 °C, while the surface and textural attributes were studied by scanning and transmission electron microscopies, specific surface area measurements and pore size analysis. For the LDH, the Ca2.3InCl(OH)6.6·4H2O and for the side-product, the Ca3In4Cl2(OH)16·6H2O stoichiometric formula was calculated. Various further hydrocalumites (M(III): Al3+, Sc3+, V3+, Cr3+, Fe3+, Ga3+) were synthesized, their surface basicity was investigated by CO2 temperature programmed desorption. These materials and the indium-containing phases were tested as catalysts in the transesterification reactions of dimethyl carbonate with glycerol. All solids proved to be active: their glycerol conversion capabilities and recycling abilities were determined and compared to the well-known Mg-, Ni-, Co–, Zn-based hydrotalcites.

In the present work, shape tailored Cu2O microparticles were synthesized by changing the nature of the reducing agent and studied subsequently. d-(+)-glucose, d-(+)-fructose, d-(+)xylose, d-(+)-galactose, and d-(+)-arabinose were chosen as reducing agents due to their different reducing abilities. The morpho-structural characteristics were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and diffuse reflectance spectroscopy (DRS), while their photocatalytic activity was evaluated by methyl orange degradation under visible light (120 min). The results show that the number of carbon atoms in the sugars affect the morphology and particle size (from 250 nm to 1.2 µm), and differences in their degree of crystallinity and photocatalytic activity were also found. The highest activity was observed when glucose was used as the reducing agent.

Carbon spheres were applied as templates to synthesize titanium dioxide hollow spheres. The templates were purified with either ethanol or acetone, and the effects of this treatment on the properties of the resulting titania were investigated. The photocatalytic activity of the catalysts was measured via the decomposition of phenol model pollutant under visible light irradiation. It was found that the solvent used for the purification of the carbon spheres had a surprisingly large impact on the crystal phase composition, morphology, and photocatalytic activity. Using ethanol resulted in a predominantly rutile phase titanium dioxide with regular morphology and higher photocatalytic activity (r0,phenol = 3.9 &times, 10&minus, 9 M∙s&minus, 1) than that containing mainly anatase phase prepared using acetone (r0,phenol = 1.2 &times, 1), surpassing the photocatalytic activity of all investigated references. Based on infrared spectroscopy measurements, it was found that the carbon sphere templates had different surface properties that could result in the appearance of carbonate species in the titania lattice. The presence or absence of these species was found to be the determining factor in the development of the titania&rsquo, s properties.

In this paper, we study the thermal activation of CO₂ on the surface of small Au nanoparticles supported on TiO₂ and titanate nanotube. We characterize the catalysts with high resolution transmission electron microscopy (HR-TEM) and total gold content measurement. We performed catalytic test in flow reactors then we investigate the surface of the catalysts during the adsorption and reaction processes by diffuse reflectance infrared spectroscopy (DRIFTS). The size of gold nanoparticles on the surface has been found to have the most important effect on the final activity of the studied catalysts. Significantly higher TOF values were obtained when the size of Au were smaller on both TiO₂ and titanate nanotube supports. The size of the Au nanoparticles with the method of their preparation was controlled. The gold adatom promotes the adsorption and scission of CO₂, but the nature of the support has got important effect, too. The explored reaction schemes may pave the way towards novel catalytic materials that can solve challenges associated with the activation of CO₂ and thus contribute to a greener chemistry related to it.

The photocatalytic transformation of methane-water mixture over Rh and Au catalysts supported on protonated (H-form) titanate nanotube (TNT) was investigated. The role of the catalyst structure was analyzed using titania reference support. Furthermore the effect of carbon-dioxide addition was also investigated. The catalysts were characterized by high resolution transmission electron microscopy and X-ray photoelectron spectroscopy (XPS). Photocatalytic tests were performed with a mercury-arc UV source illuminating a continuous flow quartz reactor which was attached to a mass spectrometer. The surface of the catalysts was analyzed by diffuse reflectance infrared spectroscopy during the photoreactions. The changes of the catalysts due to photocatalytic usage were investigated by XPS and temperature programmed reduction methods as well. Most of the methane was generally transformed to hydrogen and ethane, and a small amount of methanol was also formed. The carbon dioxide addition enhanced the rate of the photocatalytic transformation of methane on Rh/TNT with increasing the lifetime of the electron–hole pairs. Bigger gold particles with mainly plasmonic character were more active in the reactions due to the photo induced activation of the adsorbed water. Surface carbon deposits were identified on the catalysts after the photoreactions. More oxidized carbon formed on the Au-containing catalysts than on the ones with Rh.

Based on our previous investigations, it turned out that the Co3O4 material is a promising catalyst in the ambient pressure CO2 methanation. This work aims at understanding the Pt-Cobalt-Oxide surface interaction and its effect on the catalytic performance. The incorporation of Pt nanoparticles into the mesoporous Co3O4 (Pt/m-Co3O4) and commercial Co3O4 (Pt/c-Co3O4) improves the catalytic activity of both catalysts by a factor of ∼ 1.4 and ∼ 1.9 respectively at 673 K. The same tendency towards the increased basicity was also observed. Morphology-induced surface basicity was previously shown to play a key role in determining the catalytic activity of free-standing supports. From HR-TEM (-EDX), EXAFS, CO2-TPD, and CO chemisorption measurements it was established that during the pre-treatment, Co-Pt alloy particles partially covered by the CoxOy layer are formed. It has been postulated that this structure transformation generates new basic centres, the amount of which per unit surface area is significantly larger for Pt/c-Co3O4 and this in turn is responsible for the higher enhancement effect of the Pt/c-Co3O4 catalyst in the CO2 methanation. This study emphasizes the importance of the surface structure exploration for the dynamic catalytic systems in order to reach maximum activity and selectivity in the CO2 methanation.

The steam reforming of ethanol was studied at 823 K on 10% Co/Al 2 O 3 samples calcined at 973 K and reduced at different temperatures from 773 K to 1173 K. The catalysts were characterized by XPS, XRD, TPR, Raman and DRIFT spectroscopy. XRD results revealed that spinel structures are detectable after the thermal treatment of Co/Al 2 O 3 , which could be attributed mainly to Co 3 O 4 formation. TPR and XPS measurements show that even the high temperature (1173 K) reduction is not sufficient to totally reduce Co to metallic state. The ethanol conversion at 823 K was relatively stable and it was higher than 90% in all cases, but the product distribution as a function of time on stream significantly depended on the reduction temperature. The selectivities of H 2 , CO 2 , and CH 4 formation decreased in time but those of ethylene, acetone and acetaldehyde increased. The changes became less pronounced when the reduction temperature increased, so the H 2 , CO, and CO 2 selectivities increased while that of ethylene decreased significantly as a function of reduction temperature. XPS measurements revealed a new low binding energy state in the Co 2p 3/2 region during the reaction when the samples were reduced at or below 973 K. This feature was assigned to the formation of a very thin Co layer. On the used catalysts reduced at or above 973 K structured carbon was detected. On the XP spectra several carbon species were identified at the beginning of the reaction. A new feature was also found at lower binding energy which became more and more dominant with the exception of Co/Al 2 O 3 reduced at 1173 K. These species could be assigned as CoC x carbide-like structures rather than a structured carbon layer. It was found that the surface carbon formed in the reaction gradually influences the product distribution. The carbon which probably is built in the Co subsurface poisons the reactivity of the metal and the effect of the support comes in the forefront. The structured carbon layer formed on the Co/Al 2 O 3 reduced at high temperature does not influence the hydrogen formation in the ethanol reforming.

TiO 2 hollow structures (HS) were synthesized by carbon sphere template removal method. Nanometer sized carbon spheres (CS) were prepared by mild hydrothermal treatment of ordinary table sugar (sucrose). The size of these spheres can be controlled by the parameters of the hydrothermal treatment (e.g. time and pH). The obtained CSs were characterized by scanning electron microscopy (SEM), Raman spectroscopy, infrared spectroscopy (IR), X-ray diffraction (XRD) and thermogravimetry (TG). CSs were successfully coated with TiO 2 via sol–gel method. The phase composition of the TiO 2 hollow spheres were controlled by the annealing temperature during crystallization and CSs template removal. TiO 2 hollow structures (HSs) were characterized by SEM, XRD, Raman spectroscopy, TG and energy-dispersive X-ray spectroscopy (EDX). Photocatalytic performance of the TiO 2 HSs was evaluated by phenol degradation in a batch-type foam reactor under low powered UV‐A irradiation. The degradation reaction was followed by high‐performance liquid chromatography (HPLC) and total organic carbon (TOC) measurement techniques. Photocatalytic activity test results pointed out that increased rutile content up to a certain extent (resulting mixed phase anatase-rutile TiO 2 ) effects advantageously the photocatalytic performance of TiO 2 HSs and the unique morphology proved to enhance the photocatalytic activity (six times) as well as TOC removal efficiency (twelve times) compared to the sample which was prepared by the same method without the CSs.

The reforming of methane with carbon dioxide has been investigated at 773 K on 10% Co/Al2O3 reduced at different temperatures up to 1173 K. The catalysts were characterized by BET, TPR, XRD and XPS methods. TPR and XPS results revealed that during the pre-treatment of the catalysts the Co only partially reduced. The reduction degree and the amount of the structured metallic cobalt increased with the reduction temperature. The conversion of the reactants was the highest on the sample reduced at 973 K, but the turnover frequencies of CO and H2 formation increased as the reduction temperature increased. The amount of surface carbon significantly depended on the pre-treatment temperature of the catalysts. The IR spectra registered at the beginning of the reaction indicate that tilted CO was formed, but the position of the absorption bands depends on the reduction temperature of the catalysts. Similarly, the pre-treatment temperature influenced the type of the surface carbon determined by XPS. We assume that the different structures of the metallic Co formed in pretreatment resulted in the different catalytic behaviors.

The photocatalytic transformation of the methane-carbon dioxide system was investigated by in-situ methods in the present study. Titanate nanotube (TNT) supported gold and rhodium catalysts were used in the catalytic tests. Our main goal was the analysis of the role of the catalysts in the different parts of the reaction mechanism. The catalysts were characterized by X-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HRTEM) and diffuse reflectance UV–vis spectroscopy (DR-UV–vis). Photocatalytic tests were performed in a continuous flow quartz reactor equipped with mass spectrometer detector and mercury-arc UV source. Diffuse reflectance infrared spectroscopy (DRIFTS) was used to analyze the surface of the catalyst during photoreaction. Post-catalytic tests were also carried out on the catalysts including XPS, temperature programmed reduction (TPR) and Raman spectroscopy methods in order to follow the changes of the materials. Titanate nanotube can stabilize even the smallest, molecular-like Au clusters which showed the highest activity in the reactions. Approximately 3% methane conversion was reached in the best cases while the carbon dioxide conversion was not traceable. It was revealed that water has a very important role in the oxidation reaction. The main discovered reaction routes are methane dehydrogenation and oxidation, the methyl coupling and the forming of structured carbon deposits on the catalyst surface. The source of the surplus CO can be mostly the reduction of carbon dioxide. During the reduction process photoelectrons and hydrogen ions brings about the CO2 reduction via CO2 − radical anion.

Co and Rh+Co catalysts supported on Al2O3 and CeO2 were investigated by temperature programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS). The CeO2 defects, resulted from the effects of the metals, were further analyzed by Raman spectroscopy and optical absorption. Although the interaction of Co with these two supports is fairly different, it can be concluded that Rh inhibits the strong Co-support interaction. It was revealed that Co over Al2O3 forms mainly Co2+ compounds, only a smaller fraction of cobalt is in metallic state. After the addition of 0.1 % Rh, Co3O4 like species is dominant, the amount of metallic state increased after reduction. Over CeO2 the Co dissolution into the support was inhibited by Rh. A wide range of TPR results proved the stepwise reduction of Co, which was promoted by the addition of Rh. By Rh the entire mechanism of this process was altered that can be observed even by XPS. On the basis of the Raman and the optical measurements we concluded that the metals induce defect sites on the CeO2 surface, and these appear as similar features on the spectra of Co and Rh containing samples, thus their density depends on the metal loading and not on the metal type. CeO2 has a bandgap of 3.27 eV, which is not altered by the metals, but an electronic contact was detected between the metals and CeO2 by photovoltammetry. The increased number of metallic species is mainly responsible for the higher catalytic activity and for the enhanced hydrogen selectivity in the stream reforming of ethanol.

Background: Here we examined myocardial microRNA (miRNA) expression profile in a sensory neuropathy model with cardiac diastolic dysfunction and aimed to identify key mRNA molecular targets of the differentially expressed miRNAs that may contribute to cardiac dysfunction. Methods: Male Wistar rats were treated with vehicle or capsaicin for 3 days to induce systemic sensory neuropathy. Seven days later, diastolic dysfunction was detected by echocardiography, and miRNAs were isolated from the whole ventricles. Results: Out of 711 known miRNAs measured by miRNA microarray, the expression of 257 miRNAs was detected in the heart. As compared to vehicle-treated hearts, miR-344b, miR-466b, miR-98, let-7a, miR-1, miR-206, and miR-34b were downregulated, while miR-181a was upregulated as validated also by quantitative real time polymerase chain reaction (qRT-PCR). By an in silico network analysis, we identified common mRNA targets (insulin-like growth factor 1 (IGF-1), solute carrier family 2 facilitated glucose transporter member 12 (SLC2a-12), eukaryotic translation initiation factor 4e (EIF-4e), and Unc-51 like autophagy activating kinase 2 (ULK-2)) targeted by at least three altered miRNAs. Predicted upregulation of these mRNA targets were validated by qRT-PCR. Conclusion: This is the first demonstration that sensory neuropathy affects cardiac miRNA expression network targeting IGF-1, SLC2a-12, EIF-4e, and ULK-2, which may contribute to cardiac diastolic dysfunction. These results further support the need for unbiased omics approach followed by in silico prediction and validation of molecular targets to reveal novel pathomechanisms.

The decomposition of DMC was studied on multi wall carbon nanotube and on activated carbon supported Cu catalysts (Cu/MWCNT and Cu/Norit) and their catalytic activities were compared. The catalysts were characterized in detail by XPS, BET, NH3 TPD methods. The activity of the catalysts decreased in the order of Cu/MWCNT > MWCNT > Cu/Norit > Norit. Cu/MWCNT was more active than Cu/Norit although the BET surface and the number of acidic sites are higher on Norit than on MWCNT supported catalysts. The products of the decomposition were DME and CO2 in all cases and the ratio of them corresponds to the stoichiometry. On oxidized catalysts, the reaction rate was higher than on the reduced sample. The product distribution also changed: mainly DME on the reduced sample, while on the oxidized catalyst, methanol was formed. It was demonstrated in separate experiments that methanol does not decompose under the same experimental conditions, so the formation of DME in the decomposition of methanol could be excluded: methanol and DME formed via different routes. DRIFT measurements showed that DMC and on Cu/Norit DME exists on the surface of the catalysts during the reaction. We compared the catalytic activity with the acidic character of the samples and with the number of surface Cu atoms. We may conclude that the efficiency of the catalysts is influenced by the ratios of different oxidation states of Cu.

The activity of Cu/MWCNT and Cu–Ni/MWCNT catalysts was investigated in the synthesis of dimethyl carbonate (DMC) by oxidative carbonylation of methanol. The catalysts were prepared via conventional incipient wetness impregnation technique. The samples were characterized by X-ray photoelectron spectroscopy (XPS), and DRIFT. The reaction was carried out in a continuous flow system at atmospheric pressure at 393 K. The main products were methyl formate (MF), DMC and CO2. The methanol conversion on Cu/MWCNT achieved a steady state value after 2 h, but on Cu–Ni/MWCNT the conversion decreased continuously. The DMC selectivity was more than 30% and the yield was 1.2% on Cu/MWCNT. Based on the XPS data we can establish that copper reduced to its metallic form during reduction but oxidized in the reaction mixture, and is mostly in the Cu+ state, with some Cu2+ also present on the surface at the beginning of the reaction though its ratio decreased in time. We assume that the DMC formation rate depends on the surface concentration of oxidized Cu. Based upon the FTIR data adsorbed DMC is present on the surface of the Cu/MWCNT catalyst during the catalytic reaction but on Cu–Ni/MWCNT sample only methyl formate was detected in the gas phase.

The reforming of methane with carbon dioxide has been investigated at 773 K on 10% Co/Al 2 O 3 promoted with Rh and calcined at different temperatures. In addition, the dissociation of carbon dioxide and methane has also been examined. TPR and XPS results revealed that during the pre-treatment of the catalysts the Co reduced only partially but Rh promoted this process. The dissociation of carbon dioxide occurred most easily on Rh containing catalysts in the presence of methane. Rh promoted Co/Al 2 O 3 was found to be more active in the CO 2 + CH 4 reaction than the Co/Al 2 O 3 . The amount and the reactivity of surface carbon significantly depended on the calcination temperature of the catalysts. It influenced oppositely the amount of surface carbon on 0.1% Rh + 10% Co/Al 2 O 3 and on 10% Co/Al 2 O 3 . On 10% Co/Al 2 O 3 (7 0 0) the amount of carbon residue is higher than on 10% Co/Al 2 O 3 (5 0 0), but on the Rh containing samples the trend is the opposite. We may suppose that the different structures of the catalysts formed in the presence of Rh and at different calcination temperatures resulted in the different catalytic behaviours.

The effect of the nature of the support and the promotion achieved by a Rh additive on Co-based catalysts in the ethanol steam reforming reaction were studied. The catalysts with 2% Co loading were characterized by temperature-programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS). In situ diffuse reflectance Fourier-transform infrared spectroscopy (DRIFTS) identified the surface intermediates formed during the reaction, whereas gas phase products were detected by gas chromatography (GC). Upon heating in hydrogen to 773 K, cobalt could not be reduced to Co0 on alumina, but on silica the reduction was almost complete. On ceria, half of the Co could be reduced to the metallic state. By the presence of a small amount (0.1%) of Rh promoter, the reduction of both cobalt and ceria was greatly enhanced. For Co on the acidic Al2O3 support, the dehydration mechanism was dominant, although on the basic CeO2 support, a significant amount of hydrogen was also formed. Addition of a small amount of Rh as...

Au and Rh clusters, as well as Au–Rh bimetallic nanoparticles were prepared on titanate nanowires, nanotubes and on TiO 2 (1 1 0). They were characterized by X-ray photoelectron spectroscopy (XPS), low energy ion scattering spectroscopy (LEIS) and Fourier transform infrared spectroscopy (FTIR). By performing careful LEIS experiments, it was found that for appropriate Au and Rh coverage, a thin Au layer almost completely covers the Rh nanoparticles, a Rh core–Au shell structure was detected. The formation of this structure was not affected by alkali (K) adatoms. LEIS and FTIR measurements disclosed that adsorbed CO at 300 K causes the segregation of Rh atoms to the surface of metal clusters in order to bind to CO. Upon CO adsorption on Rh/titanate nanostructures the IR stretching frequencies characteristic of the twin form were dominant, whereas bimetallic nanosystems featured a pronounced linear stretching vibration as well. In spite of this structure adsorbed CO is detectable during the ethanol adsorption on gold–rhodium bimetallic cluster and the ethanol decomposition rate is twice higher than on Au/TiO 2 .

The reforming of methane with carbon dioxide has been investigated at 773 K on Rh/Al 2 O 3 promoted with TiO 2 and V 2 O 5 . In addition, the dissociation of carbon dioxide and methane has also been examined. TPR and XPS results revealed that during the pre-treatment of the catalysts not only Rh reduced but also TiO 2 slightly and V 2 O 5 significantly to V 4+ below 600 K. The dissociation of carbon dioxide occurred most easily on vanadia promoted catalyst. Vanadia and titania promoted Rh/Al 2 O 3 was found to be more active in the CO 2 + CH 4 reaction than the Rh/Al 2 O 3 . The increase of the conversion observed on V 2 O 5 and TiO 2 promoted Rh/Al 2 O 3 catalysts could be attributed to the oxygen vacancies which formed on the additives during the pretreatment and the reaction.

The steam reforming of ethanol was investigated at 723 K over Al 2 O 3 , ZrO 2 and Al 2 O 3 -ZrO 2 supported Pt catalysts. The samples were characterized by XPS and TPR methods. The surface species formed during the adsorption of ethanol and during the catalytic reaction were investigated by DRIFT and TPD. According to the XPS results the zirconia was partially reduced during the pretreatment and the surface of the catalysts was relatively poor in Zr. Adsorbed CO and surface acetate were detected during the catalytic reaction at 723 K. It means that the formation rate of these species is higher than their decomposition or further reaction. It was established that the acetate located mainly on the Al 2 O 3 surface and much smaller amount can be found on ZrO 2 and on Al 2 O 3 -ZrO 2 supported samples. The decay in the selectivity of H 2 and CO 2 caused by the surface acetate species on Pt/Al 2 O 3 decreased in the presence of ZrO 2 . DRIFT and TPD measurements showed that the zirconia destabilized the acetate groups which resulted in the enhanced H 2 and CO 2 selectivity. The highest turnover number and yield was found on Pt/Al 2 O 3 -ZrO 2 (1:3).

The reaction of ethanol and water has been investigated over K doped 1% Pt/Al2O3 catalysts. The presence of K resulted at room temperature in upward shift of the IR band of CO formed in the ethanol adsorption. At higher temperature the presence of surface acetate species was also detected which, according to the TPD results decomposed above 600 K to form CH4 and CO2. The K destabilized these forms. In the catalytic reaction the H2 selectivities were similar and much higher over all promoted Pt/Al2O3 than on the pure catalyst. In this study it was proved that the K had a destabilizing effect onto the surface acetate groups and thus improved the steam reforming activity of 1% Pt/Al2O3.

In this work, the effect of the nature of oxide support on the reaction mechanism of the partial oxidation of ethanol on Rh catalyst was studied by diffuse reflectance infrared (DRIFTS) and X-ray photoelectron spectroscopy (XPS). The conversion of ethanol and the product distribution were analysed by gas chromatography. The highest ethanol conversion was measured on Rh/CeO2 catalyst. The results showed that the nature of the oxide support affected the reaction mechanism. On supported Rh catalysts ethanol adsorption gives rise to ethoxide species, which can be decomposed to CO2, CO and CH4 and dehydrogenated, forming acetaldehyde. The latter species are oxidized to acetate or dehydrogenated to acetyl species on Rh/Al2O3 and on Rh/CeO2. On Rh/TiO2 the acetaldehyde can also be oxidized in a parallel process to HCOOH/HCOO(a) which forms CO2 and water. Furthermore, the acetate species previously formed can be decomposed to CH4, CO and/or oxidized to CO2 via carbonate species at higher temperature depending on the oxide support. On silica support acetaldehyde was the dominant intermediate and it desorbed or directly decomposed with or without oxygen to CO2 and methane. The partial oxidation of ethanol proceeds on partially oxidized Rh sites on Rh/Al2O3, Rh/TiO2 and on Rh/CeO2. In spite of the presence of O2, ceria is not fully oxidized during the partial oxidation of ethanol.

On X-ray photoelectron spectra of the Au-Rh/TiO2 catalysts the position of Au4f peak was practically unaffected by the presence of rhodium, the peak position of Rh3d, however, shifted to lower binding energy with the increase of gold content of the catalysts. Rh enrichment in the outer layers of the bimetallic crystallites was experienced. The bands due to Au0-CO, Rh0-CO and (Rh0)2-CO were observed on the IR spectra of bimetallic samples, no signs for Rh+-(CO)2 were detected on these catalysts. The results were interpreted by electron donation from titania through gold to rhodium and by the higher particle size of bimetallic crystallites.

The formation and stability of surface species generated in the interaction of ethanol and ethanol–water mixture with Al2O3 and CeO2-supported noble metal catalysts were studied by FT-IR, TPD and TPR methods. It was found that water enhanced the stability of ethoxide surface species formed in the dissociation of ethanol. Dehydrogenation of molecularly adsorbed ethanol was proposed as a key reaction step. The TPD spectra of ethanol adsorbed on supported noble metals exhibited a high temperature desorption stage which was explained by the formation and decomposition of surface acetate species. Ethylene (product of the dehydration of ethanol) was mainly formed on Al2O3-supported noble metals, while on CeO2-supported noble metals significant amount of acetaldehyde (originated from the dehydrogenation of ethanol) was also formed. In the steam reforming of ethanol the selectivity of H2 formation decreased but that of C2H4 increased in time, while the conversions were stable on alumina-supported noble metals. These observations were explained by the inhibiting effect of surface acetate species.

The formation and stability of surface species formed in the interaction of ethanol and ethanol–water mixture with Al 2 O 3 -, TiO 2 - and CeO 2 -supported Pt catalysts were studied by FTIR. The changes of the gas phase composition during the above processes were monitored by mass spectrometer. It was found that water enhanced the stability of ethoxide surface species formed in the dissociation of ethanol on Pt catalysts and suppressed the formation of CO. Dehydrogenation of molecularly adsorbed ethanol was proposed as a key reaction step. On the temperature programmed desorption (TPD) spectra of adsorbed ethanol in the case of supported Pt there is a high temperature desorption stage, which was explained by the formation and decomposition of surface acetate species. A possible mechanism of the reaction is discussed.

We studied the surface modification of supported colloidal precious metal catalysts. Chiral compounds derived from cinchona alkaloids and prolinol were synthesized and used as stabilizers/reductants to yield Pd and Pt colloidal nanoparticles. The new Pd catalysts were found to be highly active and selective catalysts for the semihydrogenation of 3-hexyn-1-ol to cis-3-hexen-1-ol. The stabilizers affected the activity of the catalyst but not the selectivity. The catalysts were also evaluated in the asymmetric hydrogenation of methyl pyruvate and isophorone. No enantioselectivity was observed, which indicated that surface modification by the stabilizer did not induce chirality in the substrate. Achiral supported Pd and Pt colloidal catalysts were modified with cinchonidine. The modified Pt catalysts demonstrated a high activity for the hydrogenation of methyl pyruvate and a modest enantioselectivity of 47%, which indicated that the chiral induction of supported colloidal catalysts is possible by modifying the catalyst surface with a chiral reagent.