•NiCo bimetallic particles over mixed Ce–Zr oxide are very active in catalytic ESR.•Increased reducibility of the NiCo formulation leads to high ethanol conversion, H2 yield and CO2 selectivity above ...530°C.•The basicity of ceria component limits ethene formation.
Mixed ceria–zirconia oxide (CZ91, Ce:Zr=9:1) has been used to support Nickel (CZ91Ni), Cobalt (CZ91Co) and bimetallic Nickel/Cobalt active phases (CZ91NiCo) to be tested in Ethanol Steam Reforming reaction (ESR). H2-TPR analyses and IR studies of adsorbed probe molecules suggest that ceria/zirconia actually favors the reduction of supported metal oxide phases. Moreover, characterization results point out that the co-presence of Nickel and Cobalt, as in the CZ91NiCo material, enhances the reducibility of both the metal oxide phases, in comparison with monometallic formulations, thus suggesting a synergetic effect between Cobalt and Nickel species. Correspondingly, bimetallic CZ91NiCo catalyst shows the best results in ESR in terms of ethanol conversion, hydrogen yield and selectivity to CO2 above 500°C, which should be explained by the high reducibility of this sample. Ethene formation was not detected in significant amount during catalytic tests. Indeed, the basicity of ceria component is mainly characterizing the surface of this family of catalysts.
•Zeolite type A was synthesized from natural resources under mild conditions.•Textural properties and crystallinity can be controlled through synthesis conditions.•Microporosity plays a key role on ...CO2/N2 and CO2/H2O selectivies.•Under dry conditions, CO2 is readily desorbed at moderate temperatures.•The presence of water hinders the desorption of the physisorbed species.
In light of the urgent need of reducing the atmospheric CO2 emissions, the use of low-cost adsorbents, that exhibit a high affinity and CO2 adsorption capacity, is a promising method from the economic and environmental point of view to separate CO2 from the flue gas emitted from large sources of emissions like power-fueled plants. Clay minerals are low-cost raw materials with high availability all over planet and great versatility in the fields of adsorption and catalysis processes. The present study pretends to elucidate the link between the reaction conditions during the synthesis of the zeolite from kaolinite and its CO2 adsorption capacity. For that purpose, the type A zeolite was synthesized via hydrothermal process in alkaline solution using metakaolinite as a starting material. The metakaolinite was obtained by calcination of kaolinite at 600 °C and some parameters such as temperature and synthesis time were modified to optimize the synthesis aiming for a high CO2 adsorption capacity adsorbent. Synthesized materials were characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), N2 adsorption–desorption at −196 °C and CO2 adsorption at 0 °C (up to 10 bars) isotherms and Nuclear Magnetic Resonance of solids (NMR). In addition, the adsorption capacity of CO2 was evaluated by means of CO2 adsorption–desorption isotherms at 25 °C up to atmospheric pressure. The obtained results indicated that synthesized zeolite 4A can be successfully prepared from natural kaolinite (via metakaolinization) at 100 °C for 48 h under alkaline conditions, showing chemical and physical properties similar to that of the commercial 4A zeolite.
Hydrodesulfurization and hydrodenitrogenation reactions must take place on different sites. The addition of Ir and Pt improves the catalytic behavior of the RuS2 catalyst Display omitted
•RuS2/SBA is ...active in simultaneous hydrodesulfurization and hydrodenitrogenation.•The hydrodesulfurization reaction is not inhibited under the presence of quinoline.•The hydrodenitrogenation reaction is improved in the presence of dibenzothiophene.•Hydrodesulfurization and hydrodenitrogenation on RuS2/SBA occur on different sites.•The presence of Ir and Pt improves the catalytic behavior of RuS2 catalyst.
Simultaneous hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) reactions over RuS2/SBA and the effect of feed composition and the presence of Pt or Ir in the catalyst formulation have been studied. Activity tests were carried out in a flow reactor under a hydrogen pressure of 3.0MPa and WHSV 32h−1. The catalysts were characterized by X-ray diffraction (XRD), N2 adsorption desorption isotherms at −196°C, CO chemisorption, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy of adsorbed CO at low temperature. Characterization results reveal that under the presence of noble metals the dispersion of the RuS2 phase is not affected, the RuS2 coordinatively unsaturated sites (CUS) are in a very sulfided ambient and their population increases; while the noble metals are poorly sulfided and undergo reduction upon reaction. The evaluation of HDN and HDS activity for RuS2/SBA when both (dibenzothiophene) DBT and (quinoline) Q were present in the feed has highlighted the high activity of the RuS2 phase in hydrotreating. The HDS reaction is hardly affected by the presence of Q molecules, with only the hydrogenation (HYD) sites responsible for cyclohexylbenzene (CHB) formation being anyhow altered. HDN results improve in the presence of DBT, even showing high HDN conversion when Q is present in great quantities. These catalytic results strongly suggest that the HDN and HDS reactions must take place on different sites. CO-FTIR spectroscopy results have evidenced that N-containing molecules block the CUS sites responsible for CO adsorption although when S-containing molecules are present, N-containing molecules should be easily transformed since CO-adsorption sites are again available. The addition of small quantities of iridium and platinum to ruthenium sulfide improves the catalytic behavior of the RuS2 catalyst. This is probably due to the greater number of CUS sites and Ir and Pt acting as active hydrogen suppliers. Moreover, these noble metals can act as real active sites where the DBT HDS reaction takes place.
To estimate the prevalence of respiratory symptoms in individuals with type 2 diabetes, as compared to the general population.
Between 2007 and 2010 the screening questionnaire of GEIRD (Gene ...Environment Interactions in Respiratory Diseases) study was administered to two samples of Verona general population, aged respectively 45-64 years and 65-84 years, and to a convenience sample of individuals with type 2 diabetes, consequently recruited at the local Diabetes Centre. Ninety-four and 165 people with type 2 diabetes, aged respectively 45-64 and 65-84 years, were compared with 676 and 591 subjects in the same age range from the general population. The influence of type 2 diabetes on respiratory symptoms was evaluated by logistic regression models, controlling for sex, age (45-54, 55-64, 65-74, 75-84 years), education level, smoking habits and heavy vehicle traffic exposure and adjusting standard errors of ORs for intra-sample correlation.
Compared to the general population, dyspnoea limiting walking pace on level ground (grade 2 dyspnoea) was more frequently reported by people with type 2 diabetes, irrespective of age (p < 0.001), while self-reported chronic cough/phlegm was more common in those aged 45-64 years (p = 0.02). These results were confirmed by multivariable analysis: compared to their counterparts from the general population, people with type 2 diabetes aged 45-54 years showed an increased risk of reporting grade 2 dyspnoea (OR = 3.92, 95% CI 3.28-4.68) or chronic cough/phlegm (OR = 1.69, 1.60-1.78). Similar figures held significant at older ages (75-84 years), although partially blunted (dyspnoea: OR = 1.79, 1.68-1.91; chough/phlegm: OR = 1.09, 1.03-1.16). As such, the interaction between age class and type 2 diabetes was significant for both respiratory disorders. The proportion of self-reported dyspnoea among individuals with type 2 diabetes significantly increased across incremental body-mass index (BMI), from 15.4 to 25.4% and further to 41.3% respectively in normoweight, overweight and obese patients (p = 0.048).
People with type 2 diabetes more frequently reported grade 2 dyspnoea and chronic cough/phlegm than the general population of the same age, although presenting similar smoking habits. Diabetes appears to anticipate the lung ageing process, recorded in the general population. The increased occurrence of dyspnoea at incremental BMI among individuals with type 2 diabetes may reflect both cardiovascular and respiratory impairment in this high-risk patient population.
•WOx/TiO2 are active and selective catalysts for methanol dehydration to DME.•Stronger Lewis and Bronsted acid sites are formed upon increasing surface W density.•Methanol dehydration rates increase ...with the strength of acid sites.
TiO2-supported WOx solids with different W loadings (between 0.2 and 9.0at.Wnm−2) were prepared by incipient wetness impregnation of TiO2 with ammonium (para)tungstate aqueous solutions. The prepared materials were characterized in detail by inductively coupled plasma emission spectrometry (ICP-OES), N2 adsorption-desorption isotherms, X-ray diffraction (XRD), temperature-programmed desorption of NH3, X-ray photoelectron and Raman spectroscopy, and infrared spectroscopy using CO and pyridine as probe molecules. We have observed that the molecular structure of WOx species and their acid features are markedly influenced by the W surface density. A relationship between catalytic performance in dimethyl ether formation via methanol dehydration and the acid properties is found.
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•DSC to evaluate the crosslinking degree of epoxy fairing compounds.•FTIR to evaluate structural changes of epoxy fairing compounds during crosslinking.•Epoxy resins reach maximum ...curing degree in one week at 25 °C regardless of humidity.
Epoxy resins, heavily loaded with fillers, are used as fairing compounds in coating systems to fill superficial imperfections and protect the hull of yachts and ships; they are complex composite materials whose final performance can be heavily affected by the conditions of application. In this paper the curing process of an innovative formulation was studied in function of the temperature and humidity, in order to evaluate how these environmental parameters influence the reaction evolution and gain further insight into the reaction mechanism.
The study of the curing process was carried out by thermogravimetric analysis, differential calorimetric analysis and FT-IR spectroscopy.
From the thermal analysis the obtained crosslink degree ranged between 92 and 99%, at 10 °C and 25 °C respectively. The samples cured at 25 °C reached the maximum curing degree in one week independently from the humidity. The samples cured at lower temperature (10 °C), even after two weeks, did not reach the complete crosslinking. On the other side, it was evident that the humidity did not influence the curing at 25 °C, while it had a slight effect at lower temperature (10 °C).
Results from FTIR spectroscopy at 25 °C evidenced changes in the bands characterizing the two components of the resin during the curing reaction, in particular the disappearance of the oxirane ring band.
Nanoporous activated carbons were fabricated using pectin, as raw material, by a two step process. As a first step, a water-dispersion of pectin had undergone hydrothermal carbonization at 230°C, ...followed by a second step consisting of chemical activation with KOH at 700°C. The obtained activated carbon showed a BET surface area of 900m2/g, with a statistical pore diameter in the nanometer range. Scanning electron microscopy confirmed the nanoporous structure of the activated carbon. FT IR analysis was used to assess the efficiency of chemical activation. Finally, the activated carbon material was characterized respect to CO2 capture capacity.
•The synthesis of activated carbon materials based on pectin is proposed.•The morphology is characterized.•CO2 adsorption capacity is investigated.
The catalytic activity in CH3OH dehydration reaction increases with Nb content because of the higher strength of Lewis acid sites and the formation of additional Brønsted acid sites. Display omitted
...► NbOx/TiO2 are active and selective catalysts for methanol dehydration to DME. ► Stronger Lewis and Brønsted acid sites are formed upon increasing surface Nb density. ► Methanol dehydration rates increase with the strength of acid sites.
A series of NbOx/TiO2 catalysts (0.9–9.0atNbnm−2) was prepared by incipient wetness impregnation of niobium (V) oxalate aqueous solutions on TiO2. Spectroscopic data reveal that NbOx phase is highly dispersed and relatively large Nb2O5 crystallites are not detected; highly distorted NbO6 octahedral structures are exclusively identified by Raman spectroscopy. Surface acidity measurements by NH3-temperature-programmed desorption experiments indicate that the overall number of Lewis acid sites in the solids decreases with Nb-loading, although their strength follows the opposite trend. A minor fraction of Brønsted acid sites is also detected for the sample with the highest Nb surface coverage used here (9.0atNbnm−2). The catalytic activity of NbOx/TiO2 in methanol dehydration to dimethyl ether is found to be determined mainly by the strength of the acid sites and the presence of Brønsted acid sites, being more active those catalysts with stronger acid sites and with a higher number of Brønsted acid sites.
The interaction of trimethoxysilane (TMS) and of 3-mercaptopropyltrimethoxysilane (MPTMS) with silica and silicon wafers has been studied by the mean of transmission FTIR spectroscopy. TMS vapor ...adsorption on silica's silanols results in the formation of Si−O−Si bonds at room temperature, mainly through the elimination of one methanol molecule per TMS molecule. Similarly, MPTMS vapor reacts with the surface through “hydroxolysis” of one of Si−O−CH3 bonds, and most of the molecules have their SH group free. The same species is formed over the silicon wafer surface. On the other side, deposition of liquid MPTMS over silicon surface leads to the detection of spectral features characterizing a condensed layer.
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