Hydrotalcite/SBA15 composites for pre-combustion CO2 capture: CO2

Hydrotalcite-like compounds (HT) show potential as CO2 adsorbent materials for pre-combustion CO2 capture applications, but require improvements in stability, adsorption capacity and kinetics. In this study, HT/SBA15 hybrids (with different Mg/Al ratios varying from 0.3 to 3) have been synthesised using a two-stage grafting method to coat a mesoporous SBA15 with hydrotalcite layers. The HT/SBA15 hybrids showed significant improvement in intrinsic CO2 uptake (per mass of HT), initial uptake rate, and multicycle stability compared to unsupported HT. Compared to previously reported nanostructured carbon supports (e.g. CNF, MWCNTs), the HT/SBA15 hybrids were found to be more thermally stable and exhibit comparable adsorption uptake and rates. In particular, the use of SBA15 as a support is shown to prevent the gradual loss in weight from thermal decomposition observed for HT/MWCNT or HT/GO composites over extended cycling

Dimerizacion de pentenos con alumina fluorada

Dimerisation of isoamylenes coming from a pentane catalytic dehydrogenation process is an option to transform these branched olefins into unsaturated compounds of ten carbons (diisoamylenes). Dimers derivatives have a wide range of industrial applications. The present research sets the basis for the development of a feasible process of branched pentene dimerisation using fluorinated alumina as catalyst. Experimental tests were carried out in a packed bed reactor. 2-methyl-2-butene was used as model reactant. The effluent composition was followed by gas chromatography and mass spectroscopy. Solid characterization was done by means of surface area, total acidity, elemental and thermogravimetric analysis

Glucose isomerisation into fructose over magnesium-impregnated NaY zeolite catalysts

The performance of magnesium-impregnated NaY zeolite catalysts for the glucose isomerisation into fructose at 100 °C has been evaluated. Although crystallinity and textural properties of the zeolites are reduced through Mg addition, glucose conversion improves (6–49%) by increasing magnesium content (0–15 wt.%) due to an increase of the number of basic sites. Conversely, selectivity to fructose drops (96–66%). Nevertheless, good fructose yields were still reached with 10 and 15 wt.% of magnesium (about 32%), being similar or even higher than those found for a commercial hydrotalcite and a pure magnesium oxide. Catalysts lose performance through carbon retention and cations leaching. Deactivation of magnesium-based zeolites was further investigated by consecutive reaction runs. If no regeneration of the catalyst is performed, the activity of the zeolites decreases mainly as a result of cations leaching, the effect reducing with the number of runs. Regeneration allows the catalyst to recover almost totally its initial activity. Interestingly, used samples show higher fructose selectivity due to the additional pore opening resulting from cations leaching and/or carbon removal. Cations leaching results in a homogeneous catalytic reaction which is most significant for the highest magnesium content. Magnesium-based NaY zeolites are revealed as potential catalysts for glucose isomerisation into fructose with high fructose productivities and good performance in consecutive reactions combined with intermediate regeneration

Electrically Heatable Graphene Aerogels as Nanoparticle Supports in Adsorptive Desulfurization and High‐Pressure CO2 Capture

Reduced‐graphene‐oxide (rGO) aerogels provide highly stabilising, multifunctional, porous supports for hydrotalcite‐derived nanoparticles, such as MgAl‐mixed‐metal‐oxides (MgAl‐MMO), in two commercially important sorption applications. Aerogel‐supported MgAl‐MMO nanoparticles show remarkable enhancements in adsorptive desulfurization performance compared to unsupported nanoparticle powders, including substantial increases in organosulfur uptake capacity (>100% increase), sorption kinetics (>30‐fold), and nanoparticle regeneration stability (>3 times). Enhancements in organosulfur capacity are also observed for aerogel‐supported NiAl‐ and CuAl‐metal‐nanoparticles. Importantly, the electrical conductivity of the rGO aerogel network adds completely new functionality by enabling accurate and stable nanoparticle temperature control via direct electrical heating of the graphitic support. Support‐mediated resistive heating allows for thermal nanoparticle recycling at much faster heating rates (>700 °C∙min−1) and substantially reduced energy consumption, compared to conventional, external heating. For the first time, the CO2 adsorption performance of MgAl‐MMO/rGO hybrid aerogels is assessed under elevated‐temperature and high‐CO2‐pressure conditions relevant for pre‐combustion carbon capture and hydrogen generation technologies. The total CO2 capacity of the aerogel‐supported MgAl‐MMO nanoparticles is more than double that of the unsupported nanoparticles and reaches 2.36 mmol·CO2 g−1 ads (at p CO2 = 8 bar, T = 300 °C), outperforming other high‐pressure CO2 adsorbents

Clinical factors associated with a Candida albicans Germ Tube Antibody positive test in Intensive Care Unit patients

Background: Poor outcomes of invasive candidiasis (IC) are associated with the difficulty in establishing the microbiological diagnosis at an early stage. New scores and laboratory tests have been developed in order to make an early therapeutic intervention in an attempt to reduce the high mortality associated with invasive fungal infections. Candida albicans IFA IgG has been recently commercialized for germ tube antibody detection (CAGTA). This test provides a rapid and simple diagnosis of IC (84.4% sensitivity and 94.7% specificity). The aim of this study is to identify the patients who could be benefited by the use of CAGTA test in critical care setting. Methods: A prospective, cohort, observational multicentre study was carried out in six medical/surgical Intensive care units (ICU) of tertiary-care Spanish hospitals. Candida albicans Germ Tube Antibody test was performed twice a week if predetermined risk factors were present, and serologically demonstrated candidiasis was considered if the testing serum dilution was >= 1: 160 in at least one sample and no other microbiological evidence of invasive candidiasis was found. Results: Fifty-three critically ill non-neutropenic patients (37.7% post surgery) were included. Twenty-two patients (41.5%) had CAGTA-positive results, none of them with positive blood culture for Candida. Neither corrected colonization index nor antifungal treatment had influence on CAGTA results. This finding could corroborate that the CAGTA may be an important biomarker to distinguish between colonization and infection in these patients. The presence of acute renal failure at the beginning of the study was more frequent in CAGTA-negative patients. Previous surgery was statistically more frequent in CAGTA-positive patients. Conclusions: This study identified previous surgery as the principal clinical factor associated with CAGTA-positive results and emphasises the utility of this promising technique, which was not influenced by high Candida colonization or antifungal treatment. Our results suggest that detection of CAGTA may be important for the diagnosis of invasive candidiasis in surgical patients admitted in ICU.This study has been supported by a Pfizer research gran

Role of age and comorbidities in mortality of patients with infective endocarditis

Purpose: The aim of this study was to analyse the characteristics of patients with IE in three groups of age and to assess the ability of age and the Charlson Comorbidity Index (CCI) to predict mortality. Methods: Prospective cohort study of all patients with IE included in the GAMES Spanish database between 2008 and 2015. Patients were stratified into three age groups:<65 years, 65 to 80 years, and = 80 years.The area under the receiver-operating characteristic (AUROC) curve was calculated to quantify the diagnostic accuracy of the CCI to predict mortality risk. Results: A total of 3120 patients with IE (1327 < 65 years;1291 65-80 years;502 = 80 years) were enrolled.Fever and heart failure were the most common presentations of IE, with no differences among age groups.Patients =80 years who underwent surgery were significantly lower compared with other age groups (14.3%, 65 years; 20.5%, 65-79 years; 31.3%, =80 years). In-hospital mortality was lower in the <65-year group (20.3%, <65 years;30.1%, 65-79 years;34.7%, =80 years;p < 0.001) as well as 1-year mortality (3.2%, <65 years; 5.5%, 65-80 years;7.6%, =80 years; p = 0.003).Independent predictors of mortality were age = 80 years (hazard ratio [HR]:2.78;95% confidence interval [CI]:2.32–3.34), CCI = 3 (HR:1.62; 95% CI:1.39–1.88), and non-performed surgery (HR:1.64;95% CI:11.16–1.58).When the three age groups were compared, the AUROC curve for CCI was significantly larger for patients aged <65 years(p < 0.001) for both in-hospital and 1-year mortality. Conclusion: There were no differences in the clinical presentation of IE between the groups. Age = 80 years, high comorbidity (measured by CCI), and non-performance of surgery were independent predictors of mortality in patients with IE.CCI could help to identify those patients with IE and surgical indication who present a lower risk of in-hospital and 1-year mortality after surgery, especially in the <65-year group

Towards autothermal hydrogen production by sorption-enhanced water gas shift and methanol reforming: a thermodynamic analysis

Hydrogen production by the water gas shift reaction (WGS) is equilibrium limited. In the current study, we demonstrate that the overall efficiency of the WGS can be improved by co-feeding methanol and removing CO2 in situ. The thermodynamics of the water gas shift and methanol reforming/WGS (methanol-to-shift, MtoS) reactions for H2 production alone and with simultaneous CO2 adsorption (sorption-enhanced, SEWGS and SEMtoS) were studied using a non-stoichiometric approach based on the minimisation of the Gibbs free energy. A typical composition of the effluent from a steam methane reformer was used for the shift section. The effects of temperature (450–750 K), pressure (5–30 barg), steam and methanol addition, fraction of CO2 adsorption (0–95%) and energy efficiency of the shift systems have been investigated. Adding methanol to the feed facilitates autothermal operation of the shift unit, with and without CO2 removal, and enhances significantly the amount of H2 produced. For a set methanol and CO input, the MtoS and SEMtoS systems show a maximum productivity of H2 between 523 and 593 K due to the increasing limitation of the exothermic shift reaction while the endothermic methanol steam reforming is no longer limited above 593 K. The heat of adsorption of CO2 was found to make only a small difference to the H2 production or the autothermal conditions