Influence of copper on nickel-based catalysts in the conversion of glycerol

The catalytic transformation of glycerol to value-added compounds was investigated over bimetallic Ni-Cu/gamma-Al2O3 catalysts with Ni/Cu atomic ratios of 8/1, 4/1, 2/1, 1/1, 1/2, 1/4, and 1/8. XPS analysis revealed that the surface composition of the catalyst exhibited progressive enrichment of Cu as its content in the catalyst increased. H-2-chemisorption indicated that the total number of exposed Ni atoms decreased as the Cu content increased. As a result, deep hydrogenolysis to produce CH4 was inhibited by the addition of Cu to the Ni catalyst, yielding higher selectivity toward the dehydration products of glycerol such as hydroxyacetone.; FTIR spectra of adsorbed CO reveal that Cu asserts both geometric and electronic effects on the adsorption properties of Ni. The geometrical effect is visualized by the progressive disappearance of the bridge bound adsorbed CO on metallic Ni by the incorporation of Cu. This suggests that the deep hydrogenolysis of glycerol to CH4 formation requires an ensemble of adjacent active Ni atoms. The electronic effect of Cu on Ni is indicated by the red shift of the IR peak of adsorbed CO as the Cu content increases. The electronic interaction between Cu and Ni species was also substantiated by XANES results. HTREM revealed metal particles very well distributed on the support with particle size of 1.5 to 5 nm. The Ni Cu samples were not a total intermetallic alloys. (C) 2014 Elsevier B.V. All rights reserved.Postprint (published version

Outcomes from elective colorectal cancer surgery during the SARS-CoV-2 pandemic

This study aimed to describe the change in surgical practice and the impact of SARS-CoV-2 on mortality after surgical resection of colorectal cancer during the initial phases of the SARS-CoV-2 pandemic

Falls Predict Acute Hospitalization in Parkinson's Disease

[Background] There is a need for identifying risk factors for hospitalization in Parkinson’s disease (PD) and also interventions to reduce acute hospital admission.[Objective] To analyze the frequency, causes, and predictors of acute hospitalization (AH) in PD patients from a Spanish cohort.[Methods] PD patients recruited from 35 centers of Spain from the COPPADIS-2015 (COhort of Patients with PArkinson’s DIsease in Spain, 2015) cohort from January 2016 to November 2017, were included in the study. In order to identify predictors of AH, Kaplan-Meier estimates of factors considered as potential predictors were obtained and Cox regression performed on time to hospital encounter 1-year after the baseline visit.[Results] Thirty-five out of 605 (5.8%) PD patients (62.5±8.9 years old; 59.8% males) presented an AH during the 1-year follow-up after the baseline visit. Traumatic falls represented the most frequent cause of admission, being 23.7% of all acute hospitalizations. To suffer from motor fluctuations (HR [hazard ratio] 2.461; 95% CI, 1.065–5.678; p = 0.035), a very severe non-motor symptoms burden (HR [hazard ratio] 2.828; 95% CI, 1.319–6.063; p = 0.008), falls (HR 3.966; 95% CI 1.757–8.470; p = 0.001), and dysphagia (HR 2.356; 95% CI 1.124–4.941; p = 0.023) was associated with AH after adjustment to age, gender, disease duration, levodopa equivalent daily dose, total number of non-antiparkinsonian drugs, and UPDRS-IIIOFF. Of the previous variables, only falls (HR 2.998; 95% CI 1.080–8.322; p = 0.035) was an independent predictor of AH.[Conclusion] Falls is an independent predictor of AH in PD patients.Peer reviewe

La renovación de la palabra en el bicentenario de la Argentina : los colores de la mirada lingüística

El libro reúne trabajos en los que se exponen resultados de investigaciones presentadas por investigadores de Argentina, Chile, Brasil, España, Italia y Alemania en el XII Congreso de la Sociedad Argentina de Lingüística (SAL), Bicentenario: la renovación de la palabra, realizado en Mendoza, Argentina, entre el 6 y el 9 de abril de 2010. Las temáticas abordadas en los 167 capítulos muestran las grandes líneas de investigación que se desarrollan fundamentalmente en nuestro país, pero también en los otros países mencionados arriba, y señalan además las áreas que recién se inician, con poca tradición en nuestro país y que deberían fomentarse. Los trabajos aquí publicados se enmarcan dentro de las siguientes disciplinas y/o campos de investigación: Fonología, Sintaxis, Semántica y Pragmática, Lingüística Cognitiva, Análisis del Discurso, Psicolingüística, Adquisición de la Lengua, Sociolingüística y Dialectología, Didáctica de la lengua, Lingüística Aplicada, Lingüística Computacional, Historia de la Lengua y la Lingüística, Lenguas Aborígenes, Filosofía del Lenguaje, Lexicología y Terminología

Catalytic performance of zinc-supported copper and nickel catalysts in the glycerol hydrogenolysis

Gas-phase catalytic conversion of glycerol to value added chemicals was investigated over zinc-supported copper and nickel catalysts. The addition of aluminum in the support was also investigated in glycerol conversion and the results indicate an increase in the acidity and adsorption capacity for both copper and nickel catalysts. HRTEM and XRD analysis revealed NiZn alloy formation in the Ni/ZnO catalyst. The XRD patterns of the prepared ZnAl mixed oxide catalysts show the presence of Gahanite phase (ZnAl2O4). In addition, H2 chemisorption and TPR results suggest a strong metal-support interactions (SMSI) effect between Ni and ZnO particles. Bare supports ZnO and ZnAl (Zn/Al¿=¿0.5) were investigated in the glycerol conversion and they did not present activity. Copper supported on ZnO and ZnAl mixed oxide (Zn/Al¿=¿0.5) was active towards hydroxyacetone formation. Nickel was active in the hydrogenolysis of glycerol both for C–C and C–O bonds cleavage of glycerol producing CH4. Strong metal-support interactions (SMSI) between Ni and ZnO has a remarkable suppression effect on the methanation activity during the glycerol conversion.Postprint (author's final draft

Catalytic performance of zinc-supported copper and nickel catalysts in the glycerol hydrogenolysis

Gas-phase catalytic conversion of glycerol to value added chemicals was investigated over zinc-supported copper and nickel catalysts. The addition of aluminum in the support was also investigated in glycerol conversion and the results indicate an increase in the acidity and adsorption capacity for both copper and nickel catalysts. HRTEM and XRD analysis revealed NiZn alloy formation in the Ni/ZnO catalyst. The XRD patterns of the prepared ZnAl mixed oxide catalysts show the presence of Gahanite phase (ZnAl2O4). In addition, H2 chemisorption and TPR results suggest a strong metal-support interactions (SMSI) effect between Ni and ZnO particles. Bare supports ZnO and ZnAl (Zn/Al¿=¿0.5) were investigated in the glycerol conversion and they did not present activity. Copper supported on ZnO and ZnAl mixed oxide (Zn/Al¿=¿0.5) was active towards hydroxyacetone formation. Nickel was active in the hydrogenolysis of glycerol both for C–C and C–O bonds cleavage of glycerol producing CH4. Strong metal-support interactions (SMSI) between Ni and ZnO has a remarkable suppression effect on the methanation activity during the glycerol conversion

Sources of deactivation during glycerol conversion on Ni/gamma-Al2O3

Hydrogenolysis of glycerol was studied using a diluted aqueous solution of glycerol in gas phase and atmospheric pressure on Ni/¿-Al2O3 catalyst. The catalytic transformation of glycerol generates products derived from dehydration, dehydrogenation, hydrogenolysis and condensation reactions. Deep hydrogenolysis route to produce CH4 prevails in the first few hours of reaction. As the reaction time progress, dehydration-dehydrogenation products start to appear. Here, a description of the deactivation sources and its effects on the catalytic performance of Ni catalyst was proposed. The catalyst was characterized before and after the catalytic reaction by high-resolution transmission electron microscopy (HRTEM) and by employing Fourier transformed infrared spectroscopy (FTIR) of adsorbed CO. A source of deactivation was due to carbonaceous deposition. FTIR at low CO dosing pressure reveal bands assignments species essentially due to linear and bridge carbonyls, whereas high pressure CO dosing produces a complex spectra due to polycarbonyls. X-ray absorption near edge structure (XANES) analysis was employed to reveal the initial degree of reduction of the fresh catalyst. The oxidation of metallic Ni in the course of reaction may also be considered as a source of deactivation. Ni oxide species promote dehydration routes. Alumina support facilitates nickel species to be more active toward interacting with glycerol. Dehydration, which takes place on the acid sites, is the mainly route related to the generation of carbon deposition and to the observed catalyst deactivation. Another source of deactivation was due to carbiding of Ni to form Ni3C. The regeneration of used Ni catalyst was achieved by oxidation-reduction steps at 723 K.Peer ReviewedPostprint (published version

Sources of deactivation during glycerol conversion on Ni/gamma-Al2O3

Hydrogenolysis of glycerol was studied using a diluted aqueous solution of glycerol in gas phase and atmospheric pressure on Ni/¿-Al2O3 catalyst. The catalytic transformation of glycerol generates products derived from dehydration, dehydrogenation, hydrogenolysis and condensation reactions. Deep hydrogenolysis route to produce CH4 prevails in the first few hours of reaction. As the reaction time progress, dehydration-dehydrogenation products start to appear. Here, a description of the deactivation sources and its effects on the catalytic performance of Ni catalyst was proposed. The catalyst was characterized before and after the catalytic reaction by high-resolution transmission electron microscopy (HRTEM) and by employing Fourier transformed infrared spectroscopy (FTIR) of adsorbed CO. A source of deactivation was due to carbonaceous deposition. FTIR at low CO dosing pressure reveal bands assignments species essentially due to linear and bridge carbonyls, whereas high pressure CO dosing produces a complex spectra due to polycarbonyls. X-ray absorption near edge structure (XANES) analysis was employed to reveal the initial degree of reduction of the fresh catalyst. The oxidation of metallic Ni in the course of reaction may also be considered as a source of deactivation. Ni oxide species promote dehydration routes. Alumina support facilitates nickel species to be more active toward interacting with glycerol. Dehydration, which takes place on the acid sites, is the mainly route related to the generation of carbon deposition and to the observed catalyst deactivation. Another source of deactivation was due to carbiding of Ni to form Ni3C. The regeneration of used Ni catalyst was achieved by oxidation-reduction steps at 723 K.Peer Reviewe

Trialling GSM data services for the mobile office

SIGLEAvailable from British Library Document Supply Centre- DSC:4335.26205(HPL--95-45) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Conversion of glycerol over 10%Ni/y-Al2O3 catalyst

The conversion of glycerol in gas phase and atmospheric pressure has been investigated over 10 wt.% Ni/γ-Al2O3 catalyst. The catalysts were prepared with nickel nitrate and pre-treated with hydrogen in the range of 623–1073 K. The resultant catalysts were characterized by N2-physisoption, H2-chemisorption, X-ray diffraction (XRD), TGA-MS, TEM, RAMAN, NH3-TPD, XPS, TPO-MS and XANES. The stability and the catalytic behavior of the catalysts were affected by the reduction pre-treatment. Glycerol reaction pathways were proposed based on dehydration, dehydrogenation and hydrogenolysis steps. The main products identified were: hydroxyacetone, pyruvaldehyde, pyruvic acid, lactic acid, lactide, acetaldehyde and methane. The number of exposed Ni atoms and the degree of reduction of the NiO species affected the hydrogenolysis reaction of glycerol to CH4 affecting the catalytic stability. The catalyst was deactivated by coke formation, by transformation of Ni phase to nickel carbide (Ni3C), as well as by oxidation of the Ni phase during the reaction. In addition, Raman analysis revealed two types of carbonaceous deposits over the used samples: on the Ni species and on the support. The regeneration treatment by oxidation–reduction reactivated the catalyst successfully