Wacker-oxidation of Ethylene over Pillared Layered Material Catalysts

This paper concerns the Wacker oxidation of ethylene by oxygen in the presence of water over supported Pd/VOx catalysts. High surface area porous supports were obtained from layer-structured materials, such as, montmorillonite (MT), laponite (LT) (smectites), and hydrotalcite (layered double hydroxide, LDH) by pillaring. Before introduction of Pd, supports MT and LDH were pillared by vanadia. The laponite was used in titania-pillared form (TiO2-LAP) as support of Pd/VOx active component. Acetaldehyde (AcH), acetic acid (AcOH) and CO2 were the products with yields and selectivities, depending on the reaction conditions and the properties of the applied catalyst. Under comparable conditions the pillared smectite catalysts gave higher AcH yield than the pillared LDH catalyst. UV vis spectroscopic examination suggested that the pillared smectites contained polymeric chains of VO4, whereas only isolated monomeric VO4 species were present in the pillared LDH. The higher catalytic activity in the Wacker oxidation was attributed to the more favorable redox property of the polymeric than of the monomeric vanadia. The V3+ ions in the polymeric species can reduce O2 to O2- ions, whereas the obtained V5+ ions are ready to pass over O to Pd0 to generate PdO whereon the oxidation of the ethylene proceeds

Roflumilast in moderate-to-severe chronic obstructive pulmonary disease treated with longacting bronchodilators: two randomised clinical trials

Background Patients with chronic obstructive pulmonary disease (COPD) have few options for treatment. The efficacy and safety of the phosphodiesterase-4 inhibitor roflumilast have been investigated in studies of patients with moderate-to-severe COPD, but not in those concomitantly treated with longacting inhaled bronchodilators. The effect of roflumilast on lung function in patients with COPD that is moderate to severe who are already being treated with salmeterol or tiotropium was investigated. Methods In two double-blind, multicentre studies done in an outpatient setting, after a 4-week run-in, patients older than 40 years with moderate-to-severe COPD were randomly assigned to oral roflumilast 500 mu g or placebo once a day for 24 weeks, in addition to salmeterol (M2-127 study) or tiotropium (M2-128 study). The primary endpoint was change in prebronchodilator forced expiratory volume in 1s (FEV(1)). Analysis was by intention to treat. The studies are registered with ClinicalTrials.gov, number NCT00313209 for M2-127, and NCT00424268 for M2-128. Findings In the salmeterol plus roflumilast trial, 466 patients were assigned to and treated with roflumilast and 467 with placebo; in the tiotropium plus roflumilast trial, 371 patients were assigned to and treated with roflumilast and 372 with placebo. Compared with placebo, roflumilast consistently improved mean prebronchodilator FEV(1) by 49 mL (p<0.0001) in patients treated with salmeterol, and 80 mL (p<0.0001) in those treated with tiotropium. Similar improvement in postbronchodilator FEV(1) was noted in both groups. Furthermore, roflumilast had beneficial effects on other lung function measurements and on selected patient-reported outcomes in both groups. Nausea, diarrhoea, weight loss, and, to a lesser extent, headache were more frequent in patients in the roflumilast groups. These adverse events were associated with increased patient withdrawal. Interpretation Roflumilast improves lung function in patients with COPD treated with salmeterol or tiotropium, and could become an important treatment for these patients

The SCR of NO with methane over In,H- and Co,In,H-ZSM-5 catalysts: The promotional effect of cobalt

Zeolite In,H-, Co,H-, and Co,In,H-ZSM-5 were characterized by operando diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), temperature-programmed reduction by hydrogen (H2-TPR), X-ray photoelectron spectroscopy (XPS), and activity in the selective catalytic reduction of NO (NO-SCR) by methane. The catalysts were shown to contain indium as [InO]+/[InOH]2+ cations, whereas cobalt was in the form of Co2+/[Co-OH]+ cations or Co-oxide clusters in amounts controlled by the applied preparation method. The NO-SCR by methane was shown to proceed in two coupled processes on distinctly different catalytic sites. One of the processes is the oxidation of NO to NO2 by oxygen over Brønsted acid sites and/or cobalt-oxide species giving NO/NO2 gas mixture (NO-COX reaction). The other process is the N2 formation, which is the result of the reaction of methane and the NO/NO2 mixture (CH4/NO-SCR reaction). Molecules of NO and NO2 were shown to become activated together as NO+/NO3− ion pair in reaction with [InO]+/[InOH]2+ or Co2+/[Co-OH]+ sites. Operando DRIFTS results suggested that the reaction of methane and NO3− generates an intermediate that rapidly reacts with the NO+ to give N2. The promoting effect of the cobalt was related to the significantly higher NO-COX activity of Co-oxide clusters than that of the Brønsted acid sites. The accelerated NO-COX reaction speeds up the formation of NO+/NO3− species and the rate of the methane activation, being the rate-determining step of the NO-SCR reaction. It was also shown that the NO-SCR reaction can proceed if NO-COX and CH4/NO-SCR active sites are separated in space. In order to avoid rate controlling NO2 transport between the sites close proximity of the sites is favorable.Fil: Lónyi, Ferenc. Hungarian Academy of Sciences; HungríaFil: Solt, Hanna E.. Hungarian Academy of Sciences; HungríaFil: Valyon, József. Hungarian Academy of Sciences; HungríaFil: Boix, Alicia Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Gutierrez, Laura Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentin

An operando DRIFTS study of the active sites and the active intermediates of the NO-SCR reaction by methane over In,H- and In,Pd,H-zeolite catalysts

Zeolites In,H-ZSM-5 (Si/Al=29.7, 1.7wt% In) and In,H-mordenite (In,H-M, Si/Al=6.7, 3.5 wt% In) were prepared by reductive solid state ion exchange (RSSIE) method and studied in the selective catalytic reduction of NO (NO-SCR) by methane. The results suggested that the methane oxidation reactions proceed by redox type mechanisms over In+/InO+ sites. The NO reduction selectivity was shown to be related to the relative rates of In+ oxidation by NO and O2. Regarding the relative rates, the In+ density of the zeolite was the most important. Above about 673K the In,H-ZSM-5 (T-atom/In=102) had higher NO reduction selectivity than the In,H-mordenite (T-atom/In=46). The operando DRIFTS examinations suggested that NO+ and NO3 - surface species were formed simultaneously on InO+Z- sites, and were consumed together in the NO-SCR reaction with methane. The reduction of the NO3 - by methane gave an activated N-containing intermediate, which further reacted with the NO+ species to give N2. The NO-SCR properties could be significantly improved by adding small amount of Pd to the In,H-zeolite catalyst. The promoting effect of Pd was interpreted as a concerted action of InO+ and the Pdn+ sites. The interplay between these sites is twofold: the Pd speeds up the equilibration of the NO/O2 mixture, thereby, increases the formation rate and the steady state concentration of the activated nitrate species, whereas the In+/InO+ sites prevent the transformation of Pd-nitrosyls to less reactive isocyanate and nitrile species.Fil: Lónyi, Ferenc. Chemical Research Center; HungríaFil: Solt, Hanna E.. Chemical Research Center; HungríaFil: Valyon, József. Chemical Research Center; HungríaFil: Decolatti, Hernán Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; ArgentinaFil: Gutierrez, Laura Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; ArgentinaFil: Miro, Eduardo Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; Argentin