Oleylamine-Stabilized Palladium(0) Nanoclusters As Highly Active Heterogeneous Catalyst for the Dehydrogenation of Ammonia Borane

Palladium(0) nanoclusters having an average particle size of 3.2 nm were generated in situ from the reduction of palladium(II) acetylacetonate in the presence of oleylamine (OAm) during the dehydrogenation of ammonia borane (AB) in THF under inert gas atmosphere at room temperature. OAm-stabilized palladium(0) nanoclusters were stable enough to be isolated as solid materials and characterized by TEM, HRTEM, XRD, UV-vis, and FT-IR techniques. They were found to be highly active catalysts in the hydrogen generation from the dehydrogenation of AB; in total, 2 equiv of hydrogen gas per AB was generated even at low catalyst concentration and room temperature. The first and second equivalent of H(2) generation from AB were completed in similar to 20 and 100 mm, respectively, from the dehydrogenation of AB in the presence of palladium (0) nanoclusters corresponding to an initial turnover frequency of 240 h(-1). (11)B NMR study of the reaction shows that hydrogen evolution likely takes place in one or both of two parallel routes: (i) through formation of cyclopolyborazane followed by its polymerization to polyborazylene and (ii) through formation of long-chain B-N linear polymers. Carbon disulfide poisoning experiments indicate that the dehydrogenation of AB catalyzed by OAm-stabilized palladium(0) nanoclusters is heterogeneous catalysis. Moreover, the work reported here includes a wealthy collection of kinetic data to determine the rate law and apparent activation energy for the catalytic dehydrogenation of AB

Silica embedded cobalt(0) nanoclusters: Efficient, stable and cost effective catalyst for hydrogen generation from the hydrolysis of ammonia borane

Cobalt(0) nanoclusters embedded in silica (Co@SiO2) were prepared by a facile two-step procedure. In the first step, the hydrogenphosphate anion (HPO42-) stabilized cobalt(0) nanoclusters were in situ generated from the reduction of cobalt(II) chloride during the hydrolysis of sodium borohydride (NaBH4) in the presence of stabilizer. Next, HPO42- anion-stabilized cobalt(0) nanoclusters were embedded in silica formed by in situ hydrolysis and condensation of tetraethylorthosilicate added as ethanol solution. Co@SiO2 can be separated from the solution by vacuum filtration and characterized by UV-Vis electronic absorption spectroscopy, TEM, SEM-EDX, ATR-IR and ICP-OES techniques. Co@SiO2 are found to be highly active and stable catalysts in the hydrolysis of ammonia borane (AB) even at low cobalt concentration and room temperature. They provide an initial turnover frequency of 13.3 min(-1) and 24,400 total turnovers over 52 h in the hydrolysis of AB at 25.0 +/- 0.5 degrees C. Moreover, Co@SiO2 retain 72% and 74% of the initial activity after ten runs recyclability and five cycles reusability test in the hydrolysis of AB, respectively. The kinetics of hydrogen generation from the hydrolysis of AB catalyzed by Co@SiO2 was studied depending on the catalyst concentration, substrate concentration, and temperature. The activation parameters of this catalytic reaction were also determined from the evaluation of the kinetic data. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved

Transition metal nanoparticles as catalyst in hydrogen generation from boron based compounds

Here, we present that transition metal(0) nanoparticles can be employed as highly active, long-lived and reusable catalyst in hydrogen generation from the boron based hydrogen storage materials for fuel cell applications. Transition metal(0) nanoparticles were prepared from the reduction of respective precursor in the presence of anionic or polymeric stabilizer. All the transition metal(0) nanoparticles (Fe, Co, Ni, Ru) prepared show very high catalytic activity in hydrogen generation from the hydrolysis of sodium borohydride or ammonia-borane at room temperature. Rhodium(0) nanoparticles stabilized by tert-butylammonium octanoate or dimethylammonium hexanoate are superb catalyst in dehydrogenation of ammonia-borane or dimethylamine borane at room temperature, respectively. Further enhancement in catalytic activity could be achieved by preparing transition metal(0) nanoclusters within supercages of zeolite-Y. Zeolite stabilized cobalt(0), nickel(0), ruthenium(0), and rhodium(0) nanoclusters are very active catalyst in hydrogen generation from the hydrolysis of sodium borohydride or ammonia-borane at room temperature

Evaluation of 2015-2016 MOTAKK HBV DNA and HCV RNA External Quality Assessment National Program Results

MOTAKK, as a national external quality control program has been launched to evaluate the molecular detection of viral infections including HBV DNA and HCV RNA in molecular microbiology diagnostic laboratories in Turkey. This program is prepared in compliance with ISO 17043:2010 (Conformity assessment general requirements for proficiency testing) standards, and aims to take the place of external quality control programs from abroad, contributing to standardization and accuracy of molecular diagnostic tests in our country. The aim of this study was to evaluate 2015 and 2016 results of the MOTAKK External Quality Control Program for HBV DNA and HCV RNA viral load. The calls were announced on the web page of MOTAKK (www.motakk.org). The quality control samples were sent to participating laboratories in 2015 and 2016. Main stocks were prepared from patients with chronic hepatitis B and C who had viral load detection with reference methods according to WHO reference materials for viral load studies to improve quality control sera. From these main stocks, samples with different viral loads were prepared from dilutions of plasma with HBV, HCV, HAV, HIV, Parvovirus B19 and CMV negative serologic markers. Quality control samples were sent to the participating laboratories along with the negative samples in the cold chain. The laboratories accomplished the related tests within 2-3 weeks and entered their results on the MOTAKK web page. These results were analysed according to ISO 13528 (Statistical methods for use in proficiency testing by interlaboratory comparison) and scoring reports were created by a software developed by MOTAKK and sent to participating labs. Each laboratory evaluated their own results in comparison with the other laboratory results, reassessed the tests via observing the distance from the mean result and the reference values. The number of laboratories participating in the HBV DNA and HCV RNA external quality control program was 70-73 in 2015-2016. Participants were able to comply with the program tools, registering, entering results and receiving the results reports problem. In HBV panel, 72.6-89.1% and 84.7-90.3% of the participant laboratories were in 1 standard deviation (SD) in 2015-2016, respectively. In HCV panel, 70.8-89.1% and 84.7-90.3% of the participant laboratories were in 1 SD in 2015-2016, respectively. A national external quality control program for HBV DNA and HCV RNA in Turkey has been prepared for the first time with this project and implemented successfully. All the data provided in the MOTAKK external quality control program final report, compensate all the data provided by the quality control program final reports from abroad; additionally, the report allows comparison of used technologies and commercial products