Deuteron spin-lattice relaxation in the presence of an activation energy distribution: Application to methanols in zeolite NaX

A new method is introduced for analyzing deuteron spin-lattice relaxation in molecular systems with a broad distribution of activation energies and correlation times. In such samples the magnetization recovery is strongly non-exponential but can be fitted quite accurately by three exponentials. The considered system may consist of molecular groups with different mobility. For each group a Gaussian distribution of the activation energy is introduced. By assuming for every subsystem three parameters: the mean activation energy E-0, the distribution width sigma and the pre-exponential factor tau(0) for the Arrhenius equation defining the correlation time, the relaxation rate is calculated for every part of the distribution. Experiment-based limiting values allow the grouping of the rates into three classes. For each class the relaxation rate and weight is calculated and compared with experiment. The parameters E-0, sigma and tau(0) are determined iteratively by repeating the whole cycle many times. The temperature dependence of the deuteron relaxation was observed in three samples containing CD3OH (200% and 100% loading) and CD3OD (200%) in NaX zeolite and analyzed by the described method between 20 K and 170 K. The obtained parameters, equal for all the three samples, characterize the methyl and hydroxyl mobilities of the methanol molecules at two different locations. (C) 2012 Elsevier Inc. All rights reserved

Catalytic performance of commercial Cu-ZSM-5 zeolite modified by desilication in NH3-SCR and NH3-SCO processes

[EN] In the presented manuscript an influence of the mesoporosity generation in commercial ZSM-5 zeolite on its catalytic performance in two environmental processes, such as NO reduction with ammonia (NH3SCR, Selective Catalytic Reduction of NO with NH3) and NH3 oxidation (NH3-SCO, Selective Catalytic Oxidation of NH3) was examined. Micro-mesoporous catalysts with the properties of ZSM-5 zeolite were obtained by desilication with NaOH and NaOH/TPAOH (tetrapropylammonium hydroxide) mixture with different ratios (TPA+/OH- = 0.2, 0.4, 0.6, 0.8 and infinity) and for different durations (1, 2, 4 and 6 h). The results of the catalytic studies (over the Cu-exchanged samples) showed higher activity of this novel mesostructured group of zeolitic materials. Enhanced catalytic performance was related to the generated mesoporosity (improved Hierarchy Factor (HF) of the samples), that was observed especially with the use of Pore Directing Agent (PDA) additive, TPAOH. Applied desilication conditions did not influence significantly the crystallinity of the samples (X-ray diffraction analysis (XRD)), despite the treatment for 6 h in NaOH solution, which was found to be too severe to preserve the zeolitic properties of the samples. The modified porous structure and accessibility of acid sites (increased surface acidity determined by temperature programmed desorption of ammonia (NH3-TPD)) influenced the red-ox properties of copper species introduced by ion-exchange method (temperature programmed reduction with hydrogen (H-2-TPR). Increased acidity of the micro-mesoporous samples, as well as the content of easily reducible copper species resulted in a significant improvement of Cu-ZSM-5 catalytic efficiency in the NH3-SCR and NH3-SCO processes. (C) 2017 Elsevier Inc. All rights reserved.This work was supported by the National Science Center under grant no. 2011/03/N/ST5/04820. Part of the research was carried out with the equipment purchased thanks to the financial support of the European Regional Development Fund in the framework of the Polish Innovation Economy Operational Program (contract no. POIG.02.01.00-12-023/08). U. D. acknowledges to Spanish Government by the funding (MAT2014-52085-C2-1-P).Rutkowska, M.; Pacia, I.; Basag, S.; Kowalczyk, A.; Piwowarska, Z.; Duda, M.; Tarach, K.... (2017). Catalytic performance of commercial Cu-ZSM-5 zeolite modified by desilication in NH3-SCR and NH3-SCO processes. Microporous and Mesoporous Materials. 246:193-206. https://doi.org/10.1016/j.micromeso.2017.03.017S19320624

Translational and rotational mobility of methanol-d(4) molecules in NaX and NaY zeolite cages: A deuteron NMR investigation

Nuclear magnetic resonance (NMR) provides means to investigate molecular dynamics at every state of matter. Features characteristic for the gas phase, liquid-like layers and immobilized methanol-d(4) molecules in NaX and NaY zeolites were observed in the temperature range from 300 K down to 20 K. The NMR spectra at low temperature are consistent with the model in which molecules are bonded at two positions: horizontal (methanol oxygen bonded to sodium cation) and vertical (hydrogen bonding of hydroxyl deuteron to zeolite framework oxygen). Narrow lines were observed at high temperature indicating an isotropic reorientation of a fraction of molecules. Deuteron spin-lattice relaxation gives evidence for the formation of trimers, based on observation of different relaxation rates for methyl and hydroxyl deuterons undergoing isotropic reorientation. Internal rotation of methyl groups and fixed positions of hydrogen bonded hydroxyl deuterons in methyl trimers provide relaxation rates observed experimentally. A change in the slope of the temperature dependence of both relaxation rates indicates a transition from the relaxation dominated by translational motion to prevailing contribution of reorientation. Trimers undergoing isotropic reorientation disintegrate and separate molecules become localized on adsorption centers at 166.7 K and 153.8 K for NaX and NaY, respectively, as indicated by extreme broadening of deuteron NMR spectra. Molecules at vertical position remain localized up to high temperatures. That indicates the dominating role of the hydrogen bonding. Mobility of single molecules was observed for lower loading (86 molecules/uc) in NaX. A direct transition from translation to localization was observed at 190 K. (C) 2012 Elsevier Inc. All rights reserved

Copper sites in zeolites- quantitative IR studies

[EN] Quantitative IR studies were realized in order to determine the concentration of various kinds of Cu sites in zeolites CuZSM-5, CulTQ-2, CuTNU-9, and CuY. These zeolites contained Cu in the form of Cu2+, Cu+ (in the form of exchange cations Cu-ex(+). and oxo-form Cu-ox(+)) and metallic Cu (in reduced samples). The experimental conditions in which known amounts of CO (used as probe molecule) reacted with each kind of Cu sites in CuZSM-5 were elaborated and subsequently the extinction coefficients of IR band of CO in Cun+(CO) adducts were established. Following values of the extinction coefficients of monocarbonyl bands were obtained: 0.11 cm(2)/mu mol for Cu2+(CO), 1.30 cm(2)/mu mol for Cu-ex(+)(CO), 0.91 cm(2)/mu mol for Cu-ox(+)(CO), and 0.79 cm(2)/mu mol for Cu degrees(CO). The procedure elaborated for CuZSM-5 was also applied for other zeolites. Consequently, the concentrations of Cu2+, Cu+ both in exchange positions and oxo-forms, as well as of Cu were determined in CuZSM-5 treated at various conditions (reduced, oxidized and treated with H2O) as well as in zeolites CuZSM-5, CuITQ-2, CuTNU-9, and CuY. (C) 2012 Elsevier Inc. All rights reserved.This research project was supported by Grant NO. 2011/01/B/ST5/00915 from the National Science Centre, Poland. A.E. Palomares thanks the Spanish Government (projects MAT2009-14528-C02-01, and CONSOLIDER INGENIO 2010) for financial support.Gora-Marek, K.; Palomares Gimeno, AE.; Glanowska, A.; Sadowska, K.; Datka, J. (2012). Copper sites in zeolites- quantitative IR studies. Microporous and Mesoporous Materials. 162:175-180. https://doi.org/10.1016/j.micromeso.2012.06.029S17518016

Multiscale exploration of hydrocarbon adsorption and hopping through ZSM-5 channels - From Monte Carlo modelling to experiment

In this article the results of statistical MC modelling corroborated by the FT-IR spectroscopy and gravimetric adsorption studies of low aliphatic hydrocarbons in ZSM-5 (Si/Al = 28 or silicalite) are presented. The extension of the existing Dubbeldam's forcefield towards inclusion of the finite aluminium-containing zeolites is proposed and its applicability is verified experimentally for the sorption of linear and branched hydrocarbons. The FT-IR spectroscopy applicability to follow the kinetics of small hydrocarbon adsorption has been successfully verified by the application of the Crank solution for diffusion to spectroscopy derived results.The present study was funded by the National Science Centre of Poland (grant 2016/23/B/ST4/00088). We acknowledge the Spanish Ministry of Sciences, Innovation and Universities (MCIU) and State Research Agency (AEI) for their funding via projects Program Severo Ochoa SEV-2016-0683 and RTI2018-101033-B-I00

Recovering waste plastics using shape-selective nano-scale reactors as catalysts

Waste plastic composed of low-density polyethylene can be converted into a potential new fuel source. This research describes a new nano-scale catalyst with well-defined and uniform surface openings. This material, called Al-SBA-15, is shape-selective, so it uses only one step to generate a gasoline-type product that requires less additional processing compared to that produced by previous catalysts.This work was supported by the Netherlands Organization for Scientific Research (NWO), under the Vidi grant no. 10284, carried out at the ITM-FWN, Groningen University. We acknowledge the support of the industrial steering committee (Shell, DSM, Norit-Cabot Nederland) and R. Winkler (Dutch Technology Foundation). Special thanks go to M. Rigutto (Shell) for his cooperation. We acknowledge E. Polushkin (Polymer Chemistry and Bioengineering, Zernike Institute for Advanced Materials, University of Groningen) for his technical assistance and the NWO for the financial support for project no. 700.58.103 (Small Angle X-ray Facility). M.R.R. acknowledges the US Department of Energy Office of Science (Basic Energy Sciences) for research funding and the National Energy Research Scientific Computing Center (NERSC), a US Department of Energy Office of Science User Facility operated under Contract No. DE-AC02-05CH11231 for access to supercomputing facilities. K.G-M and K.T. acknowledge the National Science Centre, Poland (grant no. 2015/18/E/ST4/00191). We also thank M. Hadfield (Analytix) for his assistance. D. Wiersma and B. Feringa (Groningen University) are thanked for support in setting a TGA apparatus. M. Makkee and his team (TU-Delft) are thanked for support, and guidance, in setting advanced infrastructure for heterogeneous catalysis research at Groningen University, by endorsing a capital STW research grant

Zeolite-driven Ag species during redox treatments and catalytic implications for SCO of NH3

Supported silver species are among the most promising catalysts for the depletion of ammonia emission by selective catalytic oxidation (NH-SCO). Here, an investigation on the influence of small pore CHA and RHO zeolite structures on the silver species formed and their catalytic activity for the NH-SCO reaction has been conducted. To this end, AgRHO(4) and AgCHA(4) zeolites with similar Si/Al molar ratios (≈ 4) and silver content (∼15 wt%, Ag/Al ≈ 0.6), and AgCHA(2) with Si/Al ≈ 2 and higher silver loading, while maintaining the Ag/Al ratio (∼26 wt%, Ag/Al ≈ 0.6), have been submitted to different treatments and characterized by using a large variety of techniques (XRD, UV-Vis,Ag NMR,in situXAS andoperandoFT-IR). The reduction of the AgCHA and AgRHO zeolites at low temperature (100-200 °C) produces silver clusters, which remain in the AgRHO zeolite when the temperature is increased to 400 °C. However, the silver species in the AgCHA zeolites evolve to nanoparticles (NPs) at 400 °C under H. The catalytic tests show that metal particles are the active sites while silver clusters are inactive for the NH-SCO reaction. Also, there are important differences in the stability of the reduced Ag species under oxidizing or under reaction conditions at 400 °C. Metal NPs are partially redispersed and oxidized to (Ag), while silver clusters are completely oxidized to Ag. Our results indicate that silver clusters are stabilized in the RHO-type and not in the CHA-type zeolite, and thus they display very different catalytic activities for the NH-SCO reaction.The authors acknowledge grant RTI2018-101784-B-I00 funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”. Also, the project SEV-2016-0683 funded by MCIN/AEI/10.13039/501100011033 is acknowledged. The project Prometeo/2021/077, Conselleria de Educación, Cultura y Deporte de la Generalitat Valenciana is also acknowledged. K. G.-M. acknowledges Grant No. 2015/18/E/ST4/00191 from the National Science Centre, Poland. K. T. acknowledges the scholarship within the Bekker Programme (PPN/BEK/2018/1/00406) from the Polish National Agency for Academic Exchange. C. W. Lopes (Science without Frontiers – Process no. 13191/13-6) thanks Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES – Finance Code 001) for the predoctoral fellowship. J. Martínez-Ortigosa (SEV-2012-0267-02) acknowledges the Severo Ochoa Program for a predoctoral fellowship. We gratefully acknowledge the ALBA synchrotron for allocating beamtime (proposals 2016021665 and 2017032119), CLÆSS beamline staff, and particularly Carlo Marini for their help and technical support during our experimen

Gene expression profiling reveals potential prognostic biomarkers associated with the progression of heart failure

Abstract BACKGROUND: Heart failure (HF) is the most common cause of morbidity and mortality in developed countries. Here, we identify biologically relevant transcripts that are significantly altered in the early phase of myocardial infarction and are associated with the development of post-myocardial infarction HF. METHODS: We collected peripheral blood samples from patients with ST-segment elevation myocardial infarction (STEMI): n = 111 and n = 41 patients from the study and validation groups, respectively. Control groups comprised patients with a stable coronary artery disease and without a history of myocardial infarction. Based on plasma NT-proBNP level and left ventricular ejection fraction parameters the STEMI patients were divided into HF and non-HF groups. Microarrays were used to analyze mRNA levels in peripheral blood mononuclear cells (PBMCs) isolated from the study group at four time points and control group. Microarray results were validated by RT-qPCR using whole blood RNA from the validation group. RESULTS: Samples from the first three time points (admission, discharge, and 1 month after AMI) were compared with the samples from the same patients collected 6 months after AMI (stable phase) and with the control group. The greatest differences in transcriptional profiles were observed on admission and they gradually stabilized during the follow-up. We have also identified a set of genes the expression of which on the first day of STEMI differed significantly between patients who developed HF after 6 months of observation and those who did not. RNASE1, FMN1, and JDP2 were selected for further analysis and their early up-regulation was confirmed in HF patients from both the study and validation groups. Significant correlations were found between expression levels of these biomarkers and clinical parameters. The receiver operating characteristic (ROC) curves indicated a good prognostic value of the genes chosen. CONCLUSIONS: This study demonstrates an altered gene expression profile in PBMCs during acute myocardial infarction and through the follow-up. The identified gene expression changes at the early phase of STEMI that differentiated the patients who developed HF from those who did not could serve as a convenient tool contributing to the prognosis of heart failure