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Wang L.-C.,Harvard University | Friend C.M.,Harvard University | Fushimi R.,Saint Louis University | Fushimi R.,Langmuir Research Institute | And 2 more authors.
Faraday Discussions | Year: 2016

The activation of molecular O2 as well as the reactivity of adsorbed oxygen species is of central importance in aerobic selective oxidation chemistry on Au-based catalysts. Herein, we address the issue of O2 activation on unsupported nanoporous gold (npAu) catalysts by applying a transient pressure technique, a temporal analysis of products (TAP) reactor, to measure the saturation coverage of atomic oxygen, its collisional dissociation probability, the activation barrier for O2 dissociation, and the facility with which adsorbed O species activate methanol, the initial step in the catalytic cycle of esterification. The results from these experiments indicate that molecular O2 dissociation is associated with surface silver, that the density of reactive sites is quite low, that adsorbed oxygen atoms do not spill over from the sites of activation onto the surrounding surface, and that methanol reacts quite facilely with the adsorbed oxygen atoms. In addition, the O species from O2 dissociation exhibits reactivity for the selective oxidation of methanol but not for CO. The TAP experiments also revealed that the surface of the npAu catalyst is saturated with adsorbed O under steady state reaction conditions, at least for the pulse reaction. © 2016 The Royal Society of Chemistry. Source

Guild C.,University of Connecticut | Biswas S.,University of Connecticut | Meng Y.,University of Connecticut | Jafari T.,Institute of Materials Science | And 3 more authors.
Catalysis Today | Year: 2014

In the modern technological world, applications are rapidly demanding homogeneous, reproducible, scalable processes for films and catalytic surfaces. The uses of spray pyrolytic methods for fabricating these films have received attention since the late 1980s, and today spray pyrolysis finds use in a variety of applications, ranging from biomedical to industrial, microelectronics to ceramics. In this review, basic parameters of spray pyrolysis for catalytic and thin film formation are summarized, while recent developments in spray deposition for environmental remediation, photovoltaics, fuel cell and battery materials, biomedical applications, and microelectronics are also discussed. © 2014 Elsevier Ltd. All rights reserved. Source

Redekop E.A.,Ghent University | Yablonsky G.S.,Saint Louis University | Galvita V.V.,Ghent University | Constales D.,Ghent University | And 4 more authors.
Industrial and Engineering Chemistry Research | Year: 2013

We describe the novel concept of momentary equilibrium (ME), a special event during a pulse-response transient experiment in which the non-steady-state rates of adsorption and desorption of a probe molecule are instantaneously balanced. In the absence of other reactions, any system with reversible adsorption will always pass through ME during a pulse-response experiment with effusion. We also suggest a new method for measuring the concentration of adsorption sites on heterogeneous catalysts and the corresponding equilibrium constant by observing momentary equilibrium in thin-zone temporal analysis of products (TZTAP) pulse-response experiments with modulated pulse intensity. The suggested method employs reversible adsorption of probe molecules, contrary to traditional methods of counting adsorption sites which utilize irreversible reactions. © 2013 American Chemical Society. Source

Fushimi R.,Langmuir Research Institute | Gaffney A.M.,Langmuir Research Institute
Topics in Catalysis | Year: 2014

A new technology, ChemPren, is being developed for the catalytic conversion of mixed municipal waste plastic to valuable chemicals and fuel. ChemPren provides a sustainable, clean energy solution to society's challenge of addressing the 100+ million tons of waste plastic generated annually worldwide. Currently only 7 % is recycled, with the remaining 93+ million being discarded to landfills or burned without useful energy generation. © 2014 Springer Science+Business Media New York. Source

Gaffney A.M.,Langmuir Research Institute | Jones C.A.,Langmuir Research Institute | Fushimi R.,Langmuir Research Institute
ACS National Meeting Book of Abstracts | Year: 2011

A new technology, ChemPren, is being developed based upon the catalytic conversion of mixed, waste plastics from municipal waste sites to valuable chemicals and fuel. ChemPren provides a sustainable, clean energy solution to society's challenge of addressing the 100+ million tons of waste plastic generated in the world, annually. Currently only 7% is recycled, with the remaining 93+ million being discarded to landfills or burned without energy generation. Proof of concept studies have been completed in converting mixed plastic to basic chemicals and fuel. ChemPren technology involves the fluid bed cracking of mixed plastic with a modified ZSM-5 catalyst at about 1000 F. This paper will report on recently obtained intrinsic kinetic results using the Temporal Analysis of Products Reactor, the impact of catalyst modifiers and the role of hydrogen feed source additives. Source

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