Heats of Adsorption Using Temperature Programmed Adsorption Equilibrium:  Application to the Adsorption of CO on Cu/Al2O3and H2on Pt/Al2O3

Langmuir ◽  
2004 ◽  
Vol 20 (11) ◽  
pp. 4489-4497 ◽  
Author(s):  
Salim Derrouiche ◽  
Daniel Bianchi
Keyword(s):  
Adsorption Equilibrium ◽  
Heats Of Adsorption ◽  
Adsorption Of Co ◽  
Temperature Programmed

scholarly journals A Contribution to the Experimental Microkinetic Approach of Gas/Solid Heterogeneous Catalysis: Measurement of the Individual Heats of Adsorption of Coadsorbed Species by Using the AEIR Method

Catalysts ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 265 ◽  
Author(s):  
Daniel Bianchi
Keyword(s):  
Adsorption Equilibrium ◽  
Adsorption Models ◽  
Heats Of Adsorption ◽  
Elementary Steps ◽  
Mathematical Expressions ◽  
Adsorption Temperature ◽  
Adsorption Of Co ◽  
The Individual ◽  
Adsorption Desorption ◽  
Ir Bands

The two first surface elementary steps of a gas/solid catalytic reaction are the adsorption/desorption at least one of the reactants leading to its adsorption equilibrium which can be or not disturbed by the others surface elementary steps leading to the products. The variety of the sites of a conventional catalyst may lead to the formation of different coadsorbed species such as linear, bridged and threefold coordinated species for the adsorption of CO on supported metal particles. The aim of the present article is to summarize works performed in the last twenty years for the development and applications of an analytical method named Adsorption Equilibrium InfraRed spectroscopy (AEIR) for the measurement of the individual heats of adsorption of coadsorbed species and for the validation of mathematical expressions for their adsorption coefficients and adsorption models. The method uses the evolution of the IR bands characteristic of each of coadsorbed species during the increase in the adsorption temperature in isobaric conditions. The presentation shows that the versatility of AEIR leads to net advantages as compared to others conventional methods particularly in the context of the microkinetic approach of catalytic reactions.

scholarly journals CO oxidation over Pt-modified CuO catalysts in the presence of water vapour and SO2

2015 ◽  
Vol 18 (2) ◽  
pp. 187-196
Author(s):  
Tri Nguyen ◽  
Anh Cam Ha ◽  
Loc Cam Luu ◽  
Cuong Tien Hoang ◽  
Thi Thi Yen Trinh ◽  
...  
Keyword(s):  
Co Oxidation ◽  
Water Vapour ◽  
Co Adsorption ◽  
X Ray Diffraction ◽  
Active Centers ◽  
Highly Active ◽  
Transmission Electron ◽  
Physico Chemical ◽  
Adsorption Of Co ◽  
Temperature Programmed

The optimal Pt-modified CuO supported on γ-Al2O3 and γ-Al2O3 + CeO2 catalysts have been prepared. Physico-chemical characteristics of catalysts were investigated and determined by the methods of N2 adsorption (BET), X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), temperature-programmed reduction (TPR), and hydrogen pulse chemisorption (HPC). The characteristics of carbon monoxide (CO) adsorption on catalysts were defined by the method of infrared spectroscopy (IR) in the range of 4000 – 400 cm-1. The effect of the mixture of water vapour and SO2 on the activity of these catalysts for the CO oxidation was assessed. Reactions were conducted at 200oC and 350oC in the absence and presence of the mixture of water vapour (1.1 mol %) and SO2 (0.0625 mol %). Concentrations of O2 and CO in the gas mixture were 9.2 mol % and 0.5 mol %, respectively. The results showed that in the catalysts there exist highly active centers Cu1+ and Pt2+. On the catalysts the adsorption of CO on Cu2+, Pt2+, CeO2, and γ - Al2O3 centres was observed. Addition of CeO2 led to increase the reductivity, CO adsorption but decrease in specific surface area of catalyst. The result PtCu/CeAl catalyst shown higher active, but lower stability compared to PtCu/Al catalyst. The mixture of water vapour and SO2 showed the reversible poisoning toward the Pt-CuO catalysts at a temperature of 350oC, but irreversible at 200oC

Influence of Alumina Surface Structure on Growth and Adsorption Properties of Pd Particles

1998 ◽  
Vol 05 (01) ◽  
pp. 397-401 ◽  
Author(s):  
I. Stará ◽  
V. Gonzalez ◽  
I. Jungwirthová ◽  
K. Mašek ◽  
V. Matolín
Keyword(s):  
Surface Structure ◽  
Molecular Beam ◽  
Catalytic Properties ◽  
High Energy ◽  
Co Dissociation ◽  
Metal Support Interaction ◽  
Metal Support ◽  
Adsorption Of Co ◽  
Temperature Programmed ◽  
Supported Pd

The partial CO dissociation observed on small Pd particles deposited on γ-alumina and only molecular adsorption of CO on Pd/(0001) α-alumina model catalysts show that the surface structure of alumina can influence the reactivity of supported clusters. To understand the effect of metal–support interaction, Pd particles were deposited on alumina substrates of different surface structure [(0001), (1-102)]. The surface of alumina substrates was investigated by means of reflection high energy electron diffraction (BREED). The growth of Pd particles, their structure and orientation were observed by RHEED. In order to compare the catalytic properties of supported Pd particles, the study of CO and O adsorption was performed by temperature-programmed desorption (TPD) using molecular beam techniques.

TPD Study of Carbon Monoxide Interaction with Pd/Nb Bimetallic System

1994 ◽  
Vol 59 (8) ◽  
pp. 1709-1720 ◽  
Author(s):  
Tomas Jirsak ◽  
Vladimír Nikolajenko ◽  
Zlatko Knor
Keyword(s):  
Thin Films ◽  
Work Function ◽  
Room Temperature ◽  
Temperature Programmed Desorption ◽  
Foil Surface ◽  
Temperature State ◽  
Bimetallic System ◽  
Adsorption Of Co ◽  
Higher Temperature ◽  
Temperature Programmed

Chemisorption properties of thin films of Pd evaporated onto Nb recrystallized-foil surface have been studied by temperature-programmed desorption (TPD) and by measurement of the work function changes (WFC) at room temperature. TPD results indicate two states of CO adsorbed in dependence on the thickness of the palladium layer. The low temperature state (330 K) occurs at low Pd coverages (about one monolayer). Second state, occurring at slightly higher temperature (370 K), is attributed to bulk Pd. WFC data show negligible change of the work function after deposition of small amounts of Pd onto a clean Nb surface. With increasing amount of Pd, ∆ϕ rises and reaches a saturation value. Adsorption of CO onto Pd/Nb surface caused the work function increase at all coverages of Pd deposited.

Adsorption and Reaction on Thin Metal Overlayers

1986 ◽  
Vol 83 ◽  
Author(s):  
Paul J. Berlowitz ◽  
Charles H. F. Peden ◽  
D. Wayne Goodman
Keyword(s):  
Bimetallic Catalysts ◽  
Metallic Films ◽  
Kinetic Measurements ◽  
Unique Character ◽  
Cyclohexane Dehydrogenation ◽  
Adsorption Of Co ◽  
Dehydrogenation Reactions ◽  
Temperature Programmed ◽  
Metal Overlayers ◽  
Kinetics Of

ABSTRACTThese studies have addressed the adsorption of CO on very thin (submonolayer to multilayer) deposits of Cu, Ni, Pd, and Fe on single crystals of Ru and W. The kinetics of the methanation, ethane hydrogenolysis, and cyclohexane dehydrogenation reactions have also been measured over these model bimetallic catalysts. Temperature programmed desorption (TPD) spectra of CO at submonolayer coverages reveal new desorption features which have significantly perturbed peak maxima from those observed on the bulk metals, indicating the unique character of these monolayer metallic films. This behavior has been correlated with LEED, ARUPS, work function, and kinetic measurements.

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