Experimental microkinetic approach of the CO/H2 reaction on Pt/Al2O3 using the Temkin formalism. 1. Competitive chemisorption between adsorbed CO and hydrogen species in the absence of reaction

Couble, Julien; Bianchi, Daniel

doi:10.1016/j.jcat.2017.05.015

Cited by 22 publications

(37 citation statements)

References 70 publications

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“…The Temkin equation is an empirical equation, which is based on the homogeneity of adsorption heat on the surface of the adsorbent 61 – 63 . The Temkin equation assumes the adsorption heat decreases linearly when the adsorption coverage increases 64 – 66 , and the binding energy is evenly distributed around the place before reaching the saturated adsorption (the maximum binding energy), which is suitable for the multi-molecular layer adsorption process on the inhomogeneous surface 62 , 67 . Among the three models, the R 2 of Temkin model is the largest, so the adsorption result is the most similar to Temkin model.…”

Section: Resultsmentioning

confidence: 99%

Study on the adsorption properties of methyl orange by natural one-dimensional nano-mineral materials with different structures

et al. 2021

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Methyl orange (MO) is a common anionic azo dye that is harmful to the environment and biology, so it must be treated innocuously before it can be discharged. Adsorption is an effective method to remove anionic dyes. Nanotube mineral is a natural one-dimensional adsorption material, and its unique morphology and structure endow it with good adsorption capacity. Although there are many related studies, there is a lack of in-depth discussions on the influence of nanotube’s composition and structure on the adsorption of dyes and other pollutants. In this paper, two kinds of natural one-dimensional silicate minerals [halloysite nanotubes (HNTs) and chrysotile nanotubes (ChNTs)] with similar morphology but slightly different compositions and crystal structures were used as adsorbents, and MO solution was used as simulate pollutants. It is the first time to discuss in depth the influence of the composition and structure of nanotube minerals on their charge properties and the adsorption performance of methyl orange dyes. It is found that HNTs and ChNTs have different adsorption capacity due to the difference of electronegativity between Al3+ and Mg2+ in the crystal, so they possess negative and positive charges respectively in near-neutral solution, which leads to the adsorption capacity of MO by ChNTs with positive charges which is greater than that of HNTs.

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Section: Resultsmentioning

confidence: 99%

Study on the adsorption properties of methyl orange by natural one-dimensional nano-mineral materials with different structures

et al. 2021

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“…Particularly, the method provides experimental data on the change in the coverages of the different adsorbed species due to the coadsorption. These data can be modeled using theoretical coverages obtained from the Temkin formalism for competitive chemisorption without [15] and with [16] transformation of the reactants which is a key step of the EMA of a catalytic reaction such as for CO/H 2 on Pt/Al 2 O 3 [15,16].…”

Section: Application Of the Aeir Methods To Different Topics Relevant mentioning

confidence: 99%

“…It is a fact that the Langmuir model (Equation 2) is rarely representative of experimental data for strongly adsorbed species on conventional catalysts due to the heterogeneity of the adsorption sites/adsorbed species. However, its extension to heterogeneous surfaces, via the integral approach and the distribution functions [15,16] and referenced therein, provides different equations for others adsorption models. For instance assuming a linear decrease in the heat of adsorption of an adsorbed species with the increase in its coverage, the integral approach leads to the generalized Temkin equation model [66] for non dissociative adsorption:…”

Section: Exploitation Of the Experimental Curves θX Ex = F(t A P A mentioning

confidence: 99%

“…However, among the surface elementary steps of a detailed mechanism, few of them control the global rate of the reaction: they constitute the kinetic model of the reaction [2,3]. This has led our group developing the experimental microkinetic approach (abbreviation EMA) of heterogeneous gas/solid catalytic reactions such as CO/O 2 [13,14] and CH 4 production from CO/H 2 [15,16] on Pt/Al 2 O 3 catalysts. The main point of the EMA is that considering a plausible kinetic model of a catalytic reaction (based either on literature data or a formal kinetic approach), all the kinetic parameters of interest are obtained by experimental procedures on the conventional dispersed solid catalyst.…”

Section: Introductionmentioning

confidence: 99%

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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

Bianchi

2018

Catalysts

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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.

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“…11: Transient response to successive gas switches 2% CO2/2% Ar /He → 2% CO2/1.8% H2O /2% Ar /He over 10%Ni-0.05%Rh/MgAl2O4 catalyst at 250°C. A deeper insight in the competitive adsorption between CO2 and H2O adsorbed species relevant to the DR and CDSR reactions was obtained using a competitive Temkin model [27,28] and the heats of adsorption calculated for CO2-B and for dissociatively adsorbed H2O-B species (present on the catalyst surface in the 600-800°C temperature range). Fig.…”

Section: Co2 and H2o Competitive Adsorptionmentioning

confidence: 99%

Study of CO2 and H2O adsorption competition in the combined dry / steam reforming of biogas

et al. 2021

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The combined dry-steam reforming (CDSR) of a model biogas (66% CH4 + 34% CO2) has been investigated under various feed compositions and reaction temperature conditions over a Ni-Rh/MgAl2O4 catalyst, with the objective to convert the excess of methane (compared to CO2) by steam reforming (SR). Methane, however, appeared to react preferentially with H2O rather than with CO2, leading to an inhibition of the dry reforming (DR) reaction in the presence of steam. CO2 and H2O adsorption and co-adsorption studies revealed that H2O was always adsorbed in much higher amounts than CO2 on the catalyst surface. A Temkin adsorption model applied to temperature-programmed adsorption experiments (TPAE) showed that two different strongly adsorbed CO2 and H2O species were present on the catalyst surface at moderate temperature, but only one of each remained adsorbed at temperatures relevant to the reaction conditions (600-800°C). H2O was also shown to displace CO2 from the catalyst surface, confirming that they compete, at least partially, for the same adsorption sites. At high temperature, the surface coverage by the most strongly adsorbed H2O species was predominant. These results should contribute to the development of efficient catalytic processes for biogas valorization to produce syngas and hydrogen from renewable sources.

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Experimental microkinetic approach of the CO/H2 reaction on Pt/Al2O3 using the Temkin formalism. 1. Competitive chemisorption between adsorbed CO and hydrogen species in the absence of reaction

Cited by 22 publications

References 70 publications

Study on the adsorption properties of methyl orange by natural one-dimensional nano-mineral materials with different structures

Study on the adsorption properties of methyl orange by natural one-dimensional nano-mineral materials with different structures

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

Study of CO2 and H2O adsorption competition in the combined dry / steam reforming of biogas

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