Surface Area and Porosity

Neimark, Alexander V.; Sing, K. S. W.; Thommes, Matthias

doi:10.1002/9783527610044.hetcat0037

Cited by 147 publications

(36 citation statements)

References 95 publications

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“…[14,15] In all cases, the contribution of external surface area to the total porosity of the materials is obviously very small and will thus be neglected. The physicochemical parameters derived from nitrogen physisorption for the parent SBA-15 and the differently functionalized materials are grouped in Table 1.…”

Section: Resultsmentioning

confidence: 99%

“…Cumulative pore volumes and pore size distributions were determined by using non-local density functional (NLDFT) methods considering sorption of nitrogen at -196 °C in cylindrical silica pores. [14][15][16][17][18]25] Both the kernel of equilibrium NLDFT isotherms (desorption branch) and the kernel of (metastable) NLDFT adsorption isotherms (adsorption branch) were applied for pore width determination. [25,26] For comparison, the pore size distributions were also calculated by analyzing the adsorption branch of the isotherm using the Barret-Joyner-Halenda (BJH) method.…”

Section: Incorporation Of the Grubbs I Catalystmentioning

confidence: 99%

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Substantiating the Influence of Pore Surface Functionalities on the Stability of Grubbs Catalyst in Mesoporous SBA‐15 Silica

Staub

Guillet‐Nicolas

Even

et al. 2011

Chemistry A European J

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The influence of pore surface functionalities in mesoporous SBA‐15 silica on the stability of a model olefin metathesis catalyst, namely Grubbs I, is substantiated. In particular, it is demonstrated that the nature of the interaction between the ruthenium complex and the surface is strongly depending on the presence of surface silanols. For this study, differently functionalized mesoporous SBA‐15 silica materials were synthesized according to standard procedures and, subsequently, the Grubbs I catalyst was incorporated into these different host materials. All of the materials were thoroughly characterized by elemental analyses, nitrogen physisorption at −196 °C, thermogravimetric analyses, solid‐state NMR spectroscopy, and infrared spectroscopy (ATR‐IR). By such in‐depth characterization of the materials, it became possible to achieve models for the surface/catalyst interactions as a function of surface functionalities in SBA‐15; for example, in the case of purely siliceous silanol‐rich SBA‐15, octenyl‐silane modified SBA‐15, and silylated equivalents. It was evidenced that large portions of the chemisorbed species that are detected spectroscopically arise from interactions between the tricyclohexylphosphine and the surface silanols. A catalytic study using diethyldiallylmalonate in presence of the various functionalized silicas shows that the presence of surface silanols significantly decreases the longevity of the ring‐closing metathesis catalyst, whereas the passivation of the surface by trimethylsilyl groups slows down the catalysis rate, but does not affect significantly the lifetime of the catalyst. This contribution thus provides new insights into the functionalization of SBA‐15 materials and the role of surface interactions for the grafting of organometallic complexes.

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Section: Resultsmentioning

confidence: 99%

Section: Incorporation Of the Grubbs I Catalystmentioning

confidence: 99%

Substantiating the Influence of Pore Surface Functionalities on the Stability of Grubbs Catalyst in Mesoporous SBA‐15 Silica

Staub

Guillet‐Nicolas

Even

et al. 2011

Chemistry A European J

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show abstract

“…It is important to realize that the numerical values of a given kernel depend on a number of factors, such as the assumed geometrical pore model, values of the gas-gas and gassolid interaction parameters, and other model assumptions. The calculation of pore size distribution is based on a solution of the Integral Adsorption Equation (IAE), which correlates the kernel of theoretical adsorption/desorption isotherms with the experimental sorption isotherm (for details see [21,23,31]). Comparing the calculated NLDFT (fitting) isotherm with the experimental sorption isotherm allows to check the validity of the calculation.…”

Section: Pore Size Analysismentioning

confidence: 99%

“…It has been demonstrated that the application of these novel theoretical and molecular simulation based methods leads to: (i) a much more accurate pore size analysis An important new emerging class of solid state materials are metal-organic framework materials. [31,32,23], and (ii) allows performing pore size analysis over the complete micro/mesopore size range [e.g., 9,21,22,32]. Appropriate methods for pore size analysis based on NLDFT and molecular simulation are meanwhile commercially available for many important adsorptive/adsorbent systems.…”

Section: Introductionmentioning

confidence: 99%

Physical Adsorption Characterization of Nanoporous Materials

Thommes¹

2010

Chemie Ingenieur Technik

1,251

557

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During recent years, major progress has been made in the understanding of the adsorption, pore condensation and hysteresis behavior of fluids in novel ordered nanoporous materials with well defined pore structure. This has led to major advances in the structural characterization by physical adsorption, also because of the development and availability of advanced theoretical procedures based on statistical mechanics (e.g., density functional theory, molecular simulation) which allows to describe adsorption and phase behavior of fluids in pores on a molecular level. Very recent improvements allow even to take into account surface geometrical in-homogeneity of the pore walls However, there are still many open questions concerning the structural characterization of more complex porous systems. Important aspects of the major underlying mechanisms associated with the adsorption, pore condensation and hysteresis behavior of fluids in micro-mesoporous materials are reviewed and their significance for advanced physical adsorption characterization is discussed.

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“…Furthermore, a uniform surface, no interaction between adsorbed species, monolayer adsorption and non-dissociative adsorption are assumed. In addition to the Langmuir isotherm, other approaches also exist [125].…”

Section: Kinetic Modelingmentioning

confidence: 99%

Kinetic Modeling of Catalytic Olefin Cracking and Methanol-to-Olefins (MTO) over Zeolites: A Review

Hinrichsen

2018

Catalysts

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The increasing demand for lower olefins requires new production routes besides steam cracking and fluid catalytic cracking (FCC). Furthermore, less energy consumption, more flexibility in feed and a higher influence on the product distribution are necessary. In this context, catalytic olefin cracking and methanol-to-olefins (MTO) gain in importance. Here, the undesired higher olefins can be catalytically converted and, for methanol, the possibility of a green synthesis route exists. Kinetic modeling of these processes is a helpful tool in understanding the reactivity and finding optimum operating points; however, it is also challenging because reaction networks for hydrocarbon interconversion are rather complex. This review analyzes different deterministic kinetic models published in the literature since 2000. After a presentation of the underlying chemistry and thermodynamics, the models are compared in terms of catalysts, reaction setups and operating conditions. Furthermore, the modeling methodology is shown; both lumped and microkinetic approaches can be found. Despite ZSM-5 being the most widely used catalyst for these processes, other catalysts such as SAPO-34, SAPO-18 and ZSM-23 are also discussed here. Finally, some general as well as reaction-specific recommendations for future work on modeling of complex reaction networks are given.

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Surface Area and Porosity

Abstract: The sections in this article are Introduction Physisorption of Gases Determination of Surface Area A The BET Method B The Standard Isotherm Concept Assessm… Show more

Cited by 147 publications

References 95 publications

Substantiating the Influence of Pore Surface Functionalities on the Stability of Grubbs Catalyst in Mesoporous SBA‐15 Silica

Substantiating the Influence of Pore Surface Functionalities on the Stability of Grubbs Catalyst in Mesoporous SBA‐15 Silica

Physical Adsorption Characterization of Nanoporous Materials

Kinetic Modeling of Catalytic Olefin Cracking and Methanol-to-Olefins (MTO) over Zeolites: A Review

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