Catalysis on Porous Solids

Corma, Avelino; Martı́nez, Alejandro

doi:10.1002/9783527618286.ch38

Cited by 8 publications

(3 citation statements)

References 439 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Nanoporous materials (i.e., materials with pore sizes below 100 nm) are essential in applications such as catalysis or gas adsorption. − Especially carbon nanomaterials are in focus of electrochemical energy storage applications − and water treatment , due to their high electrical conductivity and chemical stability. Their performance in these fields is most often a function of their structural properties (e.g., the specific surface area (SSA), surface chemistry, pore size, pore volume (PV), pore geometry, and pore connectivity).…”

Section: Introductionmentioning

confidence: 99%

Advanced Structural Analysis of Nanoporous Materials by Thermal Response Measurements

et al. 2015

View full text Add to dashboard Cite

Thermal response measurements based on optical adsorption calorimetry are presented as a versatile tool for the time-saving and profound characterization of the pore structure of porous carbon-based materials. This technique measures the time-resolved temperature change of an adsorbent during adsorption of a test gas. Six carbide and carbon materials with well-defined nanopore architecture including micro- and/or mesopores are characterized by thermal response measurements based on n-butane and carbon dioxide as the test gases. With this tool, the pore systems of the model materials can be clearly distinguished and accurately analyzed. The obtained calorimetric data are correlated with the adsorption/desorption isotherms of the materials. The pore structures can be estimated from a single experiment due to different adsorption enthalpies/temperature increases in micro- and mesopores. Adsorption/desorption cycling of n-butane at 298 K/1 bar with increasing desorption time allows to determine the pore structure of the materials in more detail due to different equilibration times. Adsorption of the organic test gas at selected relative pressures reveals specific contributions of particular pore systems to the increase of the temperature of the samples and different adsorption mechanisms. The use of carbon dioxide as the test gas at 298 K/1 bar provides detailed insights into the ultramicropore structure of the materials because under these conditions the adsorption of this test gas is very sensitive to the presence of pores smaller than 0.7 nm.

show abstract

Section: Introductionmentioning

confidence: 99%

Advanced Structural Analysis of Nanoporous Materials by Thermal Response Measurements

et al. 2015

View full text Add to dashboard Cite

show abstract

“…The demand for producing highly valued and marketable products from readily available crude oil products has necessitated the development of high-performance catalysts with better conversion and selectivity [1][2][3].…”

Section: Introductionmentioning

confidence: 99%

Effect of ZSM-5 Particle Size and Framework Silica-to-Alumina Ratio on Hexane Aromatization

Al-Eid¹,

Alnaimi²,

Alqarawi³

et al. 2022

Catal Res

View full text Add to dashboard Cite

Parent ZSM-5 and Ga-modified ZSM-5 catalysts with different Si/Al ratios and particle sizes were prepared. The physicochemical properties of the prepared catalysts were investigated by performing X-ray powder diffraction analysis, BET surface area analysis, and NH3-TPD analysis. The performance of the aromatization reaction of the prepared catalysts was evaluated with 1-hexane as a model compound. The zeolite catalysts with a low SiO2/Al2O3 ratio possessed better activity than those with a high SiO2/Al2O3 ratio. Ga modification significantly improved the catalyst aromatization selectivity. Through aromatization, the acid sites of Ga-modified nano-sized zeolites promoted the selective conversion of produced olefin to aromatics by removing H-atoms. For the parent ZSM-5 and Ga-modified catalysts, the catalyst stability increased with an increase in the SiO2/Al2O3 molar ratio. The nano-sized ZSM-5 catalyst with a high SiO2/Al2O3 ratio exhibited better catalytic stability than the microscale ZSM-5, and the nano-sized catalyst with a low SiO2/Al2O3 ratio showed very low stability.

show abstract

“…Examples that are suitable for hydrocracking, reforming, and naphthenic ring opening include zeolite Faujasite and Beta. In hydrocracking, larger feed molecules, for example, multialkylated ring structures or polynuclear aromatic or naphthenic molecules, are excluded by size from entering the micropores and are consequently forced to react on the external surface of the zeolite and binder. , Smaller reaction products formed in these primary reactions are further converted by cracking, dealkylation, and ring-opening inside the zeolite micropores . The proper functioning of hydrocracking catalysts requires an optimal distribution of Brønsted acid sites between the external and internal zeolites surfaces…”

Section: Introductionmentioning

confidence: 99%

Probing External Brønsted Acid Sites in Large Pore Zeolites with Infrared Spectroscopy of Adsorbed 2,4,6-Tri-tert-butylpyridine

et al. 2021

View full text Add to dashboard Cite

The current work describes the development of a semiquantitative test to measure the density of Brønsted acid sites on the external surface of large pore zeolites. The method uses 2,4,6-tri-tert-butylpyridine (TTBP) as a probe molecule, which is protonated by Brønsted acid sites to form a TTBPH + ion. The N− H stretching vibration of the TTBPH + ion is detected by infrared (IR) spectroscopy. The TTBP molecule is excluded by size from entering the micropores of 12-membered ring zeolites and interacts only with the external surface of the zeolites. The IR-TTBP test is relevant for the optimization and better understanding of zeolite-based catalysts for applications such as hydrocracking, transalkylation, reforming, or ring-opening that use large pore zeolites and where external Brønsted acidity plays a role in catalyst activity and selectivity. The method was applied to zeolites Faujasite (FAU) and Beta (BEA) as well as to silica and alumina, which are relevant components in bound zeolite formulations. Unlike pyridine, TTBP does not interact with Lewis acid sites. A correlation was found between the amount of TTBPH + ions formed over the external Brønsted acid sites of zeolite FAU and Beta with various Si/Al ratios and the expected density of external Brønsted acid sites. The latter was determined from the total Brønsted acidity measured by IR-pyridine and the fraction of external to total surface area measured by N 2 physisorption. The use of triisobutylamine (TIBA) and perfluorotributylamine (PFTBA) to measure external Brønsted acidity in zeolite ZSM-5 and Faujasite was explored. These attempts were unsuccessful because of the decomposition of TIBA and the lack of a clear marker for protonated PFTBA.

show abstract

Catalysis on Porous Solids

Cited by 8 publications

References 439 publications

Advanced Structural Analysis of Nanoporous Materials by Thermal Response Measurements

Advanced Structural Analysis of Nanoporous Materials by Thermal Response Measurements

Effect of ZSM-5 Particle Size and Framework Silica-to-Alumina Ratio on Hexane Aromatization

Probing External Brønsted Acid Sites in Large Pore Zeolites with Infrared Spectroscopy of Adsorbed 2,4,6-Tri-tert-butylpyridine

Contact Info

Product

Resources

About