Adsorption of acetic acid and methanol on H-Beta zeolite: An experimental and theoretical study

Gomes, Gláucio José; Zalazar, María Fernanda; Lindino, Cléber Antônio; Scremin, Fernando Reinoldo; Bittencourt, Paulo Rodrigo Stival; Costa, Marcelo; Peruchena, Nélida María

doi:10.1016/j.micromeso.2017.06.008

Cited by 43 publications

(37 citation statements)

References 73 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The first process commences above 63 °C and extends to 253 °C with a maximum at 180 °C, and is related to the desorption of physically adsorbed AcOH molecules on silanol groups and BAS by hydrogen bonding interactions. This is in line with previous results for desorption of AcOH on H‐β . The desorbed gases of the surface (Fig.…”

Section: Identification Of Adsorbed Species By Thermal Analysissupporting

confidence: 93%

“…The first one related to physisorbed MeOH on the H‐ZSM‐5 (between 50–206 °C). Second process occurs between 206 °C and 275 °C, and it refers to a chemical adsorption and, hence, methanol dehydration followed by thermal degradation of the chemisorbed methanol, other authors using MFI zeolite proposed that during the desorption/reaction process (between 127–177 °C) most of the protonated MeOH is desorbed without reacting, however over 227 °C the increase in hydrocarbon formation could indicate the beginning of the autocatalytic step in the MeOH conversion, results similar to those found for H‐β …”

Section: Identification Of Adsorbed Species By Thermal Analysissupporting

confidence: 69%

“…These results were attributed to the formation of a strongly adsorbed species on the acidic surface, characterizing the presence of organic intermediates as chemisorbed methoxide formed during the reaction, and gradually at higher temperatures the mass loss caused by the thermal degradation (combustion) of the formed products. The same process was observed in H‐β but at 270 °C, showing that the AcOH adsorption in H‐ZSM‐5 was weaker probably due the ratio of the active sites by mass (m 2 g − 1 ).…”

Section: Identification Of Adsorbed Species By Thermal Analysissupporting

confidence: 66%

“…Previous studies for H‐β under the same TGA‐IR conditions showed different results when compared to H‐ZSM‐5, we consider that the deposition of carbon related to the adsorption of AcOH at high temperatures is intrinsically linked with the strength of the active sites and the mass transfer (pore diameter of H‐β vs H‐ZSM‐5) of the products formed inside the channels, contributing for the greater formation of coke. Mass loss curves (TGA‐dTG, Figure ) report during sample heating (AcOH and MeOH) at 650 °C, that the adsorption of AcOH over H‐ZSM‐5 is similar in H‐β, but is clearly observed by EGA the presence of CO at high temperatures which indicates a strong adsorption of organic molecules inside the pores of H‐ZSM‐5.…”

Section: Identification Of Adsorbed Species By Thermal Analysismentioning

confidence: 81%

“…by using kinetic measurements, postulated that a surface acetic acid/ethanol complex is involved in the rate‐determining reaction step of esterification reactions on H‐zeolites . Thus, in order to obtain more information about the mechanism, in our previous work, we discussed and studied the adsorption of AcOH and MeOH on H‐β as a model of reaction of the initial step of the esterification reaction . Results showed that the adsorption of acetic acid by the carbonyl group is more favorable when compared to the adsorption of methanol in a single reaction step in a three‐dimensional structure, additionally we proposed a revised mechanism involving the acetic acid/methanol adsorbed complex.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Molecular‐level Understanding of the Rate‐determining Step in Esterification Reactions Catalyzed by H‐ZSM‐5 Zeolite. An Experimental and Theoretical Study

et al. 2019

Self Cite

View full text Add to dashboard Cite

Transformation of biomass into renewable energy products is currently one of the most promising technologies for dropping dependence on fossil fuels. Biodiesel production may improve with the use of heterogeneous catalysts, such as zeolites. In this work, computational calculations in conjunction with thermal analysis (TGA), evolved gases analysis (EGA) and IR spectroscopic studies were used in order to obtain a more detailed information on the adsorption mechanism involved in the rate-determining step of esterification reactions inside the H-ZSM-5 zeolite. ATR-FTIR spectra showed a molecular adsorption of MeOH and acetic acid (AcOH) on the H-ZSM-5 surface, IR spectrum of AcOH showed perturbations in the region of the bands relative to the carbonyl group C=O, indicating molecular interactions by the adsorption processes, as predicted by theoretical calculations. Adsorption of a single molecule of AcOH by C=O in a single adsorption step followed by coadsorption of MeOH is more stable than adsorption involving the zeolite proton sharing, however energies values suggested competitiveness between both mechanisms. Interactions between the adsorbed molecules and the lattice structure are crucial in controlling the adsorption observed experimentally.

show abstract

Section: Identification Of Adsorbed Species By Thermal Analysissupporting

confidence: 93%

Section: Identification Of Adsorbed Species By Thermal Analysissupporting

confidence: 69%

Section: Identification Of Adsorbed Species By Thermal Analysissupporting

confidence: 66%

Section: Identification Of Adsorbed Species By Thermal Analysismentioning

confidence: 81%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Molecular‐level Understanding of the Rate‐determining Step in Esterification Reactions Catalyzed by H‐ZSM‐5 Zeolite. An Experimental and Theoretical Study

et al. 2019

Self Cite

View full text Add to dashboard Cite

show abstract

Revealing the Mechanism of Ketonization of Acetic Acid on HBEA Zeolite via Metadynamics Simulations

Liu,

Zhao,

Liu

et al. 2024

ChemCatChem

View full text Add to dashboard Cite

Ketonization of biomass‐derived carboxylic acids offers a promising approach to remove oxygen and upgrade into valuable chemicals. However, the mechanism on Brønsted acid site (BAS) confined in micropores of zeolite remains elusive, due to the difficulty to observe the reaction intermediates experimentally and to locate the transition state via static density functional theory (DFT) calculations. Herein, ketonization of acetic acid on HBEA at 673 K was studied by metadynamics simulations based on DFT. The first reaction step was the concerted protonation and dehydroxylation of acetic acid, resulting in an electrophilic acylium cation and H2O (ΔG‡ = 1.53 eV). The subsequent likely steps, including C‐C coupling through the nucleophilic attack of acetic acid (path I), ketene (path II), and 1,1‐dihydroxyethene and (path III) toward acylium cation were tracked and compared. The high barriers for formation of more nucleophilic intermediates of ketene and 1,1‐dihydroxyethene made the overall path II and III less favorable than the direct coupling between acetic acid and acylium cation (path I, ΔG‡ = 2.15 eV). These results indicate that acylium cation is a key intermediate, and the C‐C coupling between acetic acid and acylium cation via nucleophilic attach is the most favorable path on BAS confined in zeolite.

show abstract

Acidity of Isomorphic Substituted Zeolites with B, Al and Ga Revisited

Petelski,

Peruchena,

Zalazar

2024

ChemPhysChem

View full text Add to dashboard Cite

Isomorphic substitution of zeolites with B, Al and Ga is a widely used approach in catalysis. The experimentally reported trend of their acidities decreases in the order: Al > Ga > B. However, a consistent explanation is still lacking in the literature. To bring more understanding of this trend, density functional theory computations were conducted on several model systems. First, the acidity of small clusters with two (2T) and five (5T) tetrahedral sites was analyzed. These systems were then projected onto three large void structures: H‐[A]‐BEA (52T), H‐[A]‐FAU (84T) and H‐[A]‐MOR (112T) with A = B, Al, Ga. Our electron density and Interacting Quantum Atom analyses show that the acidity of Al zeolites originates from the much stronger O–Al bond, which is dominated by the electrostatic attraction. The bridging hydroxyl therefore donates more charge density to the metal, the proton becomes more positive and consequently more acidic. Ga zeolites are more acidic than B zeolites due to the greater covalent nature on the O–Ga bond. The resulting acidity, as seen by ammonia, depends on both the acidic oxygen and the charge distribution of the surrounding oxygens exerted by the substituents.

show abstract

Adsorption of acetic acid and methanol on H-Beta zeolite: An experimental and theoretical study

Cited by 43 publications

References 73 publications

Molecular‐level Understanding of the Rate‐determining Step in Esterification Reactions Catalyzed by H‐ZSM‐5 Zeolite. An Experimental and Theoretical Study

Molecular‐level Understanding of the Rate‐determining Step in Esterification Reactions Catalyzed by H‐ZSM‐5 Zeolite. An Experimental and Theoretical Study

Revealing the Mechanism of Ketonization of Acetic Acid on HBEA Zeolite via Metadynamics Simulations

Acidity of Isomorphic Substituted Zeolites with B, Al and Ga Revisited

Contact Info

Product

Resources

About