Effect of acidity on ferric oxide nanoparticles supported on γ–χ–Al2O3 in the methanol dehydration reaction toward dimethyl ether

Armenta, M.A.; Maytorena, V.M.; Silva–Rodrigo, R.; Flores-Sanchez, L. A.; Quintana, Juan Manuel; Olivas, A.

doi:10.1016/j.fuel.2021.120618

Cited by 12 publications

(7 citation statements)

References 102 publications

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“…Obviously, the deconvolution Gaussian line shape of this profile accurately classified these acidic sites as two peaks of weak sites, one peak of medium sites, and a single peak of strong acidic sites (see Figure 7 b), as well as that peak of the physisorbed probe molecules of THF. Many published articles applied NH 3 ‐TPD technique[ 4 , 5 , 15 ] to classify the strength of the acidic sites, while others measured the IR‐spectra of pyridine[ 1 , 3 , 18 , 20 ] for the same purpose. Nothing was stated about quantitatively estimating the acidic sites with pyridine or using pyridine‐recorded DSC‐TPD profiles.…”

Section: Resultsmentioning

confidence: 99%

“…The above‐mentioned successful attempts,[ 1 , 2 , 3 , 4 , 5 , 6 , 7 ] which used different basic molecules, encourage us to investigate tetrahydrofuran (THF) as a probe molecule to determine acidic surface sites of our samples. Our research team has published numerous articles over the last two decades, including TPD studies of pyridine and NH 3 as probe molecules, as well as IR‐spectroscopy of pyridine[ 12 , 13 , 14 , 15 , 16 ] for the determination of the acidic sites of some catalysts.…”

Section: Introductionmentioning

confidence: 99%

“…The majority of the published articles employed the IR‐spectroscopic methods to characterise the surface acidity of solid catalysts such as: 12‐membered ring zeolites probed with 2,4,6‐tri‐ tert ‐butylpyridine, [1] TiO 2 ‐based solid catalysts by adsorption of NH 3 , [2] commercial samples of Faujasite‐type zeolite probed with six molecules as follows: pyridine, 2,6‐di‐ tert ‐butylpyridine, 2,4 dimethylquinoline, tributylamine, trihexylamine, and 2,4,6‐tri‐ tert ‐butylpyridine that with different basicities and critical diameters [3] . Others demonstrated the NH 3 ‐TPD (Temperature‐programmed desorption) profiles of Fe 2 O 3 nanoparticles supported on γ‐χ‐Al 2 O 3 , [4] and promoted Mg−Al mixed oxides with transition metals [5] . Gafurov et al [6] .…”

Section: Introductionmentioning

confidence: 99%

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Assessment of Lewis‐Acidic Surface Sites Using Tetrahydrofuran as a Suitable and Smart Probe Molecule

et al. 2022

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Measuring the Lewis‐acidic surface sites in catalysis is problematic when the material‘s surface area is very low (SBET ≤1 m2 ⋅ g−1). For the first time, a quantitative assessment of total acidic surface sites of very small surface area catalysts (MoO3 as pure and mixed with 5–30 % CdO (wt/wt), as well as CdO for comparison) was performed using a smart new probe molecule, tetrahydrofuran (THF). The results were nearly identical compared to using another commonly used probe molecule, pyridine. This audition is based on the limited values of the surface area of these samples that likely require a relatively moderate basic molecule as THF with pKb=16.08, rather than strong basic molecules such as NH3 (pKb=4.75) or pyridine (pKb=8.77). We propose mechanisms for the interaction of vapour phase molecules of THF with the Lewis‐cationic Mo and Cd atoms of these catalysts. Besides, dehydration of isopropyl alcohol was used as a probe reaction to investigate the catalytic activity of these catalysts to further support our findings in the case of THF in a temperature range of 175–300 °C. A good agreement between the obtained data of sample MoO3‐10 % CdO, which is characterised by the highest surface area value, the population of Lewis‐acidic sites and % selectivity of propylene at all the applied reaction temperatures was found.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Assessment of Lewis‐Acidic Surface Sites Using Tetrahydrofuran as a Suitable and Smart Probe Molecule

et al. 2022

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“…Other types of alumina, such as η-, γ–χ-Al 2 O 3 , or modifications by incorporating CuO, Fe 2 O 3 , ZrO 2 , Nb 2 O 3 , and TiO 2 , have been studied for this reaction, but results were not improved significantly. For example, Armenta et al examined γ–χ-Al 2 O 3 modified by Fe 2 O 3 nanoparticles and reported 46% methanol conversion at 250 °C . In another study, Osman et al evaluated the performance of a η-Al 2 O 3 catalyst with a 10% Ag promoter to enhance hydrophobicity and Lewis acidity strength, but it was unable to achieve equilibrium methanol conversion even at temperatures as high as 300 °C …”

Section: Introductionmentioning

confidence: 99%

“…For example, Armenta et al examined γ−χ-Al 2 O 3 modified by Fe 2 O 3 nanoparticles and reported 46% methanol conversion at 250 °C. 18 In another study, Osman et al evaluated the performance of a η-Al 2 O 3 catalyst with a 10% Ag promoter to enhance hydrophobicity and Lewis acidity strength, but it was unable to achieve equilibrium methanol conversion even at temperatures as high as 300 °C. 19 Zeolites with different porous structures have demonstrated superior methanol dehydration activity due to their high acidity, adjustable porosity, and large specific surface area.…”

Section: Introductionmentioning

confidence: 99%

Tuning RHO Zeolite Crystallization Time and Precursors for Stable and Improved Methanol Conversion to Dimethyl Ether Compared to Conventional Catalysts

Lotfollahzade Moghaddam,

Ghavipour,

Kopyscinski

et al. 2024

ACS Sustainable Chem. Eng.

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Energy supply is a significant concern that can be addressed by developing sustainable energy sources. Dimethyl ether (DME) shows remarkable promise in this regard, as it finds applications in diesel fuel engines and LPG systems and serves as an excellent carrier for H 2 . In this study, various RHO samples were synthesized by modifying preparation parameters and evaluated for their performance in this reaction. Through characterization analyses such as XRD, BET, NH 3 -TPD, SEM, EDS, and reactor experiments, it was determined that the optimized sample with the highest crystallization degree (10 days of hydrothermal crystallization) and synthesized with a template:Al 2 O 3 ratio of 0.5:1 possessed an optimum weak/strong acid sites ratio of 1.49 which effectively addressed the limitations of previous catalysts, such as high-temperature requirements and rapid deactivation. The RHO sample achieved the highest conversion rates at temperatures as low as 190 °C, maintaining its efficacy for several days. It was observed that the RHO sample performed superior to common ZSM-5 zeolite for this reaction owing to its higher acidity (2560 μmol g −1 against 1940 μmol g −1 ) and surface area (671 m 2 g −1 vs 230 m 2 g −1 ). These findings highlight the potential of DME as a sustainable energy source and emphasize the importance of optimizing catalyst preparation to improve the DME production efficiency and cost-effectiveness.

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Promoted catalytic performance of sugarcane bagasse ash supported by γ‐alumina as efficient, stable, and ecofriendly catalyst for dehydration of methanol to dimethyl ether

Said,

Goda,

Abd El‐Wahab

et al. 2024

Asia-Pacific J Chem Eng

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The aim of this study was to use different proportions (1% to 20% by weight) of γ‐alumina to modify sugarcane bagasse ash (SCBA) for the production of dimethyl ether (DME) through the dehydration of methyl alcohol. A simple precipitation method was utilized to fabricate (1–20 wt.%) Al2O3/SCBA catalysts. X‐ray fluorescence, X‐ray diffraction, Fourier‐transform infrared spectroscopy, transmission electron microscopy, and N2 sorption were used to explore the structural, spectroscopic, morphological, and textural features. The XRD pattern of Al2O3/SCBA catalysts showed a new peak that corresponded to the formation of γ‐Al2O3. In addition, the average crystallite sizes of pure SCBA and 10% and 20%Al2O3/SCBA catalysts were calculated and found to be 20.1, 21.6, and 22.6 nm, respectively. To evaluate the acidity of these catalysts, the dehydration of isopropyl alcohol and the chemisorption of basic probe molecules were employed. The acidity test results displayed that these catalysts have weak to moderate acidic sites. The 10% Al2O3/SCBA catalyst calcined at 400°C showed high efficiency for the conversion of methyl alcohol to DME, attaining 89% conversion with 100% selectivity. This observation can be attributed to the even distribution of active sites and the acid–base equilibrium on the surface. Moreover, its catalytic activity and selectivity remain unchanged over a continuous 2‐week operation without coke formation, demonstrating its extremely high stability. A strong correlation was observed between the catalytic activity and both the surface area and acidity of the catalysts.

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Effect of acidity on ferric oxide nanoparticles supported on γ–χ–Al2O3 in the methanol dehydration reaction toward dimethyl ether

Cited by 12 publications

References 102 publications

Assessment of Lewis‐Acidic Surface Sites Using Tetrahydrofuran as a Suitable and Smart Probe Molecule

Assessment of Lewis‐Acidic Surface Sites Using Tetrahydrofuran as a Suitable and Smart Probe Molecule

Tuning RHO Zeolite Crystallization Time and Precursors for Stable and Improved Methanol Conversion to Dimethyl Ether Compared to Conventional Catalysts

Promoted catalytic performance of sugarcane bagasse ash supported by γ‐alumina as efficient, stable, and ecofriendly catalyst for dehydration of methanol to dimethyl ether

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