On the effect of EDTA treatment on the acidic properties of USY zeolite and its performance in vacuum gas oil hydrocracking

Valderrama, José Luís Agudelo; Mezari, Brahim; Hensen, Emiel J. M.; Giraldo, Sonia A.; Hoyos, Luis Javier

doi:10.1016/j.apcata.2014.10.007

Cited by 31 publications

(20 citation statements)

References 65 publications

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“…The NMR spectrum of the original USY sample (Figure 8) shows two bands around 60 and 0 ppm that correspond to Al in tetrahedral (Al(IV)) and octahedral (Al(VI)) coordination environments, respectively. 33,34 The band at around 0 ppm disappears completely during the treatment (even for short treatment times), indicating the elimination of the octahedral Al (i.e. extra-framework species).…”

Section: Acs Paragon Plus Environmentmentioning

confidence: 99%

Time-Resolved Dynamics of Intracrystalline Mesoporosity Generation in USY Zeolite

et al. 2019

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The treatment of zeolites with surfactants in alkaline media is an effective and versatile technique to impart intracrystalline well-defined mesoporosity in these materials. In this study, the dynamics of surface reconstruction that occurs during the treatment of USY zeolite by surfactant-templating was monitored in situ by atomic force microscopy. The development of surfactant-templated mesoporosity and the concurrent healing of defects that are characteristic of steamed zeolites occur in less than one hour at room temperature, which emphasizes the low energy barriers needed to reorganize the crystalline structure of this zeolite. This transformation was also followed by X-ray diffraction, N 2 adsorption, and TEM analysis of ultramicrotomed samples to confirm that the rapid formation of surfactant-templated mesoporosity and the reconstruction of the zeolite crystals occur not only on the surface of the zeolite, but homogeneously throughout the whole zeolite. This process involves a significant and rapid breaking and re-formation of bonds; however, the zeolite does not dissolve during this process as solids recovery at any given time of the treatment is approximately 100% and the concentration of soluble Si or Al species in the liquid is negligible. Parametric analysis revealed that excessive NaOH leads to the partial transformation of zeolite into an amorphous mesoporous solid,

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Section: Acs Paragon Plus Environmentmentioning

confidence: 99%

Time-Resolved Dynamics of Intracrystalline Mesoporosity Generation in USY Zeolite

et al. 2019

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“…The positive effect of EDTA treatment on the accessibility of USY zeolite has been already discussed. 19 In the present study, this EDTA treatment step appears to be a prerequisite to make use of the enhanced mesoporosity developed by the AN treatment in the hydrocracking of VGO feedstock.…”

Section: Energy and Fuelsmentioning

confidence: 95%

Effect of USY Zeolite Chemical Treatment with Ammonium Nitrate on Its VGO Hydrocracking Performance

et al. 2015

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Chemically modified USY zeolites were obtained by ammonium nitrate (AN) treatment under hydrothermal conditions. AN treatment considerably enhanced the mesopore volume of the parent steam-treated zeolite. This treatment also caused the creation of extraframework species of weak acid nature. NiMoP-based hydrocracking catalysts were prepared using the modified zeolites and evaluated in the hydrocracking of a heavy vacuum gas oil (VGO). Hydrocracking activity results indicate that, although AN treatment significantly develops mesoporosity in the parent steam-treated USY zeolite, this single treatment was not efficient to enhance the accessibility of VGO compounds to the acid sites. However, the catalysts based on AN-treated zeolites showed significantly higher middle distillates yields than the one based on a steam-treated zeolite. The creation of an amorphous phase at the mesopore walls and the external surface of the zeolite crystals was argued to support this observation. Mild Na 2 H 2 -EDTA treatment to an AN-treated zeolite showed to be beneficial to improve the hydrocracking activity. This was attributed to the enhanced access to acid sites after the removal of polymerized extraframework aluminum species (EFAl). Consequently, a modification strategy of USY zeolites that includes AN treatments is proposed to develop catalysts with enhanced middle distillates selectivity in the hydrocracking of real feedstocks.

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“…Dealumination process is rather complicated, as many thermodynamic or kinetic factors will affect it significantly depending on the experimental conditions . Dealumination can be achieved by steaming, leaching with acids, treatment with chelating agents such as hexafluorosilicate, ammonium hydrogen difluoride (NH 4 HF 2 ), ethylenediamine tetracetic acid, acetylacetone− and many others. Acetylacetone as a bidentate and nonacidic ligand is a suitable agent for mild dealumination leading to the extraction of “loosely bond” aluminum atoms in zeolites .…”

Section: Introductionmentioning

confidence: 99%

Influence of Dealumination by Acetylacetone on Acidity and Activity of Amorphous Silica‐Aluminas

et al. 2020

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The influence of dealumination of two commercial amorphous silica‐aluminas (ASAs) with acetylacetone on their textural properties, acidity and catalytic activity was studied by N2‐sorption, NH3‐TPD, FTIR of adsorbed pyridine as well as 1H and 27Al MAS NMR. Acetylacetone treatment increases the pore volume and surface area (+20→+30%) of commercial ASA without changing the pore size. More than half of the Al species are extracted from ASA but the total acidity is preserved or even slightly increased (for the ASA with higher Al content). The percentage of acidic Al is increased by a factor 2. Dealumination results in a better access to acid sites and an increase of medium Brønsted acid sites (BAS), leading to a 1.5 higher catalytic activity for 3,3‐Dimethyl‐1‐butene (33DMB1) isomerization.

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On the effect of EDTA treatment on the acidic properties of USY zeolite and its performance in vacuum gas oil hydrocracking

Cited by 31 publications

References 65 publications

Time-Resolved Dynamics of Intracrystalline Mesoporosity Generation in USY Zeolite

Time-Resolved Dynamics of Intracrystalline Mesoporosity Generation in USY Zeolite

Effect of USY Zeolite Chemical Treatment with Ammonium Nitrate on Its VGO Hydrocracking Performance

Influence of Dealumination by Acetylacetone on Acidity and Activity of Amorphous Silica‐Aluminas

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