Mesopore differences between pillared lamellar MFI and MWW zeolites probed by atomic layer deposition of titania and consequences on photocatalysis

Zhang, Junyan; Lü, Zheng; Wu, Wei; Tran, Dat T.; Shang, Wenjin; Chen, Huiyong; Yu, Lei; Li, Zhenglong; Wang, Mei; Woehl, Taylor J.; Liu, Dongxia

doi:10.1016/j.micromeso.2018.10.009

Cited by 11 publications

(6 citation statements)

References 58 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Hence, the majority of reactions occur internally, whereas the surface sites would remain largely unoccupied. Finally, a barrier of 1.76 eV is associated with a rate constant of 3 × 10 0 s −1 , which is consistent with the experimentally observed catalytic activity 31 to within the expected errors.…”

Section: ■ Results and Discussionsupporting

confidence: 88%

“…In particular, zeolites have been used in producing a wide array of hydrocarbons as solid acid catalysts where their well-defined micropores can be incorporated with exchangeable cation sites. − They are traditionally regarded as the extension of frameworks connected by covalent bonds in three dimension (3D). Zeolites demonstrate sorption capability and high surface area, along with shape and size selectivity, which is stemmed from the topological uniqueness of zeolite angstrom-size micropores. ,− However, the difficulty of bulky molecules in reaching the acid sites, and thereby slowing down mass transport in microporous networks, often leads to the decrease in catalytic activities of zeolites, because of relatively small sizes of micropores. − One possible approach to remedy such issues is to create two-dimensional (2D) zeolite structures with near-unit-cell thickness by cleaving 3D bulk zeolites. − The acid sites can then be easily exposed on the external surfaces of 2D zeolites, which leads to the improved accessibility of bulky molecules to the sites relative to those embedded deep inside the frameworks of 3D zeolites. Multiple routes, including surfactant-templated and hydrothermal synthesis, − are available for synthesizing 2D zeolites.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Mechanistic Understanding of Catalytic Conversion of Ethanol to 1-Butene over 2D-Pillared MFI Zeolite

et al. 2020

Self Cite

View full text Add to dashboard Cite

Ethanol is an important C 2 platform molecule for producing value-added chemicals and distillate hydrocarbon fuels (e.g., jet and diesel). Among these, catalytic upgrading of ethanol to butenes can generate valuable commodity chemicals (e.g., 1-butene) and provide C 4 olefin intermediates that can be further upgraded to jet/diesel fuels. Twodimensional (2D) zeolites offer hierarchical mesoporous structures, leading to improved mass transport and reduced diffusion length, which can help to address the coking challenges faced by ethanol conversion to hydrocarbons over three-dimensional (3D) zeolites. In this study, we investigate the acidcatalyzed conversion of ethanol to 1-butene over the Brønsted acid sites (BAS) in 2D-pillared MFI zeolite (2D-PMFI) using ab initio molecular dynamics (AIMD) simulations, in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and calorimetric measurements. A detailed thermodynamic analysis, using quasi-harmonic approximation (QHA), on the Gibbs free-energy pathway of ethanol conversion shows that the consideration of entropy is critical to accurately capture the detailed thermodynamic profiles. Employing the Blue Moon ensemble method, the formation of framework-bound butoxide from ethoxy and ethene is found to be the likely ratedetermining step (RDS), proceeding via a stepwise mechanism. The reactivity of 2D-PMFI can be further tuned by manipulating RDS through careful control of the number of BAS and operating temperatures. The calculated vibrational density of states (VDOS) validate the structural models of adsorbed ethanol by comparing with the experimental DRIFTS measurements. Overall, our study provides mechanistic insights into ethanol upgrading over the 2D-PMFI and shows the importance of evaluating entropic effects in such a confined system.

show abstract

Section: ■ Results and Discussionsupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Mechanistic Understanding of Catalytic Conversion of Ethanol to 1-Butene over 2D-Pillared MFI Zeolite

et al. 2020

Self Cite

View full text Add to dashboard Cite

show abstract

“…When the powder quantity is small (e.g., 1–10 g), the conventional ALD system can still be used by spreading the powder uniformly inside a stainless-steel tray with a mesh on top. The mesh’s pore size is smaller than the powder particle size to prevent powder spilling but still allows efficient diffusion of the ALD precursors and byproducts in and out of the tray. , To fulfill the precursor’s adequate penetration deep inside the powder bed vertically, a long precursor dose and purge time are required. However, it is often observed that the powder at the bottom of the tray is unsaturated, resulting in nonuniform ALD coating, as shown in Figure a.…”

Section: Ald Overcoated Catalystmentioning

confidence: 99%

Design and Characterization of ALD-Based Overcoats for Supported Metal Nanoparticle Catalysts

et al. 2021

Self Cite

View full text Add to dashboard Cite

Supported metal nanoparticle (SMN) catalysts are enormously crucial for many catalytic applications. However, catalyst deactivation, caused by sintering and coke formation, is a ubiquitous problem that significantly undermines catalytic processing economics. The application of material overcoating onto supported metal nanoparticles by atomic layer deposition (ALD) offers the solution to inhibit catalyst deactivation. Herein, we discuss examples in which ALD has been used to stabilize SMN catalysts in gaseous and aqueous-phase reactions. We highlight the ALD tools and methods in coating high-surface-area catalysts. Besides, various techniques are introduced to understand better how to characterize the overcoating layer and the catalyst itself. Finally, the outlook for new techniques to characterize the ALD overcoated catalytic materials is discussed.

show abstract

“…ALD is film growth technique by controlling the thickness of film at atomic level, particularly in the case of metal‐oxide thin films onto ordered meso‐/microporous zeolite. In fact, tremendous attempts have been made to investigate the conformal properties of films grown by ALD [139,140] …”

Section: Assisted Synthesis and Regioselective Modified Of Zeolites By Aldmentioning

confidence: 99%

“…Zhang et al. compared the differences in mesopore characteristics between PMWW and PMFI zeolites probed by ALD of titania (TiO 2 ‐ALD) (0.23–0.88 wt.%) species [140] . Based on the analysis of the link between mesopore volume loss and weight gain from TiO 2 deposition, it can be concluded that the communication in the mesopore network in PMFI is better than that in PMWW.…”

Section: Assisted Synthesis and Regioselective Modified Of Zeolites By Aldmentioning

confidence: 99%

Atomic‐Scale Designing of Zeolite Based Catalysts by Atomic Layer Deposition

Yin

Gao

et al. 2021

ChemPhysChem

View full text Add to dashboard Cite

Zeolite‐supported catalysts have been widely used in the field of heterogeneous catalysis. Atomic‐scale governing the metal or acid sites on zeolites still encounters great challenge in controllable synthesis and developing of novel catalysts. Atomic layer deposition (ALD), owing to its unique character of self‐limiting surface reactions, becomes one of the most promising and controllable strategies to tailor the metallic deposition sites in atomic scale precisely. In this review, we present a comprehensive summary and viewpoint of recent research in designing and engineering the structural of zeolite‐based catalysts via ALD method. A prior focus is laid on the deposition of metals on the zeolites with emphasis on the isolated states of metals, followed by introducing the selected metals into channels of zeolites associates with identifying the location of metals in and/or out of the channels. Subsequently, detailed analysis of tailoring the acid sites of different zeolites is provided. Assisted synthesis of zeolite and the regioselective deposition of metal on special sites to modify the structures of zeolites are also critically discussed. We further summarize the challenges of ALD with respect to engineering the active sites in heterogeneous zeolite‐based catalysts and provide the perspectives on the development in this field.

show abstract

Mesopore differences between pillared lamellar MFI and MWW zeolites probed by atomic layer deposition of titania and consequences on photocatalysis

Cited by 11 publications

References 58 publications

Mechanistic Understanding of Catalytic Conversion of Ethanol to 1-Butene over 2D-Pillared MFI Zeolite

Mechanistic Understanding of Catalytic Conversion of Ethanol to 1-Butene over 2D-Pillared MFI Zeolite

Design and Characterization of ALD-Based Overcoats for Supported Metal Nanoparticle Catalysts

Atomic‐Scale Designing of Zeolite Based Catalysts by Atomic Layer Deposition

Contact Info

Product

Resources

About