Acid Catalysis over Low-Silica Faujasite Zeolites

Li, Xinyu; Han, He; Xu, Wenqian; Hwang, Son‐Jong; Shi, Zhichen; Peng, Lu; Bhan, Aditya; Tsapatsis, Michael

doi:10.1021/jacs.2c01022

Cited by 16 publications

(8 citation statements)

References 33 publications

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“…5(g)) reflect that H-FAU3.5 and Article https://doi.org/10.1038/s41467-023-38738-5 H-FAU2.8 zeolites exhibit a similar proton density ratio of H SOD /H SUP (Table 1, column 8). We also observed in our prior work that unlike lowsilica FAU zeolites, which contain protons on site II and site III within supercages, high-silica FAU zeolites only contain protons on site II within supercages 61 . Thus, H-FAU3.5 and H-FAU2.8 zeolites possess similar H SOD /H SUP ratios and the same atomic configurations (i.e., protons on site II within supercages, and protons on site I′ within sodalite cages).…”

Section: Sisupporting

confidence: 73%

Machine learning-assisted crystal engineering of a zeolite

Han

Evangelou

et al. 2023

Nat Commun

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It is shown that Machine Learning (ML) algorithms can usefully capture the effect of crystallization composition and conditions (inputs) on key microstructural characteristics (outputs) of faujasite type zeolites (structure types FAU, EMT, and their intergrowths), which are widely used zeolite catalysts and adsorbents. The utility of ML (in particular, Geometric Harmonics) toward learning input-output relationships of interest is demonstrated, and a comparison with Neural Networks and Gaussian Process Regression, as alternative approaches, is provided. Through ML, synthesis conditions were identified to enhance the Si/Al ratio of high purity FAU zeolite to the hitherto highest level (i.e., Si/Al = 3.5) achieved via direct (not seeded), and organic structure-directing-agent-free synthesis from sodium aluminosilicate sols. The analysis of the ML algorithms’ results offers the insight that reduced Na2O content is key to formulating FAU materials with high Si/Al ratio. An acid catalyst prepared by partial ion exchange of the high-Si/Al-ratio FAU (Si/Al = 3.5) exhibits improved proton reactivity (as well as specific activity, per unit mass of catalyst) in propane cracking and dehydrogenation compared to the catalyst prepared from the previously reported highest Si/Al ratio (Si/Al = 2.8).

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Section: Sisupporting

confidence: 73%

Machine learning-assisted crystal engineering of a zeolite

Han

Evangelou

et al. 2023

Nat Commun

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“…It is known that non-framework aluminum (NFAL) resides at specific locations inside the sodalite cages (sod) and double 6-membered rings (D6R). [50] The removal of NFAL from these positions further suggests that the zeolite reorganization is active at the unit-cell level and is one of the key reasons to facilitate the development of ordered mesophase similar to bottom-up syntheses from molecular…”

Section: Methodsmentioning

confidence: 99%

Post‐Synthetic Ensembling Design of Hierarchically Ordered FAU‐type Zeolite Frameworks for Vacuum Gas Oil Hydrocracking

Kumar Parsapur,

Hengne,

Melinte

et al. 2023

Angew Chem Int Ed

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Zeolites hold importance as catalysts and membranes across numerous industrial processes that produce most of the world’s fuels and chemicals. In zeolite catalysis, the rate of molecular diffusion inside the micropore channels defines the catalyst longevity and selectivity, thereby influencing the catalytic process efficiency. Decreasing the diffusion pathlengths of zeolites to the nanoscopic level by fabricating well‐organized nanoporous architecture can efficiently overcome their intrinsic mass‐transfer limitations without losing hydrothermal stability. We report a rational post‐synthetic design for the synthesis of hierarchically ordered FAU‐type zeolites exhibiting 2D‐hexagonal (P6mm) and 3D‐cubic (Ia[[EQUATION]]d) mesopore channels formed by a post‐synthetic approach. The synthesis involves methodical incision of the parent zeolite into unit‐cell level zeolitic fragments by in situ generated base and bulky surfactants. The micellar ensembles formed by these surfactant‐zeolite interactions are subsequently reorganized into various ordered mesophases by tuning the micellar curvature with ion‐specific interactions (Hofmeister effect). Unlike conventional crystallization, which offers poor control over mesophase formation due to kinetic constraints, here, crystalline mesostructures can be developed under dilute, mild alkaline conditions by controlled reassembly. The prepared hierarchically ordered zeolites with nanometric diffusion pathlengths have demonstrated excellent yields of naphtha and middle‐distillates in low‐pressure vacuum gas oil hydrocracking with decreased coke deposition.

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“…MFI-type zeolites possess two interconnected channel systems containing pentasyl units and are considered medium pore-size zeolites [ 87 , 88 ]. FAU-type zeolites contain larger pores [ 89 ], while the BAU-type zeolite porosity is in between those of MFI and FAU ( Figure 1 ) [ 90 ]. Diverse types and sizes of pores allow for various molecules either to penetrate the support or to be filtered out, depending on their size.…”

Section: Types Of Zeolitesmentioning

confidence: 99%

Design of Bifunctional Nanocatalysts Based on Zeolites for Biomass Processing

Matveeva

Bronstein

2023

Nanomaterials

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Bifunctional catalysts consisting of metal-containing nanoparticles (NPs) and zeolite supports have received considerable attention due to their excellent catalytic properties in numerous reactions, including direct (biomass is a substrate) and indirect (platform chemical is a substrate) biomass processing. In this short review, we discuss major approaches to the preparation of NPs in zeolites, concentrating on methods that allow for the best interplay (synergy) between metal and acid sites, which is normally achieved for small NPs well-distributed through zeolite. We focus on the modification of zeolites to provide structural integrity and controlled acidity, which can be accomplished by the incorporation of certain metal ions or elements. The other modification avenue is the adjustment of zeolite morphology, including the creation of numerous defects for the NP entrapment and designed hierarchical porosity for improved mass transfer. In this review, we also provide examples of synergy between metal and acid sites and emphasize that without density functional theory calculations, many assumptions about the interactions between active sites remain unvalidated. Finally, we describe the most interesting examples of direct and indirect biomass (waste) processing for the last five years.

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Acid Catalysis over Low-Silica Faujasite Zeolites

Cited by 16 publications

References 33 publications

Machine learning-assisted crystal engineering of a zeolite

Machine learning-assisted crystal engineering of a zeolite

Post‐Synthetic Ensembling Design of Hierarchically Ordered FAU‐type Zeolite Frameworks for Vacuum Gas Oil Hydrocracking

Design of Bifunctional Nanocatalysts Based on Zeolites for Biomass Processing

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