Mesoporous mordenites obtained by sequential acid and alkaline treatments – Catalysts for cumene production with enhanced accessibility

Laak, Adri N.C. van; Sagala, Sophia L.; Zečević, Jovana; Friedrich, Heiner; Jongh, Petra E. de; Jong, Krijn P. de

doi:10.1016/j.jcat.2010.09.011

Cited by 98 publications

(72 citation statements)

References 41 publications

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“…From the SEM images, it can be seen that CBV21A MOR contains larger crystallites up to 500 nm in length, accompanied by some smaller debris and agglomerates. The literature indicates that no synthesis route for nanocrystalline mordenite is so far available and that synthesis parameters such as silicon precursors, water content and Na 2 O/SiO 2 /Al 2 O 3 ratios strongly affect mordenite morphology in terms of the size and aspect ratios of the crystals [36][37][38]. respectively.…”

Section: Resultsmentioning

confidence: 99%

The time-on-stream stability of some selected bifunctional nanoporous-based catalysts in n-heptane hydroisomerisation

et al. 2013

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In this work, some commercial nanoporousbased catalysts, such as USY, beta and mordenite zeolites loaded with Platinum metal acting as bifunctional catalysts, were used for hydroisomerisation experiments in a fixedbed reactor at the atmospheric pressure and at feed space time 5.12 h -1 to hydroisomerise n-heptane over a temperature range of 210-270°C. The study aimed to evaluate the changes with time-on-stream in the catalytic activity, product selectivity and manner of deactivation of metalloaded zeolite catalysts, at constant contact time of 5.13 h -1 and a hydrogen-to-n-heptane molar ratio fixed at 9. Various analytical techniques were used to characterise fresh and aged catalysts. Results show that pore architecture is the most important factor affecting coke formation and deactivation in zeolite catalysts, and those catalysts with three-dimensional pore structures lacking cavities or cages were best able to resist deactivation. In addition, it was found that those catalysts with high Si/Al ratios and those which had been acid-leached or steamed showed better activity, higher selectivity towards isomeric products and better time stability. Moreover, the balance between the number of metal sites and the number of acid sites played an important role in determining the activity, selectivity and stability of the bifunctional catalysts.

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Section: Resultsmentioning

confidence: 99%

The time-on-stream stability of some selected bifunctional nanoporous-based catalysts in n-heptane hydroisomerisation

et al. 2013

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“…by carbon templating, 31 or by altering the composition to within the optimal window by dealumination prior to alkaline treatment. 32 Though, in the latter case, the mesoporous zeolite no longer comprises an Al-rich framework. Strikingly, although the literature suggests that alkalinity is of critical importance, 8 the impact of base concentration on mesoporosity development in low Si/Al ratio zeolites has not been systematically explored.…”

Section: Acs Paragon Plus Environmentmentioning

confidence: 99%

Full Compositional Flexibility in the Preparation of Mesoporous MFI Zeolites by Desilication

et al. 2011

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We demonstrate that desilication in alkaline medium is a suitable post-synthetic method to introduce intracrystalline mesoporosity in MFI zeolites independent of the Si/Al ratio in the parent material. By systematic screening of the influence of both base concentration (0.1-1.8 M NaOH) and Si/Al ratio (10-1000) on the properties of the treated zeolites, we reveal that effective mesoporosity introduction Hierarchical ZSM-5 after acid washing stands as the most active sample, which stresses the relevance of the additional post-synthesis treatment step.

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“…Consequently, a significant fraction of the framework aluminum can be removed by acid leaching without altering the basic structure [8]. Mordenite consists of 12-membered ring (MR) pore channels of 0.67 × 0.70 nm interconnected by 8-MR pores of 0.34 × 0.48 nm [9]. Because the 8-MR channels are too small for most molecules to enter, it is generally considered a one-dimensional pore system, inducing singlefile diffusion [10].…”

Section: Introductionmentioning

confidence: 99%

Mild modification method for the generation of mesoporosity in synthetic and natural mordenite

Mamo¹,

Awoke²,

Chebude³

et al. 2015

Bull. Chem. Soc. Eth.

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ABSTRACT. Zeolites are widely used as acid catalysts for the synthesis of fine chemicals in industrial processes. However, in most cases, diffusion limitations in the microporous network of zeolites prevents a good catalytic performance. In this sense, in the course of our research we have modified synthetic and natural mordenite zeolites by mild dealumination/desilication process to obtain mesoporosity. Commercial mordenite (CBV21A Si/Al = 10.5), and natural mordenite from Ethiopia (Si/Al = 6.2) have been treated under mild conditions (pH = 6) in order to maintain high crystallinity in the final zeolites. The impact of this mild treatment (based on ammonium acetate) is remarkable in the synthetic mordenite, creating good degree of mesoporosity while maintaining the bulk Si/Al ratio and crystallinity of the sample. In the case of the natural mordenite, the treatment leads to strong increase in the crystallinity of the sample, although only small mesoporosity is created. All samples were characterized by X-ray diffraction (XRD), inductively coupled plasma atomic emission spectroscopy (ICP-AES), N2 adsorption-desorption isotherms and transmission electron microscopy (TEM).

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Mesoporous mordenites obtained by sequential acid and alkaline treatments – Catalysts for cumene production with enhanced accessibility

Cited by 98 publications

References 41 publications

The time-on-stream stability of some selected bifunctional nanoporous-based catalysts in n-heptane hydroisomerisation

The time-on-stream stability of some selected bifunctional nanoporous-based catalysts in n-heptane hydroisomerisation

Full Compositional Flexibility in the Preparation of Mesoporous MFI Zeolites by Desilication

Mild modification method for the generation of mesoporosity in synthetic and natural mordenite

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