Nanostructured MFI-type zeolites as catalysts in glycerol etherification with tert -butyl alcohol

Simone, Nathália; Carvalho, Wagner A.; Mandelli, Dalmo; Ryoo, Ryong

doi:10.1016/j.molcata.2016.02.005

Cited by 28 publications

(19 citation statements)

References 34 publications

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“…As expected, the acid site density increases with decreasing Si/Al ratio or increasing Al content. However, it does vary for the same Si/Al ratio if the morphology is different, as seen in the case of 3D MFI (21) vs 2D MFI (25) and also reported by previous studies …”

Section: Resultssupporting

confidence: 83%

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Effect of Si/Al Ratio on the Catalytic Activity of Two‐Dimensional MFI Nanosheets in Aromatic Alkylation and Alcohol Etherification

et al. 2019

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Zeolite catalysts with pronounced two‐dimensional (2D) morphologies, specifically 2D MFI nanosheets composed of multilamellar stacks of MFI nanosheets, are hypothesized to offer accessibility advantages in catalytic reactions involving large, bulky molecules. The Si/Al ratio of zeolite catalysts is an important parameter determining their performance. However, the effect of Si/Al ratio on catalytic reactivity is not well understood in 2D zeolite catalysts. To provide further insight into this issue, the catalytic performance of 2D MFI nanosheet materials with different Si/Al ratios is compared using the liquid phase Friedel‐Crafts alkylation of mesitylene with benzyl alcohol & the self‐etherification of benzyl alcohol that occurs in parallel, both of which are catalyzed by Brønsted acid sites. The turnover frequency (TOF) of the catalysts is found to decrease with decreasing Si/Al ratio, with the etherification reaction being the main contributor to this trend. When the same reaction is carried out in the presence of a bulky poison, 2,6 di‐tert‐butylpyridine (DTBP), to selectively deactivate the external acid sites, only the etherification reaction of benzyl alcohol takes place in the micropores of the 2D MFI catalyst and the effectiveness factor is found to decrease with decreasing Si/Al ratio. The single component adsorption isotherms of benzyl alcohol show that the uptake normalized per acid site decreases with decreasing Si/Al ratio. Thus, increasing the density of acid sites in the micropores by decreasing the Si/Al ratio makes it more difficult for the reactant molecules to access them, as demonstrated by the decrease in TOF and the effectiveness factor. While the micropore reactions (benzene alkylation, alcohol etherification) showed a clear trend with Si/Al ratio, the reaction catalyzed on the external surface (mesitylene alkylation) did not, showing distinct differences in reactivity.

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Section: Resultssupporting

confidence: 83%

“…They found that the activity per acid site reduced with increasing density of sites achieved by decreasing the Si/Al ratio. A similar trend was observed by Simone et al . who studied the etherification of glycerol with tert ‐butyl alcohol for 2D MFI nanosheets with different Si/Al ratios.…”

Section: Introductionsupporting

confidence: 85%

Effect of Si/Al Ratio on the Catalytic Activity of Two‐Dimensional MFI Nanosheets in Aromatic Alkylation and Alcohol Etherification

et al. 2019

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“…Thus, the best catalytic behavior (X G = 75% and S h-GTBE = 37%) was associated with the highest acidity and the larger pore size of the zeolite. Likewise, Simone et al [79] achieved better results on nanostructured MFI-type zeolites than on traditional zeolites. The nanosponge-like morphology of the zeolites consisted of a three-dimensional disordered network of MFI layers with 2.5 nm thickness supporting each other, obtaining the highest selectivity to TTBG (10%) with unilamellar MFI containing a SI:Al ratio of 100, which exhibited a high proportion of the acid sites on the external surface, enabling a favorable accessibility of the reactants to these sites.…”

Section: Etherification Of Glycerol With Tert-butyl Alcoholmentioning

confidence: 99%

An Overview of the Production of Oxygenated Fuel Additives by Glycerol Etherification, Either with Isobutene or tert-Butyl Alcohol, over Heterogeneous Catalysts

et al. 2019

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Biodiesel production has considerably increased in recent decades, generating a surplus of crude glycerol, which is the main drawback for the economy of the process. To overcome this, many scientists have directed their efforts to transform glycerol, which has great potential as a platform molecule, into value-added products. A promising option is the preparation of oxygenate additives for fuel, in particular those obtained by the etherification reaction of glycerol with alcohols or olefins, mainly using heterogeneous catalysis. This review collects up-to-date research findings in the etherification of glycerol, either with isobutene (IB) or tert-Butyl alcohol (TBA), highlighting the best catalytic performances reported. Furthermore, the experimental sets employed for these reactions have been included in the present manuscript. Likewise, the characteristics of the glycerol ethers–(bio)fuel blends as well as their performances (e.g., quality of emissions, technical advantages or disadvantages, etc.) have been also compiled and discussed.

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“…It was found that the morphology of MFI nanosheets can be changed from a disordered assembly to an ordered multilamellar structure when increasing the hydrothermal aging time [12]. To control nanosheet structures, there are several types of surfactants, in particular, quaternary ammonium surfactants, as well as other templates or seeds that have been developed to synthesize various hierarchical zeolite nanosheets with different morphologies [13][14][15]. For example, tetrapropylammonium hydroxide (TPAOH) was used together with C 22−6−6 as a dual-template to control hierarchical structures [13].…”

Section: Synthesis Of Hierarchical Zeolite Nanosheetsmentioning

confidence: 99%

“…When increasing the amount of TPAOH, the morphology of the MFI nanosheet changes from intertwined particles to house-of-cards-structures. In addition, nanosheet HZSM-5 films deposited on the support and the hierarchical MFI nanosponge were successfully synthesized using C 22-6-6 in seed-assisted synthesis methods [14,15]. Their hierarchical structures exhibit the remarkably improved activity attributing to the enhanced accessibility and diffusion of bulky molecules into the zeolite framework.…”

Section: Synthesis Of Hierarchical Zeolite Nanosheetsmentioning

confidence: 99%

A Comprehensive Review of the Applications of Hierarchical Zeolite Nanosheets and Nanoparticle Assemblies in Light Olefin Production

Dugkhuntod

Wattanakit

2020

Catalysts

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Light olefins including ethylene, propylene and butylene are important building blocks in petrochemical industries to produce various chemicals such as polyethylene, polypropylene, ethylene oxide and cumene. Traditionally, light olefins are produced via a steam cracking process operated at an extremely high temperature. The catalytic conversion, in which zeolites have been widely used, is an alternative pathway using a lower temperature. However, conventional zeolites, composed of a pure microporous structure, restrict the diffusion of large molecules into the framework, resulting in coke formation and further side reactions. To overcome these problems, hierarchical zeolites composed of additional mesoporous and/or macroporous structures have been widely researched over the past decade. In this review, the recent development of hierarchical zeolite nanosheets and nanoparticle assemblies together with opening up their applications in various light olefin productions such as catalytic cracking, ethanol dehydration to ethylene, methanol to olefins (MTO) and other reactions will be presented.Catalysts 2020, 10, 245 2 of 15 windows, they can be divided into three different categories including large porous, medium porous and small porous zeolites, which are composed of a different number of tetrahedral units, or T atoms of 12, 10 and 8 membered rings, respectively. These behaviors make each zeolite serving unique shape selective properties, which are very important for the appropriate applications.Although there are several above-mentioned promising properties of zeolites, they are typically composed of a very small microporous structure, eventually resulting in some disadvantages of the diffusion limitation of guest molecules inside the framework. Some bulky molecules cannot easily penetrate into active sites located at microporous channels, and therefore a poor catalytic performance due to a very low reaction rate and a fast deactivation of catalysts is observed. To overcome these limitations and to improve the accessibility of molecules into active sites, in recent years modified zeolites obtained by introducing additional larger porous structures have been extensively developed [5][6][7][8].It is well known that hierarchical zeolites, composed of at least two levels of porous structures such as microspores and mesopores, microspores and macropores, and micropores/mesopores and macropores have been extensively studied and developed. Their microporous (<2 nm), mesoporous (2-50 nm) and/or macroporous (>50 nm) structures are well connected to each other. In this case, the additional larger porous structures can improve diffusion limitation, molecular transportation and coke deposition [9]. In the past decade, there have been several studies regarding the synthesis of hierarchical zeolites to overcome these problems. Herein, this comprehensive review opens up perspectives of the recent synthesis approaches of hierarchical zeolite nanosheets and nanoparticle assemblies, as well as the successful production of light olef...

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Nanostructured MFI-type zeolites as catalysts in glycerol etherification with tert -butyl alcohol

Cited by 28 publications

References 34 publications

Effect of Si/Al Ratio on the Catalytic Activity of Two‐Dimensional MFI Nanosheets in Aromatic Alkylation and Alcohol Etherification

Effect of Si/Al Ratio on the Catalytic Activity of Two‐Dimensional MFI Nanosheets in Aromatic Alkylation and Alcohol Etherification

An Overview of the Production of Oxygenated Fuel Additives by Glycerol Etherification, Either with Isobutene or tert-Butyl Alcohol, over Heterogeneous Catalysts

A Comprehensive Review of the Applications of Hierarchical Zeolite Nanosheets and Nanoparticle Assemblies in Light Olefin Production

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