First principles, microkinetic, and experimental analysis of Lewis acid site speciation during ethanol dehydration on Sn-Beta zeolites

Bukowski, Brandon C.; Bates, Jason S.; Gounder, Rajamani; Greeley, Jeffrey

doi:10.1016/j.jcat.2018.07.012

Cited by 51 publications

(100 citation statements)

References 73 publications

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“…Static DFT calculations were performed using VASP [133][134][135] and are similar to those we have reported previously. 59 The BEEF-vdW functional was used along with a 520 eV cutoff energy, and a force convergence criteria of 0.02 eVÅ À1 where lattice atoms were all unconstrained. The projector augmented wave (PAW) pseudopotentials were included.…”

Section: Gas-phase Dftmentioning

confidence: 99%

“…55 H 2 O inhibition quantied by negative reaction orders is oen described by reaction mechanisms that include inhibitory alcohol-water dimer species, as observed in alcohol dehydration catalyzed by Brønsted acidic Keggin-type polyoxometalate clusters 56 and Lewis acidic g-Al 2 O 3 57,58 and Sn-Beta zeolites. 59,60 Others have suggested that co-adsorbed H 2 O inhibits alcohol dehydration by stabilizing adsorbed alcohols preferentially over transition states, in the case of 1-propanol dehydration on H-Al-MFI zeolites. 61 In the liquid phase, connement of H 3 O + within H-Al-Beta zeolite pores ($0.7 nm in diameter) leads to higher rates of cyclohexanol dehydration than in bulk solution, because of enhanced association between H 3 O + and reactants and the entropic destabilization of this precursor relative to the transition state, 62 and solvation of H + by non-polar solvents rather than water leads to higher rates of phenol alkylation.…”

Section: Introductionmentioning

confidence: 99%

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Structure and solvation of confined water and water–ethanol clusters within microporous Brønsted acids and their effects on ethanol dehydration catalysis

et al. 2020

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Section: Gas-phase Dftmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Structure and solvation of confined water and water–ethanol clusters within microporous Brønsted acids and their effects on ethanol dehydration catalysis

et al. 2020

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“…Measurements of the kinetics of ethanol dehydration and etherification in the gas phase also revealed important considerations concerning the inhibition by ethanol–water dimers as well as more complicated dimer and trimer species . Inhibition by water was observed for primary linear alcohol etherification over WO x /ZrO 2 , as shown in Figure , which was also observed for 1‐octanol etherification over zeolite BEA and for 1‐pentanol etherification over Amberlyst 70 .…”

Section: Synthesis Of Ethers From Biomass‐derived Platform Chemicalsmentioning

confidence: 99%

“…For example, Bukowski et al. proposed a concerted transition state involving both the Lewis‐acidic Sn center and an adjacent weakly Brønsted‐acidic framework silanol group …”

Section: Role Of Cooperative Brønsted and Lewis Acidity In Selective mentioning

confidence: 99%

“…For example, Bukowski et al proposed a concerted transition state involving both the Lewis-acidic Sn center anda na djacent weakly Brønsted-acidic framework silanol group. [115] Because there is precedent for the role of Brønsted and Lewis acidityi nc ontrolling etherification and dehydration selectivity over metal oxides, the investigation of tuning Brønsted and Lewis acid sites by varying the ratio of Brønsted-to-Lewis acid sites, changing the strength of Lewis acid centers by varying the metal cations,a nd changing the density of Brønsted acid sites is ap romising avenue for future improvement of ether selectivity that is not afforded by Brønstedacidic polymeric resins.…”

Section: Role Of Cooperative Brønsted and Lewis Acidity In Selective mentioning

confidence: 99%

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Synthesis of Biomass‐Derived Ethers for Use as Fuels and Lubricants

2019

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Zeolite (In)Stability under Aqueous or Steaming Conditions

et al. 2020

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zeolites, modification of zeolite acidity for use as fluid catalytic cracking (FCC) catalysts or even for the preparation of novel zeolite frameworks. [1] Considering the significance of zeolite applications at the industrial level, a thorough understanding of zeolite (in)stability under aqueous conditions has been identified as a very important problem in catalysis and zeolite science. Zeolite (in)stability in water or under steaming conditions has been investigated by a number of experimental techniques, in particular magic angle spinning (MAS) NMR, IR, powder X-ray diffraction (PXRD), calorimetry and adsorption. Experimental studies have often been augmented by computational modeling and a large number of relevant theoretical papers can be found in the literature. While the main focus of this review is on reactive interactions of water with zeolites, it is also important to review the most important observations obtained for nonreactive water adsorption in zeolites. It is not surprising that all-silica zeolites, which exhibit negligible water uptake are stable even under conditions where Alcontaining zeolites lose crystallinity: the effective framework hydrolysis can only take place when sufficient water is present in the zeolite channel system. The amount of water inside the zeolite channels depends critically on the concentration of heteroatoms and/or framework defects, such as silanol nests, which show much higher affinity toward water than hydrophobic SiOSi bridges. Zeolite hydrophobicity increases with increasing Si/Al ratio and incomplete pore filling by water is commonly observed for zeolites with high Si/Al at standard pressure. It has been suggested already in the 1950s by Young that water can only adsorb on surface silanol groups, while the parts of the silica surfaces formed by SiOSi bridges are hydrophobic. [2] Both water adsorption in zeolites and zeolite (in)stability under aqueous conditions depend on the zeolite composition (Si/Al ratio, charge-compensating cations, and defect concentration in particular). Our primary goal is to review the most critical aspects of zeolite (in)stability for a broad range of temperature and partial water pressure (p 0), focusing on the framework zeolite composition (Si/Al ratio and presence of Ge, Sn, and Ti heteroatoms) and defect concentration. Zeolites (in)stability in water is discussed for increasing extent of framework degradation, starting from the nonreactive interaction with water, reversible hydrolysis of TO bonds, mild zeolite demetallation, mesopore formation, and total amorphization (Figure 1). Zeolites are among the most environmentally friendly materials produced industrially at the Megaton scale. They find numerous commercial applications, particularly in catalysis, adsorption, and separation. Under ambient conditions aluminosilicate zeolites are stable when exposed to water or water vapor. However, at extreme conditions as high temperature, high water vapor pressure or increased acidity/basicity, their crystalline framework can be destroyed....

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First principles, microkinetic, and experimental analysis of Lewis acid site speciation during ethanol dehydration on Sn-Beta zeolites

Cited by 51 publications

References 73 publications

Structure and solvation of confined water and water–ethanol clusters within microporous Brønsted acids and their effects on ethanol dehydration catalysis

Structure and solvation of confined water and water–ethanol clusters within microporous Brønsted acids and their effects on ethanol dehydration catalysis

Synthesis of Biomass‐Derived Ethers for Use as Fuels and Lubricants

Zeolite (In)Stability under Aqueous or Steaming Conditions

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