Inorganic Solid Acids and Their Use in Acid-Catalyzed Hydrocarbon Reactions

Corma, Avelino

doi:10.1021/cr00035a006

Cited by 3,023 publications

(2,020 citation statements)

References 14 publications

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“…The same authors also reported a systematic study with various alkylsilanes from C 2 to C 18 . [70] Hydrothermal stability of zeolites has been studied in great detail, as zeolites are the most widely used solid acid catalysts [71] and are often proposed for biomass conversion. [72,73] As shown by detailed characterization using 27 Al and 29 Si solid-state NMR and NH 3 -TPD, siloxane bridge hydrolysis was the main deactivation route in the presence of hot liquid water while zeolites treated under steam suffered from dealumination.…”

Section: Increasing Support Stability In Hydrothermal Conditionsmentioning

confidence: 99%

Improving Heterogeneous Catalyst Stability for Liquid-phase Biomass Conversion and Reforming

Héroguel

Rozmysłowicz

Luterbacher³

2015

Chimia

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Biomass is a possible renewable alternative to fossil carbon sources. To day, many bio-resources can be converted to direct substitutes or suitable alternatives to fossil-based fuels and chemicals. However, catalyst deactivation under the harsh, often liquid-phase reaction conditions required for biomass treatment is a major obstacle to developing processes that can compete with the petrochemical industry. This review presents recently developed strategies to limit reversible and irreversible catalyst deactivation such as metal sintering and leaching, metal poisoning and support collapse. Methods aiming to increase catalyst lifetime include passivation of low-stability atoms by overcoating, creation of microenvironments hostile to poisons, improvement of metal stability, or reduction of deactivation by process engineering.

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Section: Increasing Support Stability In Hydrothermal Conditionsmentioning

confidence: 99%

Improving Heterogeneous Catalyst Stability for Liquid-phase Biomass Conversion and Reforming

Héroguel

Rozmysłowicz

Luterbacher³

2015

Chimia

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“…Zeolites with intricate micropores have been extensively studied for a long time as an important class of industrial materials in different fields of the chemical industries such as adsorption, ion exchange, shape selective catalysis [1][2][3][4][5][6][7][8][9][10][11][12]. The early processes for synthesis of zeolites such as LTA and FAU were carried out in aluminosilicate gels containing inorganic cations, while the modern synthesis methodologies are typically involved in the use of organic structure-directing agents (SDAs) that direct the assembly pathway and ultimately fill the pore space [13,14].…”

Section: Introductionmentioning

confidence: 99%

Rational synthesis of Beta zeolite with improved quality by decreasing crystallization temperature in organotemplate-free route

Zhang

Xie

Meng

et al. 2013

Microporous and Mesoporous Materials

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“…Their constrained environments can be used to recognize molecules and promote specific transition states using shape or size as selection criteria; they are used broadly in practical applications of catalysis, ion exchange, and adsorptive separations. [1][2][3][4][5] The advent of medium-pore zeolites, with ten-membered ring structural channels of 0.5-0.6 nm dimensions led to experimental evidence and theoretical interpretations of shape selectivity, through which topological effects on reactivity reflect in general geometric factors and more specifically the exclusion of molecules or transition states based on size. [6][7][8][9][10][11] The strong effects of pore size and shape as they become "commensurate" with those of reacting species and the concomitant effects on enthalpies and entropies for adsorption and reaction have been noted broadly and convincingly; [12][13][14][15][16][17][18] these effects become less noticeable when reactants, products, and activated complexes are significantly smaller than the spaces within which reactions occur.…”

Section: Introductionmentioning

confidence: 99%

A Link between Reactivity and Local Structure in Acid Catalysis on Zeolites

2008

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T he extent to which spatial constraints influence rates and pathways in catalysis depends on the structure of intermediates, transition states, and active sites involved. We aim to answer, as we seek insights into catalytic mechanisms and site requirements, persistent questions about the potential for controlling rates and selectivities by rational design of spatial constraints around active sites within inorganic structures useful as catalysts. This Account addresses these matters for the specific case of reactions on zeolites that contain Brønsted acid sites encapsulated within subnanometer channels.We compare and contrast here the effects of local zeolite structure on the dynamics of the carbonylation of surface methyl groups and of the isotopic exchange of CD 4 with surface OH groups on zeolites. Methyl and hydroxyl groups are the smallest monovalent cations relevant in catalysis by zeolites. Their small size, taken together with their inability to desorb except via reactions with other species, allowed us to discriminate between stabilization of cationic transition states and stabilization of adsorbed reactants and products by spatial constraints. We show that apparent effects of proton density and of zeolite channel structure on dimethyl ether carbonylation turnover rates reflect instead the remarkable specificity of eight-membered ring zeolite channels in accelerating kinetically relevant steps that form *COCH 3 species via CO insertion into methyl groups. This specificity reflects the selective stabilization of cationic transition states via interactions with framework oxygen anions. These findings for carbonylation catalysts contrast sharply the weak effects of channel structure on the rate of exchange of CD 4 with OH groups. This latter reaction involves concerted symmetric transition states with much lower charge than that required for CH 3 carbonylation. Our Account extends the scope of shape selectivity concepts beyond those reflecting size exclusion and preferential adsorption. Our ability to discriminate among various effects of spatial constraints depends critically on dissecting chemical conversions into elementary steps of kinetic relevance and on eliminating secondary reactions and accounting for the concomitant effects of zeolite structure on the stability of adsorbed reactants and intermediates.

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Inorganic Solid Acids and Their Use in Acid-Catalyzed Hydrocarbon Reactions

Cited by 3,023 publications

References 14 publications

Improving Heterogeneous Catalyst Stability for Liquid-phase Biomass Conversion and Reforming

Improving Heterogeneous Catalyst Stability for Liquid-phase Biomass Conversion and Reforming

Rational synthesis of Beta zeolite with improved quality by decreasing crystallization temperature in organotemplate-free route

A Link between Reactivity and Local Structure in Acid Catalysis on Zeolites

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