Interdependent lateral interactions, hydrophobicity and acid strength and their influence on the catalytic activity of nanoporous sulfonic acid silicas

Dacquin, Jean‐Philippe; Cross, Hannah E.; Brown, R. C.; Düren, Tina; Williams, Jennifer J.; Lee, Adam F.; Wilson, Karen

doi:10.1039/c0gc00045k

Cited by 114 publications

(119 citation statements)

References 43 publications

(33 reference statements)

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“…Multifunctionalization of MSN to include hydrophobic groups, as well as catalytic groups, has been observed to significantly enhance reactivity in several such systems. [4][5][6] This effect has been explained as a result of functionalization converting an intrinsically hydrophilic interior pore surface of MSN into a hydrophobic environment thereby "expelling" the product water and shifting the equilibrium of the reversible esterification reaction. The greatest enhancement to date has been achieved through solvent-mediated control of the configuration of hydrophobic 3-(pentafluorophenyl) propyl groups which are induced to lie prone on silica surface thereby min- evans@ameslab.gov imizing the interaction of the product water with the hydrophilic MSN surface groups.…”

Section: Introductionmentioning

confidence: 99%

Controlling reactivity of nanoporous catalyst materials by tuning reaction product-pore interior interactions: Statistical mechanical modeling

Wang¹,

Ackerman²,

Lin³

et al. 2013

The Journal of Chemical Physics

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Statistical mechanical modeling is performed of a catalytic conversion reaction within a functionalized nanoporous material to assess the effect of varying the reaction product-pore interior interaction from attractive to repulsive. A strong enhancement in reactivity is observed not just due to the shift in reaction equilibrium towards completion but also due to enhanced transport within the pore resulting from reduced loading. The latter effect is strongest for highly restricted transport (single-file diffusion), and applies even for irreversible reactions. The analysis is performed utilizing a generalized hydrodynamic formulation of the reaction-diffusion equations which can reliably capture the complex interplay between reaction and restricted transport. Statistical mechanical modeling is performed of a catalytic conversion reaction within a functionalized nanoporous material to assess the effect of varying the reaction product-pore interior interaction from attractive to repulsive. A strong enhancement in reactivity is observed not just due to the shift in reaction equilibrium towards completion but also due to enhanced transport within the pore resulting from reduced loading. The latter effect is strongest for highly restricted transport (single-file diffusion), and applies even for irreversible reactions. The analysis is performed utilizing a generalized hydrodynamic formulation of the reaction-diffusion equations which can reliably capture the complex interplay between reaction and restricted transport.

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Section: Introductionmentioning

confidence: 99%

Controlling reactivity of nanoporous catalyst materials by tuning reaction product-pore interior interactions: Statistical mechanical modeling

Wang¹,

Ackerman²,

Lin³

et al. 2013

The Journal of Chemical Physics

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“…Note that increasing the sulfate concentration not only influences surface acidity, but also the degree of surface hydration as determined by TGA-MS (low temperature mass loss and evolved water in Figure 2a, Figure S1 and Table 2). High S loadings therefore enhance the hydrophilicity of our SZ catalysts which is known to suppress fatty acid esterification with methanol due to active siteblocking and/or promotion of the reverse ester hydrolysis reaction [45][46][47]. Hence the 1.7 wt % catalyst may deliver maximum esterification performance due to the combination of a high concentration of strong acid sites with significant Brønsted character, and relatively low surface hydrophilicity.…”

Section: Catalytic Esterification Of Propanoic Acidmentioning

confidence: 99%

“…MBOH decomposition yields acetone and acetylene over basic surfaces, but undergoes dehydration/isomerization over acidic surfaces to 3-methyl-3-buten-1-yne and/or prenal (3-methyl-2-buten-1-ol, (CH3)2C=CH-CHO); strong Brønsted-Lewis acid pairs are believed necessary to isomerize MBOH to prenal [45]. Amphoteric surfaces decompose MBOH to 3-methyl-3-buten-2-one (MIPK, CH3(C=O)-C(CH3)=CH2)) and 3-hydroxy-3-methyl-2-butanone (HMB, (CH3)2C(OH)-(C=O)-CH3)) [44].…”

Section: Methylbutynol Decompositionmentioning

confidence: 99%

Acidity-Reactivity Relationships in Catalytic Esterification over Ammonium Sulfate-Derived Sulfated Zirconia

et al. 2017

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New insight was gained into the acidity-reactivity relationships of sulfated zirconia (SZ) catalysts prepared via (NH 4 ) 2 SO 4 impregnation of Zr(OH) 4 for propanoic acid esterification with methanol. A family of systematically related SZs was characterized by bulk and surface analyses including XRD, XPS, TGA-MS, N 2 porosimetry, temperature-programmed propylamine decomposition, and FTIR of adsorbed pyridine, as well as methylbutynol (MBOH) as a reactive probe molecule. Increasing surface sulfation induces a transition from amphoteric character for the parent zirconia and low S loadings <1.7 wt %, evidenced by MBOH conversion to 3-hydroxy-3-methyl-2-butanone, methylbutyne and acetone, with higher S loadings resulting in strong Brønsted-Lewis acid pairs upon completion of the sulfate monolayer, which favored MBOH conversion to prenal. Catalytic activity for propanoic acid esterification directly correlated with acid strength determined from propylamine decomposition, coincident with the formation of Brønsted-Lewis acid pairs identified by MBOH reactive titration. Monodispersed bisulfate species are likely responsible for superacidity at intermediate sulfur loadings.

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“…Diverse solid Scheme 5 Protocol for the synthesis of sulfonic acid and octyl cofunctionalised sulfonic acid MCM-41catalysts. Adapted from reference [101] with permission from The Royal Society of Chemistry base catalysts are known, notably alkali or alkaline earth oxides, supported alkali metals, basic zeolites and clays such as hydrotalcites and immobilised organic bases [104]. Basicity in alkaline earth oxides is believed to arise from M 2?…”

Section: Heterogeneously Catalysed Routes To Biodieselmentioning

confidence: 99%

Catalysing sustainable fuel and chemical synthesis

Lee

2014

Appl Petrochem Res

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Concerns over the economics of proven fossil fuel reserves, in concert with government and public acceptance of the anthropogenic origin of rising CO 2 emissions and associated climate change from such combustible carbon, are driving academic and commercial research into new sustainable routes to fuel and chemicals. The quest for such sustainable resources to meet the demands of a rapidly rising global population represents one of this century's grand challenges. Here, we discuss catalytic solutions to the clean synthesis of biodiesel, the most readily implemented and low cost, alternative source of transportation fuels, and oxygenated organic molecules for the manufacture of fine and speciality chemicals to meet future societal demands.

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Interdependent lateral interactions, hydrophobicity and acid strength and their influence on the catalytic activity of nanoporous sulfonic acid silicas

Cited by 114 publications

References 43 publications

Controlling reactivity of nanoporous catalyst materials by tuning reaction product-pore interior interactions: Statistical mechanical modeling

Controlling reactivity of nanoporous catalyst materials by tuning reaction product-pore interior interactions: Statistical mechanical modeling

Acidity-Reactivity Relationships in Catalytic Esterification over Ammonium Sulfate-Derived Sulfated Zirconia

Catalysing sustainable fuel and chemical synthesis

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