Propylsulfonic Groups Research Articles

Guest-Assisted Proton Conduction in the Sulfonic Mesoporous MIL-101 MOF.

Post-synthesis modification of MIL-101(Cr)-NO2 was explored in order to decorate the organic backbone by propyl-sulfonic groups, with the aim to incorporate mobile and acidic protons for solid-state proton electrolyte applications. The resulting solid switched from insulating towards proton superconductive behavior under humidity, while the conductivity recorded at 363 K and 95 % relative humidity reached 4.8×10-3 S cm-1 . Propitiously, the impregnation of the material by strong acidic molecules (H2 SO4 ) further boosted the proton conductivity performances up to the remarkable σ value of 1.3×10-1 S cm-1 at 363 K/95 % RH, which reaches the performances of the best proton conductive MOF reported so far.

Methyl ester production by esterification/transesterification reactions on continuous test using SBA-15 catalyst

Esterification/transesterification reactions were carried out with the purpose to bring more economicity to biodiesel process, limited nowadays by the feed cost. A possible integration with a transesterification reaction was studied, once a stream rich in fatty acid from physical distillation of tallow is available, and sold by the third of the biodiesel price for soap industry. To simulate a real fatty stream, obtained from physical distillation of acid feeds in Biodiesel Units, it was used a mixture of 15% of soybean oil and 85% of oleic acid as feed. An optimization of synthesis conditions was performed to obtain a SBA-15 catalysts functionalized with methyl and propyl sulfonic groups. The best catalyst formulation (SBA-15E7) was tested on biodiesel production using a fixed bed for 600 h, at 200 °C and methanol/feed ratio of 7.8, with high WHSV (1.8 h−1) of triglyceride conversion, and producing 91% of methyl ester. The catalyst showed high stability with little amount of sulfur leached in the product due to the strong bonding of Si-C, indicating that it could be used on commercial fatty acid esterification. Moreover, the pros and cons about SBA-15 synthesis were well discussed in order to clarify difficulties of a future formulation scale-up.

Renewable glycerol esterification over sulfonic-modified mesoporous silicas

SO3H-functionalised mesoporous materials with different pore structures (SBA-15 and SBA-16) were prepared by the post-synthesis surface modification. The materials were thoroughly characterized by X-ray powder diffraction, nitrogen physisorption, temperature-gravimetric analysis, elemental analysis and solid state NMR spectroscopy. The acidic properties were investigated by the temperature-programed desorption of ammonia. The catalytic performance of SO3H-functionalised mesoporous materials was studied in glycerol esterification with acetic acid.The different amount of silanol groups in the initial SBA-15 and SBA-16 silicas predetermined the different amount of propylsulfonic groups which are formed in them and therefore significantly influenced the acidity and the catalytic performance in glycerol esterification. Much higher amount of Br?nsted acid sites was generated in SO3H modified SBA-15 catalyst, which exhibited higher activity to value-added triacetyl glycerol.

Mesoporous silica materials modified with aggregated transition metal species (Cr, Fe and Cr-Fe) in the role of catalysts for selective catalytic oxidation of ammonia to dinitrogen

Mesoporous silica sieves (SBA-15 and HMS) modified with propylsulfonic groups were used as supports for deposition of trinuclear acetate oligocations (Cr, Fe and Cr-Fe) by ion-exchange method. The obtained samples were characterized with respect to: textural parameters (low-temperature N2 adsorption), ordering of their porous structure (XRD), efficiency of organic functional groups anchoring (DRIFT, TG-DTG and elemental analysis), form and aggregation of deposited transition metal species (UV–vis-DRS), surface acidity (NH3-TPD), transition metal loadings (EDS microanalysis) and reducibility of deposited transition metal species (H2-TPR). The obtained samples were tested as catalysts for selective catalytic oxidation of ammonia by oxygen (NH3-SCO). Mesoporous silica supports modified with chromium and iron species were found to be active and selective catalysts in this process. Moreover, it was shown that the samples doped with mixed-metal oligocations (Cr2Fe1 or Cr1Fe2) were characterized by better catalytic activity in comparison to the samples modified with monometallic species (Cr3 or Fe3).

SBA-15 loaded with iron by various methods as catalyst for DeNOx process

SBA-15 modified with iron by various methods was tested as catalyst of the DeNOx process. Two methods were used for deposition of iron: (i) molecular designed dispersion method to introduce Fe in the form of monomeric cations and (ii) ion-exchange of iron acetate oligocations, [Fe3O(OAc)6·AcOH·2H2O]+, for SBA-15 modified with propylsulfonic groups to introduce aggregated iron oxide species. The obtained samples were characterized with respect to: textural parameters (low-temperature N2 adsorption), structure (XRD, TEM), efficiency of surface species anchoring (DRIFT, FTIR-PAS, TG-DTG and elemental analysis), form and aggregation of deposited iron species (Mössbauer spectroscopy, UV-vis-DRS, H2-TPR, CO-FTIR), distribution of iron oxide species in the samples (TEM-EDX). SBA-15 modified with iron was found to be effective catalysts of selective reduction of NO with ammonia. It was suggested that iron deposited in the form of aggregated FeOx species presents higher catalytic activity in the studied process comparing to monomeric Fe3+ cations.

SBA-15 mesoporous silica highly functionalized with propylsulfonic pendants: A thorough physico-chemical characterization

Organosulfonic modified SBA-15 silicas are promising catalysts for a wide spectrum of organic reactions. In particular, their catalytic activity seems to be effective only when large amounts of functional groups are anchored to the silica skeleton. However, there is evidence that the ordered mesostructure is retained only for contents of sulfonic units not exceeding 20 mol%.In this paper, for the first time to our knowledge, we fully address the gradual structural disordering mechanisms of the SBA-15 silica functionalised with increasing amounts of propylsulfonic groups in the compositional range 0–70 mol%. This investigation was carried out by means of a multi-technique wide approach including thermal analysis, TEM, XRD, N2 adsorption, FTIR/Raman and solid-state multinuclear NMR.We obtained detailed information on the structural modifications of these hybrid systems as a consequence of the sulfonation process. In particular, we showed that high functionalization degrees lead to inhomogeneous materials made of inorganic or low-functionalized clusters where the SBA-15 structure is likely retained, and hybrid clusters where the hexagonal mesoporous structure is destroyed. Moreover, full conversion of –SH into –SO3H groups is efficient until 20 mol% functionalization. In fact for higher sulfonation degrees, the formation of S–S bridges becomes a competitive mechanism, which is predominant in the sample SO3H70%, where only about 20% of the introduced organic moieties are actually oxidized. Therefore, to push sulfonic functionalization above 20 mol% is not necessarily useful, at least for applications where ordered mesoporous structure is mandatory, such as in catalysis or in membranes for polymer fuel cells.

Transformation of non-edible vegetable oils into biodiesel fuels catalyzed by unconventional sulfonic acid-functionalized SBA-15

A real understanding of intrinsic acidity and catalytic property of unconventional and sulfonic acid-functionalized SBA-15 platelet catalysts synthesized with the aid of highly solvated Zr4+ salts (shortly termed SA-SBA-15-p) for transesterification of non-edible vegetable oils into biodiesel fuel (BDF) was reported, in comparison with conventional SBA-15 catalyst (shortly termed SBA-15-conv), unconventional SBA-15 platelet catalyst (shortly termed SBA-15-p) and commercial sulfonic resins of Amberlyst-15 and SAC-13. Thorough characterizations and catalytic study revealed that the content of fatty acid methyl ester (FAME) as the main component of BDF was increased in the order of SBA-15-conv<SAC-13<SBA-15-p<Amberlyst-15<5-25SA-SBA-15-p, which correlated closely with the loading, distribution, strength of acidic sites. Among them, the unconventional 15SA-SBA-15-p catalyst with proper loadings of propylsulfonic groups (1.15mmolS−1g−1) and superficial Zr4+ clusters (0.66mmolg−1) as a mixed solid Bronsted and Lewis acid, which had differential heat of NH3 adsorption in the range of 90–125kJmol−1, gave highest FAME content with low concentrations of byproducts, such as glycerides and free fatty acid (FFA). In addition to high water and FFA tolerance levels, the used 15SA-SBA-15-p catalyst could be easily regenerated by ethanol extraction and its high activity was maintain. By contrast, the SBA-15-conv catalyst without any Lewis and Bronsted acids had almost no activity in BDF synthesis. The unconventional SBA-15-p catalyst with superficial Zr4+ clusters as a pure solid Lewis acid gave a moderate FAME content accompanying with a high concentration of unreactive glycerides. Commercial sulfonic resins of Amberlyst-15 and SAC-13 with strongly phenylsulfonic and Nafion sulfonic groups as pure solid Bronsted acids gave moderate FAME contents accompanying with high concentrations of unreactive glycerides and unwanted FFA byproducts. Furthermore, they were significantly deactivated by water, FFA and regeneration treatment due to the poison and leaching of sulfonic groups and the decomposition of thermally unstable framework.

Shape-selective organic–inorganic zeolitic catalysts prepared via interlayer expansion

Interlayer expansion of layered zeolite precursors is achieved via the insertion of an additional T-atom in between the layers, typically by means of a silylating agent as source of the T-atom. (3-Mercaptopropyl)methyldimethoxysilane was used as Si-source in the interlayer expansion of the layered zeolite precursors RUB-36 and RUB-39. The structure expansion was confirmed with PXRD. The incorporation of the silylating agent was followed with 29Si MAS NMR, 13C CP MAS NMR and thermogravimetric analysis. The incorporated thiol groups were oxidized with H2O2 to obtain sulfonic acid groups in between the layers. 13C CP MAS NMR was used to characterize the organic species and monitor the conversion of thiol to propylsulfonic groups. The shape-selective properties of the obtained materials were investigated in acid-catalyzed tetrahydropyranylation reactions.

Efficient and stable solid acid catalysts synthesized from sulfonation of swelling mesoporous polydivinylbenzenes

Abstract Efficient and stable solid acid catalysts, sulfonic groups functional swelling mesoporous polydivinylbenzenes (PDVB- x -SO 3 Hs), were synthesized from sulfonation of swelling mesoporous polydivinylbenzenes (PDVB- x s) by chlorosulfonic acid in CH 2 Cl 2 . Nitrogen adsorption–desorption isotherms showed that PDVB- x -SO 3 Hs have high surface area and abundant mesoporosity. Elemental analysis and acid–base titration techniques showed that PDVB- x -SO 3 Hs have high concentration of sulfonic groups. Esterifications of acetic acid with cyclohexanol, hexanoic acid with ethanol, lauric acid with ethanol and acylation of anisole with acetyl chloride showed that PDVB- x -SO 3 Hs are more active than arenesulfonic, propyl-sulfonic groups functional mesoporous silicas (SBA-15-Ar-SO 3 H, SBA-15-Pr-SO 3 H) and strongly acidic ion-exchange resin (Amberlyst 15). The superior performance of PDVB- x -SO 3 Hs is attributed to their unique features including large surface area, abundance of mesoporosity as well as high content of sulfonic groups.

Luminescence of Intraporous Cerium(III) Complexes in Alkyl Sulfonic Mesoporous Silica

Mesoporous silica materials derivatized with propyl-sulfonic groups (SBA-15) with a monovalent cation-exchange capacity of ∼1 meq/g were exchanged with Ce(III) ions to ∼0.5 meq/g to form Ce(III)SBA material displaying high-intensity purple photoluminescence. XPS and NIR-DRS analysis suggests the Ce(III) ion is bound to two proximal propyl-sulfonate groups and capped with a hydroxyl in a complex [≡Si−(CH2)3SO3]2Ce(III)OH·xH2O (x > 4), where the coordinated water can be almost completely removed by anoxic dehydration at 350 C to x < 0.2. The white hydrated (x ≥ 4) CeSBA and the brown-colored dehydrated (x < 0.2) CeSBA exhibit fluorescence with comparable integrated intensities at 368 and 394 nm, respectively. The Ce(III) 4f electron is located by XPS above the top of the Si 3p O 2p valence band, thus identifying the Ce(III) 4f orbital as the HOMO. Photoluminescence emission and excitation spectra of the 5d → 4f transition display Stokes shifts and structure sensitivity consistent with a direct transition pr...

Etherification of benzyl alcohols with 1-hexanol over organosulfonic acid mesostructured materials

Etherification of benzyl alcohols with 1-hexanol was performed in liquid-phase over propyl- and arene-SO 3H-modified mesostructured SBA-15 silica. H 2O TPD measurements indicate a stronger interaction of arene-sulfonic acid sites with water molecules than that occurring in propyl-sulfonic groups. Hence, the higher catalytic activity of propyl-sulfonic-modified SBA-15 material is related to the more hydrophobic microenvironment of –SO 3H sites which reduces the acid site deactivation associated with adsorption of water generated during the reaction. Moreover, propyl- and arene-sulfonic functionalized SBA-15 materials show a clear improvement of the catalytic performances as compared to other commercial homogeneous and heterogeneous acid catalysts in this particular reaction.

Catalytic application of sulfonic acid functionalized mesoporous benzene–silica with crystal-like pore wall structure in esterification

The first catalytic applications of sulfonic acid-functionalized hydrophobic mesoporous benzene–silica with lamellar pore wall structure are reported. The mesoporous benzene–silica attached with propylsulfonic groups to the crystal-like periodic pore walls exhibited the catalytic activity in the esterification of acetic acid with ethanol. The catalytic results show the higher conversion compared to the commercial Nafion-H.

Ethane-bridged hybrid mesoporous functionalized organosilicas with terminal sulfonic groups and their catalytic applications

The synthesis of a new class of sulfuric acid-functionalized ethane-bridged, mesoporous hybrid organosilicas is reported where the propylsulfonic groups attached with ethane-bridged silica exhibited reasonable catalytic activity in esterification of acetic acid with ethanol as well as the hydrolysis of cyclohexylacetate. Materials were synthesized by co-condensation of ethane-bridged organosilane (MeO)3SiCH2CH2Si(OMe)3 with 3-mercaptopropyltrimethoxysilane (MeO)3SiCH2CH2CH2SH in the presence of octadecyltrimethylammonium chloride surfactant. Powder X-ray diffraction patterns and nitrogen sorption analysis reveal the formation of mesoporous material with uniform porosity. The maximum content of incorporated mercaptopropylsilane in the mesoporous framework obtained was 3.45 mmol g−1. The thiol (–SH) moieties of mercaptopropyl groups that protrude into the pore channels are readily accessible for further oxidation. The surface moieties functionalized with propylsulfonic groups (–CH2CH2CH2–SO3H) were generated by the controlled oxidation of propylthiol surface groups using concentrated HNO3. A maximum acid exchange capacity (acid–base titration methods) of 1.38 H+ mmol g−1 was achieved after oxidation. Further, the materials were characterized using elemental analysis, FT-IR, 29Si and 13C MAS-NMR, transmission electron microscopy and TGA. Two probe reactions, the esterification of acetic acid with ethanol and its reverse the hydrolysis of cycloacetonate, showed the significance of the material in catalytic applications. The catalytic results showed the esterification activity is comparable to that of commercial Nafion-H and also the involvement of hydrophobic nature of the material in the hydrolysis reaction.

HPLC determination of (+)-pseudoephedrine and (-)-ephedrine in Japanese herbal medicines containing Ephedra herb using solid-phase extraction.

We developed a rapid and simple HPLC method combined with solid-phase extraction (SPE) for quantitative analysis of (+)-pseudoephedrine (PEP) and (-)-ephedrine (EP) in Japanese herbal (Kampo) medicines such as Kakkon-to, Sho-seiryu-to, Goshaku-san and Bofu-tsusho-san. SPE was performed on TOYOPAK IC-SP M containing propylsulfonic groups. Determination of PEP and EP was carried out using ion-pair reversed-phase HPLC with sodium dodecyl sulfate. N-Benzyldiethylamine was used as an internal standard. The analytical procedure was validated with regard to specificity, linearity, accuracy, and precision. These data suggest that the analytical method developed in this study is useful for quantitative analysis of PEP and EP in various formulations of Kampo medicine containing Ephedra herb.