Fuming Sulfuric Acid Research Articles

Synthesis and Application of Bifunctional Porous Polymers Bearing Chloride and Sulfonic Acid as Cellulase-Mimetic Solid Acids for Cellulose Hydrolysis

A two-step strategy was demonstrated to synthesize porous polymeric solid acids with bifunctionality (chloride and sulfonic acid) to mimic cellulase for hydrolyzing cellulose. The solid acids were synthesized from aromatic monomers bearing chloride through Friedel-Crafts polymerization and then sulfonated with fuming sulfuric acid to introduce sulfonic acid. The chloride and sulfonic acid were expected to function as the cellulose-binding group (CBG) and the cellulose-hydrolytic group (CHG), respectively. It was found that the synthesized cellulase-mimetic solid acids were more effective in hydrolyzing microcrystalline cellulose (Avicel) than non-cellulase-mimetic solid acid (Amberlyst 15) and sulfuric acid at the same acid loading. Ball-milled Avicel could be hydrolyzed by up to 84.9 % by the cellulase-mimetic solid acids. The performance of the solid acids was supposedly attributed to the synergetic roles of the CBG and the CHG and the porous structure of the synthesized solid acids.

Sulfated Pillared Clay as Catalyst in Glycerol Esterification with Caprylic Acid

Sulfated pillared clay (AP-S) was tested in the catalytic conversion of glycerol by esterification reaction with caprylic acid (octanoic acid, OA). The clay was treated with concentrated fuming sulfuric acid. The presence of sulfur as well as an increase in the acidity of the solid demonstrate the suitability of the sulfatation process. The best conditions for the esterification reaction with OA were OA:glycerol molar ratio 8:1, 423 K and 5 wt% catalyst. Total glycerol conversion was achieved after 5 h and yield of 27, 43 and 30 % respectively for monocarpylin, dicaprylin and tricaprylin were obtained.

Enhancing the biodiesel manufacturing process by use of glycerin to produce hyacinth fragrance

Oxidized and sulfonated-activated carbons (AC) were tested in the catalytic conversion of glycerol by acetalization reactions. The solids were treated with concentrated nitric acid and/or fuming sulfuric acid (AC, AC-N, AC-S, and AC-NS). The presence of sulfur and an increase in the acidity of the solids demonstrate the suitability of the oxidation as well as the sulfonation process, especially in the sample treated with concentrated nitric acid and fuming sulfuric acid (AC-NS). The best catalyst for the reaction of glycerol acetalization with phenylacetaldehyde was AC-NS, with a phenylacetaldehyde conversion of 95 % after 90 min at 383 K and selectivity of 88 and 12 %, respectively, to dioxolane and dioxane. These products can be used as hyacinth fragrance flavoring compounds. Furthermore, a contribution of homogeneous catalysis in these systems was not identified. Thus, we identified a possibility of glycerol conversion, a biodiesel by-product, into value-added products by suitable catalysts produced from activated carbons.

Improvement of the Nitration Process in 2-Amino-5-chloro-4-methylbenzenesulfonic Acid Synthesis

The nitration process as one step in 2-amino-5-chloro-4-methylbenzenesulfonic acid synthesis was improved by optimizing nitration reaction conditions, improving product separation method to eliminate salty scrap acid and cycle use of the concentrated sulfuric acid. The effect of various parameters such as temperature, quality of fuming sulfuric acid, quality of fuming nitric acid, and reaction time was studied for optimization of the nitration reaction condition. In the optimum conditions, the mass ratio of fuming sulfuric acid to sodium 2-chlorotoluene-4-sulfonate and molar ratio of fuming nitric acid to sodium 2-chlorotoluene-4-sulfonate were 4 and 1.05, respectively. The reaction temperature was −5 °C, and the time of reaction was 3 h. By applying the optimum reaction conditions, the yield of nitration reaction was increased to 91%, larger than that of the current industrial process whose yield is only 65.7%. The solubilities of sodium 2-chloro-5-nitrotoluene-4-sulfonate in aqueous sulfuric acid soluti...

Biodiesel production from Silybum marianum L. seed oil with high FFA content using sulfonated carbon catalyst for esterification and base catalyst for transesterification

In this research work, waste of polyethylene terephthalate (PET) was converted into activated carbon and the latter was used in the preparation of a carbon acid catalyst. Waste of PET was converted into activated carbon via carbonization and steam activation, then the activated carbon was sulfonated using fuming sulfuric acid in order to produce the carbon acid catalyst. The prepared carbon acid catalyst was tested for esterification of high acid value non-edible oil, Silybum marianum L. seed oil (SMSO) via optimized protocol. Amount of the carbon acid catalyst, methanol to oil molar ratio, temperature and time were the experimental variables optimized. Esterification of SMSO with methanol using the prepared carbon acid catalyst reduced its parent acid value (20.0mgKOH/g) to the acceptable limits for base-catalyzed transesterification (<2.0mgKOH/g) using 6.0% w/w of the catalyst, 15:1 methanol to oil molar ratio, 68°C reaction temperature and 180min of reaction. The performance of the catalyst was reduced gradually during its recycling and reached to 60.0% at the 5th cycle. Kinetics of esterification of SMSO using the prepared carbon acid catalyst followed pseudo first order kinetics, and the activation energy was found to be 70.98kJ/mol. The esterified oil was converted to biodiesel through optimized base-catalyzed transesterification with methanol. Biodiesel with (96.98% yield and purity of 96.69% w/w) yield was obtained using 0.80% KOH w/w, 6:1 methanol to oil molar ratio, 60°C reaction temperature, 75min of reaction and 600rpm rate of stirring. The biodiesel properties were within the recommended biodiesel standards as prescribed by ASTM D 6751 and EN 14214. Transesterification of the esterified oil was found to fellow first order kinetics, and the activation energy was calculated to be 17.92kJ/mol.

Glycerol conversion into value-added products in presence of a green recyclable catalyst: Acid black carbon obtained from coffee ground wastes

Black carbon from coffee grounds (BCC) was treated with sulfuric acid (BCC-S) or fuming sulfuric acid (BCC-SF) and utilized as catalysts in glycerol etherification reactions. The BCC-SF showed a high amount of sulfur groups, about 8%. However, the treated BCC-S showed the lowest amount of sulfur groups, about 3%. Furthermore, these catalysts show high catalytic activity in the glycerol etherification with tert-butyl alcohol (TBA), the activity being higher for the BCC-SF. The yields for mono-tert-butyl glycerol (MTBG), di-tert-butyl glycerol (DTBG) and tri-tert-butyl-glycerol (TTBG) were very similar to those obtained using a commercial resin, Amberlyst-15. The yields for BCC-SF were about 40 and 20% for the MTBG and DTBG + TTBG, respectively. Furthermore, the acid black carbons showed high stability of the active groups and can be reused in consecutive reactions.

Sulfated Zirconium Catalyst for Synthesis of Dialkylated Diphenylether Disulfonate Gemini Surfactants

AbstractDialkylated diphenylether disulfonate with different alkyl chain lengths (Cn‐DADS, n = 8, 10 and 12) has been synthesized by Friedel‐Crafts alkylation of olefins (C8, C10 and C12) and diphenyl oxide, followed by sulfonation and neutralization with fuming sulfuric acid. Sulfated zirconia solid acids were prepared and used to catalyze the alkylation reaction. The structure of sulfated zirconia solid acids was identified by infrared spectroscopy. The title compounds were confirmed by infrared spectroscopy and electrospray ionization‐mass spectrometry. Equilibrium surface tension measurements show that the critical micelle concentration (CMC) decreases with an increase in chain length, and the surface tension at CMC (γcmc) of C8‐DADS is the lowest. The minimum area per molecule (Amin) values of Cn‐DADS increase, while the surface excess concentration (Γmax) values decrease with the increase of the alkyl chain length. C10‐DADS has the highest pC20 and CMC/C20 among Cn‐DADS.

Application of sulfonated nanoporous carbons as acid catalysts for Fischer esterification reactions

Heterogeneous acid catalysts were prepared by sulfonation of nanoporous carbons (NPCs). The NPCs were produced by pyrolysis of resorcinol–formaldehyde nanoporous resins (NPRs). The NPRs were synthesized as wet gels by condensation of resorcinol and formaldehyde in a sol–gel polycondensation using Na2CO3 as catalyst. A cationic polyelectrolyte (poly(diallyl dimethyl ammonium chloride)) was used as pore stabilizer, allowing to dry the gels in air without any special procedures. Five NPRs with different properties were synthesized by varying the monomer to catalyst ratio (Resorcinol/Na2CO3, R/C). The morphological and textural characterizations of the NPCs were performed by scanning electron microscopy and nitrogen adsorption–desorption isotherms. The results indicate that using a molar ratio of R/C=200, a nanoporous carbon NPC with large surface area (695m2/g) is obtained. This NPC was sulfonated by reaction with three different sulfonating agents: (i) concentrated sulfuric acid; (ii) fuming sulfuric acid and (iii) chlorosulfonic acid in order to obtain a novel Fischer esterification catalyst. The amount of acid groups attached to the NPC surface was determined by titration using a modified Boehm method. The catalytic activity, for Fischer esterification reaction of different sulfonated NPCs, was compared with sulfonated NPRs, sulfonated commercial porous carbons and polymeric acid catalyst (cationic ion exchange resins, sulfonated fluoropolymers). The modification of NPCs with concentrated sulfuric acid seems to render the materials with more catalytic activity. The best sulfonated material NPC (PC200-H2SO4) shows a high catalytic activity for the esterification of acetic acid (90.8%) and oleic acid (60.6%) with ethanol. The conversion and conversion rate values are better than commercial acid catalysts. The results suggest that sulfonated NPC catalysts are promising materials for the synthesis of biodiesel and related reactions.

Detecting the Genesis of a High-Performance Carbon-Supported Pd Sulfide Nanophase and Its Evolution in the Hydrogenation of Butadiene

A new procedure for preparation of palladium sulfide nanoparticles, which are deposited and anchored over highly graphitized carbon nanofibers, is presented. The preparation method is based on the use of PdSO4 as metal precursor or alternatively in the previous functionalization of the carbon surfaces with sulfonic groups by treatment with fuming sulfuric acid. Using an in situ high-energy X-ray diffraction technique, in both cases it is demonstrated that during the reduction treatment, the initially present palladium hydride is transformed into a palladium sulfide (Pd4S). The catalytic properties of these materials have been tested in the gas-phase butadiene partial reduction to butenes. Although metallic palladium nanoparticles supported in the same carbon fibers produce butane as the principal product, the supported Pd4S nanocrystals mainly yield different isomers of butenes independently of the conversion level. Furthermore, applying the same X-ray diffraction method reveals that this catalytic phase is stable during reaction.

Development of a Continuous Flow Sulfoxide Imidation Protocol Using Azide Sources under Superacidic Conditions

The development of a continuous flow sulfoxide imidation protocol for a pharmaceutically relevant target molecule is described. Sulfoxide imidation is a key step in the preparation of certain ATR kinase inhibitors. Reactions with NaN3 or TMSN3 and concentrated sulfuric acid under literature conditions provided low conversions and poor selectivities. In contrast, reactions employing fuming sulfuric acid afforded the target sulfoximine with a selectivity of ∼90% after a reaction time of only 10–15 min at 50 °C. The imidation reaction using TMSN3 as reagent was successfully performed in a flow reactor utilizing CH2Cl2/H2SO4 biphasic conditions. The mixture was subsequently quenched in-line with H2O. Phase separation, neutralization, and re-extraction with an organic solvent furnished the product in excellent purity and good yields, albeit with loss of chirality.

Synthesis and characterization of sulfonated poly(p-phenylenediamine) prepared by different procedures

The sulfonation of poly(p-phenylenediamine) (P(pPD)) polymer was reported and described in this study. The sulfonated P(pPD) polymers (SP(pPD)) with a degree of sulfonation (S/N molar ratio) range of 0.07–0.38 were prepared using two different methods; postsulfonation of P(pPD) polymers with fuming sulfuric acid under different reaction conditions and chemical oxidative copolymerization of p-phenylenediamine (pPD) and 2,5-diaminobenzenesulfonic acid (DABSA) monomers with different ratios, using sodium persulfate ((Na)2S2O8) as an oxidant. The SP(pPD) polymers obtained were fully characterized and compared by FT-IR, 1H and 13C NMR, GPC, WAXD, TGA and SEM. The results obtained showed that the yield, molecular weight, solubility, degree of sulfonation, molecular and morphological structure, and thermal stability of the SP(pPD) polymers are significantly dependent on the polymerization conditions and the sulfonation method. The solubility of SP(pPD) polymers was significantly improved compared to the P(pPD) polymer in most solvents due to the steric effect of the sulfonic groups (−SO3H). On the other hand, the yield, molecular weight and conductivity values obtained for the SP(pPD) polymers were always lower than the values found for P(pPD) polymer, which was attributed to the steric hindrances and the electro-withdrawing effects of the sulfonic groups on the aromatic rings. The TGA results revealed that P(pPD) and SP(pPD) polymers have good thermal stability and decompose above 300 °C in nitrogen.

Synthesis and Surface Properties of Disodium Monoalkyl Diphenyl Oxide Disulfonate

AbstractDisodium monoalkyl diphenyl oxide disulfonates (MADS) with different carbon chains (Cn‐MADS, n = 8, 12, 16) were synthesized through the steps of alkylation‐sulfonation‐neutralization using fatty alcohols (C8, C12, C16), diphenyl oxide and fuming sulfuric acid (20 % free SO3) as reagents. The structures of the products were identified by infrared spectroscopy and electrospray ionization‐mass spectrometry. The surface properties, emulsification, wettability alteration and salinity and hardness tolerance of the products were systematically investigated. The results show that the critical micelle concentration (CMC) of C8MADS, C12MADS and C16MADS are 7.24 × 10−3, 1.49 × 10−3 and 2.09 × 10−4 mol/L. The surface tensions at the CMC (γCMC) of each product are 37.5, 38.9 and 46.8 mN/m. The negative logarithm of the surfactant concentration in the bulk phase required to produce a 20 mN/m reduction in the surface tension of the solvent (pC20) increases with the increase in the alkyl chain length. The emulsifying ability of C12‐MADS is better than C8‐MADS and C16‐MADS, and the MADS showed less oil‐wet nature. The salinity and hardness tolerance of MADS is much stronger than that of conventional surfactants.

Tellurium Sulfates from Reactions in Oleum and Sulfur Trioxide: Syntheses and Crystal Structures of TeO(SO4), Te4O3(SO4)5, and Te(S2O7)2

AbstractThe reaction of K2TeO4 with fuming sulfuric acid (65 % SO3) in sealed glass ampoules at 250 °C led to colorless single crystals of TeO(SO4) [triclinic, P$\bar{1}$, Z = 8, a = 819.89(3) pm, b = 836.95(4) pm, c = 1179.12(5) pm, α = 82.820(2)°, β = 70.645(2)°, γ = 81.897(2)°, V = 753.11(6) × 106 pm3]. A horseshoe type [Te4O3] fragment is the basic motif in the layer structure of the compound. The [Te4O3] moieties are linked to infinite chains by further oxide ions. Monomeric [Te4O3] horseshoes are found in the crystal structure of Te4O3(SO4)5 [trigonal, P3221, Z = 3, a = 859.05(2) pm, c = 2230.66(7) pm, V = 1425.61(6) × 106 pm3], which was obtained from TeO2 and fuming sulfuric acid (65 % SO3) at 200 °C as colorless single crystals. By switching to neat SO3 as reaction medium colorless crystals of Te(S2O7)2 [P21/n, Z = 4, a = 1065.25(3) pm, b = 818.50(2) pm, c = 1206.27(3) pm, β = 102.097(1)°, V = 1028.40(5) × 106 pm3] form when ortho‐telluric acid, H6TeO6, is used as the tellurium source. The compound was reported previously, however, obviously with a wrong crystallographic description. In the crystal structure the tellurium atoms are coordinated by two chelating disulfate ions. Further Te–O contacts link the [Te(S2O7)2] units to an extended network.

Studies of sulfonated polyphenylene membranes containing benzophenone moiety for PEMFC

The sulfonated polyphenylenes containing benzophenone structure (sulfonated Parmax 1200, S-Parmax) were prepared by sulfonation reaction of Parmax 1200 with 30% fuming sulfuric acid, and degree of sulfonation was controlled by sulfonation reaction time. These polymers have all carbon structure without ether linkages that have the possibility of attack by nucleophiles (made by PEMFC operating system). The polyphenylene structure of Parmax provides a stiff and resistant backbone, whereas the pendant benzoyl group enables the solubility of the material, and also provides sites for chemical modifications. The structure properties of the synthesized polymers were investigated by 1H NMR spectroscopy. The membranes were studied by ion exchange capacity (IEC), water uptake, and proton conductivity. These membranes deterioration test was performed by Fenton reagent, and compared with normal sulfonated poly(ether sulfone)s and Nafion. The power densities of membranes were performed by single cell.

Sulfonated niobia and pillared clay as catalysts in etherification reaction of glycerol

Sulfonated niobia (HY-340 CBMM) and pillared clay (Fluka) were tested in the catalytic conversion of glycerol by etherification reactions. The solids were treated with concentrated fuming sulfuric acid (AS100 and NS100), and a 30% aqueous solution of this acid (AS30 and NS30). Both the presence of sulfur and the increase in the acidity of the solids demonstrate the suitability of the sulfonation process, especially in samples treated with concentrated fuming sulfuric acid. The best catalyst for the reaction of etherification with tert-butyl alcohol was AS100, with a glycerol conversion of 95% after 5h at 393K and yield of 60.3, 33.2 and 5.4%, respectively for mono-tert-butyl-glycerol (MTBG), di-tert-butyl-glycerol (DTBG) and tri-tert-butyl-glycerol (TTBG).

Solid state NMR study of chemical structure and hydrothermal deactivation of moderate-temperature carbon materials with acidic SO3H sites

Hydrothermal stability of carbon based acid catalysts synthesized by sulfonating carbohydrates pyrolyzed at moderate temperatures (300–600°C) has been reported previously. To test the effect of carbon structure on hydrothermal stability, we produced catalysts by dry pyrolysis at 350°C and 450°C or by hydrothermal carbonization, followed by sulfonation with fuming sulfuric acid, as well as by direct sulfonation of glucose. The catalysts were characterized by BET, titration, Raman spectroscopy, TGA, XPS, reaction testing, and 13C solid state NMR. Catalysts were hydrothermally treated and then analyzed for sulfur retention and catalytic activity. The lower temperature carbon catalysts showed the best stability, however all showed significant activity loss. Solid state NMR of materials made from 13C-glucose was used to characterize the structural details in an attempt to correlate functional groups to hydrothermal stability of catalyst active sites. Structural models generated from NMR data showed that the most stable catalysts contained a significant fraction of furan rings and hardly any polycondensed aromatic rings.

Hydrolysis of cellulose to produce glucose with solid acid catalysts in 1-butyl-3-methyl-imidazolium chloride ([bmIm][Cl]) with sequential water addition

Selective glucose production by cellulose hydrolysis with initial or sequential water addition in the presence of solid acid catalysts in 1-butyl-3-methyl-imidazolium chloride ([bmIm][Cl]) under microwave irradiation was investigated at 120 °C and 1.2 MPa of N2 atmosphere. For revealing the effect of water on cellulose hydrolysis in [bmIm][Cl], the phase behavior during the reaction was observed. Colored compounds formed at lower amounts of water, while some amounts of cellulose precipitated at higher amounts of water. Glucose yield was highest (65 mol%) at 25 wt% water in [bmIm][Cl] for the case of initial water addition. To improve the glucose yield, sequential water addition in which water was added in steps as the reaction proceeded was examined. Glucose yields in the presence of Amberlyst-15 in [bmIm][Cl] were 68.5 and 75.0 mol% by two-step and three-step water addition, respectively. Employing three-step water addition, Dowex 50wx8-100 (ion-exchange resin), hydrothermally synthesized carbon catalyst and three types of nano-zeolites were assessed. The carbon catalyst-modified fuming sulfuric acid and H-type zeolites (mordenite and faujasite) gave comparable glucose yields as Amberlyst-15. Sequential water addition is an effective technique for improving reaction efficiency in cellulose/solid acid catalyst/ionic liquid reaction systems.

Enhanced thermoelectric performance and ammonia sensing properties of sulfonated polyaniline/graphene thin films

Highly conducting nanocomposite film of polyaniline (Pani) with graphene (GN) was prepared by incorporating GN nanoplatelets in Pani matrix, followed by sulfonating it with fuming sulfuric acid. Sheet-like GN nanoplatelets were distributed uniformly in a Pani matrix, leading to high electrical conductivity due to π–π interaction between sulfonated Pani (s-Pani) and GN. Studies of the thermoelectrical behavior and ammonia-sensing behavior on GN@s-Pani showed high DC electrical conductivity retention under ageing conditions as well as excellent reproducible sensing response towards ammonia vapor in contrast to acid-protonated Pani.

Analysis of recycled poly (styrene-co-butadiene) sulfonation: a new approach in solid catalysts for biodiesel production

The disposal of solid waste is a serious problem worldwide that is made worse in developing countries due to inadequate planning and unsustainable solid waste management. In Mexico, only 2% of total urban solid waste is recycled. One non-recyclable material is poly (styrene-co-butadiene), which is commonly used in consumer products (like components of appliances and toys), in the automotive industry (in instrument panels) and in food services (e.g. hot and cold drinking cups and glasses). In this paper, a lab-scale strategy is proposed for recycling poly (styrene-co-butadiene) waste by sulfonation with fuming sulfuric acid. Tests of the sulfonation strategy were carried out at various reaction conditions. The results show that 75°C and 2.5 h are the operating conditions that maximize the sulfonation level expressed as number of acid sites. The modified resin is tested as a heterogeneous catalyst in the first step (known as esterification) of biodiesel production from a mixture containing tallow fat and canola oil with 59% of free fatty acids. The preliminary results show that esterification can reach 91% conversion in the presence of the sulfonated polymeric catalyst compared with 67% conversion when the reaction is performed without catalyst.

Fabrication of Low-Fouling Ultrafiltration Membranes Using a Hydrophilic, Self-Doping Polyaniline Additive

A simple, scalable method for fabricating fouling-resistant ultrafiltration membranes is described. A self-doped, sulfonated form of polyaniline was blended into polysulfone (PSf) ultrafiltration (UF) membranes to enhance hydrophilicity and fouling resistance. Polyaniline in its base form was sulfonated with fuming sulfuric acid, yielding sulfonated polyaniline (SPANi) with a degree of sulfonation of ∼0.5 confirmed by XPS. The SPANi polymer was dedoped and dissolved in a solution of polysulfone in N-methylpyrollidone at varying concentrations. During phase inversion to form membranes, SPANi is redoped and precipitated within the PSf membrane films in a facile one-step process. Composite membranes containing increasing amounts of SPANi were compared to the pure PSf membranes to determine changes in performance, hydrophilicity, and antifouling characteristics. The composite membranes exhibit fluxes similar to those of the pure PSf membrane and maintain rejection properties similar to those of current UF mem...