Sulfated Oxide Research Articles

Enhancement in Conversion and Selectivity of Trivalerin Using Reactive Distillation

The feasibility and potential of reactive distillation was studied to evaluate the enhancement in trivalerin selectivity in the esterification of valeric acid with glycerol using n-octane as an entrainer over sulfated iron oxide catalyst. Effect of process parameters such as entrainer loading, reaction temperature and reaction time was evaluated. Results have indicated that the selectivity towards trivalerin can be enhanced up to 95.07%, in comparison to batch process (74.80%) using stoichiometric molar ratio which describes the novelty of this work. Kinetic models such as Pseudohomogeneous, Eley Rideal, and Langmuir-Hinshelwood model were used to study the kinetics of the reaction. Eley Rideal model supported the proposed mechanism with higher reliability and accuracy, resulting in the activation energy of 23.77 kJ/mol, which is plausibly less as compared to batch process (27.37 kJ/mol).

Acidic and catalytic co-functionalization for tuning the sensitivity of sulfated tin oxide modified by ruthenium oxide to ammonia gas

This work is aimed at elaborating a route for co-modification of acidic and catalytic sites on the surface of nanocrystalline tin oxide with the aim to enhance the sensitivity to ammonia gas. Sulfated tin oxide with controlled amount 0–10 wt.% of SO42− as the acidic modifier was synthesized by wet chemical deposition. It was modified by the catalytic additive of ruthenium oxide (0–5 wt.% Ru). Surface acidity was evaluated by temperature-programmed desorption and in situ infrared spectroscopy of adsorbed ammonia. The concentration of Lewis and Broensted acid sites was strongly dependent on sulfate content. Increasing amount of ruthenium oxide depressed surface acidity of catalytically-modified materials. Sensor response to 2–100 ppm NH3 in air was measured depending on the materials composition. At Ru-loading lower 0.5 wt.% the sensor signal was detected at temperature 200–300 °C and its value was monotonously dependent on SO42− content. The highest ammonia sensitivity was detected at lower temperature of 140–150 °C for co-functionalized tin oxide with comparable contents of Ru and SO42− (1–3 wt.%). From the sensing tests and in situ infrared spectroscopy data it was deduced that the improved sensing of ammonia gas was provided by equivalent impacts from the processes of target molecules adsorption on sulfate-promoted acid sites and NH3 oxidation on the catalytic clusters of ruthenium oxide.

Active Species of Sulfated Metal Oxide Catalyst for Propane Dehydrogenation

Active Species of Sulfated Metal Oxide Catalyst for Propane Dehydrogenation

Surface Characterization of Sulfated Iron Oxide and Its Synthesis of Biodiesel Under Microwave Radiation

AbstractThe solid acid catalysts SO42−/Fe2O3were prepared by impregnation technique, and the preparation conditions were different in calcination temperature, concentration of impregnation solution of H2SO4and impregnation time. The characterization was performed by using Fourier transform infrared spectrometer (FTIR), X-ray diffraction (XRD), Temperature programed desorption of NH3(NH3‒TPD), N2‒BET and microwave absorbing test. As shown by FTIR spectra, the S=O functional group existed in the sample, which was essential for the strong acidity of the SO42‒/MxOytype solid acids. The XRD results indicated that when the calcination temperature exceeded 400℃, iron in SO42‒/Fe2O3transformed from amorphous to crystalline phase. The results from NH3-TPD showed that the prepared sample possessed strong acid and superacid sites. As shown by N2-BET results, the BET surface area of the samples was up to 200m2/g, and their pore size distributions essentially belonged to mesoporous characteristic distribution. The SO42−/Fe2O3solid acid catalysts were used for the transesterification of castor oil under microwave radiation to produce biodiesel. The amounts of FAME in the product were analyzed by high-performance liquid chromatography. The highest yield of product was 65.3 wt.% when the reaction temperature was 65 ℃, alcohol/oil molar ratio was 30/1, catalyst loading was 20 wt.%, the reaction time was 3 h and the power of microwave was 300 w. Furthermore, the reaction results showed that SO42‒/Fe2O3had better catalytic activity under microwave radiation than under conventional heating condition.

Selectivity Engineering in Synthesis of Thymol Using Sulfated ZrO2–TiO2

Selective synthesis of thymol (6-isopropyl-3-methylphenol), a perfumery chemical, is challenging and was studied in this work by a continuous vapor phase alkylation of m-cresol using isopropyl alcohol over different solid acids. A series of novel zirconia–titania mixed sulfated oxides were prepared by the hydrothermal method and tested for isopropylation of m-cresol to prepare thymol. A sulfated catalyst with 2:1 mol ratio for zirconia/titania showed the best conversion and selectivity for thymol in a continuous fixed bed vapor phase reactor. The catalyst is stable and active for a long period of time, up to 20 h (TOS). Isopropylation of m-cresol was carried out in a continuous fixed bed vapor phase reactor under N2 as a carrier gas, 6.72/h WHSV, and 1:3 mol ratio of m-cresol to IPA at 220 °C. Reaction mechanism and kinetic model were developed. The reaction is kinetically controlled having an activation energy of 8.27 kcal/mol.

Sulfation of aluminum oxide and its structure and adsorption characteristics

Aluminum oxide was modified by sulfuric acid using the adsorption method under static and dynamic conditions, as well as through impregnation. The areas occupied by a molecule in a saturated monolayer on hydro- and dehydroxylated aluminum oxide were equal to 0.44 and 0.36 nm2, respectively. The dependence of the surface and adsorption properties and porosity characteristics of aluminum oxide on its thermal treatment and the modifying sulfo-groups content has been demonstrated. On aluminum oxide with a sulfo-group content close to that of the monolayer, the pyridine sorption proceeds on both Lewis and Bronsted acid sites. The increase of the contribution of specific interactions on the sulfated aluminum oxide was shown using the adsorption of saturated and aromatic hydrocarbons.

Nano-Structured Superacidic Sulfated Zirconium Oxide Catalyst: Synthesis, Characterization and Application in One-Pot Isomerization of n-Alkanes Predicting Their Reaction-Kinetics

Nano-Structured Superacidic Sulfated Zirconium Oxide Catalyst: Synthesis, Characterization and Application in One-Pot Isomerization of <i>n</i>-Alkanes Predicting Their Reaction-Kinetics

Adsorption and catalytic properties of sulfated aluminum oxide modified with cobalt ions

The adsorption properties of sulfated aluminum oxide (9% SO 4 2- /γ-Al2O3) and a cobalt-containing composite (0.5%Сo/SO 4 2- /γ-Al2O3) based on it are studied via dynamic sorption. The adsorption isotherms of such test adsorbates as n-hydrocarbons (C6–C8), benzene, ethylbenzene, chloroform, and diethyl ether are measured, and their isosteric heats of adsorption are calculated. It is shown that the surface sulfation of aluminum oxide substantially improves its electron-accepting properties, and so the catalytic activity of SO 4 2- /γ-Al2O3 in the liquid-phase alkylation of benzene with octene-1 at temperatures of 25–120°C is one order of magnitude higher than for the initial aluminum oxide. It is established that additional modification of sulfated aluminum oxide with cobalt ions increases the activity of this catalyst by 2–4 times. It is shown that adsorption sites capable of strong specific adsorption with both donating (aromatics, diethyl ether chemosorption) and accepting molecules (chloroform) form on the surface of sulfated γ-Al2O3 promoted by cobalt salt.

Efficiency enhancement in inverted planar perovskite solar cells by synergetic effect of sulfated graphene oxide (sGO) and PEDOT:PSS as hole transporting layer

We report a simple solution route for preparing a sGO-PEDOT composite HTL by combining solution-processable sGO with commercialized PEDOT:PSS solution. The PSCs based on these sGO-PEDOT composite HTLs were systematically investigated.

Porous sulfated metal oxide SO4 2−/Fe2O3 as an anode material for Li-ion batteries with enhanced electrochemical performance

Sulfated metal oxide SO42−/Fe2O3 was prepared by a novel facile sol–gel method combined with a subsequent heating treatment process. The as-synthesized products were analyzed by XRD, FTIR, and FE-SEM. Compared with the unsulfated Fe2O3, the agglomeration of particles has been alleviated after the incorporation of SO42−. Interestingly, the primary particle size of the SO42−/Fe2O3 (about 5 nm) is similar to its normal counterparts even after the calcination treatment. More importantly, SO42−/Fe2O3 exhibits a porous architecture, which is an intriguing feature for electrode materials. When used as anode materials in Li-ion batteries, SO42−/Fe2O3 delivered a higher reversible discharge capacity (992 mAh g−1), with smaller charge transfer resistance, excellent rate performance, and better cycling stability than normal Fe2O3. We believed that the presence of SO42− and porous architecture should be responsible for the enhanced electrochemical performance, which could provide more continuous and accessible conductive paths for Li+ and electrons.

Elementary Transformation of Glycerol to Trivalerin: Design of an Experimental Approach

A novel synthesis of trivalerin was accomplished from esterification of glycerol with valeric acid over sulfated iron oxide, a green catalyst. Trivalerin is a valuable compound, extensively acknowledged for its significance as an enzymatic substrate. It is an excellent coalescing and glycogenic agent. Moreover, it acts as an appropriate building block in the production of noteworthy pharmaceutical intermediates. A recent study has reported that trivalerin reduces the extent of Salmonella enteritidis colonization in chickens. This work scrutinizes trivalerin synthesis through single-step glycerol esterification. The effect on significant reaction parameters of trivalerin formation was explored by employing a response surface methodology at two factors and three levels with one central point in the central composite design. The catalyst revealed a maximal acid conversion of 85.5% at a reaction temperature of 453.15 K and a glycerol:valeric acid molar ratio of 5:3. The highest trivalerin selectivity of 74.89...

Power generation using a low-cost sulfated zirconium oxide based cathode in single chamber microbial fuel cells

Innovative and cost effective electrode materials to be used as cathodes in lab-scale MFC prototypes were prepared from mixtures of commercial Platinum on Vulcan (Pt/C) and sulfated zirconia (SZrO2). The catalytic activity of the SZrO2 based catalysts towards the oxygen reduction reaction (ORR) was studied by cyclic voltammetry (CV) and linear sweep voltammetry (LSV), showing comparable electrochemical activity between a mixture with one half of the platinum (Pt) amount and another one containing a higher percentage of Pt. Pt and SZrO2 mixtures showed similar catalytic performance compared to simple Pt/C used as a reference.SZrO2 was used as the cathodic catalyst in a microbial fuel cell (MFC) using phosphate buffer solution and sodium acetate as fuel. The maximum current density and power density recorded are 4220 (mA m−2) and 1079 (mW m−2), respectively. These values are better than those obtained using Pt/C (2539 mA m−2 and 662 mW m−2). Good performances were also reached with a platinum-free cathode based on SZrO2 supported on Vulcan (1420 mA m−2 and 536 mW m−2), demonstrating that these catalysts can be used as substitutes for commercial Pt/C.

Solid acid as catalyst for biodiesel production via simultaneous esterification and transesterification of macaw palm oil

Heterogeneous catalysis applied to esterification and transesterification of non-edible oil offers a strategy to the clean synthesis of the biodiesel and is driving research interested into the development of acid catalysts for efficient conversion of low quality vegetable oils into fuels to meet future societal demands. Thus, sulfated niobium oxide catalyst was synthesized by the impregnation method and used as a heterogeneous catalyst aimed at biodiesel production via macaw palm oil through high free fatty acid content transesterification with ethanol. The effect of two reaction parameters, molar ratio of ethanol to macaw palm oil and reaction temperature, on ester content and viscosity was studied by the response surface methodology (RSM). The ester content was determined by GC. The catalyst shows excellent activity (99.2% ester content and 4.5mm2/s viscosity) towards biodiesel production. Its optimum reaction conditions were: 120:1 molar ratio of ethanol to macaw palm oil at 250°C reaction temperature. The catalysts characterization was carried out by using the X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FT-IR), and N2 Adsorption-desorption and Surface Acidity Analyses.

Biodiesel additive ethyl levulinate synthesis by catalytic membrane: SO4−2/ZrO2 loaded hydroxyethyl cellulose

In this study, different catalytic membranes have been improved for use as heterogeneous acid catalyst to synthesize fuel bioadditive ethyl levulinate from levulinic acid and ethanol. Catalyst design was done by wet impregnation method. Catalytic membrane was prepared by solution casting method by loading of catalyst in hydroxyethyl cellulose polymer. Catalytic membranes including tungstosilicic acid hydrate, tungstosilicic acid supported on zirconium oxide and sulfated zirconium oxide were prepared and characterized. According to experimental results, sulfated zirconium oxide loaded catalytic membrane was found more effective when compared to the other catalytic membranes studied. Effects of reaction parameters such as reaction time, catalyst loading on membrane, reaction temperature, catalytic membrane amount, initial molar ratio on the conversion of levulinic acid were also investigated. Pseudo homogeneous second order kinetic model was applied to the experimental data. Activation energies and kinetic constants were determined. The theoretical conversion data were fitted well with the experimental data.

Production of biodiesel using HZSM-5 zeolites modified with citric acid and SO42−/La2O3

The present study aims at evaluating the efficiency of the HZSM-5 zeolite dealuminated with citric acid and modified with sulfated lanthanum oxide (SO42−/La2O3) as catalysts for the production of biodiesel via esterification. The effects of the treatments in the structural, textural and acid properties of produced catalysts were monitored by PXRD, adsorption/desorption of N2 and measurements of acidity by FTIR using pyridine and collidine as probe molecules. The catalysts were tested in the reaction of esterification using oleic acid and methanol as reactants. Different molar ratios (1:10, 1:20 and 1:45) and amounts of catalyst (2%, 5% and 10%) were tested and the conversion of oleic acid into methyl oleate analysed. Results show that the dealumination with citric acid and impregnation of SO42−/La2O3 over HZSM-5 produced catalysts more active for the conversion of oleic acid for the production of biodiesel, when compared to the parent HZSM-5 zeolite. The increase of external surface properties (acidity and area) was the main parameter influencing the activity of the catalysts for the considered reaction.

Erratum to: Processing Refinery Gas Streams into Environmentally Friendly Motor Fuels on Next-Generation Catalysts

In order to process refinery gas streams into environmentally friendly motor fuels, it has been proposed to use superacid catalytic systems based on sulfated zirconium oxide, mixed heteropoly acids, and nanosized nickel powder supported on acid-activated montmorillonite. We have studied the characteristics of the effects of temperature and catalyst composition on the oligomerization process of the butane—butene fraction, obtaining C5-C12 iso-olefins.

Synthesis and Characterization of Sulfonated Carbon-Based Graphene Oxide Monolith by Solvothermal Carbonization for Esterification and Unsymmetrical Ether Formation

Herein, we report solvothermal carbonization of biomass, such as glucose, in the presence of a small amount of graphene oxide (GO) as a structure-directing agent that yields a carbon-based graphene oxide monolith (CGO monolith). The CGO monolith was functionalized with chlorosulfonic acid under mild reaction conditions to achieve sulfated carbon-based graphene oxide (SO3H@CGO monolith). It was used for the esterification of levulinic acid with benzyl alcohol and the etherification of benzyl alcohol with butanol as model reactions. The activity of the catalyst was compared with different solid acid catalysts, such as GO, CGO monolith, nanocrystalline sulfated titania (NCST), SO3H@HTC (sulfated hydrothermal carbon), amberlyst-15, and SO3H@GO for esterification of levulinic acid with benzyl alcohol. The SO3H@CGO monolith showed excellent conversion (97%) toward benzyl levulinate at 110 °C with low catalyst loading (0.008 g/cm3) and mole ratio. The catalyst was well characterized by SEM, EDXA, TEM, XRD, FTIR,...

Structural and Spectroscopic Characterization of A Nanosized Sulfated TiO₂ Filler and of Nanocomposite Nafion Membranes.

A large number of nano-sized oxides have been studied in the literature as fillers for polymeric membranes, such as Nafion®. Superacidic sulfated oxides have been proposed and characterized. Once incorporated into polymer matrices, their beneficial effect on peculiar membrane properties has been demonstrated. The alteration of physical-chemical properties of composite membranes has roots in the intermolecular interaction between the inorganic filler surface groups and the polymer chains. In the attempt to tackle this fundamental issue, here we discuss, by a multi-technique approach, the properties of a nanosized sulfated titania material as a candidate filler for Nafion membranes. The results of a systematic study carried out by synchrotron X-ray diffraction, transmission electron microscopy, thermogravimetry, Raman and infrared spectroscopies are presented and discussed to get novel insights about the structural features, molecular properties, and morphological characteristics of sulphated TiO2 nanopowders and composite Nafion membranes containing different amount of sulfated TiO2 nanoparticles (2%, 5%, 7% w/w).

Facile Synthesis of Tributyrin Catalyzed by Versatile Sulfated Iron Oxide: Reaction Pathway and Kinetic Evaluation

Tributyrin, the triglyceride ester, exhibits strong properties as inhibitor of cancer cell growth in both humans and animals, which can increase the shelf life of drug. In this paper, tributyrin was synthesized by esterification reaction of butanoic acid with glycerol catalyzed by a low cost, ecofriendly green catalyst sulfated iron oxide. Effect of varying catalyst loading, stirring speed, and temperature on initial reaction rate was investigated. Reaction kinetics and adsorption and thermodynamic parameters were determined by evaluating the effect of concentration of butanoic acid, glycerol, and water addition on reaction rate. Eley–Rideal model using activity coefficients was employed to account for nonideality of the system to elucidate the experimental data. A maximal acid conversion of 91.8% was obtained at the temperature of 448.15 K. Activation energy was calculated to be 25.348 kJ/mol. The end product of reaction was characterized by means of thin layer chromatography (TLC), Fourier transform inf...

One-Pot Isomerization of n-Alkanes by Super Acidic Solids: Sulfated Aluminum-Zirconium Binary Oxides

Abstract Super acidic nanostructured sulfated aluminum-zirconium binary oxides in mole ratios of Zr4+: Al3+ as 2:1 (SAZ-1), 1:1 (SAZ-2), 1:2(SAZ-3) and the reference catalyst super acidic sulfated zirconia (SZ) were synthesized by a precipitation method. Firstly, the catalytic performance of these four catalysts was evaluated during the isomerization of n-hexane to 2-methyl pentane and 3-methyl pentane, n-heptane and n-octane to their corresponding branched chain isomers at low temperature and pressure conditions (40°C and 1 atm). SAZ-1 performed the highest active and selective isomerization of n-hexane, n-heptane, and n-octane into their corresponding branched chain isomers. The catalytic activity of the reference catalyst SZ was the lowest among the four synthesized catalysts. TEM analysis applied to SAZ-1 and SZ indicated the presence of particle-bulks having average size of 20 nm; moreover, these materials presented an amorphous nature, having no particular surface morphology. XRD confirmed the amorphous structure of SAZ-1 and SZ as well as indicated their internal phase structure. FTIR generated ideas about different linkages and bond connectivities between atoms and groups in SAZ-1 and SZ. Ammonia-TPD of these two materials confirmed the higher super acidic nature of SAZ-1 and lower super acidic nature of SZ. Catalyst evaluation and characterization allowed to propose a reaction mechanism, elucidating a possible role of Brønsted and Lewis acid sites on the studied reaction-catalyst, being the former active sites the main factor leading to isomerization reaction. AFM and SEM pictures indicated the nature of the surface of the catalysts. Nevertheless, SEM analysis before and after the reaction displayed that catalyst morphology was modified and could influence the activity of the catalyst. The use of SAZ-1 is cost saving as well as energy saving.