Extraction of ferulic acid and feruloylated arabinoxylo-oligosaccharides from wheat bran using pressurized hot water

Producción CientíficaPressurized water was tested as solvent for the hydrolysis and extraction of Ferulic acid (FA) and feruloylated arabinoxylooligosaccharides (F-AXOS) from destarched wheat bran (DWB). Results were dependent on the severity factor of the process (combination of temperature and time), obtaining the maximum extraction yields at 200°C and 3.5 min. 78% of the total FA was successfully extracted, being 17% in its free form and the rest, covalent ester-bounded to arabinoxylans. Under such conditions, 80% of the arabinoxylans are extracted with a degree of FA esterification of 1.34 g FA/100 g AXOS, and an average molecular weight of 1,3·104 Da. Pressurized Microwave Assisted Extraction was also studied to evaluate potential intensification of the process using microwaves. However, no significant differences were observed with the microwave heating. Residual solid after extraction was mainly composed by lignin and cellulose (56% and 21%, respectively) showing that hot compressed water technology can be integrated in the first steps of a biorefinery for the total valorization of the wheat bran.Ministerio de Economía, Industria y Competitividad - Fondo Europeo de Desarrollo Regional (project CTQ2015-64892-R

Synthesis of Supported Mesoporous Catalysts Using Supercritical CO₂

Metal and metal oxide nanoparticles have attracted increased attention due to their unusual physical and chemical properties. The nature, dispersion, and size of the nanoparticles are key factors in determining the activity and selectivity of the supported catalysts. Supercritical fluid deposition (SCFD) is a promising method to deposit metallic nanoparticles and films on inorganic porous supports. CO2 is the most commonly used supercritical fluid (sc-CO2) for material synthesis because it is nontoxic, nonreactive, nonflammable, and inexpensive. This work presents the synthesis of cobalt, nickel, and ruthenium nanoparticles on MCM-41, Al-MCM-41, MCM-48, and activated carbon supports in sc-CO2. Batch and continuous deposition are studied, with two high-pressure reactor configurations: column or alternative (sandwich). To avoid the length of the bed being too long, the reagents were separated into smaller amounts and placed alternately, keeping the total mass of the precursor and support constant. The prepared samples were characterized by scanning electron (SEM/EDX) and transmission electron microscopy (TEM)

Study of the Nature and Location of Silver in Ag-Exchanged Mordenite Catalysts. Characterization by Spectroscopic Techniques

 Catalysts based on Na-mordenite (symbolized as M) exchanged with 5, 10, and 15 wt % of Ag were characterized by X-ray photoelectron spectroscopy (XPS), extended X-ray absorption fine line structure (EXAFS), X-ray absorption near edge spectroscopy (XANES) and UV-vis diffuse reflectance spectroscopy (DRS) to investigate the effect of different treatments on the chemical state and surface concentration of the silver species. The AgxM catalysts were analyzed in oxidizing (O2) or reducing (H2/Ar) atmospheres and also after being used in the selective catalytic reduction of NOx or in successive cycles of toluene adsorption/desorption. In calcined samples, EXAFS profiles showed two types of AgO spheres of coordination, one due to a dispersed phase of silver oxide and the other due to Ag+ ions in interaction with the oxygen of the zeolite framework. The UV-vis DRS spectra showed the coexistence of isolated Ag+, Agn(delta)+ (n < 10) cationic clusters and AgxO particles. In addition, through the modified Auger parameter (alpha), calculated from XPS measurements, it was possible to identify Ag+ ions at exchange sites (alpha = 722 eV) and AgxO ( alpha = 725 eV) highly dispersed on the surface. Both species constitute stable active centers for the selective catalytic reduction of NOx under severe reaction conditions. However, during the adsorption-desorption of toluene, the reduction of silver oxides produces Ag(0) due to thermal hydrocarbon decomposition.   Fil: Aspromonte, Soledad Guadalupe. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Investigaciones En Catálisis y Petroquímica; Argentina. Universidad Nacional del Litoral; ArgentinaFil: Mizrahi, Martin Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina. Universidad Nacional de La Plata; ArgentinaFil: Schneeberger, Florencia A.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Investigaciones En Catálisis y Petroquímica; ArgentinaFil: Ramallo Lopez, Jose Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina. Universidad Nacional de La Plata; ArgentinaFil: Boix, Alicia Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Investigaciones En Catálisis y Petroquímica; Argentina. Universidad Nacional del Litoral; Argentin

Study of the nature and location of silver in Ag-exchanged mordenite catalysts: characterization by spectroscopic techniques

Catalysts based on Na-mordenite (symbolized as M) exchanged with 5, 10, and 15 wt % of Ag were characterized by X-ray photoelectron spectroscopy (XPS), extended X-ray absorption fine line structure (EXAFS), X-ray absorption near edge spectroscopy (XANES) and UV-vis diffuse reflectance spectroscopy (DRS) to investigate the effect of different treatments on the chemical state and surface concentration of the silver species. The AgxM catalysts were analyzed in oxidizing (O2) or reducing (H2/Ar) atmospheres and also after being used in the selective catalytic reduction of NOx or in successive cycles of toluene adsorption/desorption. In calcined samples, EXAFS profiles showed two types of AgO spheres of coordination, one due to a dispersed phase of silver oxide and the other due to Ag+ ions in interaction with the oxygen of the zeolite framework. The UV-vis DRS spectra showed the coexistence of isolated Ag+, Agn(delta)+ (n < 10) cationic clusters and AgxO particles. In addition, through the modified Auger parameter (alpha), calculated from XPS measurements, it was possible to identify Ag+ ions at exchange sites (alpha = 722 eV) and AgxO ( alpha = 725 eV) highly dispersed on the surface. Both species constitute stable active centers for the selective catalytic reduction of NOx under severe reaction conditions. However, during the adsorption-desorption of toluene, the reduction of silver oxides produces Ag(0) due to thermal hydrocarbon decomposition.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Ag, Co supported in NaMOR and AlMCM-41 for hydrocarbons adsorption and catalytic reduction of NOx

La emisión de óxidos de nitrógeno (NOx), hidrocarburos sin quemar (HCs) y óxidos de carbono (COx), provienen principalmente de fuentes móviles (medios de transporte) y centrales de potencia. En este trabajo se estudiaron sistemas catalíticos capaces de entrampar los hidrocarburos durante la etapa de baja temperatura, para luego eliminarlos cuando se alcanzan las condiciones óptimas del motor. Para ello, se emplearon como soportes catalíticos, una zeolita microporosa NaMordenita comercial y materiales mesoporosos MCM-41 y AlMCM-41 sintetizados mediante el método sol-gel. Los metales Ag o Co fueron incorporados por intercambio iónico, impregnación húmeda incipiente o mediante CO2 supercrítico. Los catalizadores preparados mediante intercambio iónico mostraron una pequeña fracción de óxido altamente disperso, en coexistencia con iones intercambiados en los sitios de la mordenita. La deposición con CO2 supercrítico representó un método eficaz para incorporar nanopartículas de óxido de cobalto dispersas en los sustratos mesoporosos. Estas especies resultaron activas para la oxidación preferencial de CO en atmósfera reductora. Los catalizadores Ag- o Co-Mordenita fueron activos y selectivos en la RCS-NOx con tolueno o butano. El agua mantiene la superficie limpia de depósitos carbonosos. Sólo los materiales AgMordenita mostraron una elevada capacidad de adsorción y retención de HCs. El tolueno interacciona con el catión a través de los electrones pi y mediante los grupos metilo con los oxígenos de la red próximos al catión. El butano sólo lo hace mediante los grupos C-H. De este modo, los catalizadores de Ag intercambiada en NaMOR permiten acoplar la adsorción de hidrocarburos con la RCS-NOx.The emission of nitrogen oxides (NOx), unburned hydrocarbons (HCs) and carbon oxides (COx), mainly from mobile sources (vehicles) and power plants. In this work, catalytic systems capable of trapping hydrocarbons during low-temperature stage, and then delete them when they reach optimum engine conditions are studied. Thus, were used as catalyst supports, a microporous zeolite and mesoporous materials commercial NaMordenita MCM-41 and AlMCM-41 synthesized by the sol-gel method. Ag or Co metals were incorporated by ion exchange or incipient wet impregnation using supercritical CO2. The catalysts prepared by ion exchange showed a fraction of highly dispersed oxide, in coexistence with ion exchanged mordenite sites. The supercritical CO2 deposition represented an effective method to incorporate cobalt oxide nanoparticles dispersed in mesoporous substrates. These species were active for the preferential oxidation of CO in a reducing atmosphere. Ag, Co-Mordenite catalysts were active and selective in NOx-SCR with toluene or butane. Water keeps the clean surface of carbon deposits. Only materials AgMordenita showed high adsorption capacity and retention of HCs. The toluene interacts with the cation via pi electrons and by the methyl groups with the oxygens of the net near the cation. Butane only done by C-H groups. Thus, the catalysts of Ag exchanged NaMOR allow coupling the adsorption of hydrocarbons with the RCS-NOxConsejo Nacional de Investigaciones Científicas y Técnica

Improving of cold-start and combustion emissions in lean NO conditions with active and selective AgAl mesoporous catalysts

Mesoporous AgAl-MCM41 catalytic adsorbents were synthesized.Template-ion exchange (tie) and incipient wet impregnation (iwi) methodswere employed to incorporate Ag. The presence of non-structural andstructural Ag(I) ionic species were detected. As the former refers to theions that occupy an active site, the latter are part of the supporthexagonal network. In addition, Ag2O nanoparticles were observed.The samples were used in C7H8 adsorption at 100 ºC and in the selectivecatalytic reduction of NOx with toluene as reductant and H2O. The maximumNOx conversion was achieved with AgAl-iwi catalyst. Under dry conditions,a conversion of 84 % was reported. With 2 or 10 % H2O, the conversion wasmaintained between 80 and 90 % and it is maintained at 70 % after 50 h ofreaction and successive cycles of water incorporation. In addition, theamount of toluene adsorbed follows the next order: AgAl-iwi > AgAl-tie >Al-MCM41 > MCM41. Instead, the quantity of C7H8 desorbed by the AgAl-tieis 34 % above 400 ºC. The AgAl-iwi solid show a ratio between theadsorbed and desorbed toluene of 99 % in a wide range of temperature.This behavior is due to the presence of non-structural Ag(I) ions, whichare the adsorption sites for the toluene.Comparing the performance of these materials with the AgNa-mordenite, theAgAl-iwi is more active catalyst and effective adsorbent between 100 and550 ºC. Thus, the mesoporous structure allows a better dispersion of theactive sites, as well as the diffusion of toluene.Fil: Aspromonte, Soledad Guadalupe. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Boix, Alicia Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentin

Effect of Ag?Co interactions in the mordenite on the NOx SCR with butane and toluene

A study of the lean NOx reduction activity with butane and toluene in the presence of water over bimetallic and monometallic Ag, Co exchanged on Na-mordenite catalysts was performed. The Ag-Co interactions were analyzed through X-ray photoelectron spectroscopy (XPS) and Temperature-programmed reduction (TPR) techniques. It is shown that the metal silver particles formed at low temperature during the TPR experiment improve the dissociation of hydrogen thus facilitating the reduction of Co2+ species. The incorporation of 3.2 wt. % of silver to CoM catalyst, significantly improved the NOx to N2 conversion with butane, which reached 95 % under wet conditions (2 % H2O). However, this effect was not observed when toluene was the reducing agent.Fil: Aspromonte, Soledad Guadalupe. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Miro, Eduardo Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Boix, Alicia Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; Argentin

Deactivation studies of the SCR of NOx with hydrocarbons on Co-mordenite monolithic catalysts

The catalytic reduction of NOx with hydrocarbons (butane or methane) on CoMOR washcoated monolithic catalysts was studied in the presence of steam and excess oxygen. The significant changes observed in the catalytic behavior of CoMOR powder and monoliths depended essentially on the hydrocarbon nature (carbon number) and the concentration of water in the feed. When the reducing agent was methane, a low concentration of water (2%) decreased the NO to N2 conversion. However, when butane was used instead of methane, the maximum NOx conversions increased from 50 to 58% and from 52 to 64% for the CoMOR powder and monolith, respectively. The presence of water inhibited the NO adsorption when the reducing agent was methane but when butane was used, water helped to remove the surface-carbon deposits as indicated by TPO and XPS results. This fact explains the increase observed in the NOx conversion. The characterization with TPR and UV-vis spectroscopy showed that the main Co species present in the selective catalysts were the Co(II) ions exchanged at different sites of the mordenite and highly dispersed CoxOy moieties. More rigorous reaction conditions, i.e. 10% of water, led to the irreversible deactivation with both reductants. The Co3O4 phase was detected in all the deactivated powder and monolithic catalysts. The Co3O4 spinel was formed from the cobalt ion migration, which was promoted in wet atmosphere. In addition, for monolithic catalysts washcoated with CoMOR, the silica binder inhibited the water deactivation effect probably due to the silica-cobalt interaction, as a CoxOySi silicate.Fil: Boix, Alicia Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Aspromonte, Soledad Guadalupe. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Miro, Eduardo Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentin

Hydrolysis of cellulose to glucose by supercritical water and silver mesoporous zeolite catalysts

The hydrolysis of cellulose into glucose is a critical step for the conversion of lignocellulosic biomass into fuels and chemical products. The combination of supercritical water hydrolysis in ultrafast reactors, with the subsequent hydrolysis of the cello-oligosaccharides on silver-exchanged mesoporous mordenite zeolite, offers the possibility of a clear enhancement in the conversion of cellulose and in glucose formation. Complete dissolution of cellulose is achieved in the supercritical step and 81.8% of formed oligosaccharides are hydrolyzed in the catalytic step, with a yield into glucose of 77.0%. A fraction of Al is octahedrally coordinated, indicating a distribution of acid sites after the silver exchange. A deactivation of the catalyst between the first and third reaction cycle is observed, with a reduction in hydrolyzed carbon from 81.8% up to 45.6%. However, the selectivity to glucose only varies from 94.1 to 81.8%. Afterwards, the activity remains constant up to the fifth cycle. The presence of Ag(0) particles, together with the formation of coke, are responsible for the partial blockage of the pores of the support and loss of catalytic activity.Fil: Aspromonte, Soledad Guadalupe. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Romero, A.. Universidad de Valladolid; EspañaFil: Boix, Alicia Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Alonso, E.. Universidad de Valladolid; Españ

Mesoporous bio-materials synthesized with corn and potato starches applied in CO2 capture

The development of environmentally friendly techniques to obtain mesoporous solids allows the construction of new and better materials, making potential use of natural resources. In this study, mesoporous silica with high specific surface area and controlled porosity is synthesized by a novel and facile method, which employs potato or corn starches as directing structure agent. Using SEM microscopy, the ellipsoidal morphology of potato starch and the irregular and polygonal shape of corn starch were determined. Pattern A and B were identified by XRD, corresponding to samples of cereals and tubers, respectively. The stages of gelatinization and retrogradation of the starches were studied, obtaining mesoporous silicas with type IV adsorption/desorption isotherms and specific surface areas of 708.6 m2 g−1 with potato starch and 1018.1 m2 g−1 with corn starch for short gelatinization times (4 h, 353 K) and long retrogradation (14 h, 298 K). In addition, the use of HCl solution promoted the hydrolysis of starch in its monomeric unit (glucose) and the consequent bimolecular nucleophilic substitution with silica. The materials obtained presented a random mesoporous order and a CO2 adsorption capacity at 373 K in the range between 150.2 and 131.4 mg CO2 g−1.Fil: Aspromonte, Soledad Guadalupe. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Tavella, María Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Albarracín, Micaela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Tecnología de los Alimentos; ArgentinaFil: Boix, Alicia Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentin