Some sensors based on pure α-Fe2O3 (hematite) and doped with %Pt-loadings (respectto oxide) of 0,1; 0,2 y 0,3% have been prepared by precipitation method for detection ofmethane, sodium carbonate as precipitating agent and polyethylene glycol (PEG) as antiagglomerationagent. The samples were characterized by X-ray diffraction (XRD), sorptionof N2 (BET method) and transmission electron microscopy (TEM). The XRD patterns showedthat the crystalline structure of starting iron oxide has not been affected by the introduction ofPt as doping material. All the sensors depicted micro-mesoporous isotherms correspondingto type IV. TEM micrographs showed the average particle size of samples, ranging from 50to 150 nm. Sensor tests were performed in a range of concentrations from 300 to 900 ppmand operation temperatures between 150 and 400 ºC. The sensor with 0,3% of Pt and 0,3%of PEG (20000) present...

Catalytic combustion of n-hexane was studied over various mixed oxides based on Co-Mn by the redox properties of these materials. The catalysts were prepared by coprecipitation applying an aging time of 24h, from nitrate precursor of Co2+ and Mn2+ with molar Co/Mn ratios corresponded to 5; 2; 1; 0,5 and 0,2. The oxides were characterized by N2 sorption (BET technique), X-ray diffraction (XRD), infrared Fourier transform spectroscopy (FTIR) and temperature programmed reduction (TPR). The isotherms of N2-sorption were of type IV corresponded to micro-mesoporous material, with the presence of cilindric pores. X-ray analysis revealed the presence of mixed phases corresponding to spinel MnCo2O4 and tetragonal (CoMn)(CoMn)2O4. FTIR spectroscopy showed combined signals in the mixed samples, revealing metallic interaction. TPR analysis showed better reducibility in mixed samples in relation with...

Catalysts based on mixed oxide of type NixFe1-xO4 (x=0,5 a 0,9) were prepared by coprecipitation for oxidative dehydrogenation (ODH) of ethane and were characterized by X-ray diffraction (XRD), sorption of N2 (BET’s method), temperature programmed reduction (TPR) and laser Raman spectroscopy (LRS). The ODH of ethane has been performed in a fixed bed reactor for a constant W/F ratio of 0.48 g.s/mL. The substitution of introduction of Ni+2 by Fe+3 into NiO framework allowed the formation of spinels detected by XRD analysis, dealing to a substantial increasing of specific surface, lesser pore and cristallite size compared with the values corresponding to simples samples (NiO y Fe2O3). The selectivity improved drastically at temperatures ranging from 250 to 400°C, taking into count that CO2 and ethylene were the final products. The maximum selectivity to ethylene was 84% which was obtaine...

Catalysts based on titanium doped nickel oxides Ni1-αTiα O with α from 0.01 to 0.05, were prepared by a controlled evaporationmethod at 550 °Cforselective oxidative dehydrogenation (ODH) of ethane to ethylene. The introduction of small amounts of Ti into the NiO lattice had noticeable effects on the nickel simple oxide properties, increasing the BET surface. In addition, it was observed a sustained depletion of crystallite size following XRD analysis, a generation of new acid sites, evaluated by NH3-TPD, a redistribution of reducible species to lower and higher temperatures studied from H2 -TPR profile and a depression of nonstoichiometric oxygen with the increasing composition of titanium detected by O2 -TPD. The catalytic tests were carried out under steady state conditions at a constant W/F of 0.48 g.s/ mL in order to evaluate the conversion and modifying W/F from 0.24 to 0.48 g.s...

Catalysts based on vanadyl phosphates have been prepared for the oxidative dehydrogenation (ODH) of ethane to ethylene. The bulk catalysts VOP (VOPO4.2H2O), FeVOP(1) (Fe0.14VO0.86PO4) and FeVOP(2) (Fe0.21VO0.79PO4) have been synthesized by the Ladwig method, which consists in the preparation of vanadyl phosphate under reflux with phosphoric acid. The catalysts supported on γ-Al2O3 (FeVOP-Al) were prepared by the wet impregnation method. From XRD, the bulk catalysts presented crystalline structures described by the arrangement of the tetrahedral of PO4 and of the octahedral VO6. The TPR analysis revealed that the introduction of Fe to the structure of the VOP forms less reducible species and in the case of the supported samples, the increase of the active phase linearly increased the consumption of H2. The γ-Al2O3 support to the iron-vanadyl-phosphate catalysts allowed the formation of ...

Biosorption is an effective process for removing synthetic dyes from aqueous solutions. The use of prickly pear cladode biomass (PCB) was studied to remove the methylene blue cationic dye (MB) from the aqueous solution. The characterization techniques: FTIR, SEM and point of zero load (pHPZC) show the chemical and physical characteristics of PCB. Experimental parameters that affect the biosorption process, such as pH, contact time and biomass / volume dose, were evaluated in a continuous system. The equilibrium experimental data were adjusted to the Langmuir isotherm model, the maximum biosorption capacity of the MB was 156.25 mg / g with a dose of PCB/volume of 4 g / L, pH 8 and contact time of 120 min. Kinetic data can be well described with the pseudo-second order model, biosorption appears to be controlled by chemisorption and may be involved with adsorption on the surface and diffus...

A series of Ce alpha Mn1-alpha O2 catalysts supported on gamma-alumina with various molar concentrations of Ce (alpha, from 0 to 0.90) was synthesized by coprecipitation, applying two different precipitating agents, namely, sodium hydroxide (method 1) and sodium carbonate (method 2), with the use of sodium permanganate as a redox agent for precipitation. XRD profiles of the supported samples revealed the predominant abundance of a typical fluorite crystalline structure. TPR thermograms of supported samples were displaced towards lower temperatures with increasing Mn concentration, in contrast with the bulk samples. The supported Ce-Mn samples exhibited a greater performance in n-hexane elimination than did the corresponding simple oxides. The sample Ce0.33M O-0.67(2) obtained by method 2 presented the best activity, probably due to the enrichment of Ce4+, Mn3+ and Mn4+ surface species, a...

The use of waste green tea leaves (TV) with particle diameter 30 and 40 of the Tyler series, on the removal of the dyes basic yellow 57 (AM 57), basic blue 99 (AZB 99) and acid red 18 was investigated from aqueous solutions at room temperature by intermittent desorption experiments. The parameters evaluated in the adsorption capacity were: pH, mass of adsorbent, the concentration of dye adsorption rate and ionic strength, supported by the FTIR, SEM, EDX and TGA analysis. The results are analyzed using mathematical models of Langmuir, Freundlich, Temkin, Dubinin- Radushkevich and Redlich -Peterson. The results show that the adsorption is given by a mixed mechanism. The determined parameters show a high affinity of the adsorbent with AZ 99 with a maximum adsorption capacity of 287.2 mg g- 1, followed with by AM 57 120 mg g -1 and the RA 18 with 58 mg g- 1 elucidating the potential use of t...

Ru-Fe catalytic system supported on titania for the selective hydrogenation of methyl palmitate towards the cetyl alcohol product was studied. The Ru-Fe-based catalysts supported on TiO2 were prepared by the wet coimpregnation method: Ru, as active metal and Fe, as a catalytic promoter, supported on TiO2 , synthesized by the sol-gel method, which allowed better textural properties with respect to commercial support. Sorption analysis of N2(g) showed type IV isotherms with cylindrical pores and XRD diffractograms revealed profiles similar to the support, suggesting high metal dispersion. The reduction profiles of the Ru-Fe/TiO2 catalysts showed a shift of the hydrogen consumption peaks towards higher temperatures with the increase of the metal loading, indicating a possible metal-support interaction. TPD-H2 analysis showed that the Ru-Fe catalysts supported on titania presented more types...

The objective of the present investigation is apply activated carbon obtained prepared from aguaje seeds (Mauritia flexuosa) for the removal of mercury. Activated carbon obtained was modified with manganese oxide to compare the adsorption capacity between the modified and unmodified carbon. The use of ultrasound in a solution with a pH 9 favored the fixation of manganese on the surface of the activated carbon, which was determined using the techniques of DRX and ICP-OES. The kinetic tests carried out at pH 3,5 (over zero charge potential) with a concentration of 5 ppm of mercury show a higher adsorption capacity at modified carbon at pH 9 in accordance with the pseudo second order model. Adsorption isotherms indicate a predominantly Freundlich behavior.

Catalysts based on Cu-Mn mixed oxides (with molar ratio Cu/Mn in the range of 0,33 to 3) have been prepared by sol-gel method of self-combustion for removal of n-hexane. Two combustion agents, citric acid and ethylenglycol, were applied to study their influence in the final catalyst. Additionally, simple oxides have been synthesized using the same procedure for comparison reasons. The catalysts were characterized by X-ray diffraction (XRD) and sorption of N (BET method). All samples depicted surfaces, preferentially assigned to 2 2 mesoporosity whose values ranged from 4 to 50 m /g. All XRD difractograms of mixed samples showed the presence of a good crystalinity indepently of composition, with the formation of spinnel-hopcalite phase meanwhile Mn and Cu simple oxide showed peaks attributed to Mn O , Mn O and CuO, respectively. Curves of activity, measured as number of 2 3 3 4 VOC molecu...

Catalysts based on Ce-Pr mixed oxides, , were prepared by coprecipitation (x ranged from 0,1 to 0,9) for combustion of n-hexane. For comparison purposes, the pure simple oxides were also prepared. Catalysts were characterized by sorption of N and X-ray 2 diffraction (XRD). The analysis of adsorption isotherms of catalysts showed profiles of type 2 IV, with specific surfaces ranging from 9,1 to 62,3 m /g, with the prevalence of mesoporosity. The X-ray diffractogram patterns for pure and mixed oxide catalysts show the majority presence of stable fluorite phase. The introduction of Pr in mixed oxide composition maintains the crystal structure of fluorite-like type. The catalytic tests were carried out in a fixed bed reactor with a starting concentration of n-hexane of 2000 ppm and weight hourly space -1 velocity (WHSV) of 80 h . The total combustion temperatures for mixed oxides catalysts w...

Catalysts based on Ru-Ni supported on γ-Al2 O3 were prepared by the wet impregnation method with pH adjustment. The surface area of the supported catalysts was greater than that corresponding to the support with the adsorption isotherms corresponding to micromesoporous solids. The diffractograms of the reduced Ru-Ni catalysts were similar to that of the γ-Al2 O3 support, suggesting the formation of highly dispersed phases. The TGA analysis revealed the mass loss of less than 20 % that would corroborate the transition of ruthenium and nickel hydroxides to their respective oxides. The reduction profiles of the Ru-Ni /γ-Al2 O3 showed lower H2 consumption than those corresponding to Ru/ γ-Al2 O3 , revealing possible interactions between the metal phase and the support. In the hydrogenation of methyl palmitate, carried out under the operating conditions of a batch reactor, the activity wa...

Se prepararon sensores basados en SnO dopados con paladio (0, 1, 3, 5 y 7%) mediante el método de impregnación húmeda. Para caracterizarlos, se usaron las técnicas de espectroscopia infrarroja con transformada de Fourier (FTIR), adsorción y desorción de N2 (BET), difracción de rayos X (XRD), microscopía electrónica de barrido (SEM) y espectroscopia de energía dispersiva de rayos X (EDX). Los sensores se evaluaron con etanol para que conformaran, junto a dos sensores comerciales, una nariz electrónica (E-nose) que lograse detectar componentes volátiles del aroma en vinos peruanos. Los resultados fueron interpretados a través del análisis de componentes principales (PCA) con la finalidad de buscar una técnica que complementase la información recolectada por la cromatografía de gases (GC) y la cromatografía líquida (HPLC), y justamente comparando los PCAs obtenidos del GC...

Se evaluaron diez vinos peruanos, tanto comerciales como artesanales, con el objetivo de diferenciarlos en base a su forma de fabricación y haciendo uso de las cromatografías GC y HPLC. Se encontraron que los componentes de aroma más comunes, en el caso del GC, entre todas las muestras de vino fueron el ácido sórbico, el 1 fenil etanol y el ácido propanoico. Y del análisis HPLC se reconocieron los compuestos quercetina y resveratrol. Se halló que los vinos VP2 y VP3 son los que poseen más contenido de estas sustancias, lo que señala que estos vinos poseen mayor carácter anti­inflamatorio y anti­cancerígeno. Mediante la espectroscopía UV se midió el contenido de fenoles, antocianinas y flavonoides totales indicando que el vino VP5 es el que presenta mejor carácter antioxidante. Los vinos artesanales en cambio presentaron bajo poder antioxidante, indicando que el procedimi...