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The bioconversion of furfural to furfuryl alcohol is an attractive route in biomass valorization that could replace traditional contaminant methods. The use of whole cells has been explored for this purpose. Bacillus cereus without previous treatment with furanic compounds was used to selectively obtain furfuryl alcohol. Growing and resting cells were employed. Using growing cells of B. cereus, lower yields to alcohol were obtained because of furfural toxicity. However, employing resting cells it was possible to reach higher yields to furfuryl alcohol. Optimal operative conditions were studied: different concentrations of furfural, glucose and molybdenum, pH, and temperature. Thus, glucose (100 mM) and molybdenum (0.1 mM) were added to maintain cell biomass obtaining a yield to furfuryl alcohol close to 80% at 30 °C, pH 7.2 from 30 mM of furfural.

Acetic acid decomposition to produce hydrogen was studied over Pd/Al2O3, Pt/Al2O3, Ni/Al2O3, and Co/Al2O3 catalysts. Pd/Al2O3 and Pt/Al2O3 systems exhibited high levels of conversion and hydrogen selectivity, with Pt/Al2O3 showing a hydrogen selectivity of 51.3% at 973 K. This behavior was influenced by the high dispersion and small particle size of Pt as well as the dissociative adsorption of acetic acid (acetate species) as exhibited by Pt/Al2O3 and Pd/Al2O3 systems. Additionally, Ni/Al2O3 and Co/Al2O3 were less active and presented low selectivity to hydrogen. These catalysts exhibited low dissociation of acetic acid on their surfaces, therefore hindering acetic acid transformation and hydrogen generation. However, when Ni/Al2O3 and Co/Al2O3 were reduced at 973 K, the conversion of acetic acid and hydrogen formation increased favorably. Co/Al2O3 showed less deactivation during time on stream. Deposited carbon on catalysts corresponded to the formation of carbon filaments for Pd/Al2O3 and Co/Al2O3 and of carbon nanotubes in the case of Ni/Al2O3.

Different composites based on ZnO/Ag3PO4 and ZnO–malachite (Cu2(OH)2CO3) were synthesized in order to determine their effectiveness in the treatment of municipal and industrial wastewaters (mainly polluted by enteropathogenic bacteria, dyes, and heavy metals). The addition of Ag3PO4 and malachite did not significantly modify the physicochemical properties of ZnO; however, the optical properties of this oxide were modified as a result of its coupling with the modifiers. The modification of ZnO led to an improvement in its effectiveness in the treatment of municipal and industrial wastewater. In general, the amount of malachite or silver phosphate and the effluent to be treated were the determining factors in the effectiveness of the wastewater treatment. The highest degree of elimination of bacteria from municipal wastewater and discoloration of textile staining wastewater were achieved by using ZnO/Ag3PO4 (5%), but an increase in the phosphate content had a detrimental effect on the treatment. Likewise, the highest Fe and Cu photoreduction from coal mining wastewater was observed by using ZnO–malachite (2.5%) and ZnO/Ag3PO4 (10%), respectively. Some of the results of this work were presented at the fourth Congreso Colombiano de Procesos Avanzados de Oxidación (4CCPAOx)

Energy and the environment will always play key roles in society. The climate emergency cannot be ruled out to enable the transition for a clean energy future. Currently, non-renewable energy resources are declining, therefore is important to continuously explore renewable resources. Biomass is a renewable resource that can be applied to reduce climate changes and to accomplhish emission policies. Cellulose is the most abundant type of biomass worldwide, which can be transformed into biofuels and potential building block platform molecules (e.g furfural) throughout biological or chemical methods. Furfural can be synthetized from cellulose using hydrolysis and dehydration reactions. Furfural has a furan ring and carbonyl functional group which makes it an important intermediary to produce higher value-added molecules at industrial level. These molecules include gasoline, diesel and jet fuel. However, furfural can also be transformed by hydrogenation, oxidation, decarboxylation and condensation reactions. The selective hydrogenation of furfural produces furfuryl alcohol, an important industrial compound, which is widely employed in the production of resins, fibers, and is considered an essential product for pharmaceutical applications. On the other hand, the oxidation of furfural produces furoic acid which is appliedin the agrochemical industry, where it is commonly transformed to furoyl chloride which is finally used in the production of drugs and insecticides. The oxidation and reduction of furfural can carry out through heterogeneous and homogeneous catalysis, and biocatalysis. Selectivity is an important issue in furfural hydrogenation and oxidation reactions since different products can be obtained by using monometallic or bimetallic catalysts and/or different catalyst supports. In biocatalysis approach, different enzymes, complete cells, tools of modern biotechnology, DNA sequencing, regulation of metabolic networks, overexpression of genes that encode enzymes of interest and optimization of the cellular properties of the microorganism are used. Herein, a review on the current status of furfuryl alcohol and furoic acid production from furfural by heterogeneous catalysis and biocatalysis has been studied. The stability, selectivity and activity of catalystsalong with the different furfural oxidation and reduction conditions have been pointed out. Additionally, the main enzymes, microorganisms and mechanism involved in the furfural degradation process have also been discussed. publishersversion published

The search for catalysts with features that can improve coke resistance and decrease byproduct formation is a current goal in H2 production from renewable sources. In this work, the effect of the presence of Ni nanoparticles over Co/La-Ce oxides on the ethanol decomposition reaction was studied. Catalysts were synthetized using as precursor a La0.8Ce0.2NixCo1-xO3 perovskite-type material to ensure a low segregation of phases and a high dispersion of metals. After reduction at 873 K, the perovskite structure was destroyed, and metal Co-Ni particles were supported over a lanthanum-cerium oxide. The materials were characterized by different techniques before and after reaction. Solids exhibited metal particle sizes between 5 and 15 nm demonstrating the advantages of the preparation method to obtain Ni-Co alloys. Although the results of adsorption of ethanol followed by diffuse reflectance infrared fourier transformed spectroscopy (DRIFTS) showed acetate species strongly adsorbed on the catalyst&rsquo, s surface, the material (Ni0.7Co0.3/La0.8Ce0.2) with the lowest particle size was the most stable system leading to the lowest amount of carbon deposits during ethanol decomposition. This catalyst showed the better performance, with a higher ethanol conversion (98.4%) and hydrogen selectivity (75%). All catalysts exhibited carbonaceous deposits, which were an ordered and disordered carbon phase mixture.

Levulinic acid (LA) transformation to different pyrrolidones via reductive amination was studied using an Ir/SiO2-SO3H catalyst in liquid phase. The effects of solvent, amine concentration, H2 partial pressure, catalyst mass, and reuse were studied. The spent catalysts were evaluated by DRIFTS to obtain evidence of the interaction of levulinic acid with aniline on the catalyst surface. The sulfonic groups on SiO2 improved the yield to pyrrolidones and avoided side reactions. A reaction mechanism is proposed where the reductive amination occurs between LA and amine towards an intermediate amine that is then cycled. The Gibbs free energy for the reaction mechanism was evaluated. Besides, the HOMO and LUMO of the amine reactants and intermediates using density functional theory (DFT) with the B3LYP-D3 method were theoretically determined to understand the rate-limiting and the cyclization steps. Fil: Martínez, José J.. Universidad Pedagógica y Tecnológica de Colombia; Colombia Fil: Silva, Leonardo. Universidad Pedagógica y Tecnológica de Colombia; Colombia Fil: Rojas, Hugo A.. Universidad Pedagógica y Tecnológica de Colombia; Colombia Fil: Romanelli, Gustavo Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Ciencias Aplicadas "Dr. Jorge J. Ronco". Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Ciencias Aplicadas; Argentina Fil: Santos, Lucas A.. Universidade Federal de Lavras. Departamento de Química; Brasil Fil: Ramalho, Teodorico C.. Universidade Federal de Lavras. Departamento de Química; Brasil Fil: Brijaldo, María H.. Universidade Federal Fluminense; Brasil Fil: Passos, Fabio B.. Universidade Federal Fluminense; Brasil

espanolResumen Se estudiaron catalizadores de oro (Au) soportados en tres oxidos metalicos diferentes dado que la naturaleza del soporte podria determinar el tipo de sitios activos necesarios para llevar a cabo las reacciones de hidrogenacion selectiva de aldehidos α,(-insaturados. La hidrogenacion de cinamaldehido se estudio como la reaccion de prueba. El cinamaldehido tiene dos posibilidades de adsorcion (vertical y planar), asi que si existen especies de oro cargadas, pueda verse el efecto de una adsorcion preferencial. Los resultados sugieren que la presencia de particulas intermedias (~5,7 nm) y la existencia de sitios de Au( son necesarias para incrementar la selectividad hacia la reduccion del enlace C=O. Esto se observo preferencialmente en el catalizador de Au/SiO2. En el caso de Au/Fe2O3 y Au/TiO2, en los cuales es posible otro tipo de interacciones metal-soporte, la selectividad decrecio probablemente como consecuencia de la adsorcion del cinamaldehido en forma vertical y planar, ocasionada por la presencia de particulas de Au° de tamanos de ~9,8 nm y ~4,5 nm, respectivamente EnglishAbstract We studied gold catalysts supported on three different metallic oxides as the nature of the support could determine the type of active sites needed to carry out the selective hydrogenation reactions of α,(-unsaturated aldehydes. The hydrogenation of cinammaldehyde was studied as reaction test. The cinnamaldehyde has two preferential adsorption possibilities (vertical atop and planar) and, therefore, if there are charged gold species, the preferential adsorption may be detected. The results suggested that the presence of intermediates particles (~5,7 nm) and Au( sites can be necessary to increase the selectivity towards the reduction of the C=O group. This behavior was preferentially seen on the Au/SiO2 catalyst. In the Au/Fe2O3 and Au/TiO2 catalysts, where other metal-support interactions are possible, the selectivity decreased possibly due to the adsorption modes of cinnamaldehyde in planar and vertical atop geometry, which may be explained by the size of the Au° particles: ~9,8 nm and ~4,5 nm, respectively.

Las características físicas y químicas del hidrógeno lo han convertido en un vector energético prometedor con grandes aplicaciones en celdas de combustibles, así como materia prima para la participación en diversos procesos químicos a nivel de industrial. Una de las fuentes renovables de energía utilizada para la obtención de hidrógeno es la biomasa. Se han empleado varias moléculas modelo de biomasa para la generación de hidrógeno, las cuales incluyen principalmente alcoholes, carbohidratos, ácidos carboxílicos, alcanos entre otras. Estas moléculas son transformadas mediante rutas termoquímicas, bioquímicas, fotoquímicas, electroquímicas, catalíticas, etc., con el objetivo de alcanzar el mayor rendimiento a hidrógeno. En cada una de ellas, numerosas condiciones de reacción son utilizadas, sustratos y catalizadores son empleados. En esta revisión se abordarán algunos de los tópicos anteriormente mencionados y se vislumbraran algunas prospectivas y futuras investigaciones que pueden llevarse a acabo en el campo de la generación de hidrógeno.

Methanol decomposition (MD) was studied over nickel supported over layered double oxides (LDO) and layered double oxides modified with B2O3 (B-LDO). Catalysts with nickel metal content ranging from 5 to 20 wt. % were synthesized by the impregnation method, and materials were characterized by atomic absorption, TGA, XRD, HRTEM, FTIR, and N2 physisorption. The catalytic properties in the MD reaction were studied in the 100−450 °C range. The conversion and selectivity were studied in a conventional flow reactor along with TPSR of methanol followed by GC-QMS. In-situ DRIFTS studied the evolution of adsorbed species. The adsorbed intermediates apparent higher reactivity (methoxy and formate) on boron-containing catalysts corroborated Ni/B-LDO catalysts improved activity. Overall, both nickel and boron modify the methanol interaction with the surface of Ni/B-LDO catalysts, improving its reactivity.

The effect of palladium precursor on the catalytic properties of Pd/Al 2 O 3 and Pd/TiO 2 catalysts toward acetic acid decomposition was investigated. The catalysts were prepared by incipient wetness impregnation of titania and alumina with solutions of palladium acetylacetonate, palladium chloride and palladium nitrate. All the catalysts were characterized by N 2 -physisorption, XRD, H 2 -TPR, H 2 -chemisorption, XPS and IR spectroscopy (DRIFTS in situ ). Carbonaceous compounds were formed on the used catalysts and were investigated by TPO, TGA experiments and Raman spectroscopy. The results suggested that Pd/Al 2 O 3 Nit (prepared using palladium nitrate) was the most active catalyst for conversion of acetic acid, followed by Pd/Al 2 O 3 Aca (prepared using palladium acetylacetonate) which was the most selective for H 2 . Alumina supported catalysts showed the best performance in acetic acid decomposition and hydrogen production.

The production of 2,5-dimethylfuran (DMF) from 5-hydroxymethylfurfural (HMF) over different copper supported catalysts was investigated. An adequate metal dispersion and the nature of acid sites played a role in catalytic activity. Alumina containing catalysts showed the best performance in HMF hydrogenation and DMF production due to both higher acidity and copper particle size. Cu/Al2O3, Cu/Fe2O3-Al2O3, Cu/Nb2O5-Al2O3-623 and Cu/Nb2O5-Al2O3-773 showed a complete HMF conversion at 1 h of reaction and a DMF yield higher than 85% with a negligible quantity of ring-hydrogenation products (

Acetic acid decomposition for hydrogen production was investigated on Pd/SiO 2 , Pd/Nb 2 O 5 , Pd/La 2 O 3 and Pd/Fe 2 O 3 catalysts. The conversion of acetic acid started at 673 K and the products of the reaction were H 2 , CO, CH 4 , CO 2 , H 2 O and C 2 H 4 O. Pd/Fe 2 O 3 was the most active catalyst for conversion of acetic acid and showed high hydrogen selectivity and good catalytic stability, followed by Pd/Nb 2 O 5 and Pd/La 2 O 3 , whereas in the case of Pd/SiO 2 , there was not any H 2 formation. The Pd/Fe 2 O 3 catalysts presented reduced Pd–Fe and Pd 0 /Fe 2 O x sites, producing complete conversion of acetic acid and a higher level of hydrogen selectivity (73%). Additionally, acetic acid adsorption on Pd/Fe 2 O 3 , Pd/Nb 2 O 5 and Pd/La 2 O 3 catalysts yielded the formation of acetate surface species. However, in the case of Pd/SiO 2 , there was molecular adsorption of acetic acid. During the reaction, there was formation of an ordered and disordered carbon mixture on Pd/La 2 O 3 , Pd/Nb 2 O 5 and Pd/SiO 2 catalysts, while carbon of a more ordered nature was produced on Pd/Fe 2 O 3 .

The dehydration of fructose and glucose to 5-hydroxymethylfurfural was studied using LaOCl/Nb2O5 in hot compressed water conditions. The catalysts were prepared by impregnation of LaCl3 on Nb2O5 with different loadings. The solids were characterized by EDX, XRD, TGA and N2 physisorption at 77 K and pyridine and CO2 adsorption followed by FTIR; the strength of acidity and basicity was determined by NH3- TPD and CO2- TPD, respectively. The use of acid–base systems for HMF production mainly from glucose requires weak basic sites and moderate acidity condition that is reached with LaOCl/ Nb2O5 as was confirmed by acidity and basicity analyses. The presence of Nb2O5 increase HMF yield (>50%) and prevented the formation of undesirable products in hot compressed water conditions, similar results could be obtained with DMSO., Centro de Investigación y Desarrollo en Ciencias Aplicadas

Gold, platinum and iridium colloids were supported on sulfonic acid-functionalized silica and were employed for the reductive amination of furfural. The catalysts were characterized by N2-physisorption at 77 K, X-ray diffraction, H2 chemisorption and XPS. The results indicated that Ir, Au and Pt colloids were uniformly dispersed on the SiO2-SO3H support. XPS results showed the interaction of sulfonic acidgroups and metal sites which favors the formation of imine and its subsequent hydrogenation to amines. Fil: Martinez, José J.. Universidad Pedagogica y Tecnológica de Colombia. Facultad de Ciencias; Colombia Fil: Nope Vargas, Eliana Rocio. Universidad Pedagogica y Tecnológica de Colombia. Facultad de Ciencias; Colombia Fil: Rojas, Hugo. Universidad Pedagogica y Tecnologica de Colombia; Colombia Fil: Brijaldo, Maria H.. Universidade Federal Fluminense. Departamento de Engenharia Química e de Petróleo; Brasil Fil: Passos, Fabio. Universidade Federal Fluminense. Departamento de Engenharia Química e de Petróleo; Brasil Fil: Romanelli, Gustavo Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Ciencias Aplicadas "Dr. Jorge J. Ronco". Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Ciencias Aplicadas; Argentina

Catalytic hydrogenation of m-dinitrobenzene over Pt/TiO2–Al2O3 catalysts was investigated. The effect of the enrichment of TiO2 was analyzed. The results showed that the increase in TiO2 content produced an enhancement in the activity of the catalyst. In these consecutive reactions, both rate constants (k1 and k2) were determined and it whatever the catalyst, k1 is higher than k2. The limiting step of the reaction was the transformation of m-nitroaniline to m-phenylenediamine. This behavior was explained by the modification in the acceptor-donor electron character of the group in the meta position.

The catalytic hydrogenation of m-dinitrobenzene (m-DNB) was studied using Au catalysts supported on oxides with magnetic properties. The catalysts were characterized by magnetic susceptibility measurements, XRD, N2 adsorption, TPR, and XPS analysis. The results showed that the gold nanoparticles supported on Fe3O4-SiO2 led to the formation of Auδ– sites. However, this type of site did not alter the catalytic behavior. The catalysts showed high activity and were easily separable. The presence of Fen+ sites prevented the formation of intermediate hydroxylamines.

The hydrogenation of m-dinitrobenzene to m-phenylenediamine was carried out as a model hydrogenation reaction of importance to the pharmaceutical and fine chemicals industries with the aim of investigating the kinetics of the reaction. The effect of different conditions: hydrogen pressure, m-dinitrobenzene concentration, reaction temperature, and weight of catalyst on the conversion of m-dinitrobenzene and the yield of m-phenylenediamine were studied using Pt/TiO2 catalyst. During the kinetic study, the intermediate m-nitroaniline was detected. Therefore, the overall reaction was treated as consecutive reactions: first the reduction of m-dinitrobenzene to m-nitroaniline and then, the reduction of m-nitroaniline to m-phenylenediamine. The apparent activation energies of the reaction were determined in each step, to be 33.4 ± 0.4 and 39.8 ± 0.6 kJ/mol. Those results indicated that the hydrogenation of m-nitroaniline toward m-phenylenediamine is the rate determining step in the hydrogenation of m-dinitrobenzene. Two rate equations assuming Langmuir–Hinshelwood mechanism provided the best fit to the experimental data.

The m-dinitrobenzene hydrogenation to m-phenylenediamine in liquid phase was studied with platinum supported on SiO 2 , TiO 2 , Al 2 O 3 and Nb 2 O 5 catalysts. Incipient impregnation method was used to prepare the catalysts with 1wt% of Pt. The effect of the support and the reduction temperature (473 K or 773 K) were analyzed. The materials were characterized by X-ray diffraction (XRD), nitrogen physisorption (77 K), hydrogen chemisorption (298 K), transmission electron microscopy (TEM), temperature programmed reduction (H 2 -TPR) and temperature programmed desorption of ammonia (NH 3 -TPD). The results showed that Pt/ TiO 2 (HT) catalyst had a higher yield (60%) toward m- phenylenediamine and conversion level (98.2%) of m-dinitrobenzene. This behavior can be attributed to the reduction of PtO x crystallites to metallic Pt, small particle size and the strong metal-support interaction due to the migration of TiO x species on the Pt crystallites.

Los catalizadores Pt/SiO2, Pt/Al2O3 y Pt/TiO2 se prepararon mediante impregnación húmeda, a una concentración del 1% en peso del metal. Los catalizadores resultantes se caracterizaron mediante análisis de difracción de rayos X (DRX), fisisorción de nitrógeno a 77 K y quimisorción de hidrógeno a 298 K. Estos sistemas catalíticos se emplearon en la reacción de hidrogenación de m-dinitrobenceno para la obtención de m-feniléndiamina, una amina aromática de extensa aplicación en el campo de la química fina. Las reacciones se llevaron a cabo en un reactor tipo batch, a 0.82 MPa de presión de hidrógeno, 343 K y etanol como disolvente. Los productos de reacción se siguieron mediante cromatografía de gases. El catalizador Pt/TiO2 exhibió el mayor nivel de conversión de m-dinitrobenceno (91.5 %) y selectividad hacia m-feniléndiamina (72.4 %). Este omportamiento se atribuyó a la presencia fuerte interacción entre el metal y el soporte.

Estudiamos la síntesis de catalizadores coloidales de Au, Ir e Ir-Au, soportados en TiO2. Los sólidos obtenidos fueron caracterizados por difracción de rayos X (XRD), reducción a temperatura programada (TPR), fisisorción de nitrógeno, quimisorción de hidrógeno y microscopia electrónica de transmisión (TEM). La actividad catalítica se evaluó en la hidrogenación selectiva de acroleína en fase gas. Los resultados de caracterización indicaron que las partículasmetálicas no estaban completamente reducidas, por lo que fue necesario un posterior tratamiento térmico de reducción a 773 K; tratamiento que no afectó el tamaño de partícula obtenido por microscopia electrónica de transmisión. La adición de iridio a oro incrementó la capacidad de disociación de hidrógeno con respecto al catalizador de oro monometálico y mejoró su actividad catalítica en la hidrogenación selectiva del grupo C=O de la acroleína. Palabras claves: Hidrogenación, acroleína, coloides, oro, iridio, TiO2.