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(NH4)4[NiMo6O24H6].5H2O / g-C3N4 materials for selective photo-oxidation of Csingle bondO and Cdouble bondC bonds

Caudillo-Flores, U; Ansari, F; Bachiller-Baeza, B; Colon, G; Fernandez-Garcia, M; Kubacka, A
Applied Catalysis B-Environmental, 278 (2020) 119299


Novel composite photo-catalysts having (NH4)(4)[NiMo6O24H6]center dot 5H(2)O Polyoxometalate (POM) species deposited over g-C3N4 are synthesized. Materials were characterized through a multitechnique approach showing the stability of the carbon nitride component both through the synthesis process and under reaction. Contrarily, the POM component evolves under reaction conditions to maximize the interaction with the support. Such a behavior renders, as measured by the quantum efficiency, highly active photo-catalysts in the photo-oxidation of 2-propanol and styrene both under UV and sunlight illumination, setting up the basis for a green catalytic process. The material having a 4 wt. % POM showed improved activity with respect to both parent constituents but also higher selectivity to the partial oxidation of the alcohol and the aromatic hydrocarbon to generate added value chemical compounds. A multitechnique approach investigating charge carrier fate demonstrates the key role played by the interaction between components to promote activity and selectivity in selective oxidation reactions.

Diciembre, 2020 | DOI: 10.1016/j.apcatb.2020.119299

Thermo-optic response of MEH-PPV films incorporated to monolithic Fabry-Perot microresonators

Rostra, JG; Soler-Carracedo, K; Martin, LL; Lahoz, F; Yubero, F
Dyes and Pigments, 182 (2020) 108625


Poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylene vinylene] (MEH-PPV) is a semiconducting optically active polymer widely used in optoelectronics research. MEH-PPV can be commercially acquired in a large range of molecular weights. However, the influence of this property on the optical performance of the polymer is often disregarded. In this paper, the thermal dependence of the refractive index of MEH-PPV thin films prepared from high and medium molecular weight polymers is investigated. Thus, monolithic Fabry-Perot (FP) microcavities are fabricated, in which the active polymer film is part of their defect layer. It is found that when these devices are used as optical temperature sensors, the position of the emission band of the microcavities excited with a blue diode laser shifts to lower wavelengths when temperature increases with sensitivities in the 0.2-0.3 nm/degrees C range. This effect is ascribed to the variation in the refractive index of the polymer active layer within the resonator with temperature. According to theoretical simulations of optical transmittance by classical transfer matrix method and the evaluation of the optical eigenmodes by finite element methods of the manufactured FP resonator cavities, it is found that the MEH-PPV films present negative thermo-optic coefficients of about-0.018 K-1 and-0.0022 K-1 for high and medium molecular weight polymers, respectively, in the temperature range between 20 and 60 degrees C. These values are about the highest reported so far, to the best of our knowledge, and points to high performance thermal sensor applications.

Noviembre, 2020 | DOI: 10.1016/j.dyepig.2020.108625

Tribological performance of Nb-C thin films prepared by DC and HiPIMS

Sala, N; Abad, MD; Sanchez-Lopez, JC; Cruz, M; Caro, J; Colominas, C
Materials Letters, 277 (2020) 12834


Nanostructured NbC thin films with variable contents of Nb and C were prepared by direct current (DC) magnetron sputtering, and for the first time, via high power impulse magnetron sputtering (HiPIMS) searching for an improvement in the tribological properties. X-ray diffraction shows that increasing the carbon incorporation, the crystalline composition evolves from Nb2C to NbC phase. Further carbon enrichment leads to a nanocomposite structure formed by small NbC crystals (8-14 nm) dispersed in a-C matrix. The friction coefficient varied from high friction (0.8) to low friction (0.25) and the hardness values between 20 and 11 GPa depending on the film composition. A densification of the coatings by changing the methodology from DC to HiPIMS was not observed. 

Octubre, 2020 | DOI: 10.1016/j.matlet.2020.128334

Microstructure and thermal conductivity of Si-Al-C-O fiber bonded ceramics joined to refractory metals

Vera, MC; Martinez-Fernandez, J; Singh, M; Casalegno, V; Balagna, C; Ramirez-Rico, J
Materials Letters, 276 (2020) 128203


We explore joining Si-Al-C-O fiber-bonded ceramics to Cu-clad-Mo using an Ag-Ti-Cu brazing alloy. A temperature of 900 degrees C and times in the range of 10-20 min are required to obtain sound joints irrespectively of the fiber orientation. The reaction layer is 1-2 mu m thick and free of pores and defects. The thermal conductivity of the joined samples is well described considering that the metal and the ceramic are in series for thermal resistance. This implies that the joint is highly conductive and forms an almost perfect 

Octubre, 2020 | DOI: 10.1016/j.matlet.2020.128203

Multiple pollutants removal by functionalized heterostructures based on Na-2-Mica

Pazos, MC; Bravo, LR; Ramos, SE; Osuna, FJ; Pavon, E; Alba, MD
Applied Clay Science, 196 (2020) 105749


Organomica, C8-2-Mica, was obtained from a high charged synthetic mica, Na-2-Mica, by cation exchange reaction with octylammonium cations and these were used to host other bulky guest species such as polyhydroxy aluminium cations, Al(13)20. The hydrolization of 3-mercaptopropyltrimethoxysilane (MPTMS) allowed the covalent attachment with hydroxyl groups of the oligomeric cation, providing thiol groups that create specific adsorption sites, Al(13)20/SH. The structure of the adsorbents was analysed by XRD and Infrared spectroscopy and these were tested as an adsorbent for the removal of zinc and herbicide MCPA from aqueous solutions. C8-2-Mica was the best adsorbent for MCPA and thiol groups favoured the adsorption of Zn2+. Moreover, Al(13)20/SH showed excellent adsorptive properties for the simultaneous adsorption of MCPA and Zn2+.

Octubre, 2020 | DOI: 10.1016/j.clay.2020.105749

Free-Carbon Surface for PtCu Nanoparticles: An In Situ Near Ambient Pressure X-ray Photoelectron Spectroscopy Study

Castillo, R; Navarro-Jaen, S; Romero-Sarria, F; Perez-Dieste, V; Escudero, C; Centeno, MA; Daturi, M; Odriozola, JA
Journal of Physical Chemistry C, 124 (2020) 19046-19056


Usually, nanoparticle synthesis methodologies require the use of organic molecules (capping agent, solvent molecules, etc.), which results in carbon deposits on the nanoparticle surface. These residues modify the surface properties mainly affecting the catalytic behavior. In this work, unsupported poly(vinylpyrrolidone) (PVP)-stabilized PtCu (1:3 molar ratio) bimetallic alloy nanoparticles were synthetized and characterized. An alternative surface cleaning method has been designed, which successfully removes the presence of organic fragments. To address this key issue, we have combined a first nanoparticle washing step with a near ambient pressure X-ray photoelectron spectroscopy (NAPXPS) study in order to obtain a clean active site and the total understanding of the carbon elimination mechanism. The dynamic evolution of the surface organic species composition under different gas mixtures at 750 mTorr and 350 degrees C has been studied, and only under CO2 exposure, NAPXPS analysis revealed a total availability of the active site by the removal of the organic nanoparticle coating.

Septiembre, 2020 | DOI: 10.1021/acs.jpcc.0c04713

Synthesis of all equiatomic five-transition metals High Entropy Carbides of the IVB (Ti, Zr, Hf) and VB (V, Nb, Ta) groups by a low temperature route

Chicardi, E; Garcia-Garrido, C; Hernandez-Saz, J; Gotor, FJ
Ceramics International, 46 (2020) 21421-21430


The six possible equiatomic five-transition metal High Entropy Carbides (HECs) of the IVB (Ti, Zr, Hf) and VB (V, Nb, Ta) groups of the periodic table, i.e., TiZrHfVNbC5, TiZrHfVTaC5, TiZrHfNbTaC5, TiZrVNbTaC5, TiHfVNbTaC5 and ZrHfVNbTaC5, were successfully obtained via a powder metallurgy route at room temperature, specifically, by one-step diffusion mechanosynthesis starting from the elemental constituents (using graphite as the carbon source). Three of those HECs, TiZrHfVTaC5, TiZrVNbTaC5 and ZrHfVNbTaC5, were developed for the first time. Their development was possible without any subsequent thermal treatment, in contrast to the usual way (reactive sintering at 1800-2200 degrees C), and in a powder form, make them potential advanced raw ceramics for hard, refractory and oxidation resistance coatings or matrix phase composites.

Septiembre, 2020 | DOI: 10.1016/j.ceramint.2020.05.240

Experimental evidence of HCO species as intermediate in the fischer tropsch reaction using operando techniques

Diaz-Sanchez, RM; de-Paz-Carrion, A; Serrera-Figallo, MA; Torres-Lagares, D; Barranco, A; Leon-Ramos, JR; Gutierrez-Perez, JL
Applied Catalysis B-Environmental, 272 (2020) 119032


Fischer Tropsch's reaction, known from 1925, receives special attention nowadays due to its key role in the CO2 or biomass valorization to liquid fuels and chemicals. Several aspects on the exact mechanism or the role of water in this reaction are not yet completely clear. Formyl species, HCO, have been proposed as the most probable reaction intermediate, but they have never been observed under operation conditions closed to the real ones. In this work, using DRIFTS-MS operando techniques, HCO intermediates are detected under a H2/CO flow and 200 °C. IR bands at 2900 cm−1 and 1440 cm−1 attributed to ν(C–H) and δ(HCO) vibrations modes characterize these species. Evolution of these bands with the reaction time evidences its high reactivity with OH groups, which explains the positive effect of water on the CO conversion previously observed.

Septiembre, 2020 | DOI: 10.1016/j.apcatb.2020.119032

Bimetallic PdAu catalysts for formic acid dehydrogenation

Santos, JL; Leon, C; Monnier, G; Ivanova, S; Centeno, MA; Odriozola, JA
International Journal of Hydrogen Energy, 45 (2020) 23056-23068


A series of monometallic and bimetallic palladium gold catalyst were prepared and studied for the formic acid dehydrogenation reaction. Different Pd/Au compositions were employed (PdxAu100-x, where x = 25; 50 and 75) and their impact on alloy structure, particle size and dispersion was evaluated. Active phase composition and reaction parameters such as temperature, formic acid concentration or formate/formic acid ratio were adjusted to obtain active and selective catalyst for hydrogen production. An important particle size effect was observed and related to Pd/Au composition for all bimetallic catalysts. 

Septiembre, 2020 | DOI: 10.1016/j.ijhydene.2020.06.076

Design of a nanoprobe for high field magnetic resonance imaging, dual energy X-ray computed tomography and luminescent imaging

Gonzalez-Mancebo, D; Becerro, AI; Corral, A; Garcia-Embid, S; Balcerzyk, M; Garcia-Martin, ML; de la Fuente, JM; Ocana, M
Journal of Colloid and Interface Science, 573 (2020) 278-286


The combination of different bioimaging techniques, mainly in the field of oncology, allows circumventing the defects associated with the individual imaging modalities, thus providing a more reliable diagnosis. The development of multimodal endogenous probes that are simultaneously suitable for various imaging modalities, such as magnetic resonance imaging (MRI), X-ray computed tomography (CT) and luminescent imaging (LI) is, therefore, highly recommended. Such probes should operate in the conditions imposed by the newest imaging equipment, such as MRI operating at high magnetic fields and dual-energy CT. They should show, as well, high photoluminescence emission intensity for their use in optical imaging and present good biocompatibility. In this context, we have designed a single nanoprobe, based on a core-shell architecture, composed of a luminescent Eu3+:Ba0.3Lu0.7F2.7 core surrounded by an external HoF3 shell that confers the probe with very high magnetic transverse relaxivity at high field. An intermediate, optically inert Ba0.3Lu0.7F2.7 layer was interposed between the core and the shell to hinder Eu3+-Ho3+ cross-relaxation and avoid luminescence quenching. The presence of Ba and Lu, with different K-edges, allows for good X-ray attenuation at high and low voltages. The core-shell nanoparticles synthesized are good potential candidates as trimodal bioprobes for MRI at high field, dual-energy CT and luminescent imaging. 

Agosto, 2020 | DOI: 10.1016/j.jcis.2020.03.101

Physicochemical surface analysis and germination at different irrigation conditions of DBD plasma‐treated wheat seeds

Molina, R; Lalueza, A; Lopez-Santos, C; Ghobeira, R; Cools, P; Morent, R; de Geyter, N; Gonzalez-Elipe, AR
Plasma Processes and Polymers, (2020)


Plasma treatment is increasingly being explored as an effective presowing treatment improving seed germination. This study examines the synergetic effect of the irrigation condition and the physicochemical surface properties of wheat seeds subjected to atmospheric dielectric barrier discharge plasma activation on their water uptake and germination. Extensive surface analysis revealed a remarkably enhanced wettability of plasma-treated seeds due to the insertion of oxygen-containing functionalities on their surface. However, long plasma exposures damaged the outermost layers of the pericarp due to a pronounced oxidative etching effect. Although the seed germination capacity was not affected by the plasma treatments, short plasma exposures were shown to enhance water uptake and accelerate seed germination, especially under water-scarcity conditions.

Agosto, 2020 | DOI: 10.1002/ppap.202000086

An electrochemical evaluation of nitrogen-doped carbons as anodes for lithium ion batteries

Gomez-Martin, A; Martinez-Fernandez, J; Ruttert, M; Winter, M; Placke, T; Ramirez-Rico, J
Carbon, 164 (2020) 261-271


New anode materials beyond graphite are needed to improve the performance of lithium ion batteries (LIBs). Chemical doping with nitrogen has emerged as a simple strategy for enhancing lithium storage in carbon-based anodes. While specific capacity and rate capability are improved by doping, little is known about other key electrochemical properties relevant to practical applications. This work presents a systematic evaluation of electrochemical characteristics of nitrogen-doped carbons derived from a biomass source and urea powder as anodes in LIB half- and full-cells. Results show that doped carbons suffer from a continuous loss in capacity upon cycling that is more severe for higher nitrogen contents. Nitrogen negatively impacts the voltage and energy efficiencies at low charge/discharge current densities. However, as the charge/discharge rate increases, the voltage and energy efficiencies of the doped carbons outperform the non-doped ones. We provide insights towards a fundamental understanding of the requirements needed for practical applications and reveal drawbacks to be overcome by novel doped carbon-based anode materials in LIB applications. With this work, we also want to encourage other researchers to evaluate electrochemical characteristics besides capacity and cycling stability which are mandatory to assess the practicality of novel materials. 

Agosto, 2020 | DOI: 10.1016/j.carbon.2020.04.003

Performance trends in wall-flow diesel particulate filters: Comparative analysis of their filtration efficiency and pressure drop

Orihuela, MP; Chacartegui, R; Gomez-Martin, A; Ramirez-Rico, J; Villanueva, JAB
Journal of Cleaner Production, 60 (2020) 12063


Soot and particulate emissions from the transport sector are a major concern worldwide, given their harmful effects on public health and the environment. On-road vehicles are the main contributing source to this kind of pollution. They are strictly regulated in many countries, with limitations on the number and concentration of released particles, and they must be equipped with particle abatement systems. Wall-flow particulate filters are the most popular and effective devices to reduce particulate emissions from diesel and gasoline vehicles. Diesel Particulate Filters (DPFs) have been a recurrent research topic since the last century. There are different research studies analysing different aspects of these systems, at different levels, using different methodologies and different approaches. Their results are not always comparable. This work analyses the latest advances and trends in this technology by comparing two relevant performance parameters: their filtration efficiency and pressure drop. The findings of this study suggest that, in order to be competitive, upcoming DPFs should have filtration efficiencies above 80%, and pressure drops below 10 kPa, for space velocities of 1.5.10(5) h(-1) or more at the clean state. They should reach similar to 100% efficiency after a short operation period, before the soot load reaches 0.2 g/L. Later, they should keep a low pressure drop for a longer time, with a reference of no more than 13 kPa for 6 g/L of soot load. Based on this analysis, this work proposes some test criteria and suggestions for the main parameters. 

Julio, 2020 | DOI: 10.1016/j.jclepro.2020.120863

Calcium-Looping Performance of Biomineralized CaCO3 for CO2 Capture and Thermochemical Energy Storage

Arcenegui-Troya, J; Sanchez-Jimenez, PE; Perejon, A; Valverde, JM; Chacartegui, R; Perez-Maqueda, LA
Industrial & Engineering Chemistry Research, 59 (2020) 12924-12933


The commercial deployment of calcium-looping (CaL)-based technologies relies on the availability of nontoxic, widely available and cheap CaCO3 rich materials. Biomineralized CaCO3 from waste amply fulfills the aforementioned requirements. In the present work, we study the performance of eggshell and snail shell from food waste as CaO precursors for CaL applications. The results obtained suggest the feasible use of these waste materials. The multicyclic conversion exhibited by biomineralized CaCO3 was comparable to that demonstrated by limestone, which is a commonly proposed material for CaL applications. In addition, the temperature needed to completely calcine biomineralized CaCO3 in short residence times is lower than that required to fully calcine limestone. This would mitigate the energy cost of the technology.

Julio, 2020 | DOI: 10.1021/acs.iecr.9b05997

Influence of Sr-doping on structural, optical and photocatalytic properties of synthesized Ca3(PO4)2

Y.Naciri; A.Hsini; Z.Ajmal; A.Bouddouch; B.Bakiz; J.A.Navío; A.Albourine; J-C.Valmalette; M.Ezahri; A.Benlhachemi
Journal of Colloid and Interface Science, 572 (2020) 269-280


Well-crystallized Ca3(PO4)2 doped and un-doped nano-particles with the maximum strontium content (40 wt% Sr) followed by calcination at 800 °C for 3 h were synthesized via facile co-precipitation method. DTA/TGA, X-ray diffraction (XRD), energy dispersive scanning electron microscopy (SEM/EDX), UV–vis diffuse reflectance spectrum (UV–vis DRS), Raman spectroscopy and photoluminescence (PL) techniques were used for material characterization. The (XRD) patterns of as-synthesized Sr-doped Ca3(PO4)2 solid solution samples exhibited a systematic shift toward lower angles by possessing a single rhombohedral crystal structure without any secondary phases. The UV light driven photocatalytic activity was assessed for rhodamine B (RhB) degradation. As a result, ultrafast photodegradation activity was observed after Sr doping. Moreover, the 30 wt% Sr-Ca3(PO4)2 sample showed the highest photocatalytic degradation among the Sr-doped Ca3(PO4)2 samples toward RhB. It was further suggested that as-synthesized 30 wt% Sr-Ca3(PO4)2 superior photocatalytic performance is ascribed to the more proficient partition of photogenerated electron-hole pairs. Furthermore, the involved mechanism of superior photocatalytic performance of the 30 wt% Sr-Ca3(PO4)2 solid solution was also investigated. In addition, regeneration cycles indicated the higher stability of the photocatalyst to be effectively recycled up to four times without any considerable reduction in photocatalytic performance. Thus, these informations further provides us a scalable pathway to fabricate Sr doped Ca3(PO4)2 and its consequent use as an efficient photocatalyst for rhodamine B (RhB) contaminated wastewater treatment.

Julio, 2020 | DOI: 10.1016/j.jcis.2020.03.105

ICTAC Kinetics Committee recommendations for analysis of multi-step kinetics

Vyazovkin, S; Burnham, AK; Favergeon, L; Koga, N; Moukhina, E; Perez-Maqueda, LA; Sbirrazzuoli, N
Thermochimica Acta, 689 (2020) 178597


The present recommendations have been developed by the Kinetics Committee of the International Confederation for Thermal Analysis and Calorimetry (ICTAC). The recommendations provide guidance on kinetic analysis of multi-step processes as measured by thermal analysis methods such as thermogravimetry (TGA) and differential scanning calorimetry (DSC). Ways of detecting the multi-step kinetics are discussed first. Then, four different approaches to evaluation of kinetic parameters (the activation energy, the pre-exponential factor, and the reaction model) for individual steps are considered. The approaches considered include multi-step model-fitting as well as distributed reactivity, isoconversional, and deconvolution analyses. For each approach practical advice is offered on its effective usage. Due attention is also paid to the typical problems encountered and to the ways of resolving them. The objective of these recommendations is to help a non-expert with efficiently performing multi-step kinetic analysis and interpreting its results.

Julio, 2020 | DOI: 10.1016/j.tca.2020.178597

Sustainable, High-Barrier Polyaleuritate/Nanocellulose Biocomposites

Tedeschi, G; Guzman-Puyol, S; Ceseracciu, L; Benitez, JJ; Cataldi, P; Bissett, M; Heredia, A; Athanassiou, A; Heredia-Guerrero, JA
ACS Sistainable Chemistry & Engineering, 8 (2020) 10682-10690


Free-standing and flexible biocomposite films formed by a polyaleuritate matrix and nanocellulose fillers (i.e., cellulose nanofibrils) have been fabricated by a sustainable process. For this, 9,10,16-trihydroxyhexadecanoic (aleuritic) acid from shellac and nanocellulose were blended at different ratios in water through a sonication process. Polymerization of the polyhydroxylated fatty acid into polyaleuritate was induced by a solvent-free, melting polycondensation reaction in the oven. These biocomposites were characterized to evaluate their chemical (by ATR-FTIR spectroscopy) and physical (e.g., density, thermal stability, rigidity, gas permeability, surface energy, etc.) properties. The compatibility between the polyester matrix and the polysaccharide fillers was excellent due to the interaction by H bonds of the polar groups of both components. The addition of nanocellulose increased all determined mechanical parameters as well as the wettability and the barrier properties, while the thermal stability and the water uptake were determined by the polyaleuritate matrix. The physical properties of these biocomposites were compared to those of petroleum-based plastics and bio-based polymers, indicating that the developed materials can represent a sustainable alternative for different applications such as packaging.

Julio, 2020 | DOI: 10.1021/acssuschemeng.0c00909

Evaluation of the Oxygen Mobility in CePO4-Supported Catalysts: Mechanistic Implications on the Water-Gas Shift Reaction

Navarro-Jaen, S; Bobadilla, LF; Romero-Sarria, F; Laguna, OH; Bion, N; Odriozola, JA
Journal of Physical Chemistry C, 124 (2020) 16391-16401


The hexagonal and monoclinic phases of CePO4 have been demonstrated to be excellent catalytic supports for Pt-based water-gas shift (WGS) catalysts. Consequently, the elucidation of the WGS reaction mechanism in these materials constitutes a fundamental aspect in order to explain their catalytic behavior. Because the observed WGS reaction path is closely related to the absence or presence of oxygen vacancies in the support, the study of the oxygen mobility in these solids constitutes a key factor for the understanding of the structure of the materials and its influence on the reaction mechanism. In this study, the oxygen mobility in CePO4 supports and the corresponding Pt catalysts has been evaluated by means of isotopic exchange experiments using O-18(2) and (CO2)-O-18 as probe molecules. Results demonstrate that the evaluated solids present a low exchange activity when O-18(2) is used, indicating the absence of oxygen vacancies in these solids, thus suggesting a poor influence of the WGS redox mechanism. On the contrary, a high oxygen exchange activity is observed using (CO2)-O-18, demonstrating that the exchange in these materials takes place through the formation of carbonate-like intermediates, thus suggesting the associative mechanism of the WGS reaction as the preferred path in these solids. Operando diffuse reflectance infrared spectroscopy experiments under WGS reaction conditions confirm these results, proving that the WGS reaction in the studied materials takes place through a formate-mediated associative mechanism.

Julio, 2020 | DOI: 10.1021/acs.jpcc.0c03649

Metal catalysts supported on biochars: Part I synthesis and characterization

Santos, JL; Maki-Arvela, P; Monzon, A; Murzin, DY; Centeno, MA
Applied Catalysis B-Environmental, 268 (2020) 118423


In the current study, synthesis and detailed characterization of cellulose biochars as a waste biomass model component and vine shoot biochars as a real waste biomass catalyst was performed. Although initially biochars exhibit poor textural properties, a simple activation process can make them much more suitable as a catalyst supports. A combination of physical (CO2) and chemical activation (ZnCl2) was evaluated. The characterization results indicated that the surface area and pore volume of the biochars have increased significantly by chemical activation treatment with ZnCl2. A series of metal catalysts (Pd, Au and Ru) supported on biochars was prepared and characterized. The prepared materials represent a set of noble metal catalysts supported on biochars with different textural and surface properties, which can be used to evaluate the catalytic role of the active phase and carbon support nature in catalytic reactions of interest, such as hydrodeoxygenation, described in the part II.

Julio, 2020 | DOI: 10.1016/j.apcatb.2019.118423

Hydrodeoxygenation of vanillin over noble metal catalyst supported on biochars: Part II: Catalytic behaviour

Santos, JL; Maki-Arvela, P; Warna, J; Monzon, A; Centeno, MA; Murzin, DY
Applied Catalysis B-Environmental, 268 (2020) 118425


Vanillin hydrodeoxygenation was investigated using noble metal (Pd, Au, Ru) supported on active carbon prepared from waste derived biochars, which were produced via pyrolysis in CO2 atmosphere. Chemical activation with ZnCl2 and HNO3 was also used in the preparation of active carbon to enhance the specific surface area and demineralize material, respectively. Both fresh and spent catalysts were characterized with X-ray diffraction, DRIFTS, zeta potential measurement and HR-TEM. The highest selectivity to p-creosol, 92 % selectivity at complete vanillin conversion after 3 h was obtained in vanillin hydrodeoxygenation at 100 degrees C under 30 bar in hydrogen in water with Pd/C catalyst prepared via pyrolysis under CO2 from wine waste and using ZnCl2 as a chemical activation agent. Hydrodeoxygenation activity increased with increasing metal dispersion. A kinetic model including adsorption of vanillin described well the experimental data.

Julio, 2020 | DOI: 10.1016/j.apcatb.2019.118425