Miguel Angel Centeno

• Spanish National Research Council

Two series of functionalized activated carbons have been prepared and used for glucose to fructose isomerization reaction. Alkali earth chlorides and alkali halides have been chosen for the functionalization with the final goal to study the effect of cation and anion variation on isomerization activity. A part of the samples has been subjected to a...

The effect of facet exposure in ceria nanostructures on the catalytic properties of Pd/CeO₂ during methanol decomposition was investigated. The results showed the structure sensitive nature of this reaction, with the catalytic activity depending on the facet exposed in the ceria nanostructures. Operando DRIFTS-MS and DFT calculations demonstrated t...

This work proposes catalytic systems for fructose dehydration to 5-hydroxymethylfurfural using a series of functionalized carbon nanofibers. The catalysts were synthesized via finely selected covalent grafting in order to include a variety of functionalities like pure Bronsted acid, tandem Brønsted/Lewis acid, and tandem Lewis acid/Lewis base catal...

This study presents a novel approach for boosting the selectivity of 5-hydroxymethylfurfural (HMF) production from glucose through electrochemical modification of graphite materials. Three distinct graphitic substrates were subjected to controlled electrochemical treatments utilizing sodium sulfate or phosphoric acid as electrolytes. The process ex...

The impact derived from incorporating water into CH 4 /CO 2 biogas stream for the generation of syngas was investigated over the Rh/MgAl 2 O 4 catalyst using operando steady-state and transient DRIFT spectroscopy coupled with MS.

The RWGS reaction is gathering momentum as effective route for CO2 valorisation and given its endothermic nature the challenge lies on the design of active low-temperature catalysts. Herein we have designed two catalysts based on subnanometric Pt clusters rendering effective CO2 conversion and more importantly high CO selectivity in the low-tempera...

La zeolita Y es un sólido microporoso que se utiliza como componente activo del catalizador en el proceso de ruptura catalítica. Se estudiaron las propiedades texturales de una zeolita comercial USY lixiviada y de una serie de catalizadores con 25, 35 y 45% de zeolita frescos y tratados a 1033 K durante 16 h con 20% de vapor de agua. Las muestras s...

Today's rising energy costs, coupled with increasing energy demand, make it necessary to search for more efficient energy processes. In recent years, there have been increasing efforts to develop efficient catalysts based on waste-derived char, by a single step where the carbon precursor and the metallic active phase one undergo a single common the...

This work shows a new method for the preparation of 100% carbon-structured devices. The method is based on resorcinol-formaldehyde polymerization, using starch as a binder with the addition of a certain amount of external carbon source before polymerization. Molds obtained by 3D printing are used to shape the structured devices in the desired shape...

In this study, palladium is proposed as an active site for formic acid dehydrogenation reaction. Pd activity was modulated with Co metal with the final aim of finding a synergistic effect that makes possible efficient hydrogen production for a low noble metal content. For the monometallic catalysts, the metal loadings were optimized, and the increa...

Cotton stalks-based biochars were prepared and used to synthetize Ru-supported catalysts for selective production of γ-valerolactone from levulinic acid in aqueous media. Different biochars' pre-treatments (HNO 3 , ZnCl 2 , CO 2 or a combination of them) were carried out to activate the final carbonaceous support. Nitric acid treatment resulted in...

The production of CO via Reverse Water Gas Shift (RWGS) reaction is a suitable route for CO2 valorization. In this study a series of modified spinels AB2O4 (A site = Ni, Zn and Cu and B site=Fe) are investigated as RWGS catalysts and their structure-to-function relationships derived from the changes on the A-site cation are rationalized. For all fe...

Different metal halide catalysts supported on a commercial active charcoal have been synthesized, activated, characterized and tested in glucose dehydration to 5-hydroxymethylfurfural using a biphasic water/methyl isobutyl ketone media. The influence of the cation nature (K+, Ca2+, Sr2+, Mg2+) and anion nature (F-, Cl-, Br-) on the catalytic perfor...

Formic acid has recently been revealed to be an excellent hydrogen carrier, and interest in the development of efficient and selective catalysts towards its dehydrogenation has grown. This reaction has been widely explored using homogeneous catalysts; however, from a practical and scalable point of view, heterogeneous catalysts are usually preferre...

In this work carbon nanofibers (CNF) have been successfully functionalized by using different approaches and finally used for the preparation of Ru based catalysts. The organometallic approach has demonstrated to...

There are multiple factors that influence the catalyst performance in the reaction of formic acid dehydrogenation: the nature of catalyst and/or support, the used solvent and reaction variables such as temperature, time, formic acid concentration, presence/absence of formates and pH of the solution. This work evaluates a series of important paramet...

Nowadays, global climate change is likely the most compelling problem mankind is facing. In this scenario, decarbonisation of the chemical industry is one of the global challenges that the scientific community needs to address in the immediate future. Catalysis and catalytic processes are called to play a decisive role in the transition to a more s...

This study deals with the production and activation of biochars and their use as supports for a series of ruthenium catalysts for hydrogenation of l-arabinose/d-galactose sugar mixture. The synthesized biochars differ in physicochemical properties and surface chemistry influencing ruthenium metal uptake and dispersion and as a consequence its catal...

This work includes a complete study of the reaction of reforming a simulated producer gas stream comparing a Ni-based catalyst with another one promoted with potassium to enhance the resistance to coke formation. Although coke deposition is unavoidable in the presence of tars in the stream, the analysis of different reaction parameters revealed tha...

Seeking for advanced catalytic systems for the CO 2 methanation reaction, the use of Ni supported catalysts over redox materials is often proposed. Profiting the superior redox properties described for layered perovskite systems , this work has investigated a series Ni supported YMn 1-x Al x O 3 (x = 0, 0.2, 0.5, 0.8, 1) perovskite catalysts. The o...

The aim of this work was to clarify the effect of the support on CO selective methanation with Ru/TiO2 catalysts. TPR, XRD and TEM measurements confirmed that the changes in the activity and selectivity should be ascribed to anatase:rutile ratio, RuO2+TiO2 solid solution formation, as well as the metal content and the thermal treatment used. All th...

Fischer-Tropsch (FTS) reaction is a well-known catalytic process for the conversion of synthesis gas into liquid fuels. The addition of a water gas shift (WGS) catalyst to the FTS one has been postulate to notably increase the efficiency of the process. In order to investigate this issue, we conducted the FTS reaction over a Co-Re/Al2O3 catalyst co...

Exploring available catalytic systems to understand their behavior is a must to properly design efficient catalysts aiming to definitively drive biomass from laboratory to industrial scale. Glucose transformation to levulinic acid involves cascade reactions with specific requirements, different active sites in each case and secondary reactions hard...

Liquid fuels produced via Fischer-Tropsch synthesis from biomass-derived syngas constitute an attractive and sustainable energy vector for the transportation sector. This study focuses on the role of potassium as a promoter in Ni-based catalysts for reducing coke deposition during catalytic dry reforming. The study provides a new structural link be...

The active forms of Au and Pt in CeO2-based catalysts for the water-gas shift (WGS) reaction are an issue that remains unclear, although it has been widely studied. On one hand, ionic species might be responsible for weakening the Ce-O bonds, thus increasing the oxygen mobility and WGS activity. On the other hand, the close contact of Au or Pt atom...

Methanol adsorption over both supported NiSn Nps and analogous NiSn catalyst prepared by impregnation was studied by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) to gain insights into the basis of hydrogen production from methanol steam reforming. Different intermediate species such as methoxides with different geome...

Coke deposition is one of the key issues in the dry reforming of methane on Ni catalysts. In the present work, we investigate the effect of potassium addition for suppressing carbon deposition in the Dry Reforming of Methane. The results obtained demonstrated that potassium contents above 3 wt% promote carbon gasification, favouring both Reverse Wa...

A series of mesoporous carbonaceous materials were synthesized by the nanocasting technique using boehmite as a template and glucose as a carbon precursor. After pyrolysis and template removal, the resulting material is a mesoporous carbon that can be additionally doped with N, B and K during prepyrolysis impregnation. In addition, the influence of...

In heterogeneous catalysis, the benefits of employing adequate textural properties on the catalytic performances are usually stated. Nevertheless, the quantification of the extent of improvement is not an easy task since variations on the catalysts' specific areas and pore structures might involve modifications on a number of other surface catalyti...

Designing an economically viable catalyst that maintains high catalytic activity and stability is the key to unlock dry reforming of methane (DRM) as a primary strategy for biogas valorization. Ni/Al2O3 catalysts have been widely used for this purpose; however, several modifications have been reported in the last years in order to prevent coke depo...

This work proposes an innovative Ni catalyst supported over YMnO 3 perovskite as a promising catalytic system for CO 2 methanation reaction. Under reductive conditions, the attendance of Mn redox couples within the layered perovskite structure promotes the constitution of sub-stoichiometric YMnO 3-x units which, by means of the flexible YMnO 3-x re...

Dry reforming of methane (DRM) is an effective catalytic route for transforming CO2 and CH4 into valuable syngas and thus potentially attractive for mitigating the emission of environmental harmful gases. Therefore, it is crucial to develop rationally Ni-based catalysts highly resistant to coking and sintering. In this scenario, the addition of sma...

One of the most remarkable benefits of the microreactors is the achievement of more efficient processes by enhancing the heat and mass transfer phenomena, which is the key factor for processes intensification in chemical reactions, resulting in higher conversion, selectivity and yield towards desired products. Currently, the entire scenario of micr...

In this study, pure and Co substituted nanosized lanthanum ferrite (LaFe1-xCoxO3; x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, and 1) perovskites were synthesized by inorganic sol–gel route, and investigated as catalysts for styrene oxidation environmental reaction using H2O2 as oxidant. The effect of cobalt content on physico-chemical properties of LaFeO3 pero...

The present manuscript presents for the first time the structuring of a Ru/TiO2 catalyst that was achieved by means of the washcoating procedure using homemade metal micromonoliths (Fecralloy®) of 1330 cpsi. For this, an optimized formulation of the slurried catalyst as well as a reproducible protocol for the coating of the micromonoliths were succ...

By evaluating the functional modifications induced by Zr and Fe as dopants in Pt/CeO2‐MOx/Al2O3 catalysts (M = Fe and Zr), the key features for improving water gas shift (WGS) performance for these systems have been addressed. Pt/ceria intrinsic WGS activity is often related to improved H2 surface dynamics, H2O absorption, retentions and dissociati...

A series of -SO3R functionalized activated carbons (R=H, O, aryl) were prepared and applied in fructose dehydration reaction to 5-hydroxymethylfurfural. Different sulphonating methods introduce groups on catalyst surface with distinct donor-acceptor and hydrophilic properties. Their nature influences significantly not only activated carbon’s textur...

The relevance of steel industry worldwide is undeniable. However, this constitutes one of the main sources of CO2 emission into the atmosphere. Therefore, it is one of the great industries called upon to rethink its production processes in order to transform it into business models that are not only productive but also sustainable and friendly to t...

The proposed study tries to reply on one important question concerning glucose dehydration: What is the role of bare or tandem Lewis/Brønsted acid sites in the reaction and which are better? A series of mono and bifunctional catalyst are designed and screened for the glucose dehydration reaction. The results clearly reveal that catalyst activity is...

This work explores the preparation of graphene-related materials (GRMs) grown on stainless steel foams via catalytic decomposition of methane (CDM). The main active phases for the reaction are the Fe nanoparticles segregated from the stainless-steel after the activation stage of the foam. The effect of the feed composition and reaction temperature...

In this study the size-activity dependence of palladium based catalysts in formic acid dehydrogenation reaction was investigated and evaluated. A wide range of particle sizes was considered and the catalyst series were prepared upon variation of some synthetic parameters, precursor and solvent nature in particular. Synthesis method variations affec...

Biomass waste product was used to generate biochars as catalytic supports for selective hydrogen production from formic acid. The supports were obtained after pyrolysis in CO2 atmosphere of non-pretreated and chemically ZnCl2 activated raw materials (vine shoot and crystalline cellulose). The support series includes materials with different textura...

Usually, nanoparticles synthesis methodologies require the use of organic molecules (capping agent, solvent molecules, etc) which results in carbon deposits on the nanoparticles surface. These residues modify the surface properties mainly affecting to the catalytic behavior. In this work, unsupported poly(vinylpyrrolidone) (PVP)-stabilized PtCu (1:...

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 suc...

Novel catalytic systems should be tested for the valorization of CO2 through the Sabatier reaction, since this process is gaining great importance within strategic sectors of the chemical industry. Therefore, this work explores the feasibility of structuring a catalyst (0.5%Ru–15%Ni/MgAl2O4) for CO2 methanation using metal micromonoliths. The coati...

The modulation and characterization of the acidity of a vermiculite were carried out, which was modified by delamination by means of hydrothermal and acid treatments with the subsequent incorporation of AlZr and AlCe species to modulate the acidity. The effect of these species was evaluated regarding the structural (XRD, XPS and IR), textural (N2 s...

A series of functionalized nanographitic carbons is prepared, characterized and tested in fructose dehydration reaction to 5-hydroxymethylfurfural. The functionalization treatment was selected to introduce various Brönsted acid sites and to modify the textural and catalytic properties of the initial carbon material. Within the series, the sulfonate...

This study pretends to evaluate and understand the effect of moisture presence during CO2/CH4 separation on small-pore SAPO-34 molecular sieves. Two SAPO-34 samples with different physicochemical properties (composition, crystal size and texture) were prepared by hydrothermal synthesis using either one or a mixture of two templates. Transient opera...

This work is devoted to the study of the role of both metals in the intermetallic Pt x Cu y / γ Al 2 O 3 catalysts commonly employed in CO-PROX reaction. Therefore, monometallic Pt and Cu based catalysts and PtCu in-termetallic compound with different molar ratios (Pt 3 Cu 1 and Pt 1 Cu 3) supported catalysts were carefully synthesized and deeply c...

Enhancement of the main physicochemical properties of a natural bentonite was carried out by means of modifications using surfactant, reflux, microwave treatment and, subsequently, the incorporation of AlZr and AlCe species. The evolution of the main changes in each modification stage was evaluated by means of X-ray diffraction, N2 sortometry, scan...

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 combinatio...

A Colombian metallurgical coke was modified in its surface chemistry and was used as support of iron sulfide catalysts for direct coal liquefaction. The modification was made by treatments with diluted oxygen and HNO3 at different conditions. Changes in surface chemistry were studied by determining the point of zero charge (PZC), the isoelectric po...

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 combinatio...

Carbon aerogels and carbon xerogels were synthesized through resorcinol – formaldehyde polycondensation using Na2CO3 as catalyst. The effect of soluble starch introduction in the organic gel preparation on the porous surface properties of these materials was studied. The role of the drying process of the organic gels on the changes in the surface a...

This work is a detailed study on how to optimize gold colloids preparation and their deposition to very different in nature carbon materials. The change of the continuous phase and its dielectric constant is used to assure the good dispersion of the hydrophilic/hydrophobic carbons and the successful transfer of the preformed small size colloids to...

An innovative route for bio‐compounds upgrading via “hydrogen‐free” hydrodeoxygenation (HDO) is proposed and evaluated using guaiacol as a model compound in a high‐pressure batch reactor. Experimental results showed that noble metal supported on activated carbon catalysts are able to conduct tandem multiple steps including water splitting and subse...

Two gold-based catalysts were obtained by Au chemical reduction of the HAuCl4 precursor. The resulting nanoparticles were stabilized and immobilized on montmorillonite (Mt) and montmorillonite-ceria (Mt/CeO2). All preprared catalysts were active in 4-nitrophenol to aminophenol reduction at room temperature. Synergy between montmorillonite and ceria...

Ni-Mg-Al based catalysts were prepared using different preparation methods (impregnation, impregnation-coprecipitation and coprecipitation) and tested in steam reforming of methane. The differences observed in catalytic activity were directly correlated to the physicochemical properties and the different degree of Ni-Mg-Al interaction. The reducibi...

The bi-reforming of methane (BRM) has the advantage of utilising greenhouse gases and producing H2 rich syngas. In this work Ni stabilised in a pyrochlore-double perovskite structure is reported as a viable catalyst for both Dry Reforming of Methane (DRM) and BRM. A 10 wt.% Ni-doped La2Zr2O7 pyrochlore catalyst was synthesised, characterised and te...

By means of the polyol method, a series of 5 wt% Ru/Al 2 O 3 catalysts was synthesized controlling the particle size of the ruthenium species. The physico-chemical characterization demonstrated the successful particle size control of the Ru species, in such a way that higher the Ru/PVP ratio, higher the Ru particle size. Moreover, there are evidenc...

In this work, we present a highly active catalyst based on Ru nanoparticles dispersed on alumina, which showed an unexpected activity for CO2 methanation. This exceptional catalytic behavior was attributed to the presence of residual species that remained on the surface after synthesis. Furthermore, through Operando DRIFTS (diffuse reflectance infr...

The influence of the protecting agent’s nature on gold particle size and dispersion was studied in this work over a series of gold-based catalysts. CO and glucose oxidation were chosen as catalytic reactions to determine the catalyst’s structure–activity relationship. The nature of the support appeared to be the predominant factor for the increase...

The importance of water availability during the WGS reaction has been extensively reported. Thus, the search of new supports able to interact with the water molecule is of great importance. In this work, a series of phosphate-type supports containing Ce, Ca and Ti have been studied, demonstrating that water interaction with the support is closely r...

The current scenario where the effects of global warming are more and more evident, has motivated different initiatives for facing this, such as the creation of global policies with a clear environmental guideline. Within these policies, the control of Greenhouse Gase (GHG) emissions has been defined as mandatory, but for carrying out this, a smart...

The performance of rotating metallic monolith stirrer reactor was studied for selective lactose oxidation in liquid phase at 65 °C, atmospheric pressure and with air as oxidant agent. The Au/Al2O3deposition on metallic substrates was performed by wash-coating, producing catalyst coating thicknesses between 5 and 20 μm. Monoliths with different conf...

Routinely, it seems assumed that the catalytic layer coated on monoliths and microchannel reactors preserve the properties of the initial powder catalyst. However, this assumption should be reasonably demonstrated since the set of chemical and physical manipulations involved in the preparation of these catalytic devices hardly does not alter the su...

A series of cobalt-based catalysts have been synthesized using as support γ-Al2O3 promoted by ceria/zirconia mixed oxides with a variable Ce/Zr molar ratio. The obtained catalysts demonstrated oxide promotion results in the protection of the major textural properties, especially for Zr-rich solids. Reducibility of cobalt species was enhanced by the...

Biochar-based Pt catalysts, unpromoted and Na-promoted, were prepared by an incipient wetness impregnation method and characterised by Inductively coupled plasma mass spoectrometry (ICP-MS) analysis, X-ray diffraction, N2 adsorption and transmission, and scanning electron microscopy. It was demonstrated that a sodium promoter modifies the acid-base...

For Pt catalysts which have demonstrated great activity on the WGS reaction, the activation of water is described as the rate-limiting step. Such limitation could be overcome through the design of supports able to supply water. In this study, the hexagonal and monoclinic phases of CePO4 have been evaluated as supports for Pt WGS catalysts. The hexa...

The viability of water gas shift catalytic system for mobile application passes through obligatory reactor volume reduction, achieved normally by using less charge of more efficient catalyst. Completely new concept for catalyst design is proposed: a catalytic system including classically reported WGS catalysts of different nature or active phase (C...

The dry reforming of methane with CO 2 is a common route to transform CO 2 /CH 4 mixtures into added value syngas. Ni based catalysts are highly active for this goal but suffer from deactivation, as such promoters need to be introduced to counteract this, and improve performance. In this study, mono-and bi-metallic formulations based on 10 wt.% Ni/...

Active and selective structured RuO2/Al2O3 catalysts for CO methanation using a flow simulating CO2-rich reformate gases from WGS and PROX units (H2 excess, CO2 presence and 300 ppm CO concentration) were prepared. Both, the RuO2/Al2O3 powder and the slurry prepared from it for its structuration by washcoating of the metallic micromonolithic struct...

Different carbon supported metal catalysts were synthesized, and characterized with various physico-chemical methods and tested in vanillin hydrodeoxygenation under 30 bar total pressure in water as a solvent at 100 °C. The catalysts exhibited high specific surface area and the metal dispersion decreased in following order: Pt/C > Pd/C > Au/C > Rh/...

Zeolites are natural or synthetic materials with porous chemical structures that are valuable due to their absorptive and catalytic qualities. Metal-Organic Frameworks (MOFs) are manmade organometallic polymers with similar porous structures. This introductory book, with contributions from top-class researchers from all around the world, examines t...

Clean hydrogen production via WGS is a key step in the development of hydrogen fuel processors. Herein, we have designed a new family of highly effective catalysts for low-temperature WGS reaction based on gold modified copper-zinc mixed oxides. Their performance was controlled by catalysts’ composition and the Au-Cu synergy. The utilization of hyd...

Eu-doped ZrO2 solid solutions have been synthesized in order to prepare proton conductors as water-enhancer additives for the WGS reaction. Elemental characterization has been carried out revealing homogeneous dopant distribution resulting in fluorite-type solid solutions for Eu2O3 contents up to ∼9 mol.%. Representative samples of the Eu-doped ZrO...

In this study, an investigation about the oxygen sensing properties of lanthanum orthoferrite (LaFeO3) ceramics is reported. LaFeO3 nanoparticles were synthesized by using tartaric sol-gel route and annealed in air at different temperatures (500, 700 and 900°C). The samples have been characterized by using thermal analysis (TA), BET surface area an...

Rh/MnO2-CeO2/Al2O3 catalysts with different manganese-to-ceria ratios have been synthesized, characterized and tested in CO-PrOx reaction. The physicochemical properties of the solids were studied by XRD, Raman spectroscopy, BET surface area, H2-TPR, TGA-DTG and TEM. The differences observed in the textural, structural and redox properties were rel...

A novel multilayer approach for designing structured WGS catalyst is employed in this study as a response to the lack of new strategies in the literature. The approach proposes the use of two successive layers with different functionalities on metallic micromonolith substrate. The WGS catalyst behavior is modulated by the nature of the inner layer...

Carbon formation and sintering remain the main culprits regarding catalyst deactivation in the dry and bi-reforming of methane reactions (DRM and BRM, respectively). Nickel based catalysts (10 wt.%) supported on alumina (Al2O3) have shown no exception in this study, but can be improved by the addition of tin and ceria. The effect of two different S...