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In most current processes aimed at producing biodiesel glycerol is still a co-product, and its valorisation is essential for the biorefinery. This work relies on previous results showing the dependence of the selective dehydration of glycerol to acetol (hydroxyacetone) on achieving a moderate acidity and the redox functionality of copper to complete the chemical process. In this sense, this reaction was studied using CuO supported on silica. Different silicas and copper incorporation methodologies were investigated to develop the best CuO/SiO material. Interestingly, these CuO-based materials developed acidity and became more active when increasing the copper oxide dispersion, thereby going from poorly to intensely effective to dehydrate glycerol selectively to acetol. Catalysts were characterised by different techniques (i.e., ICP, N adsorption, XRD, TPR, HR-TEM, etc.) to explain the differences observed in catalytic activity and acetol yield based on their physicochemical properties., Financial support by Spanish Government (CTQ-2015-67592, PGC2018-097277-B-I00 and SEV-2016-0683) is gratefully acknowledged. J.M. thanks Spanish Government (CTQ-2015-67592) for the Ph.D. fellowship. Authors also thank Miriam Parreño Romero and the Electron Microscopy Service of Universitat Politècnica de València for their support.

The competitiveness of the biodiesel industry may be improved by adding value through co-products and integration with the oleochemical industry, especially for novel products such as biolubricants, a product of increasing world demand. In this study the synthesis of biolubricants from soybean oil was evaluated using transesterification, epoxidation and oxirane ring opening reactions. Water, 2-ethylhexanol and their mixtures were used to obtain hydroxyl-rich and/or ether-type branched molecules. All chemical modifications were monitored by Nuclear Magnetic Resonance (1H NMR) and evaluated through the physicochemical properties of the products. Several potential biolubricant samples were synthesized with viscosities at 40 °C ranging from 26.6 to 99.6 cSt, viscosity index from 26 to 139, densities at 20 °C from 0.925 to 0.964 g/cm3, and pour points from −3 to −12 °C. From these results, a proposal of a feasible industrial process for the production of biolubricants from soybean oil is presented, consisting of 16 units, of which 15 may be integrated with an existing biodiesel plant.

Olive stones were employed as feedstock for furfural production in two stages: 1) autohydrolysis of hemicellulosic fraction to recover their pentoses, mainly xylose, and 2) subsequent dehydration of pentoses into furfural. Autohydrolysis step was optimized by using different experimental conditions (temperature: 160-200 ºC and time: 30-75 min), giving rise to liquors with different xylose concentrations, since hydrolysis was incomplete in some cases. The combined use of a commercial γ-Al2O3 and CaCl2 led to total hydrolysis of non-hydrolyzed pentosans after autohydrolysis step, and the subsequent dehydration of pentoses into furfural. The maximum values of furfural yield and efficiency were 23 and 96%, respectively, after only 60 minutes at 150 ºC by using liquor obtained by autohydrolysis at 180 ºC and 30 min (L5.1) as source of pentoses. This liquor, L5.1, provided better catalytic results than other liquors which had shown higher xylose concentration after autohydrolysis, probably due to these latter also exhibited a higher concentration of organic acids; thus, the presence of organic acids such as acetic and lactic acid could promote side undesired reactions leading to lower furfural yields. Finally, γ-Al2O3 was more effective for furfural production under these experimental conditions than other solid acid catalysts, such as mesoporous Nb2O5, Nb-doped SBA-15 and Zr-doped HMS silicas, probably due to alumina has a higher density of acid sites. Spanish Ministry of Economy and Competitiveness (RTI2018-94918-B-C44 project), Junta de Andalucía (RNM-1565), FEDER (European Union) funds (UMA18-FEDERJA-171) and Malaga University. C.G.S. and J.A.C. thank to FEDER funds and Malaga University respectively for financial support. L.S.C. gratefully acknowledges support from Spanish MINECO via the concession of a Ramon y Cajal contract (RYC-2015-17109).

The oxidative condensation of furfural and ethanol has been studied using supported gold colloidal nano particles. The influence of the nature of stabilizer (polyvinylalcohol, polyvinylpyrrolidone), the choice of thermal treatment and washing for removing the stabilizer, on the catalytic performance has been evaluated. Variation of the mean gold particle size and surface coverage of the gold nanoparticles onto the support surface were achieved by modifying the stabilizer to Au weight ratio. Thus, the mean gold particle size was varied in the range of 3-8 nm. The catalytic results showed that the choice of stabilizer, the stabilizer to Au weight ratio, thermal treatment of the catalyst, affect catalytic activity and selectivity/yield to the desired products. When PVA was the chosen stabilizer, the highest yield to furan-2-acrolein (33%) was attained with a PVA to Au weight ratio of 2.4. On the contrary, when PVP was the stabilizer, the best catalytic performance was achieved in its absence, with the yield of furan-2-acrolein reaching 21%. These results showed the strong impact of stabilizer to control catalytic activity and to enhance, in the case of PVA, the yield to the target product, whereas a strong negative effect was observed with PVP. Moreover, a mild thermal treatment of the catalyst and a washing step for the removal of the stabilizer from the catalyst had a positive effect on the catalytic performance.

Two fibrous clay minerals (sepiolite and palygorskite) have been employed as adsorbents to assess their adsorption capacity of pure CO2 in a volumetric setup. The raw sepiolite reached a CO2 uptake of 1.48 mmol g−1 due to the presence of nanocavities acting as a molecular sieve. Both sepiolite and palygorskite were modified by microwave-assisted acid treatment, which led to an increase in specific surface area and pore volume due to Mg2+ leaching, particularly in the case of sepiolite. However, the partial digestion of these fibrous structures does not improve CO2 adsorption uptake due to the progressive increase of the size of nanocavities. In a next step, both fibrous clay minerals were functionalized with amine species by different procedures (grafting with (3-Aminopropyl) triethoxysilane (APTES), impregnation with polyethyleneimine (PEI) and double functionalization by grafting with APTES and then impregnation with PEI. In all cases, it can be observed that the incorporation of amine species favors the chemical interaction between the amines species and the CO2 molecules, although it also produces obstruction of the nanochannels so the adsorption takes place mainly on the outer surface of the fibers. Finally, the incorporation of amine species by double functionalization led to the highest CO2 adsorbed concentration of 2.07 mmol g−1 at 760 mm Hg and 65 °C due to a larger proportion of available amines sites as well as the use of higher adsorption temperature, which favored the diffusion of CO2 molecules within the adsorbent.

In this work, a series of Cu-Mg-Al hydrotalcites and the oxide mixture obtained by their calcination at 600 °C were synthesized by coprecipitation from metal nitrates. The effect of the coprecipitation temperature of the precursor on the structure and texture of these materials was investigated. The solids were characterised by inductively coupled plasma (ICP), atomic absorption spectrophotometry (AAS), an energy dispersive spectrometer (EDAX), thermogravimetric analysis (TGA-DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR). It has been studied the activity of these solids as catalysts for diesel soot combustion. The materials are formed by nanoparticles, and the coprecipitation temperature has influence in the morphology of hydrotalcites. Moreover, the catalytic performance of calcinated solids is influenced by the synthesis conditions. A low temperature coprecipitation is beneficial for the diesel soot combustion. In this sense, the solid obtained by coprecipitacion at 40 °C shows the best catalytic activity (Tmax = 375 °C). This catalyst contains cooper oxides, potassium and nitrate ions which can acts as promoters of the soot combustion. The studied solids showed activity and high resistance to the deactivation caused by hydro-treatment. Fil: Comelli, Nora Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Investigaciones en Tecnología Química. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Investigaciones en Tecnología Química; Argentina Fil: Ruiz, Maria Lucia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Investigaciones en Tecnología Química. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Investigaciones en Tecnología Química; Argentina Fil: Leguizamón Aparicio, María Silvia del Valle. 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: Merino, Nora Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Investigaciones en Tecnología Química. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Investigaciones en Tecnología Química; Argentina Fil: Cecilia, Juan Antonio. Universidad de Málaga. Facultad de Ciencias; España Fil: Rodríguez Castellón, Enrique. Universidad de Málaga. Facultad de Ciencias; España Fil: Lick, Ileana Daniela. 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: Ponzi, Marta Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Investigaciones en Tecnología Química. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Investigaciones en Tecnología Química; Argentina

The traditional SBA-15 was modified using pore 1,3,5-trimethylbenzene as pore expander to be evaluated in the adsorption of biomolecules bovine serum albumin (BSA) and cellulase (CEL). In order to study the influence of the acidity in the biomolecules adsorption, porous silicas with molar ratio in a range between 5 and 15 were synthesized. The obtained materials were characterized by X-ray diffraction, transmission electron microscopy, N2 adsorption-desorption at -196 °C, NH3 thermoprogrammed desorption, infrared spectroscopy and X-ray photoelectron spectroscopy. Then, their adsorption capacity for BSA and CEL was evaluated in batch experiments at 25 °C. The obtained data revealed that BSA adsorption is well-fitted to the Toth model in all adsorbents, while CEL adsorption is well-adjusted to the Henry model. In both cases, the adsorbent with a molar ratio Si/Zr = 15 and pore expander reached the highest adsorption values and showed high desorption capacity.

[EN] Porous Clays Heterostructures (PCH) from natural pillared clays (bentonite with a high proportion of montmorillonite) have been used as supports of iron oxide for two reactions of environmental interest: i) the elimination of toluene (a representative compound of one of the most toxic subsets of volatile organic compounds, aromatics) by total oxidation and ii) the selective oxidation of H2S to elemental sulfur. For both reactions these catalysts have resulted to be remarkably more efficient than similar catalysts prepared using conventional silica as a support. Thus, in the total oxidation of toluene it has been observed that the catalytic activity obtained using siliceous PCH is two orders of magnitude higher than that with conventional silica. The catalytic activity has shown to be dependant of the capacity of the support for dispersing iron oxide in a way that the higher the dispersion of iron oxide on the surface of the support, the higher is the activity. In the case of the selective oxidation of H2S to S both higher catalytic activity and higher selectivity to S have been observed using siliceous porous clays heterostructures than using conventional silica. Highly dispersed FeOx species have been shown as highly selective towards elemental sulfur whereas more aggregated FeOx species favour the formation of sulphur oxides decreasing the selectivity to S. Analyses of the surface by XPS have shown the predominance of sulfate species in the catalysts presenting low selectivity to elemental sulfur., The authors would like to acknowledge the DGICYT in Spain (CTQ2015-68951-C3-1-R, CTQ2015-68951-C3-3-R, CTQ2012-37925-C03-2, CTQ2012-37925-C03-3 and CTQ2012-37984-C02-01) and FEDER for financial support. We also thank the University of Valencia for funding (UV-INV-AE-16-484416) and SCSIE-UV for assistance.

We have previously demonstrated the influence of the niobium species over the glycerol dehydration reaction and how the catalyst regeneration by thermal treatment modified the catalytic performance due to the transformation of superficial niobium species. This experimental conclusion encouraged us to find a way to maintain and even improve the catalytic behavior of these Nb-based catalysts. Thus, herein, it is reported the influence of phosphoric acid treatment on 8 wt% Nb 2 O 5 supported on a zirconium doped mesoporous silica (Si/Zr = 5 molar ratio) catalyst, varying the Nb/P molar ratio between 0.1 and 1. Catalysts were full characterized and tested in the glycerol dehydration at 325 °C. This acid treatment modifies the nature of species present on the catalyst surface, as inferred from 31 P NMR data, where the presence of zirconium hydrogenphosphate was detected. A comprehensive study of the influence of acid properties on the catalytic activity has been carried out. Thus, the selectivity to acrolein was improved, which was attributed to this hydrogenphosphate phase and the catalyst stability was associated to the existence of acid sites of low and moderate strength. The best catalyst was studied at higher reaction temperatures, showing the highest glycerol conversion and achieving an acrolein selectivity of 74%, at 350 °C. This catalyst was also regenerated, maintaining its catalytic activity.

Several biochars and activated carbons are prepared from cellulose fraction of some agricultural wastes (linen, cotton and wheat). The obtained carbons are characterized by X-ray diffraction (XRD), transmission electronic microscopy (TEM), 13C nuclear magnetic resonance (13C NMR), CO2 adsorption-desorption at 0 °C, Raman spectroscopy and X-ray photoelectron spectroscopy. The biochars are synthesized at different pyrolysis temperatures while activated carbons are obtained from a biochar (pyrolysis at 500 °C) using KOH as activation agent in different amounts. The adsorption values in the biochars increase proportionally to the temperature levels (about 2.5 mmol CO2 g−1 at 25 °C and 760 mm of Hg). The highest the temperature of pyrolytic treatment, the highest the adsorption values. These values remain stable for several cycles in the case of samples synthesized at the highest temperature. The chemical activation of the biochar with KOH improves its microporosity as well as its CO2 adsorption capacity (3.6 mmol CO2 g−1 at 25 °C and 760 mm of Hg). Moreover, these biochars and activated carbons are evaluated for the adsorption of N2 or H2. The N2 and H2 adsorption capacity is much lower than that of CO2. Consequently, these biochars and activated carbons are highly selective for the CO2 capture. They have also shown a high H2 adsorption at −196 °C which makes them having a high potential in H2 storage at low temperature levels.

Traditionally, copper chromite has been used in furfural hydrogenation to obtain valuable products, like furfuryl alcohol. However, the presence of Cr poses serious environmental issues, in such a way that different Cr-free catalysts have been proposed as alternative. In this work, two commercial Cu-based catalysts without Cr, currently used in alcohol reforming (R120) and water-gas shift (W220), have been successfully evaluated in FUR hydrogenation to produce selectively furfuryl alcohol. Both R120 and W220 catalysts were characterized, with special emphasis on the elucidation of metallic properties, dispersion and oxidation states of Cu species, and compared to copper chromite. The R120 catalyst attained the best catalytic performance and stability over time, reaching a turnover frequency (TOF) of 0.31 s−1 at 190 °C, after 1 h of reaction. The catalytic results demostrated that these Cr-free commercial catalysts have high potential to replace copper chromite as shown the stability test for 24 h.

Chitosan has been used in the synthesis of catalysts for the furfural hydrogenation to obtain furfuryl alcohol. Cu-based catalysts supported on a carbonaceous matrix have been synthesized by complexation of Cu2+ species with the free electron pairs of the amino groups of chitosan under acid conditions, dried and subsequent pyrolysis. The catalytic behavior shows how the most active catalyst is Chi30Cu (30 wt% Cu), reaching a conversion close to 65% after 5 h at 190 °C. In all cases, a progressive deactivation is observed as a consequence of the adsorption of furfural and furfuryl alcohol on the support. With regard to the obtained products, these catalysts are selective to furfuryl alcohol, so these catalysts are environmentally sustainable and have great potential to be used in the synthesis of furfuryl alcohol as an alternative to copper chromite, which is highly toxic due to the presence of Cr species.

Three cationic exchange resins (PD206, CT269DR and CT275DR), supplied by Purolite ® , with different physicochemical properties have been evaluated in the esterification reaction of the free fatty acid from the castor oil with 2-ethylhexanol in order to obtain products with interesting properties to be used as biolubricant basestock. These resins have been characterized by SEM, elemental analysis (CNHS), TG/DTA and XPS. Likewise, these catalysts have been analyzed after the catalytic reaction to evaluate changes in the active phase during the esterification reaction. The catalytic data reveal that the macroreticular-type resins (CT269DR and CT275DR) show higher conversion values, about 95% after 4 h, than a gel-type resin (PD206) due to several factors, such as the higher amount of available acid sites or the denser divinylbenze matrix, which provides higher thermal and mechanical resistance and minimizes sulfur leaching. The deactivation of the active phase has been ascribed to the strong adsorption of reagents and products on the sulfonic groups located at the surface, as indicated in the XPS spectra of the spent catalysts. The products characterization showed that 2-ethylhexyl ricinoleate exhibited excellent properties at low temperature (pour point −39 °C), viscosity index value compatible with commercial synthetic basestock oils, higher biodegradability than mineral oil and better oxidation stability than the original feedstock.

Porous clay heterostructures (PCH) have been synthesized from raw bentonite, obtaining porous materials with high surface area and micro-, meso- and macroporosity. Both raw bentonite and PCH have been evaluated in CO2 adsorption processes at 1 bar and 25 °C. In both cases, adsorption isotherms were well fitted using the Langmuir model, obtaining an increase of the CO2 adsorption from 0.112 mmol CO2 g−1 for the raw bentonite to 0.640 mmol CO2 g−1 in the PCH. In order to improve the CO2 adsorption capacity, raw bentonite and PCH were functionalized with amine species, via grafting using 3-aminopropyltriethoxysilane (APTES) and via impregnation with polyethylenimine (PEI) or tetraethylenepentamine (TEPA). The isotherms of the amine-functionalized samples were adjusted to the Dual-Langmuir model, which assumes the coexistence of physical and chemical adsorption sites. From the profiles of the CO2 isotherms, it can been observed that grafted-PCH with APTES shows the coexistence of physical and chemical interactions, reaching 1.023 mmol CO2 g−1. The adsorption of CO2 on PCH impregnated with TEPA and mainly with PEI is governed by chemical interactions between the amine species located in the porous structure and/or on the surface of the adsorbent and the CO2 molecules, attaining maximum values of 1.644 and 1.465 mmol CO2 g−1 for TEPA and PEI, respectively.

Silica-supported catalysts based on mono and bimetallic nickel and iron phosphides with different Ni:Fe molar ratios (1:0, 3:1, 2:1 and 0:1) were synthesised and tested in the hydrodeoxygenation (HDO) reaction of phenol, a model molecule present in bio-oil derived from pyrolysis of biomass. Tests were performed in a fixed bed reactor under hydrogen pressure (1.5 and 3 MPa) for different contact times. Freshly reduced catalysts were characterised by physisorption of N 2 at −196 °C, CO chemisorption, X-ray diffraction, transmission electronic microscopy, temperature-programmed desorption of ammonia and hydrogen, and X-ray photoelectron spectroscopy. Characterization results revealed that the presence of Ni increased their ability to activate hydrogen and the number of active sites, while the presence of Fe favored the spillover process. By increasing the amount of Ni, the surface became enriched with P, and this was associated with the presence of surface P-OH groups that provided Bronsted acid sites to activate O-containing compounds as well as surface hydrogen species that minimised deactivation by coke deposition. Ni-containing phases presented higher HDO capabilities than FeP ones, but generated some O-containing intermediates. In contrast, the FeP catalyst transformed all phenol molecules into O-free compounds (cyclohexane and mainly cyclohexene).

In this study, the influence of the pore size in mesoporous silica (SBA-15) and the loading of niobium oxide species (Nb 2 O 5 ) have been evaluated on the esterification reaction of free fatty acids from castor oil to obtain products that can be used as bio-based lubricant feedstocks. Characterization techniques such as XRD, N 2 sorption, Raman spectroscopy, NH 3 -TPD, XPS and TEM have been employed to characterize the synthesized catalysts, demonstrating the high dispersion of the niobia species. The catalytic results showed that the SBA-15 support with an average pore size of 8.5 nm and a loading of 12 wt.% of Nb 2 O 5 was the best catalyst to obtain higher conversion values in the esterification reaction of ricinoleic acid. This fact was probably due to the pore diameter of this catalyst was the most suitable for the diffusion of reagents and products. The textural properties were more relevant than the acidic properties for Nb 2 O 5 supported on silica catalysts. The reuse data indicated that the conversion values decrease after each cycle probably due to the formation of carbonaceous deposits in the active sites, discarding the niobium leaching which is negligible. The catalytic activity could be almost thoroughly recovered by using a thermal regeneration treatment.

Sepiolite was treated in HNO 3 solutions with the assistance of microwave radiation. This treatment caused the progressive depletion of Mg 2+ , the gradual degradation of the sepiolite structure and the formation of an amorphous silica phase, which contributes to a noticeable increase of the surface area. The use of microwaves during acid treatment, after few minutes, led to materials with similar S BET to those obtained after 48 h with conventional heating methods. The influence of mineralogical impurities, crystallinity and chemical composition in the reactivity of sepiolite to this treatment was also studied. The obtained materials were impregnated with polyethylenimine and assessed for CO 2 capture and CO 2 /N 2 selectivity at different temperatures. Experimental equilibrium data were fitted to Langmuir and Sips models. The adsorption data revealed that sepiolite can be an interesting adsorbent for CO 2 capture, achieving a capacity of 1.70 mmol g −1 at 338 K and 1 bar, providing a high CO 2 /N 2 selectivity (440 mol CO 2 /mol N 2 ).

The growing expansion of biodiesel industries led to an increasing formation of by-products as glycerol, which can be considered as building block molecule to high-added value products. The use of natural materials, formed by calcium carbonate, has recently become an interesting approach to the development of inexpensive and widely available basic catalysts. In this work, the use of eggshell waste as catalytic precursor was evaluated in the glycerol etherification reaction to obtain glycerol oligomers. Both raw and calcined eggshell were characterized by XRD, FTIR, N2 adsorption-desorption at −196 °C, particle size analysis, SEM, CO2-TPD and TG/DTG. For comparative purposes, commercial CaO was also tested. The solids were tested as-received and calcined in the reaction. Several parameters as catalyst loading, reaction temperature, reaction time and the leaching of calcium to the reaction medium were evaluated. The optimal reaction conditions for the calcined eggshell were catalyst loading of 2 wt.%, temperature of 220 °C and reaction time of 24 h, promoting 85% glycerol conversion and oligomers yielding of 43% (Di- and Triglycerol). The material tested shows leaching; however, taking account its low cost and good basic properties, calcined eggshell can be considered as promising catalyst for glycerol oligomerization.

The present research evaluates the adsorption of reactive dyes, Remazol Violet 5R (RV5R) and Acid Blue 25 (AB25), using Porous Clay Heterostructures (PCHs) prepared from natural bentonite. Natural bentonite, PCH with silica pillars (Si-PCH) and PCH with silica-zirconia (SiZr-PCH) were characterized by elemental analysis, XRD, N 2 adsorption-desorption at − 196 °C, FT-IR, TG and XPS. The adsorption experiments were carried out in a stirred tank in order to evaluate the effect of pH, contact time and initial concentration. The adsorption isotherms were well fitted by Langmuir (L), Langmuir-Freundlich (LF) and Redlich Peterson (RP) models. The equilibrium data were described using the Langmuir-Freundlich model for both dyes and both materials, obtaining a maximum adsorption capacity of 209.9 mg g − 1 and 265.9 mg g − 1 for AB25 using Si-PCH and SiZr-PCH, respectively. In the case of RV5R, the maximum adsorption capacity was 127.07 mg g − 1 and 185.7 mg g − 1 for Si-PCH and SiZr-PCH, respectively. The adsorption process takes place by electrostatic interactions between the silanol groups of the PCHs with functional groups of the dyes, such as amine or hydroxyl. From the obtained results, it can be concluded that PCHs showed to be a promising material for the adsorption of dye.

Cu-CeO 2 - x catalysts, with a Cu/Ce molar ratio between 0.2 and 6.0, have been synthesized by coprecipitation, calcination and subsequent reduction. These samples have been characterized by X-ray diffraction, H 2 temperature-programmed reduction, N 2 O titration, N 2 adsorption-desorption at −196 °C and X-ray photoelectronic spectroscopy, among other techniques. They exhibit small average particle sizes, high dispersion of copper species, porosity and high metal surface. Their catalytic behavior was evaluated in the gas-phase hydrogenation of furfural (FUR), evidencing high activity and stability due to the strong interaction Cu-CeO 2 . The highest conversion was attained for catalysts with higher copper content, which display higher metal surface, with a value of 83% after 5 h of time-on-stream (TOS) for the Cu-CeO 2 -6 catalyst, at 190 °C, by using a H 2 :FUR molar ratio of 11.5 and a WHSV of 1.5 h −1 . In all cases, only furfuryl alcohol (FOL) and 2-methylfuran (MF) were obtained as reaction products, being majority MF for shorter TOS and FOL for longer, which can be explained by the deactivation of the highly hydrogenating sites by carbonaceous deposits and the oxidation of the active phase by water generated in the dehydration process to obtain MF.

Nb-Zr oxides were evaluated for glucose dehydration to 5-hydroxymethylfurfural. A linear relationship was found between the amount of acid sites and niobium content. Pure Nb2O5 showed the highest acid concentration and surface area and both Bronsted and Lewis acid sites, whereas Zr-containing catalysts mostly showed Lewis acid sites. Thus, a correlation between the amount of acid sites and catalytic performance was demonstrated, in the absence of metal salt, being Nb2O5 the most active catalyst. However, the catalytic results obtained by the combination of CaCl2 and Zr-containing catalysts, which only showed Lewis acid sites, suggested the direct formation of HMF, without fructose formation, unlike that observed for Nb2O5, which possesses both Bronsted and Lewis acid sites. A HMF yield of 44% was attained by using Nb3Zr7 as acid catalyst and CaCl2 after 90 min at 175 oC. These catalysts can be reused at least 3 catalytic runs without any pretreatment.

ZrO2, Al2O3 and ZrO2/Al2O3 with different Zr/Al molar ratio, have been synthesized by coprecipitation and subsequent calcination. The resulting catalysts were characterized by X-ray diffraction, transmission electron microscopy, N2 adsorption-desorption at -196 °C, CO2-thermoprogrammed desorption, NH3-thermoprogrammed desorption and X-ray photoelectron spectroscopy. Then, the catalysts were evaluated in the Meenwein-Ponndorf-Verley reduction of furfural (FUR) using 2-propanol as sacrificing alcohol. The catalyst with a Zr/Al molar ratio of 1, Zr5Al5, reached the highest conversion value at shorter reaction times, attaining a FUR conversion of 95 % with a yield of furfuryl alcohol (FOL) above 90 % after 5 h of reaction at 130 °C, due to its greater amount of acid sites, as well as higher specific surface area and pore volume.

The traditional mesoporous silica (SBA-15) was synthesized by hydrothermal route. The swelling agents 1,3,5-trymethylbenzene (TMB) and heptane were used to expand the pore size and fluoride (NH4F) was used to modify the length of the pores, leading to porous silicas with different textural properties. The adsorbents, identified as SBA-15 (S), SBA-15 (S1) (TMB), SBA-15 (S2) (TMB and NH4F) and SBA-15 (S3) (NH4F and heptane), were characterized regarding their texture, mesoscopic ordering and chemical surface and finally their adsorption capacity was evaluated using three model biomolecules (Bovine Serum Albumin – BSA, Lysozyme – LYS and Cellulase – CEL). Adsorption behavior of BSA, LYS and CEL onto these SBA-15 samples was investigated by batch experiments at 25 °C. Highest biomolecule uptake obtained for S2 and S3 were attributed to the larger pore diameter, shorter channel length and the formation of interparticle voids, which provides easier access of these biomolecules to the surface of the adsorbent and minimized the diffusion problems. All cellulase adsorption isotherms followed Henry’s Law. The adsorption capacity of cellulase in S2 was 250 mg/g for a liquid-phase equilibrium concentration of 6 mg/mL, while BSA and LYS adsorption isotherms were well fit by the Langmuir model and the maximum adsorption capacities were 581 and 786 mg/g, respectively.

Hollow silica microspheres have been synthesized with high surface area and homogenous porous size distribution to be evaluated for their CO2 adsorption capacity. All adsorbents were well fitted to the Henry model, except HMS-F that displays the highest CO2 adsorption capacity, which was adjusted to the Langmuir model. In order to increase the CO2 capture, the hollow silica microspheres were functionalized via grafting 3-aminopropyltriethoxysilane (APTES) and via impregnation with polyethyleniminethylenediamine branched (PEI) or tetraethylenepentamine (TEPA). In all cases, the adsorption isotherms of the amine functionalized silica are fitted to the Dual-Langmuir model, where physical and chemical adsorption sites are described. The isotherms reveal that grafted-silicas with APTES display the coexistence of both adsorption sites, while the adsorption process of impregnated-silicas with PEI or TEPA are governed by chemical interactions. The adsorption isotherms show that the most promising adsorbent for CO2 capture is HMS-F-TiPB, which reached a CO2 adsorption capacity of 3.4 mmol g−1 at 760 mmHg and 25 °C, maintaining this adsorption capacity 5 cycles.

In this study, a porous clay with tunable pores was used as catalytic support, with the purpose of enhancing the accessibility of dispersed WO3 inside the pores and minimizing the mass transfer limitations of bulky fatty acids and larger alcohols in the catalyst. WO3-based catalysts supported on porous clay heterostructures (PCH) with Si–Zr pillars prepared by incipient wetness impregnation were evaluated for the esterification reaction of ricinoleic acid (FACO) with 2-ethylhexanol (2-EH). Various catalysts with different Si/Zr molar ratios (Si/Zr = 1, 2, 5, 10 and 15) and different WO3 loadings (5, 10, 20 and 30 wt.%) were prepared and the influence of their properties on the catalytic performance was studied. The catalysts were characterized by XRD, nitrogen adsorption–desorption isotherms at − 196 °C, NH3-TPD, XPS, Raman and UV–vis spectroscopies. The leaching of the catalysts was determined by ICP-MS. The highest values of reaction conversion were achieved by using the PCH with a Si/Zr molar ratio of 15 and 20 wt.% of WO3, denoted as Zr15–20WO3. The best reaction conditions were a temperature of 120 °C using 10 wt.% catalyst with a 2-EH-to-FACO molar ratio of 2:1, being the observed values of conversion equal to 71 and 91% after 8 and 24 h, respectively. The catalysts did not show leaching of zirconium and tungsten species in the reaction medium which demonstrated the high stability of these catalysts.

A synthesis method in two steps was used to obtain Co 3 O 4 –CeO 2 (COCE) catalysts. Firstly, freeze-drying precursors to obtain a submicrometric ceria powders support were calcined at a temperature as low as 400 °C. Then, the support was impregnated with a Co(II) acetate solution by incipient wetness impregnation, varying the loading of Co between 5 and 20 wt%, and calcined again at 400 °C. x COCE samples were tested for the preferential oxidation of CO in a H 2 -rich stream (CO-PROX). All samples showed catalytic activity and high selectivity towards CO 2 at low reaction temperatures, being 15COCE the most active catalyst. Moreover, simulating a CO-PROX unit operation, the influence of the presence of CO 2 and H 2 O in the feed was tested, showing a high activity and selectivity mainly to CO 2 .

A series of Cu/ZnO catalysts (Cu:Zn molar ratio = 0.2–6.0), prepared by coprecipitation and subsequent calcination and reduction, has been characterized and evaluated in the gas-phase hydrogenation of furfural (FUR). All catalysts exhibit high stability, with conversion values higher than 55 mol% after 5 h of time-on-stream (TOS) at 463 K with a H2:FUR molar ratio of 11.5 and a WHSV of 1.5 h−1. The best catalytic performance is found for the catalyst with the lowest copper loading, which maintains a conversion of 93 mol% after 5 h of TOS, with a selectivity of 82 mol% towards furfuryl alcohol. After 24 h of TOS, this catalyst still shows a furfuryl alcohol yield of 60 mol%. The strong metal-support interactions in the catalysts with lower copper contents explain their higher stabilities. In all cases, the carbon percentages in the used catalysts are lower than 1.5%, thus indicating that carbonaceous deposits could be the cause of the slight deactivation of Cu/ZnO catalysts, together with metal sintering in catalysts with higher copper contents.

Glycerol dehydration to acrolein is one of the most promising routes to valorize the surplus of such by-product of the biodiesel industry. In this context, a family of solid acid catalysts based on tungsten oxide supported over zirconium doped mesoporous SBA-15 silica has been synthesized and the influence of phosphoric acid treatment on the catalytic behavior has been also evaluated. These catalysts have been characterized by using the following techniques: XRD, N2 adsorption-desorption at −196 °C, NH3–TPD, pyridine adsorption coupled to FT-IR spectroscopy, X-ray photoelectron spectroscopy, Raman and diffuse reflectance UV–visible spectroscopies, and they have been tested in the gas-phase dehydration of glycerol. Under the operating conditions assayed, all catalysts were active and acrolein was always the main product. The catalytic performance of support was enhanced when WO3 was supported and after treatment with H3PO4. The best catalytic results were achieved for 20W catalyst which showed values of glycerol conversion and acrolein yield of 97% and 41%, respectively, after 2 h on stream at 325 °C, and this activity was even maintained after 8 h. Moreover, the treatment with phosphoric acid improved the acrolein yield at 2 h on stream, but the deactivation of these catalysts was more pronounced probably because of the deterioration of textural and acid properties.

The effect of the microwave assisted acid treatment (MAT) on the structure and texture of dioctahedral (montmorillonite and nontronite) and trioctahedral (saponite and stevensite) smectites were studied by SEM, nitrogen adsorption, XRF, XRD and FTIR. The effectiveness of this treatment is notably influenced by the chemical composition of the octahedral sheet. Thus, trioctahedral smectites seem to be very reactive to the microwave assisted acid treatment. In saponite and stevensite this treatment caused in the first 20 min the progressive Mg 2 + depletion of the octahedral sheet, the gradual destruction of the smectite structure and the formation of an amorphous silica phase which contributes to a noticeable increase of the BET specific surface area. After 20 min of microwave assisted acid treatment the increase in SSA is of 315 m 2 /g in saponite and 244 m 2 /g in stevensite. The assistance of microwaves during the acid treatment allows us to get, in 20 min, specific surface areas equivalent to those obtained after 48 h with conventional heating methods. On the contrary, dioctahedral smectites seems to be less reactive to the microwave assisted acid treatment.

Five palygorskite samples from different geological environments including lacustrine and perimarine deposits and hydrothermal fillings were treated by a microwaveassisted acid leaching process inaqueous HNO3 solution (0.2 M). In all cases, the samples have been characterized by X-ray fluorescence (XRF), X-ray diffraction (FTIR), Fourier transform infrared spectroscopy (FTIR), N2 adsorption-desorption at −196 °C and Scanning electron microscope (SEM). The mineralogical study indicates that palygorskite is the predominant mineral although the presence of other associated minerals has been observed including: quartz, calcite, dolomite, feldspars, smectite, illite-mica and traces of chlorite and sepiolite. After the acid treatment the main mineralogical change is the disappearance of the carbonates, not being observed in any case the occurrence of amorphous silica. Palygorskite remains virtually unchanged from acid attack in four of the samples studied. Only in the sample with the highest Mg(II) content (Mace), mineralogical and chemical data evidence the partial solution of the octahedral layer in the fibrous clay mineral due to the release of magnesium. The textural study indicates significant differences in the specific surface area of the samples ranging from 75 to 225 m2 g−1, this variation being related mostly to the purity of the samples. Under similar experimental conditions, palygorskite is more resistant to acid attack than magnesian clay minerals (saponite or sepiolite). In addition, a relationship has been observed between the magnesium content of palygorskite and the susceptibility to microwave-assisted acid attack. In all cases, an increase in the specific surface area value has been observed, reaching a highest SBET value of 354 m2 g−1 for Mace sample after 16 min of microwave-assisted acid treatment as a consequence of the partial leaching of its octahedral sheet, although its fibrous structure is maintained yet.

A series of C-rich nickel nitride nanoparticles supported on silica has been prepared by the urea glass route, with urea as nitrogen and carbon source, and characterized by different physico-chemical techniques. They consist of Ni3N nanoparticles of 20-25 nm embedded into a carbonaceous matrix. These catalysts are much more active and stable than a nickel supported silica catalyst, which drastically deactivates. The supported Ni3N catalyst, with a 10 wt.% Ni, maintained a furfural conversion higher than 80% after 5 h of time-on-stream, at 170 ⁰C, with a high WHSV of 6 h-1. Complete initial furfural conversion values were observed at reaction temperatures varying from 170 to 230⁰C, and the selectivity toward furan and furfuryl alcohol (decarbonylation and hydrogenation products, respectively) was tuned by varying this temperature. After the catalytic tests, XPS and XRD have demonstrated that nanoparticles are stable, although carbonaceous deposits were also detected. Spanish Ministry of Innovation, Science and Universities (Project RTI2018-094918-B-C44) and FEDER (European Union) funds. J.A.C. thanks University of Malaga for contracts of PhD incorporation

[EN] A family of Fe-based catalysts supported hollow silica mesospheres has been synthesized and tested in the catalytic partial oxidation of H2S to elemental sulfur at 170.180 degrees C, atmospheric pressure and under 300 min of time-on-stream. The characterization of the synthesized catalysts by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance UV-vis spectra (DRS), H-2-termoprogrammed reduction (H-2-TPR), N-2 adsorption-desorption at -196 degrees C and X-ray photoelectron spectroscopy (XPS) reveals the formation of a catalytic system with high micro- and mesoporosity with high dispersion of the Fe2O3 species. The catalytic results reported high activity in the selective oxidation of H2S, reaching a highest conversion value close to 94% with a selectivity towards elemental sulfur of 98% after 300 min of time on stream (TOS) at 180 degrees C for the HMS-10Fe catalyst. The comparison of Fe-containing HMS (10 wt% of iron loading) with other SiO2-based supports, as a fumed silica (Cab-osil) or a mesoporous silica (SBA-15), presents different H2S conversion values, following the next trend: HMS-10Fe > SBA-10Fe > Cab-10Fe. These results suggest that the use of a support with a narrow pore tend to facilitate the iron dispersion favoring higher conversion rates., The authors wish to acknowledge the financial support provided by the Ministry of Economy and Competitiveness (Spain) (MINECO) CTQ2015-68951-C1-3R y CTQ2015-68951-C3-3R, Junta de Andalucia (Spain) P12-RNM 1565 and FEDER funds. In addition, the authors also thank Fundacao Cearense de Apoio ao Desenvolvimento Cientifico e Tecnologico (FUNCAP) by the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES) - Processo: PDSE 99999.002602/2014-08.

The effect of the microwave assisted acid treatment on five kerolite-Mg-stevensite samples from the Neogene Madrid Basin was studied. Samples with lower amount of kerolite are more prone to suffer chemical modifications thought the microwave assisted acid treatment than the kerolite-rich clay ones by the partial leaching of Mg2+-species located in the octahedral sheet. This fact supposes that two structures with similar chemical compositions (kerolite and stevensite) display a different response to the microwave assisted acid treatment. Thus, Mg-smectite with interlayer cations, such as stevensite, are more labile to the acid treatment than kerolite, which does not have interlayer cations in such a way that acid digestion of stevensite occurs simultaneously at the edges of particles and within the interlayer space, whereas in the case of kerolite, it occurs exclusively at the particle edges. The acid treatment implies an increase of the specific surface area in all cases, reaching a highest SBET value of 435 m2/g. In the case of samples with higher stevensite content, the increase in the SBET is mainly due to increases of the microporosity, whereas in the sample with higher kerolite content the increase in the SBET is mainly ascribed to increase of the external surface area of the particles. Then, these materials were evaluated in CO2 capture processes reaching a maximum value of 1.98 mmol/g at 65 °C and 760 mm Hg.

A series of solid acid catalysts based on vanadium and vanadium–phosphorous supported on a zirconium doped mesoporous SBA-15 silica has been synthesized, characterized by using XRD, N2 sorption, NH3–TPD, FT-IR spectroscopy, X-ray photoelectron spectroscopy and diffuse reflectance UV–vis spectroscopy, and evaluated in the gas-phase dehydration of glycerol. Under the operating conditions used, all materials are active in the glycerol dehydration, being acrolein the main product in all cases. Although higher values of conversion are obtained in the presence of vanadium oxide based catalysts, acrolein yield improves after the treatment with phosphoric acid, attaining a value of 42% after 2 h of reaction at 325 °C with the 12VP0.2 catalyst, which contains 12 wt.% of V2O5 and a V/P molar ratio of 0.2. However, the incorporation of phosphorous to the catalytic system partially destroys the mesoporous structure. Allyl alcohol has been also detected using vanadium based catalysts, due to a partial reduction of V2O5 species during the reaction, increasing its yield with the vanadium oxide loading. All catalysts suffer from deactivation by coke deposition on the catalyst surface, being the carbon content considerably higher for catalysts without phosphorous.

In this study ZSM-12/MCM-48 adsorbents have been synthesized at three ZSM-12 content, and also were functionalizated with amine groups by grafting. All the adsorbents synthesized were evaluated for CO 2 capture. The X-ray diffraction analysis of the ZSM-12/MCM-48 composite showed the main characteristic peaks of ZSM-12 and MCM-48, and after the functionalization, the structure of MCM-48 on the composite impregnated was affected due amine presence. For the composites without amine, the ZSM-12 content was the factor determining in the adsorption capacity of CO 2 and for the composites with amine the amount of amine was that influenced in the adsorption capacity.

Ni 2 P and CoP catalysts (5 wt.% of metal) supported on a commercial SiO 2 were tested in the gas phase catalytic hydrodechlorination (HDCl) of mono (chlorobenzene-ClB) and polychlorobenzenes (PCBs) (1,2- dichlorobenzene (1,2-DClB), 1,3-dichlorobenzene (1,3-DClB), 1,4-dichlorobenzene (1,4-DClB), and 1,2,4-trichlorobenzene (1,2,4-TClB)) at atmospheric pressure. It was investigated how the number and position of chlorine atoms in the molecule influence the HDCl activity. The prepared catalysts were characterized by X-ray diffraction (XRD), CO chemisorption, N 2 adsorption–desorption at −196 °C, and X-ray photoelectron spectroscopy (XPS). Characterization results indicated better active phase dispersion and greater amount of P on the Ni 2 P catalyst surface. Catalytic results showed that the Ni 2 P was more active and stable in this type of reactions. The hydrodechlorination activity decreased by increasing the number of chlorine atoms in the molecule and chlorine substituents in close proximity. The observed trend in the HDCl activity was: ClB > 1,4-DClB > 1,3-DClB > 1,2-DClB > 1,2,4-TClB. The exception was the catalytic response after 24 h on stream observed for the Ni 2 P in the HDCl reaction of 1,2,4-TClB, which was equal to that observed for the 1,4-DClB molecule, and also yielding benzene as the main reaction product.

CuO–CeO2 catalysts have been synthesized using polymethyl metacrylate (PMMA) microspheres as template and copper and cerium acetates as precursors, leading to a homogeneous porous framework of nanocrystalline materials with uniform pore size distribution and well dispersed copper species between 1 and 9 wt.%. The catalysts have been characterized by X-ray Diffraction (XRD), Field-Emission Scanning Electron Microscopy (FE-SEM), High-resolution Transmission Electron Microscopy (HRTEM), Raman spectroscopy, adsorption-desorption of N2 at −196 °C, thermoprogrammed reduction with H2 (H2-TPR) and X-ray photoelectron spectroscopy (XPS). CuO–CeO2 catalysts have been evaluated in the CO-PROX reaction, reaching high conversion values (>95%) at 115 °C for all samples. Moreover, these catalysts have been tested under high content of CO2 and H2O in the feed, simulating a CO-PROX unit, obtaining conversion efficiency values higher than 90% at 115 °C, which indicates a high tolerance of the catalysts in both CO2 and H2O gases.

This study reports on the preparation and characterization of porous clay heterostructures (PCH) as a high-surface-area support for CuO–CeO 2 based catalysts for the preferential oxidation of CO in excess of H 2 (CO-PROX). After pillaring the montmorillonite clay with silica (Si-PCH) and silica-zirconia (SiZr-PCH), the Cu-Ce active phase was loaded by incipient wet impregnation setting the cerium amount constant (20 wt%) and investigating three different copper loadings (3, 6 and 12 wt%). The use of pillars of silica or silica-zirconia inserted in the interlayer space of a natural clay provides a high surface area support that can favor the dispersion of both CuO and CeO 2 active phases, leading to the formation of a high amount of copper-ceria interfacial sites, responsible for a very high catalytic activity in the CO-PROX reaction. The results obtained from characterization of the materials by XRD, N 2 physisorption, H 2 -TPR, XPS and CO 2 -TPD suggest that this synthesis method gives rise to catalysts with copper species highly active and selective for the CO-PROX reaction. The catalysts exhibit high CO conversion values and the sample with 6 wt% of copper on Si-PCH displays very good performances, comparable to those based on precious metal catalysts, even at low temperatures. The system reducibility was found modified by the incorporation of zirconium in the support, with a slight decrement of the CO conversion value, compared to the same material without Zr. The influence of the presence of CO 2 and H 2 O in the gas feed was also studied in order to simulate the real operating conditions of a PEMFC feed stream. Correlations between catalytic performances and physicochemical properties of the materials have been made.

Catalysts of platinum and molybdenum supported on MCM-48 materials were synthesized and characterized by XRD, XPS and N2 adsorption–desorption. Catalytic activity was evaluated in the model reaction of hydrodesulfurization of dibenzothiophene. Catalytic results showed high catalytic performance of ca. 95% for PtMo/MCM-48 catalyst with the formation of biphenyl (BP) as the main product, typical from direct hydrodesulfurization (DDS) pathway and ciclohexylbenzene (CHB) in a minor proportion from the hydrogenation prior to the desulfurization pathway.

In this work, we have investigated how the typical honeycomb arrangement of SBA-15 and the mechanisms of CO 2 uptake are affected by the addition of chemicals upon synthesis (to modify pore width and length) and post-synthesis amine functionalization. SBA-15 was synthesized hydrothermally by a conventional route (S00) and such synthesis was then subject to modifications: by adding heptane as a swelling agent (S10) and increasing amounts of ammonium fluoride (S11, S12, S13 and S14) to shorten channels length. All of the synthesized silicas were then subject to APTES grafting and PEI impregnation. CO 2 isotherms were obtained for the pure and amine-loaded samples. They were fitted to the Dual-Site Langmuir model for all functionalized adsorbents, so that it was possible to discriminate the relative importance of chemisorption and physisorption sites. The increasingly disordered frameworks brought about by fluoride addition led to the formation of mesocellular silica foams (MCFs), which were not advantageous to increase CO 2 uptakes in the case of amine-grafting because they have a lower silanol density and hence bind less nitrogen as compared to the conventional SBA-15. In the case of PEI-impregnation, it was found that an addition of a low amount of fluoride is important in the regulation of the chemisorption/physisorption ratio. Promising CO 2 uptakes (2.3 mmol CO 2 /g or 4.6 mmol/g PEI at 25 °C and 1 bar) were found for a load of 50% (wt) PEI in MCF synthesized with the highest NH 4 F/SiO 2 molar ratio (equal to 0.065), which was attributed to a better accessibility of amino groups to CO 2 , as compared to the conventional SBA-15 support subject to the same PEI load.

The catalytic activity of precursor dolomite as a heterogeneous catalyst in biodiesel production has been investigated. The dolomitic material is a double calcium and magnesium carbonate, which when calcinated decomposes into CaO and MgO that are highly basic. The materials were characterized by XRD, TG–DTG, CO2-TPD, FTIR, XPS, SEM, and N2 adsorption/desorption at −196 °C. The raw material was activated and used as a catalyst for the transesterification of canola and sunflower oils with methanol. The conversion of canola and sunflower oils to methyl esters was optimized, under different catalyst amount and oil/methanol ratio, and the maximum conversions were: canola (98.81 ± 0.02 wt.%) and sunflower (96.52 ± 0.43 wt.%).

Three sepiolites with differences in composition and structural ordering were treated with 0.2 N HCl and 0.2 N HNO 3 solutions assisted with microwave radiation. This treatment caused in the firsts 16 min the progressive Mg 2 + depletion of the octahedral sheet, the gradual degradation of the sepiolite structure and the formation of an amorphous silica phase which contributes to a noticeable increase of the BET specific surface area. The assistance of microwaves during the acid treatment allows us to get specific surface areas equivalent to those obtained after 48 h with conventional heating methods. The influence of mineralogical impurities, “crystallinity” and chemical composition on the reactivity of sepiolite were also studied.

CuO supported on CeO2, Ce0.8Zr0.2O2 and Ce0.8Al0.2O2 based catalysts (6%wt Cu) were synthesized and tested in the preferential oxidation of CO in a H2-rich stream (CO-PROX). Nanocrystalline supports, CeO2 and solid solutions of modified CeO2 with zirconium and aluminum were prepared by a freeze-drying method. CuO was supported by incipient wetness impregnation and calcination at 400 � C. All catalysts exhibit high activity in the CO-PROX reaction and selectivity to CO2 at low reaction temperature, being the catalyst supported on CeO2 the more active and stable. The influence of the presence of CO2 and H2O was also studied.

The CO 2 adsorption capacity of different APTES-grafted mesoporous silicas of SBA-15 type has been investigated and the influence of support textural properties and the role of the presence of silanol groups on the adsorption capacity are analyzed. Four adsorbents based on SBA-15 were prepared using tetraethyl orthosilicate (TEOS) as silicon source, with and without the addition of trimethyl-benzene (TMB) and n -heptane as swelling agents, and adding in some cases ammonium fluoride as a solubility enhancer. 3-(triethoxysilyl)propylamine (APTES) was then used as grafting agent by reaction with free silanol groups on the silica surface so as to provide pending amino groups for CO 2 capture. The adsorption behavior for all supports was adequately described by a Freundlich model, whereas for the APTES-grafted silica, a dual-site Langmuir model was applied, which allowed us to quantify and qualify two different adsorption sites. The addition of n -heptane as swelling agent led to pore sizes beyond 10 nm and improved significantly the grafting efficiency, leading to higher CO 2 uptakes as compared to the starting supports. At 1 bar and 25 °C and anhydrous conditions, CO 2 uptakes of 2.4 mmol g −1 or 0.64 mol CO 2 per mol N were achieved (which reveals a significant contribution of physisorption). This sample could be successfully regenerated at 100 °C, maintaining a constant capacity for 3 adsorption–desorption cycles. At 0.15 bar and 60 °C, anhydrous conditions, CO 2 uptake reaches 1.5 mmol g −1 . This value may be theoretically doubled in the presence of humidity, and there is room for further improvement if supports with the same pore size (13 nm) and higher surface areas (e.g. 1000 m 2 /g) are successfully synthesized.

Catalytic transfer hydrogenation is an alternative catalytic approach for the reduction of carbonyl groups, instead of the use of dihydrogen gas. In this sense, a series of catalysts has been prepared by thermal treatment of layered double hydroxides, hydrotalcite type, of Mg(II) and Fe(III), with different Mg/Fe molar ratios. The resulting mixture of metal oxides was characterized by X-ray diffraction, TEM, N2 adsorption-desorption, CO2-TPD, NH3-TPD and XPS, and then catalysts were tested in the Meenwein-Ponndorf-Verley (MPV) reduction of furfural to obtain furfuryl alcohol. The catalytic results show that the catalyst with a Mg/Fe molar ratio of 3 allows reaching the highest furfural conversion at a lower reaction time, with a FOL yield close to 90% after 6 h of reaction at 443 K. The detailed analysis of these catalysts also revealed that the basicity plays a more predominant role in the MPV reaction than acid sites.