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The separation of a mixture of C5&ndash, C9 n-paraffins was achieved by Inverse Gas Chromatography (IGC) by using boehmite, AlO(OH), in a packed column with short exposure times and temperatures, from 45 &deg, C to 52 &deg, C. The boehmite was characterized by XRD, ATG, SEM, IR spectroscopy and N2 adsorption. The material exhibited a low crystalline boehmite (AlOOH) structure and presented high hydration (pseudoboehmite). The reverse gas chromatography measurements showed that the elution temperatures of the C5&ndash, C9 n-paraffins were low compared with those obtained for other adsorbents. The differential heat of adsorption values ensures the satisfactory separation of the components in the C5&ndash, C9 mixture under suitable chromatographic conditions.

In the present study a series of Au–transition metal oxides supported on a clay mineral such as sepiolite were tested in the preferential oxidation of CO in an excess of H2 under simulated solar light irradiation and in the absence of light, at 30 °C and atmospheric pressure. Transition metal oxides (ZnO, Fe2O3, NiO, MnO2, and Co3O4) were dispersed over the sepiolite surface where, subsequently, Au nanoparticles with an average particle size between 2 and 3 nm were successfully deposited–precipitated. The obtained photocatalysts were characterized by XRD, XRF, DRUV-Vis, N2 adsorption–desorption and HRTEM in order to evaluate the optical, structural and chemical properties of the prepared samples. Despite the low amount of gold (nominal 1.0 wt%), the catalysts exhibited an outstanding behavior under light irradiation, with reaction rates between 4.5 and 5.2 mmol COox gcat−1 h−1 for the Au–NiSep, Au–CoSep and Au–ZnSep samples. These photocatalysts exhibited a high dispersion of the respective transition metal oxides over the sepiolite support and the presence of low-coordinated hemispherical gold nanoparticles. The superior photocatalytic efficiency of these samples was ascribed to the reduction of the electron–hole pair recombination of photogenerated charge carriers by the excitation of the localized surface plasmon resonance of the Au nanoparticles. The BET surface area and the gold particle size seemed to be relevant factors affecting the catalytic performance.

We investigated the photocatalytic behavior of gold nanoparticles supported on CeO2-TiO2 nanostructured matrixes in the CO preferential oxidation in H2-rich stream (photo-CO-PROX), by modifying the electronic band structure of ceria through addition of titania and making it more suitable for interacting with free electrons excited in gold nanoparticles through surface plasmon resonance. CeO2 samples with different TiO2 concentrations (0-20 wt %) were prepared through a slow coprecipitation method in alkaline conditions. The synthetic route is surfactant-free and environmentally friendly. Au nanoparticles (

The climate situation that the planet is experiencing, mainly due to the emission of greenhouse gases, poses great challenges to mitigate it. Since CO2 is the most abundant greenhouse gas, it is essential to reduce its emissions or, failing that, to use it to obtain chemicals of industrial interest. In recent years, much research have focused on the use of CO2 to obtain methanol, which is a raw material for the synthesis of several important chemicals, and dimethyl ether, which is advertised as the cleanest and highest efficiency diesel substitute fuel. Given that the bibliography on these catalytic reactions is already beginning to be extensive, and due to the great variety of catalysts studied by the different research groups, this review aims to expose the most important catalytic characteristics to take into account in the design of silica-based catalysts for the conversion of carbon dioxide to methanol and dimethyl ether.

Gold nanoparticles precipitated-deposited on titania nanostructures (1.0 wt% nominal loading) were studied in the preferential CO oxidation in excess of H2 at room temperature and atmospheric pressure, both in dark and under simulated solar light irradiation. Titania supports were synthesized by means of two hydrothermal methods markedly acid and basic, giving rise to rutile nanorods and anatase deformed nanorods structures, respectively. Characterization techniques such as N2 physisorption, XRD, XPS, DRUV-vis, HRTEM and XRF were performed in order to study the chemical, structural and optical properties of the catalysts. Well defined rutile nanorods structures were obtained from the acidic treatment allowing a regular distribution of gold nanoparticles and resulting quite active in the CO-PROX reaction. In particular the sample from the acidic synthetic approach calcined at 700 °C displayed the best results as it was highly selective to CO2 under both dark and simulated solar light irradiation.

Hybrid materials (HMs) based on a combination of bacterial cellulose (BC) and hydroxyapatite (HA) have demonstrated promising capabilities, especially for bone repair. The insertion of strontium into a BC/HA matrix has a role in the body related to bone remodeling. This study aimed to obtain HMs containing BC/HA doped with strontium ions (Sr2+) by two routes of synthesis, differing in the way strontium was inserted. The HMs produced were characterized to elucidate the morphology and metal/biopolymer interaction, and also strontium adsorption/desorption profiles were evaluated. The biomaterials produced were able to interact with Sr2+, showing a distinct adsorption/desorption profile for each material. BC/CaHA/Sr showed an ion exchange between Ca2+ present in hydroxyapatite by the Sr2+ in solution, characterized by mainly a physisorption mechanism. BC/SrAp demonstrated a chemical bond of Sr2+ on the BC surface by a chemisorption mechanism. The desorption study showed that the Sr release reached a plateau after 11 and 60 days and after 4 months, 91 and 6% of the adsorbed Sr2+ was released by BC/CaHA/Sr and BC/SrAp, respectively. These results suggest that the delivery of Sr2+ can be modulated during bone repair depending on the way Sr2+ is inserted into the hybrid matrix.

In this study the photo-response behaviour of Au/TiO2 systems in the preferential CO oxidation in a H2-rich stream (CO-PROX) was investigated by the first time under simulated solar light irradiation at room temperature and atmospheric pressure. Au nanoparticles, with an average size of 2–5 nm, were precipitated-deposited on a mesoporous TiO2, previously synthesized by sol-gel type procedure and thermally treated at different temperatures to obtain anatase/rutile mixed phases. Structural, chemical and optical properties were studied by means of AAS, N2 physisorption, XRD, HR-TEM, DRUV–vis and XPS, investigating the effects of TiO2 polymorphs (anatase, rutile and combination thereof). All samples, containing a very low amount of noble metal (0.5 wt%), resulted very active in the photocatalytic CO-PROX at ambient conditions, attaining very high CO conversion and CO2 selectivity values. The Au/TiO2 sample containing both anatase/rutile polymorphs in the support displayed the highest activity, both in dark and under simulated solar light, due to the simultaneous presence of these two titania crystalline phases, capable to lower the effective band gap of the composite system (2.90 eV) and improving the photocatalytic activity in the studied reaction. This kind of materials may provide a sustainable and feasible approach to selectively oxidize CO in H2-rich stream under solar light irradiation and ambient conditions.

Bifunctional PdNb catalysts were studied in the hydrodesoxygenation (HDO) reaction of dibenzofuran (DBF) at 275 °C and 15 bar of H2 pressure. The influence of both the support employed (silica and zirconium phosphate heterostructure (PPH)) and the catalyst preparation procedure were evaluated in the catalytic response in the HDO reaction. The catalysts were prepared by incipient wetness impregnation by using two synthetic routes. The catalysts were characterized by means of X-ray diffraction (XRD), N2 adsorption-desorption, thermoprogrammed desorption of NH3 (TPD-NH3), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and elemental analysis. The results show that silica supported catalysts are much more active than those supported on PPH. While the characterization results point to a higher dispersion of the supported catalysts on PPH and better textural and acidic properties, the PdCl2 precursor salt remains on these catalysts even after calcination and catalytic tests, explaining the lower catalytic performance presented by these systems: fewer active centers and more residues of carbon. With respect to the preparation method, regardless the support employed, the catalysts synthesized by incorporating Pd after Nb incorporation and calcination, are more active, most probably due to a better phase dispersion and therefore to a higher amount of active centers.

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.

Molybdenum was incorporated into catalysts based on noble metals (Pt or Pd) and supported on silica in order to evaluate how its presence can modify the catalytic response of monometallic catalysts for hydrodeoxygenation (HDO). To this end, the catalysts were evaluated in the hydrodeoxygenation (HDO) reaction of dibenzofuran (DBF) and characterized by different experimental techniques to understand its structure, texture and acidic properties. Catalytic results showed that the active phase had much influence on the activity and selectivity to different reaction products, although, in all cases, bicyclohexane (BCH) was the main reaction product observed. Molybdenum played a very important role in the case of bimetallic catalysts, mainly in the case of palladium. Molybdenum species improved the selectivity to O-free products related to its capacity to break the C O bond. However, molybdenum activity was nil in the absence of noble metal. Moreover, regardless of the noble metal employed, the reducibility, acidity and dispersion of the molybdenum species changed and this is possibly associated to a synergism effect between noble metal and Mo.

From the point of view of saving and conservation of natural resources, the use of alternative components in construction materials is now an international concern. In this work, the valorization of two industrial wastes with no value in the market, biomass ash and exhaust dust filter from gases purification raw materials for the production of sustainable silica–calcareous units by the method of cementation was studied. After characterization of the raw materials, bricks were manufactured by mixing different ratios of residues, biomass ash (100−50 wt%) and dust filter (0–50 wt%) formed by pressure at 10 MPa and cured in water at room temperature for 28 days. The results indicate that as the dust filter content increases, the bulk density and mechanical strength of the silica–calcareous units decrease due to the lower density and high carbonation of the filter dust residue and the higher proportion of cement-based products formed in the pozzolanic reaction. Bricks containing 90 wt% of biomass ash-10 wt% of dust filter meet the criteria established by the regulations with an apparent density of 1471 kg/m3, water absorption of 24.2%, a compressive strength of 18.2 MPa and a thermal conductivity of 0.48 W/mK. In addition, the concentration of heavy metals obtained by leaching of the silica–calcareous ecobricks did not exceed the limits established by EPA 658/2009.

A series of Al-grafted mesoporous SBA-15 silica was synthesized and tested as catalysts in the gas-phase dehydration of glycerol to acrolein. Different Si/Al molar ratios were employed to tune the structure, texture and acidity of catalysts in order to analyze their effect on the catalytic performance. Different characterization techniques, such as powder X-ray diffraction, X-ray photoelectron spectroscopy, 27Al MAS NMR, N2 adsorption–desorption at −196 °C, ammonia temperature programmed desorption (NH3-TPD) and adsorption of pyridine coupled to Fourier transform infrared spectroscopy were employed. All materials were active in glycerol dehydration, being acrolein the main product in all cases. The catalyst with the highest Al content (AlSBA-2.5) showed the highest acrolein yield (27.6%) after 8 h of time-on-stream. A clear relationship between the effective production of acrolein and the acidity of catalysts could be established. Catalysts suffered from deactivation by coke deposition on the surface, but they can be reused, at least during three catalytic cycles, after regeneration at 550 °C in air during 4 h after each cycle.

A study was conducted to investigate the effect of the preparation route of ZrO2 in CuO–CeO2/ZrO2 catalysts for the oxidation of carbon monoxide at low temperature (COX). Four ZrO2 supports were synthetized via either type sol-gel methodology or precipitation. The final Cu-Ce-Zr oxide catalysts were prepared by incipient wetness co-impregnation with copper and cerium solutions (with a loading of 6 wt% of CuO and 20 wt% of CeO2). The catalyst crystalline phases, texture and active species reducibility were determined by XRD, N2 physisorption at −196 °C and H2-TPR, respectively; meanwhile the surface composition and copper-cerium electronic states were studied by XPS. The catalytic activity was evaluated in the oxidation of CO to CO2, in the 40–215 °C temperature range. Catalytic results evidenced that the samples prepared by a sol-gel methodology showed, after the impregnation, a severe decrease of specific surface area and pore volume attributable to a wide degree of pore blockage caused by the presence of metal oxide particles and a collapse of the structure partially burying the active sites. A simple co-impregnation of a zirconia support, obtained through facile and fast precipitation, provided instead a catalyst with very good redox properties and high dispersion of the active phases, which completely oxidizes CO in the range 115–215 °C with T50 of 65 °C. This higher observed activity was ascribed to the formation of a larger fraction of highly dispersed and easily reducible Cu species and ceria nanocrystallites, mainly present as Ce(IV), with an average size of 5 nm.

The present study investigates the feasibility of using fly or bottom biomass ash as a partial replacement in the production of eco-friendly construction materials. The fly and bottom ashes from combustion of biomass (olive pruning and pine pruning) generated in a Spanish Power Plant were used as raw materials to replace clay for the production of fired bricks. First, the mineralogical and chemical composition and thermal behavior of the ashes and clay were determined. Next, ceramic bricks were manufactured by compressing clay and different quantities of fly or bottom biomass (0–30 wt%). Different firing temperatures, 900 and 1000 °C, were studied. The effect of adding fly or bottom biomass ash on the technological behavior of the brick was assessed by studying linear shrinkage, water absorption, bulk density, compressive strength, thermal conductivity and the morphology. The results have shown that the optimum sintering temperature was 1000 °C. The increase in the firing temperature from 900 to 1000 °C, raised the compressive strength and decreased the water absorption. The addition of 30 wt% of bottom or fly biomass ash produced bricks with very high water absorption values and low mechanical properties. Based on the results obtained, the optimum amounts of bottom or fly ash were 20 wt%. These percentages produced bricks whose mechanical properties were suitable and thermal conductivity decreased by 21% respect to the standard bricks. The addition of bottom biomass ash produced bricks with slightly better properties, due to the most appropriate composition of these ashes. The bricks do not present environmental problems according to the leaching study. Therefore, fly and bottom biomass ash from the combustion of olive-pine pruning could be used as secondary raw materials in ceramic brick production.

This study analyzes the feasibility of using biomass combustion ash waste (rice husk or wood ash from boards) as secondary raw materials in the manufacture of clay bricks. The ash was characterized using particle size distribution analysis, chemical composition analysis by X-ray diffraction (XRD) and X-ray fluorescence (XRF), thermal analysis, elemental analysis, and scanning electron microscopy (SEM). Either rice husk ash or wood ash was used to replace different amounts (10–30 wt%) of clay in brick manufacture. Brick samples were formed by compression at 54.5 MPa and fired at temperatures of 900 or 1000 °C for 4 h, at a heating rate of 3 °C/min. The bricks’ properties were compared to conventional products containing only clay and prepared following standard procedures. The bricks’ technological properties depended on type and amount of ash used, and firing temperature. The results showed small variations due to firing temperature. Firing at 1000 °C achieved greater densification and thus lower water absorption and higher compressive strength firing at 900 °C produced higher porosity, which reduced compressive strength. Based on the results, 1000 °C was selected as the optimal firing temperature; and 10 wt% rice husk ash and 20 wt% wood ash as the optima amounts of biomass ash waste. Moreover, the bricks containing wood ash showed properties similar to the control bricks containing only clay and improved thermal conductivity. Finally, the bricks containing 10 wt% rice husk ash and 30 wt% wood ash fulfilled standard requirements for clay masonry units.

The oxidation of glycerol into lactic acid using activated carbon with Pd or Pt as heterogeneous catalysts was study. Several reaction parameters were evaluated: catalyst loading, catalyst weight, NaOH/glycerol molar ratio, temperature and reaction time. The textural and structural properties of the carbon supported catalysts (fresh and spent) were evaluated by N 2 adsorption-desorption isotherms at −196 °C, XRD, SEM, EDX, TEM and XPS. It was possible to achieve a glycerol conversion of about 99% with selectivity to lactic acid of 68% and 74% using 10% Pd/C and 5% Pt/C as catalysts, respectively, at 230 °C of reaction temperature. Moreover, Pd/C and Pt/C catalysts were used in five reaction cycles without significant loss of activity, highlighting the great stability of the prepared catalysts.

This work investigates the recycling of pyrrhotite ash (PA) waste as a method to provide a secondary raw material for clay brick bodies. PA is an industrial waste mainly composed by iron oxide particles (64,9 wt%). It was produced during the production of sulfuric acid from the combustion of pyrrhotite ore. This waste was characterized by X-ray fluorescence, X-ray diffraction, Fourier transform infrared spectroscopy and differential thermal analysis. The morphology and distribution of particles size were also studied. Clay bricks containing yellow clay and different content of PA (10–50 wt%) were prepared, fired at 1000 °C and tested to evaluate their technological properties (e.g. linear shrinkage, water absorption, bulk density, apparent porosity and flexural strength). The microstructure of the sintered bricks was also evaluated by scanning electron microscopy (SEM). The test results indicate that the addition up to 30 wt% of PA waste to clay bricks could be used, which would enhance the possibility of its reuse in a safe and sustainable way.

The production of biodiesel from acidic non-edible oil and waste lipid feedstocks has the drawback of forming soaps in the conventional transesterification process. A solution is the esterification reaction that uses superacid homogenous catalysts; however, it generates dangerous effluents. To overcome this, heterogeneous acid catalysts such as heteropolyacid supported on activated carbon have been studied for the production of biofuel. Due to its high surface area, the activated carbon allows high dispersion of the active phase. The aim of this work was to study the esterification of oleic acid over 12-tungstophosphoric acid (HPW) supported on activated carbon derived from passion fruit biomass (ACP), prepared by chemical activation using ZnCl2. The composites (HPW/ACP) were prepared containing 10–30 wt% of HPW by following two procedures: aqueous impregnation method and incipient moisture. The results showed that the activated carbon prepared from the residue of the passion fruit seed presented a high surface area (465 m2. g−1) and that the HPW impregnation method on activated carbon was a decisive factor on the catalyst performance. XPS, SEM, NMR and N2 adsorption-desorption results showed that in the catalyst obtained by aqueous impregnation (HPW/ACP) surface area decreased (50 m2 g−1), HPW was highly dispersed in the internal pores of the ACP support and presented superior acidity. The incipient moisture impregnation (HPW/IACP) formed HPW particles on the external surface of the support with little interaction among them, resulting in surface area of 90 m2 g−1. The best result of oleic acid esterification with methanol led to 86.4% conversion with catalyst HPW30/ACP, at 100 °C, after 2 h of reaction. The leaching of HPW active phase after the reaction was low ∼1.0–2.6%. This study showed the importance of the HPW impregnation method on activated carbon to obtain a more stable and more active catalyst for the production of biodiesel. A detailed analysis of the catalyst synthesis from a fruit industry residue demonstrated the possibility of operating in a closed-loop system towards cleaner production.

Copper oxide supported on zinc oxide catalysts was tested for the photocatalytic degradation of methylene blue (MB) and methyl orange (MO) dyes under UV irradiation at 25, 35 and 45 °C. These Cu/ZnO catalysts with variable copper loadings (2.5, 5 and 7.5 wt%) were prepared by impregnation and characterized by atomic absorption spectroscopy (AAS), X-ray diffraction (XRD), N2 adsorption–desorption, transmission electron microscopy (TEM), diffuse reflectance UV–visible absorption spectroscopy, and X-ray photoelectron spectroscopy (XPS). XRD and XPS data revealed that copper was in the form of copper oxide (CuO), and the crystal size was 240.8 and 49.3 nm for ZnO and CuO, respectively. Experiments showed that xCu/ZnO catalysts were highly active for MB and MO degradation compared with the zinc oxide supports due to the presence of copper oxide acting as an electron trap inhibiting electron-hole recombination. Furthermore, photodegradation activity was improved with increasing temperature. The 5Cu/ZnO catalyst exhibited greater degradation activity in both dyes, reaching 99% degradation at 45 °C after 15 and 75 min for MB and MO, respectively, due to its greater dispersion of CuO in ZnO and higher concentration of hydroxyl groups on the surface compared with other catalysts. Thermodynamic calculations indicated that the interaction of MB with the surface was stronger than that of MO and possibly related to the presence of hydroxyl groups on the surface, as indicated in the XPS results. The effects of different scavengers of the main species involved, such as hydroxyl radicals, superoxide radical anions and positive holes, were studied to propose photodegradation mechanisms of the dyes on these systems. The superoxide radical was the main reactive species during the photocatalytic degradation of MB and MO.

This paper presents the catalytic activity of ruthenium phosphides supported on SBA-15 material as hydrodesulfurization (HDS) catalysts of gasoline model compounds. It was studied the influence of the P/Ru molar ratio of 0.5, 1, 2, 3, and 4.5 (samples were labeled as 0.5-P/Ru, 1-P/Ru, 2-P/Ru, 3-P/Ru and 4.5-P/Ru) in the hydrodesulfurization of 3-methyl-thiophene as a model molecule and evaluated under mild reaction conditions. The ruthenium phosphide phase was synthesized from a conventional phosphate reduction method using RuCl3 and (NH4)2HPO4 as precursors. The catalysts were characterized by XRPD, N2 adsorption–desorption isotherms, TEM, EDS, XPS, NH3-TPD, H2-TPD and CO chemisorption. All catalysts maintained the mesoporous structure characteristic of the SBA-15 support, although pore blockage occurred at high P loadings. TEM images and EDS mapping showed well dispersed active phosphide phases, mainly RuP and Ru2P, as evidenced by XRPD. 3-P/Ru catalyst became to be the most active in the HDS reaction, with a high isomerization ability, which was assigned to its medium acidity and higher amount of active species on the surface that activates H2 species.

The effect of the Si/Al ratio of the ZSM-5 support on the structure and activity of Mo/HZSM-5 catalysts in methane dehydroaromatization (MDA) was studied. ZSM-5 (with Si/Al = 15, 25, and 40) supported Mo oxide catalysts (MoOx/ZSM-5) with 3 and 10 wt% Mo loading were prepared by incipient wetness impregnation followed by calcination in air at 500 °C. The as-prepared catalysts were activated by temperature programmed reduction in hydrogen in order to maximize Mo dispersion. To understand the structure-activity relationship, the fresh and spent samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N2 adsorption isotherms, Scanning Transmission Electron Microscopy with Energy Dispersive X-Ray Spectroscopy (STEM-EDS), X-ray absorption spectroscopy (EXAFS and XANES), thermogravimetric analysis (TGA), and Raman spectroscopy. The results show that the Si/Al ratio does not influence the the local structure around the Mo centers. It does however affect the number of available Bronsted acid sites in the support and the amount of Mo species entering the zeolite channels. A lower Si/Al ratio and higher Mo loading resulted in a higher Mo occupation within the zeolite channels. The higher channel occupation directly correlated with higher benzene selectivity and yield, as well as a lower catalyst deactivation rate.

Hydroxyapatite-associated bacterial cellulose (BC/HA) is a promising composite for biomedical applications. However, this hybrid composite has some limitations due to its low in vivo degradability. The objective of this work was to oxidize BC and BC/HA composites for different time periods to produce 2,3 dialdehyde cellulose (DAC). The BC and oxidized BC (OxBC) membranes were mineralized to obtain the hybrid materials (BC/HA and OxBC/HA) and their physico-chemical, degradability, and bioactivity properties were studied. The results showed that OxBC/HA was more bioactive and degradable than BC/HA, which isa function of the degree of BC oxidation. High glucose levels in the BC degradation were observed as a function of oxidation degree, and other products, such as butyric acid and acetic acid resulted from DAC degradation. Therefore, this chemical modification reaction favors BC degradation, making it a good biodegradable and bioactive material with a potential for bone regeneration applications.

Featured Application: In this work, an inexpensive and available material, as volcanic glass, is used to absorb metals from wastewater and then it is used to the separation of light liquid-olefins.Abstract: Raw porous volcanic glass from Cuba was used as an adsorbent for Cu2+ removal from dyes after activation with an acid solution. After Cu2+ adsorption, it was also evaluated its capacity to separate n-paraffins from a mixture by inverse gas chromatography (IGC), and the results were compared with those obtained with bare volcanic glass without copper. The main goal of this work is to highlight the great applicability of natural volcanic glass, which can be reused without pretreatment as an adsorbent. The results from copper adsorption were quite promising, considering the availability and low cost of this material; the sample without acid treatment turned out to be the most adequate to remove copper. Moreover, the results from IGC revealed that the separation of paraffins from the mixture was achieved with both bare volcanic glass and glass containing Cu, although greater heat adsorption values were obtained when copper was present in the sample due to the stronger interaction between paraffin and copper. The high availability and low cost of this porous material make it a potential and attractive candidate to be used in both heavy metal removal and paraffin separation for industrial purposes.

A family of alkali metal-based frameworks containing the tetraphosphonate ligand hexamethylenediamine- N,N,N′,N′-tetrakisIJmethylenephosphonic acid), HDTMP, is reported. A cation size-induced structural diversity, from monodimensional solids (Li+ and Na+) through layered (K+) to pillared-layered (Rb+ and Cs+) structures, was found. The proton conductivity properties of the Li compounds (hydrated and dehydrated) are reported and the influence of dehydration/rehydration processes in enhancing proton transfer processes is highlighted. Reversible changes in the dimensionality occurred upon full dehydration/rehydration with minor rearrangements in the framework, implying variations in the Li+–ligand connectivity but preserving the tetracoordination of the metal ion. The reversibly dehydrated–rehydrated sample displayed the highest proton conductivity (5 × 10−3 S cm−1 at 80 °C and 95% RH), a behavior attributed to reversible formation/ reformation of P–OIJH)–Li bonds that, in turn, provoked changes in the acidity of acid groups and water mobility in the temperature range of impedance measurements. Proyecto MAT2016-77648-R del ministerio y proyecto P12-FQM-1656 de la Junta de Andalucía Ministerio de Economía y Competitividad por el contrato Ramon y Cajal (RyC2015-17870).

In the present study a porous lamellar zirconium phosphate heterostructure (PPH) formed from zirconium(iv) phosphate expanded with silica galleries (P/Zr molar ratio equal to 2 and (Si + Zr)/P equal to 3) was prepared to host noble metals. Textural and structural characterization of PPH-noble metal materials was carried out in order to elucidate the location and dispersion of the metallic particles and the properties of the resulting material to be used in catalytic processes. In the present paper, their activity in the catalytic hydrodeoxygenation (HDO) reaction of dibenzofuran (DBF) was evaluated. X-ray diffraction (XRD), solid state nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS) evidenced that the structure of the pillared zirconium phosphate material was not modified by the incorporation of Pt and Pd. Moreover, transmission electron microscopy (TEM) showed a different dispersion of the noble metal. The acidity of the resulting PPH-noble metal materials also changed, although in all cases the acidity was of weak nature, and the incorporation of noble metals affected Bronsted acid sites as observed from 31P NMR spectra. In general, the textural, structural and acidic properties of the resulting materials suggest that PPH can be considered a good candidate to be used as a catalytic support. Thus, the catalytic results of the PPH-noble metal samples indicated that the Pd sample showed a stable behavior probably ascribed to a high dispersion of the active phase. However, the Pt sample suffered from fast deactivation. The selectivity to the reaction products was strongly dependent on the noble metal employed.

A high surface area K-promoted iron-based catalyst is prepared by thermal decomposition of ammonium glycolate complexes, followed by impregnation with an aqueous solution of potassium carbonate, drying and calcination. It is found that the duration of the calcination has a dramatic effect on the textural and structural properties of the obtained material, as well as on the iron oxidation state. Fast calcinations allow to synthetize materials isostructural with Fe3O4/γ-Fe2O3 that, after a carburization treatment with CO/H2 mixtures, are highly active in the CO2 hydrogenation to lower (C2–C4) olefins at mild process conditions (300 °C and 5 barg). Interestingly, the decrease of the operating pressure leads to a shift from the “hydrocarbon synthesis” regime to reverse water gas shift regime. The selectivity to lower olefins is instead maximised at mild process conditions due to the moderate chain growth probability and the slow rate of olefin secondary hydrogenations, which dominate at higher pressure and temperatures, respectively. The former process is activated by type II catalytic sites (iron carbides), while the latter occurs on type III catalytic sites (Fe0). Type I catalytic sites also exist (Fe3O4) and are responsible for the RWGS activity of the catalyst. Collected data suggest that CO is the primary product of CO2 hydrogenation, while hydrocarbons are formed via CO hydrogenation, following a Fischer-Tropsch type mechanism. Eventually, the performances of the prepared catalyst are compared with those of K-promoted reference model samples based on commercial α-Fe2O3 and Fe3O4 powders. It is found that, due to a better carburization and the higher surface area, the catalyst prepared by fast decomposition of ammonium glycolate complexes is more active than the reference materials in terms of both CO2 conversion and C2–C4 olefins selectivity.

V2O5powders modified with different theoretical silver contents (1, 5, 10, 15, and 20 wt% as Ag2O) were obtained with acicular morphologies observed by scanning electron microscopy (SEM). Shcherbinaite crystalline phase is transformed into the Ag0.33V2O5crystalline one with the incorporation and increase in silver content as was suggested by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis. With further increase in silver contents the Ag2O phase appears. Catalysts were active in photocatalytic degradation of malachite green dye under simulated solar light, which is one of the most remarkable facts of this work. It was found that V2O5-20Ag was the most active catalytic formulation and its activity was attributed to the mixture of coupled semiconductors that promotes the slight decrease in the rate of the electron-hole pair recombination.

In this work, SBA-15 silica and silica-titania have been used as supports for photocatalysts based on AuCu alloy (Au:Cu = 1) to be used in the preferential oxidation of CO (CO-PROX) in excess of hydrogen at room temperature and atmospheric pressure both in the dark and under simulated solar light irradiation. To study their textural, structural, chemical and optical properties, the samples were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), adsorption-desorption of N2 at &minus, 196 &deg, C, 13C and 29Si solid state nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS) and diffuse reflectance ultraviolet-visible (DRUV-vis) spectroscopy. Titanium was present mainly in the form of titania aggregates, but also as small particles interacting with the SBA support. In both catalysts, the metal alloy nanoparticles displayed an average size of 4 nm as demonstrated by TEM measurements. AuCu/Ti-SBA turned out to be photoactive and selective in the photo-CO-PROX reaction showing the highest activity, with conversion and selectivity towards CO2 of 80%, due both to the presence of titania incorporated in SBA-15 and to the synergistic effect of Cu when alloyed with Au.

Cobalt nanoparticles have been prepared by reduction of cobalt chloride by sodium borohydride. They are very active catalysts for ethanol steam reforming at moderate temperature. The best catalytic materials show full ethanol conversion and hydrogen yields of the order of 83% and stable activity for 8 h when tested at 773 K, GHSV 324,000 h −1 with diluted 1:6 ethanol:water feed in He 41.6%. The amount of coproduced methane is very low (yield

This work evaluates the effect of incorporation of olive stone ash, as secondary raw material, on the properties of fired clay bricks. To this end, three compositions containing 10, 20, and 30 wt% olive stone ash in a mixture of clays (30 wt% red, 30 wt% yellow, and 40 wt% black clay) from Spain were prepared. The raw materials, clay and olive stone ash, were characterized by means of XRD, XRF, SEM-EDS, and TG-TDA analysis. The engineering properties of the press molded specimens fired at 900°C (4 h) such as linear shrinkage, bulk density, apparent porosity, water absorption, and compressive strength were evaluated. The results indicated that the incorporation of 10 wt% of olive stone ash produced bricks with suitable technological properties, with values of compressive strength of 41.9 MPa but with a reduced bulk density, by almost 4%. By contrast, the incorporation of 20 wt% and 30 wt% sharply increased the water absorption as a consequence of the large amount of open porosity and low mechanical strength presented by these formulations, which do not meet the standards for their use as face bricks. The bricks do not present environmental problems according to the leaching test.

NiO/Al2O3 mechanical mixtures and impregnated catalytic materials have been prepared and analysed by XRD, DR-UV–vis-NIR, skeletal FT-IR, XPS, FE-SEM techniques. The presence of the carcinogenic and easily reducible NiO phase (bunsenite) is detected by XRD, DR-vis and DR-NIR with a sensitivity limit well lower than 1000 ppm, which is the lower limit by law to classify a NiO-containing waste, such as spent catalysts, as dangerous. This species is also observed by XPS and FE-SEM with a similar sensitivity limit. Hardly reducible surface dispersed Ni2+ species are also observed by DR-vis with a sensitivity limit lower than 1000 ppm. A surface spinel-like phase, with a composition NixAl2O3+x, with x ≤ 0.25 is formed at higher loadings, and is distinguished from the highly dispersed Ni2+ species using IR and XRD. This defective surface spinel like species can be distinguished from stoichiometric bulk NiAl2O4 by applying DR-NIR spectroscopy. The stoichiometric bulk nickel aluminate phase NiAl2O4 (which is also classified as carcinogenic) does not form from γ-Al2O3 or δ-Al2O3 and nickel species at temperatures up to 1073 K.

A series of mesoporous silica-supported nickel catalysts (2.2 wt% Ni) were prepared by impregnation employing the incipient wetness technique using Ni(II) formate as the impregnation salt. Three different atmospheric conditions were employed during the thermal treatment: air, He and H 2 . The catalysts were characterised by chemical analysis, XRD, N 2 adsorption at −196°C, H 2 -TPR, H 2 -TPD and XPS. A direct relationship was found between catalytic activity in the gas-phase hydrogenation of acetonitrile and the Ni 2p 3/2 binding energy assigned to the Ni 0 atoms of the reduced catalysts, where the catalytic activity decreased with increasing binding energy. The best catalyst obtained was that prepared by thermal decomposition in air and subsequent reduction in a hydrogen atmosphere; this catalyst displayed a high metallic surface and a low value for the Ni 2p 3/2 binding energy of Ni 0 .