Papers by Ramon Moreno Tost
Current Opinion in Green and Sustainable Chemistry
ACS Sustainable Chemistry & Engineering
Journal of Catalysis, 2009
A series of 10%Co/ITQ-2 model catalysts have been prepared by combining a reverse micellar synthe... more A series of 10%Co/ITQ-2 model catalysts have been prepared by combining a reverse micellar synthesis with a surface silylated ITQ-2 delaminated zeolite. The catalysts display rather uniform Co 0 particle size distributions in the 5-11 nm range as ascertained by XRD, H 2 -chemisorption and (HR)TEM. Additionally, a low dispersed 30%Co/SiO 2 reference sample (d(Co 0 ) = 141 nm) has been prepared by supporting a Co 3 O 4 nanopowder on spherical SiO 2 . H 2 -TPR and DR UV-vis spectroscopy reveal that the preparative approach leads to highly reducible catalysts in the d(Co 0 ) range of 5.6-141 nm, while the activation energies for the stepwise Co 3 O 4 ? CoO ? Co 0 reduction are found to be particle size dependent. Formation of barely reducible surface and bulk Co silicate species is observed for samples with d(Co 3 O 4 ) 6 5.9 nm. Under realistic Fischer-Tropsch synthesis conditions (493 K, 2.0 MPa) the TOF increases from 1.2 Â 10 À3 to 8.6 Â 10 À3 s À1 when d(Co 0 ) is increased from 5.6 to 10.4 nm, and then it remains constant up to a particle size of 141 nm. In situ and at work FTIR of adsorbed CO reveal a severe cobalt surface reconstruction towards more open crystal planes and/or defect sites (Co-carbonyl bands in the region of 2000-2025 cm À1 ) and suggest adsorbed C adatoms (surface carbidic species), derived from CO dissociation, as the true restructuring agent. Under FTS conditions, this Co surface reconstruction occurs similarly irrespective of the metal particle size. Moreover, an enhancement in the proportion of Co-SiO 2 interfacial Co d+ sites (Co-CO band at 2060 cm À1 ) takes place particularly in small cobalt nanoparticles (5.6 nm) likely as a consequence of nanoparticle flattening, as suggested by TEM after catalysis. These Co-SiO 2 interfacial sites are tentatively proposed as responsible for the decreased TOF observed for d(Co 0 ) < 10 nm.
Journal of Dispersion Science and Technology, 2012
Journal of Dispersion Science and Technology, 2012
Adsorption-Journal of the International Adsorption Society, 2011
This work presents some applications of ZrO 2 supported over SBA-15 silica as promoter of sulfate... more This work presents some applications of ZrO 2 supported over SBA-15 silica as promoter of sulfated zirconia and as support from CuO/CeO 2 catalytic system for preferential oxidation of CO to CO 2 in hydrogen rich streams, used as feed for proton exchange membrane fuel cells (PEMFC). Different amounts of ZrO 2 , from 10 to 30 wt.% were incorporated. These prepared materials were characterized by powder XRD, adsorption-desorption of N 2 at 77 K, transmission and scanning electron microscopy (TEM and SEM) and X-rays photoelectron spectroscopy (XPS). The acidity was studied by thermo-programmed desorption of ammonia (NH 3 -TPD). These materials were tested, after treatment with H 2 SO 4 , by 2-propanol dehydration and 1-butene isomerization catalytic tests. The samples were found quite good catalyst with strong acid sites, the sample with 20 wt.% of ZrO 2 being the better performing sample. Finally this material was successfully used as support for a CuO/CeO 2 system, with 6 wt.% of Cu and 20 wt.% of Ce. The resulting catalyst was tested in the preferential oxidation of CO (CO-PROX) attaining conversions close to 100% and high selectivity to CO 2 .
Fuel, 2013
h i g h l i g h t s " Calcium zincate treated at 400°C is active in the ethanolysis of sunflower ... more h i g h l i g h t s " Calcium zincate treated at 400°C is active in the ethanolysis of sunflower oil. " By using a 3 wt.% of catalyst at 78°C, FAEE yields higher than 95 wt.% are reached after 3 h. " The catalytic activity is maintained even in the presence of free fatty acids (until 1.1°acidity) in the sunflower oil. " The addition of Na 2 CO 3 to the catalyst allows removing Ca and Na from biodiesel (<5 ppm).
Energy & Fuels, 2010
International regulations have established the decrease on sulfur content in fuels down to as low... more International regulations have established the decrease on sulfur content in fuels down to as low as 10 ppm in a few years from now. Cyclic sulfur compounds are noticeably refractory to hydrodesulfurization (HDS) processes, which are the usual technology found in oil refineries. To meet the increasingly strict environmental requirements, selective physisorption may be a feasible option toward lowering the sulfur content of the outlet streams of current HDS units. The present work investigates the adsorption of benzothiophene (BT) and dibenzothiophene (DBT) in hydrophobic microporous activated carbons impregnated with PdCl 2 . The adsorbents used were commercial samples (Norit, Amersfoort, The Netherlands) modified by wet impregnation of PdCl 2 in acidic media, followed by drying at 130°C under He flow. They were characterized by N 2 adsorption isotherms, transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectronic spectroscopy (XPS). Characterization results provide evidence that palladium was effectively supported on the activated carbon as the chloride itself and as metallic palladium. A total of 20 mL of BT and DBT solutions in hexane (500 ppm) were put in contact with 100 mg of each adsorbent, and the adsorbed capacities were measured by the concentration differences. Additionally, Fourier transform infrared (FTIR) spectra were measured upon adsorption of BT vapors. The impregnation of PdCl 2 enhances sulfur adsorption capacity for most studied cases, and sulfur compounds with an increasing number of aromatic rings are preferentially adsorbed.
ChemSusChem, 2013
A series of silica-based MCM-41-supported niobium-oxide catalysts are prepared, characterized by ... more A series of silica-based MCM-41-supported niobium-oxide catalysts are prepared, characterized by using XRD, N2 adsorption-desorption, X-ray photoelectron spectroscopy, Raman spectroscopy, and pyridine adsorption coupled to FTIR spectroscopy, and tested for the dehydration of D-xylose to furfural. Under the operating conditions used all materials are active in the dehydration of xylose to furfural (excluding the MCM-41 silica support). The xylose conversion increases with increasing Nb2 O5 content. At a loading of 16 wt % Nb2 O5 , 74.5 % conversion and a furfural yield of 36.5 % is achieved at 170 °C, after 180 min reaction time. Moreover, xylose conversion and furfural yield increase with the reaction time and temperature, attaining 82.8 and 46.2 %, respectively, at 190 °C and after 100 min reaction time. Notably, the presence of NaCl in the reaction medium further increases the furfural yield (59.9 % at 170 °C after 180 min reaction time). Moreover, catalyst reutilization is demonstrated by performing at least three runs with no loss of catalytic activity and without the requirement for an intermediate regeneration step. No significant niobium leaching is observed, and a relationship between the structure of the catalyst and the activity is proposed.
Chemosphere, 2008
Copper based catalysts supported on mesoporous materials, which were in turn based on a surfactan... more Copper based catalysts supported on mesoporous materials, which were in turn based on a surfactant expanded zirconium phosphate for the formation of silica galleries in the interlayer space, were prepared by the impregnation method. They were then characterised and tested in the selective catalytic reduction of NO with ammonia as active catalysts for the control of the NO x emissions from heavy duty vehicles. Copper catalysts displayed a high catalytic performance, even in the presence of 14% (v/v) of H 2 O and 100 ppm of SO 2 . They also displayed improved catalytic behaviour when compared to a CuZSM5 catalyst.
Catalysis Today, 2010
Zinc oxide, obtained by thermal decomposition of zinc oxalate, has been impregnated with differen... more Zinc oxide, obtained by thermal decomposition of zinc oxalate, has been impregnated with different amounts of calcium oxide, and used as solid catalyst for transesterification processes. Catalysts have been characterized by chemical analysis, XRD, XPS, FT-IR, SEM, N 2 adsorption ...
Catalysis Today, 2011
This work investigates the use of MgAl mixed oxides as base catalysts for the etherification of g... more This work investigates the use of MgAl mixed oxides as base catalysts for the etherification of glycerol. Two different experimental strategies have been employed for the synthesis of the hydrotalcite precursors: coprecipitation and urea hydrolysis. The hydrotalcites and ...
Catalysis Today, 2010
Two SBA-15 type materials were synthesized using a low-cost route, a pure silica SBA-15 and an Al... more Two SBA-15 type materials were synthesized using a low-cost route, a pure silica SBA-15 and an Al containing SBA-15 (with a Si/Al ratio of 10), where Al was added by a post-synthesis modification. The later solid was achieved without any significant loss in the textural properties of SBA-15, besides improving its properties as support of catalysts. Copper impregnated catalysts were prepared through the incipient wetness impregnation of the two supports. With both supports, the copper weight loading were 1, 3 and 6 wt%. The copper incorporation kept the support mesoporous structures, obtaining a better dispersion of the active phase in the containing aluminium support. All the catalysts showed a moderated catalytic activity in the SCR of NO with propane in presence of an excess of oxygen in the whole studied interval of temperatures and a much better performance was observed when using NH 3 instead of propane. The changes of the active phases were studied by operando XAS spectroscopy. Factor analysis of in operando XANES results with sample SiAl 6 indicate that no Cu 0 was detected, but only Cu 1+ and Cu 2+ . The temperature where the Cu 1+ /Cu 2+ ratio is maximum occurs at the reaction temperature where the observed catalytic NO conversion is also maximum.
Catalysis Letters, 2009
The activity of the CuO-CeO 2 couple supported on a MSU silica doped with zirconium (Si/Zr = 7), ... more The activity of the CuO-CeO 2 couple supported on a MSU silica doped with zirconium (Si/Zr = 7), was evaluated in the preferential oxidation of CO (CO-PROX) in hydrogen-rich gas stream (1.2% CO, 1.2% O 2 , 50% H 2 , 0-15% CO 2 , 0-10% H 2 O He balance) and the catalytic performance was compared with that of CuO-CeO 2 supported on a pure MSU silica. The samples were characterized by X-ray powder diffraction (XRPD), N 2 physisorption at 77 K, temperature-programmed reduction (H 2 -TPR) and X-ray photoelectron spectroscopy (XPS). Correlations between catalytic performances and physicochemical properties of the materials have been made.
Applied Catalysis B: Environmental, 2009
This work investigates the use of calcined calcium zincate as solid base catalyst for the methano... more This work investigates the use of calcined calcium zincate as solid base catalyst for the methanolysis of sunflower oil to FAME (biodiesel). The precursor and catalyst were characterized by XRD, XPS, SEM, EGA-MS, FTIR and N 2 adsorption. The thermal treatment at temperatures as low as 400 8C leads to a base catalyst which is very active and stable in biodiesel production from different vegetable oils (sunflower and soybean). The presence of carbonate on the calcium zincate, used as precursor, is negligible after remaining in contact with air for two weeks. The catalyst obtained at 400 8C shows FAME yields higher than 90% after 45 min of reaction, and the kinetic of the heterogeneous process (60 8C, methanol:sunflower oil molar ratio of 12, 3 wt.% of catalyst) is very close to that observed under homogeneous conditions (KOH dissolved in methanol). Under these experimental conditions, the catalyst is stable against lixiviation since it can be reutilized for three catalytic runs of 1 h, reaching yields higher than 85%. Moreover, by increasing the acidity of the oil until 1.18 (typical value of fried oils), the catalytic performance is maintained. The presence of water has a negative influence on the catalytic activity, since the addition of a 0.2 wt.% of water into the reaction medium decreases the FAME yield until 80% after 3 h of reaction, although this yield is still higher than 60% after adding a 1 wt.% of water. This catalyst is also very active in the transesterification of soybean oil. ß
Applied Catalysis B: Environmental, 2009
Copper-catalysts, based on the ZSM-5 (CuZSM5) and Cuban natural Mordenite (CuMORD) zeolites have ... more Copper-catalysts, based on the ZSM-5 (CuZSM5) and Cuban natural Mordenite (CuMORD) zeolites have been prepared by a conventional ion-exchange method and their catalytic activity in the selective catalytic reduction (SCR) of NO was studied using ammonia in presence of H 2 O and SO 2 . A commercial catalyst SCR (CATCO) based on V 2 O 5 -WO 3 -TiO 2 , was also studied as reference. This paper presents experimental results using catalysts without the toxic vanadium and exploits a neural network based approach to predict NO x conversion efficiency of three SCR catalysts. The derived mathematical functions are integrated in a numerical model for diesel road vehicle simulation to simulate diesel vehicles equipped with such SCR catalysts. The main results indicate that despite of toxic vanadium and N 2 O formation, CATCO shows the better NO x conversion efficiencies. However, CuMORD does not form N 2 O and have better performance than the CuZSM5. The simulation results show lower level of NO x for heavyduty and light-duty diesel vehicles compared with homologation load cycles. ß
Applied Catalysis B: Environmental, 2011
This research focuses on the synthesis and characterization of mesoporous niobosilicate molecular... more This research focuses on the synthesis and characterization of mesoporous niobosilicate molecular sieves and their catalytic activity in biodiesel production by transesterification of sunflower oil with methanol. Catalysts were prepared by two procedures: impregnation of a MCM-41 silica with different amounts of niobium oxalate and subsequent calcination, and structural incorporation of Nb into a MCM-41 silica during the synthesis step. Characterization techniques such as XRD, XPS, TEM, NH 3 -TPD and N 2 sorption have been employed to characterize the synthesized catalysts. The biodiesel yield increases with the catalyst acidity, attaining a value of 95% with a 7.5 wt% of a MCM-41 silica impregnated with a 8% of Nb 2 O 5 , at 200 • C, after 4 h of reaction and a methanol/oil molar ratio of 12. The potential of this family of catalysts to treat low-grade oils has been demonstrated by increasing the acidity of the sunflower oil by adding oleic acid (1.1 wt%) and water (0.2 wt%) to the reaction mixture, since the biodiesel yield is maintained close to 80%. Moreover, the catalyst reutilization has been demonstrated during five catalytic runs by employing a low-grade oil, with no leaching of the active phase.
Applied Catalysis A: General, 2008
Bimetallic PdRh (with Pd/Rh mole ratio = 2/1) catalysts supported on a mesoporous aluminosilicate... more Bimetallic PdRh (with Pd/Rh mole ratio = 2/1) catalysts supported on a mesoporous aluminosilicate have been prepared and three methods of metal incorporation in the support have been compared: direct incorporation into the synthesis gel, impregnation and ion-exchange. Physico-chemical characterisations (nitrogen adsorption-desorption, hydrogen chemisorption, transmission electron microscopy, X-ray photoelectron and extended X-ray absorption fine structure spectroscopies), as well as simulated coking and regeneration tests are described. The dispersion, metal particle size and the formation of bimetallic particles within the material depend on the method of metal incorporation. Direct incorporation and ionexchange methods lead to co-existence of PdRh intermetallic aggregates and segregated Pd; on the other hand, the impregnation method leads to the formation of very small and well dispersed PdRh alloy particles, with Pd preferentially located on the alloy particle surface.
Applied Catalysis A: General, 2009
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Papers by Ramon Moreno Tost