Fernando Lizana - Academia.edu (original) (raw)

Papers by Fernando Lizana

Reaction Kinetics, Mechanisms and Catalysis, 2018

Application of nano-scale supported Au in catalytic hydrogenation delivers high chemoselectivity ... more Application of nano-scale supported Au in catalytic hydrogenation delivers high chemoselectivity but low activity using (pressurized) H 2 far in excess of stoichiometric requirements. We have tackled the issues of low reaction rate and inefficient hydrogen utilization through a series of approaches taking Au/CeO 2 (mean Au size = 2.8 nm) as a test catalyst. Increased spillover hydrogen (using physical mixtures of Au/CeO 2 with CeO 2 and SiO 2) and the promotional effect of water (via catalytic dissociation on surface oxygen vacancies) resulted in a fourfold increase in the selective rate of furfural hydrogenation to furfuryl alcohol. In contrast, Pd/CeO 2 and Ni/CeO 2 promoted decarbonylation (to furan), hydrogenolysis (to 2-methylfuran) and ring reduction (to tetrahydrofurfuryl alcohol). Coupling (2butanol ? 2-butanone) dehydrogenation over Cu/SiO 2 (mean Cu size = 7.8 nm) with furfural hydrogenation over Au/CeO 2 further increased rate with full utilization of the hydrogen generated in dehydrogenation. The coupling strategy allows ''hydrogen free'' hydrogenation that circumvents the limitation of Au in standard catalytic hydrogenation. This can open new avenues to exploit the ultra-selectivity of Au for continuous production of high value commodity products.

Catalysis Communications, 2017

The selective conversion of biomass-derived carvone in H2 was studied over (Al2O3, C and CeO2) su... more The selective conversion of biomass-derived carvone in H2 was studied over (Al2O3, C and CeO2) supported Pd (mean size 2.8-3.0 nm), taking bulk Pd as benchmark. 100% carvacrol yield was achieved over Pd/Al2O3, Pd/C and bulk Pd at an inlet H2/Carvone = 1/6, with appreciably higher rates for the supported catalysts. Carveol formation over Pd/CeO2 was attributed to-C=O activation at surface oxygen vacancies (confirmed by O2 titration) generated during TPR. Carvotanacetone and carvomenthone formation were observed at H2/Carvone > 1/6.

Reaction Kinetics, Mechanisms and Catalysis, 2016

We have established viability of cyclohexanone (C6ONE) production via coupled gas phase (1 atm, 4... more We have established viability of cyclohexanone (C6ONE) production via coupled gas phase (1 atm, 423 K) continuous hydrodechlorination/hydrogenation of mono-and di-chlorophenols over bulk Pd and Pd/Al2O3. The catalysts have been characterised by temperature programmed reduction, H2 chemisorption, powder XRD and TEM analyses. Hydrodechlorination is not a thermodynamically limiting step where under catalytic control we achieve significantly greater C6ONE yields relative to those from standard phenol hydrogenation. We account for this response in terms of a direct chlorophenol  C6ONE conversion facilitated by electron delocalisation in the intermediate generated via electrophilic hydrogen cleavage of C-Cl bond(s). The C6ONE selectivity/conversion profiles coincided for bulk and supported Pd and we demonstrate structure sensitivity for the production of C6ONE from 2,4-dichlorophenol with higher specific rates over larger Pd particles (2→250 nm).

Preparation, Characterization, and Applications, 2015

Catalysis Science & Technology, 2011

Catal. Sci. Technol., 2011, Advance Article DOI:10.1039/C1CY00051A (Paper) PDF Version. Gold cata... more Catal. Sci. Technol., 2011, Advance Article DOI:10.1039/C1CY00051A (Paper) PDF Version. Gold catalysis at the gassolid interface: role of the support in determining activity and selectivity in the hydrogenation of m-dinitrobenzene. ...

Applied Catalysis A: General, 2014

ABSTRACT The development of selective Pd-based catalyst for semi-hydrogenation of dehydroisophyto... more ABSTRACT The development of selective Pd-based catalyst for semi-hydrogenation of dehydroisophytol (DIP), a C-20-alicynol, is reported. A series of unsupported mono- (Pd) and bimetallic (Pd-M) nanopartides (NPs) with Pd/M molar ratios of 1.5 - 5.0 (M=Ag or Cu) were examined as model systems. The Pd-Ag and Pd-Cu NPs with controlled crystal sizes of similar to 3.3 nm were prepared by Ag (Cu) electroless deposition on pre-formed poly(N-vinyl-2-pyrrolidone)-stabilized Pd colloids. Bimetallic Pd-Ag NPs adopted a core (Pd)-shell (Ag) structure whereas a mixed alloy was attained in the Pd-Cu nanocrystals. A (partial) Pd surface segregation induced by reaction with H-2 was in evidence for the Pd-Ag NPs. A significant increase in selectivity up to 97% (at X-DIP = 99%) to the target alkenol was demonstrated following the incorporation of a second metal. This result is attributed to the dilution of the surface Pd-sites by Ag (Cu) and a modification of the Pd electronic properties. Pd-Ag NPs, having shown the highest selectivity, were further deposited on a structured support based on sintered metal fibers (SMF) coated with ZnO. The improved selectivity achieved over the unsupported Pd-Ag colloidal NPs was retained over the structured catalytic system. The bimetallic Pd(5.0)AganO/SMF (S-IP = 93%) demonstrated a drastic increase in IP selectivity relative to the monometallic Pd/ZnO/SMF (S-IP = 78%) and state-of-the-art Lindlar catalyst (S-IP = 62%) at DIP conversion >= 99% with the stable activity during 50 h, suggesting catalyst feasibility for selective semi-hydrogenation of long chain alkynols with important applications in the manufacture of vitamins and fine chemicals.

Topics in Catalysis, 2014

ChemCatChem, 2012

We present 100 % selectivity to p‐chloroaniline through the continuous gas‐phase (atmospheric pre... more We present 100 % selectivity to p‐chloroaniline through the continuous gas‐phase (atmospheric pressure; T=393–523 K) catalytic hydrogenation of p‐chloronitrobenzene over an activated CuAl (molar Cu/Al ratio 3:1) hydrotalcite. The synthesis by continuous co‐precipitation and application of a CuNiAl (atomic Cu/Ni/Al ratio 2.75:0.25:1) catalyst is also described. Temperature‐programmed reduction in hydrogen and XPS analyses of the ternary catalyst suggest CuNi interaction with no evidence of (bulk) alloy formation (based on XRD). Under the same reaction conditions, CuNiAl exhibited a higher (by up to a two‐fold) hydrogenation rate when compared to CuAl, while the exclusive nitro‐group reduction was maintained.

Chemical Engineering Journal, 2014

h i g h l i g h t s Establish deactivation of Au/Al 2 O 3 in p-chloronitrobenzene ? p-chloroanili... more h i g h l i g h t s Establish deactivation of Au/Al 2 O 3 in p-chloronitrobenzene ? p-chloroaniline. Kinetic control explicitly established by parameter and experimental estimation. Severe deactivation at H 2 /reactant 639 due to coking (from XPS/TGA-DSC analysis). Oxidative/reduction regeneration restores initial activity and selectivity.

Nanotechnology, 2012

Catalytic hydrodechlorination (HDC) is an effective means of detoxifying chlorinated waste. Gold ... more Catalytic hydrodechlorination (HDC) is an effective means of detoxifying chlorinated waste. Gold nanoparticles supported on Fe(3)O(4) have been tested in the gas phase (1 atm, 423 K) HDC of 2,4-dichlorophenol. Two 1% w/w supported gold catalysts have been prepared by: (i) stepwise deposition of Au on α-Fe(2)O(3) with subsequent temperature-programmed reduction at 673 K (Au/Fe(3)O(4)-step); (ii) direct deposition of Au on Fe(3)O(4) (Au/Fe(3)O(4)-dir). TEM analysis has established the presence of Au at the nano-scale with a greater mean diameter (7.6 nm) on Au/Fe(3)O(4)-dir relative to Au/Fe(3)O(4)-step (4.5 nm). We account for this difference in terms of stronger (electrostatic) precursor/support interactions in the latter that can be associated with the lower pH point of zero charge (with respect to the final deposition pH) for Fe(2)O(3). Both catalysts promoted the preferential removal of the ortho-Cl substituent in 2,4-dichlorophenol, generating 4-chlorophenol and phenol as products of partial and total HDC, respectively, where Au/Fe(3)O(4)-step delivered a two-fold higher rate (2 × 10(-4) mol(Cl) h(-1) m(Au)(-2)) when compared with Au/Fe(3)O(4)-dir. This unprecedented selectivity response is attributed to activation of the ortho-C-Cl bond via interaction with electron-deficient Au nanoparticles. The results demonstrate the feasibility of a controlled recovery/recycling of chlorophenol waste using nano-structured Au catalysts.

Journal of Materials Science, 2014

Molybdenum and tungsten carbide (Mo 2 C, W 2 C) and nitride (Mo 2 N) were prepared from MoO 3 and... more Molybdenum and tungsten carbide (Mo 2 C, W 2 C) and nitride (Mo 2 N) were prepared from MoO 3 and WO 3 by temperature-programmed treatment with C 2 H 6 /H 2 and N 2 /H 2. We have examined the influence of synthesis procedure, applying single-step (direct carburisation) and two-step (nitridation-carburisation and partial reductioncarburisation) processes, on crystallographic phase and catalytic response in the gas phase hydrodechlorination (HDC) of 1,3-dichlorobenzene (1,3-DCB). Single-step carburisation generated (hexagonal close-packed) hcp-Mo 2 C and hcp-W 2 C. Two-step nitridation-carburisation yielded (face-centred cubic) fcc-Mo 2 C via fcc-Mo 2 N in a topotactic transformation where surface area was increased (to 145 m 2 g-1) at higher gas hourly space velocity (from 4800 to 96000 h-1) and decreasing heating rate (from 0.6 to 0.3 K min-1). Partial reduction of MoO 3 prior to carburisation produced a composite (fcc ? hcp)-Mo 2 C. Negligible ambient temperature H 2 chemisorption (B0.3 lmol g-1) was recorded for the synthesised (nitride and carbide) materials, but temperature-programmed desorption (TPD) resulted in significant H 2 release (up to 67 lmol g-1 for (fcc ? hcp)-Mo 2 C) that was generated during temperatureprogrammed reduction. Under the same reaction conditions, hcp-and fcc-carbides delivered equivalent specific HDC activity that was appreciably lower (by a factor of up to 20) than that obtained with fcc-Mo 2 N. The composite (fcc ? hcp)-Mo 2 C exhibited the highest HDC rate that can be correlated with H 2 released during TPD and which approached the performance of a benchmark Ni/SiO 2 catalyst. HDC selectivity (to chlorobenzene) as a function of 1,3-DCB conversion coincided for all the nitride and carbide systems but deviated from Ni/SiO 2 , which favoured concerted HDC to benzene.

Journal of Materials Science, 2012

TiO 2-R(100) TiO 2-R(100) TiO 2-R(100) TiO 2-R(94) TiO 2-R(100) TiO 2-R(20) TiO 2-R(67) TiO 2-R(16)

Journal of Catalysis, 2013

The gas-phase hydrodechlorination of 2,4-dichlorophenol (at 423 K) has been studied over Au/Fe 2 ... more The gas-phase hydrodechlorination of 2,4-dichlorophenol (at 423 K) has been studied over Au/Fe 2 O 3 prepared by deposition-precipitation. Support and catalyst were characterised by TPR, XRD, H 2 chemisorption/TPD, BET area/porosity and TEM/SEM measurements. Fe 2 O 3 was reduced to Fe 3 O 4 and Fe following TPR to 673 K and 1273 K, respectively; inclusion of Au lowered (by 200 K) support reduction temperature. TPR of Au/Fe 2 O 3 to 423 K generated quasi-spherical Au particles (mean size = 2.6 nm) that promoted hydrogenolysis of ortho-Cl, generating 4-chlorophenol via a stepwise mechanism. We attribute this unprecedented selectivity to reactant interactio n through-OH at electron-deficient Au sites, rendering ortho-Cl susceptible to attack. Solvent effects are demonstrated for a range of carriers where conversion of aqueous 2,4-DCP delivered the highest rate (1 Â 10 À3 mol Cl h À1 m À2 Au), equivalent to that achieved with Ni/SiO 2 at 573 K. Selectiv ity in the cleavage of sterically constrained Cl in mono-, di-and tri-chlorophenols is also demonstrated.

Journal of Catalysis, 2009

The effect of Au particle size, supported on TiO 2 , on the gas-phase hydrogenation of m-dinitrob... more The effect of Au particle size, supported on TiO 2 , on the gas-phase hydrogenation of m-dinitrobenzene has been considered. The catalysts (Au loading = 0.1 and 1 mol%) were prepared by impregnation with HAuCl 4 and a range of Au particle sizes (3.4-10.0 nm) was generated by temperature-programmed reduction over the interval 603 K 6 T 6 1273 K. A thermal treatment of TiO 2 at T P 873 K was required for the allotropic change from anatase to rutile but the presence of Au lowered the requisite temperature for complete transformation by up to 400 K. m-Dinitrobenzene hydrogenation exhibited a particle size sensitivity where higher specific rates were obtained with smaller Au particles, irrespective of the support composition (i.e. anatase:rutile ratio). The reaction over each Au/TiO 2 catalyst generated m-phenylenediamine (reduction of both-NO 2 groups) and/or m-nitroaniline (reduction of one-NO 2 group). A parallel/ consecutive kinetic model has been applied to quantify the catalytic selectivity where Au particles <5 nm favoured m-nitroaniline production. The dependence of hydrogenation performance on Au particle size is accounted for in terms of a modification to Au electronic character, which impacts on m-dinitrobenzene adsorption/activation.

CHIMIA, 2012

The relationship between catalytic response and properties of the active phase is difficult to es... more The relationship between catalytic response and properties of the active phase is difficult to establish in classical heterogeneous catalysis due to the number of variables that can affect catalytic performance. Ultrahigh-vacuum surface methods applied to model catalyst surfaces are useful tools to assess fundamental issues related to catalytic processes but they are limited by the significant differences with catalysts in the working state. In an attempt to overcome this issue, (unsupported) nano-metal systems with controlled size and shape have been synthesized and tested in selective alkyne hydrogenation. The results revealed a dependency of nano-particles (NPs) morphology (size and shape) and allowed the identification of the active sites for this type of reaction. The nature of the stabilizer (steric and electrostatic stabilization) used in the NPs preparation has been shown to influence catalytic performance. The tailored active phase was subsequently immobilized on suitable n...

Catalysis Today, 2014

Monodispersed Pd nanoparticles (NPs) have been prepared by colloidal technique and deposited on a... more Monodispersed Pd nanoparticles (NPs) have been prepared by colloidal technique and deposited on a structured support consisting of carbon nanofibers (CNF) grown on sintered metal fibres (SMF). The surface properties of Pd NPs have been fine-tuned by (i) changing the nature of stabilizing agent (electrostatic vs. steric), (ii) controlling Pd NPs size (2-10 nm) and (iii) grafting N-containing ligands onto the CNF/SMF surface. In the semi-hydrogenation of acetylene (T = 393 K; P = 1 bar) catalytic response was insensitive to the nature of the reducing agent where equivalent activity/selectivity were obtained over Pd NPs with similar dispersion, prepared with the same stabilizer. A similar product distribution was recorded over Pd NPs with similar crystal size irrespective of the colloidal stabilizer (electrostatic vs. steric). In contrast, a stronger inhibiting effect on hydrogenation rate has been found with electrostatic stabilizer (sodium di-2-ethylhexylsulfosuccinate) as compared to the steric ones (polyvinylpyrrolidone or polyvinylalcohol) and assigned to geometric and electronic effects. Decrease (from 8 → 2 nm) in Pd NPs size results in a concomitant decrease in activity (antipathetic size-sensitivity), but higher selectivity to target ethylene product. Grafting of nitrogen-containing modifiers (polyvinylpyridine or polyethylenimine) on the CNF/SMF support results in a significant increase in olefin selectivity (up to 93%) where the catalyst shows remarkable stability during 120 h on-stream. This is explained by the electronic modifications promoted by interactions between the Pd NPs and the grafted ligands as confirmed by XPS analysis. In comparison, stabilizer-free Pd/CNF/SMF has low selectivity to ethylene (65%). In summary, controlled size Pd (core) nanoparticles with organic ligands (shell) demonstrated increased selectivity and remarkable stability in catalytic gas-phase alkyne semi-hydrogenation opening new tools for rational catalyst design.

Catalysis Today, 2011

A tetragonal molybdenum nitride (␤-Mo 2 N) has been prepared by temperature programmed treatment ... more A tetragonal molybdenum nitride (␤-Mo 2 N) has been prepared by temperature programmed treatment of MoO 3 in flowing N 2 + H 2 and for the first time shown to catalyze the liquid phase selective hydrogenation (T = 423 K; P H 2 = 11 bar) of a series of para-substituted (-H,-OH,-O-CH 3 ,-CH 3 ,-Cl,-I and-NO 2) nitrobenzenes to give the corresponding aromatic amine. Reaction over Pd/Al 2 O 3 , as a benchmark catalyst (Pd particle size ca. 18 nm), resulted in a composite hydrodechlorination/hydrogenation of p-chloronitrobenzene (as a representative nitroarene) to generate nitrobenzene and aniline. ␤-Mo 2 N has been characterized in terms of temperature-programmed reduction (TPR), H 2 chemisorption/temperature programmed desorption (TPD), BET surface area/pore volume, elemental analysis, powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning (SEM) and transmission (TEM) electronic microscopy. Elemental analysis, XRD, SEM and TEM have confirmed the formation of tetragonal ␤-Mo 2 N, characterized by an agglomeration of flake-like crystallites. Post-synthesis, the nitride was passivated by contact with 1% (v/v) O 2 /He at ambient temperature and XPS analysis has demonstrated the formation of a superficial passivating oxide overlayer without bulk oxidation. Prereaction, activation by TPR to 673 K was necessary to remove the passivating film. Hydrogen TPD has revealed significant hydrogen uptake (0.7 mol m −2) associated with ␤-Mo 2 N. Nitro group reduction kinetics have been subjected to a Hammett treatment where the reaction constant (p = 0 4) is diagnostic of an increase in rate due to the presence of electron-withdrawing substituents on the aromatic ring, consistent with a nucleophilic mechanism. The results presented in this study establish the viability of ␤-Mo 2 N to promote selective nitroarene hydrogenation.

Catalysis Letters, 2008

We report, for the first time, 100% selectivity in the continuous gas phase hydrogenation of m-di... more We report, for the first time, 100% selectivity in the continuous gas phase hydrogenation of m-dinitrobenzene to m-nitroaniline (m-NAN) over Au/Al 2 O 3. The synthesis and application of an alumina supported Au-Ni alloy is also described where alloy formation is demonstrated by XRD, diffuse reflectance UV-Vis and HRTEM analyses. Under the same reaction conditions, Au/Al 2 O 3 delivered a higher (by close to an order of magnitude) hydrogenation rate compared with the alloy. Au-Ni/Al 2 O 3 promoted the formation of both m-NAN and m-phenylenediamine, i.e. partial and complete hydrogenation: the results are consistent with a stepwise reduction mechanism.