Fernando Cárdenas-Lizana

Bio: Fernando Cárdenas-Lizana is an academic researcher from Heriot-Watt University. The author has contributed to research in topics: Catalysis & Temperature-programmed reduction. The author has an hindex of 29, co-authored 77 publications receiving 2237 citations. Previous affiliations of Fernando Cárdenas-Lizana include University of Edinburgh & École Polytechnique Fédérale de Lausanne.

Modern Trends in Catalyst and Process Design for Alkyne Hydrogenations

Abstract: This review provides an overview of the recent achievements in catalytic process development for alkyne hydrogenations. It underlines the necessity of simultaneous optimization over different length scales from molecular/nanoscale of active phase, up-to macro-scale of catalytic reactor design. One case study, the hydrogenation of 2-methyl-3-butyn-2-ol, is analyzed in detail to illustrate the practical application of this approach. Finally, it presents the personal view of the authors concerning the new trends and paths available in the field.

Effect of Metal Dispersion on the Liquid-Phase Hydrodechlorination of 2,4-Dichlorophenol over Pd/Al2O3

Abstract: The effect of metal particle size on the aqueous-phase (T = 303 K) catalytic hydrodechlorination (HDC) of 2,4-dichlorophenol (2,4-DCP) over Pd/Al2O3 has been investigated. A range of palladium dispersions (8%−67%) was achieved using a H2 thermal treatment over the temperature range of 423 K ≤ T ≤ 1273 K. The catalyst samples have been characterized in terms of transmission electron microscopy (TEM), X-ray diffraction (XRD), surface area/porosity, H2 chemisorption, and point-of-zero-charge measurements. The HDC of 2,4-DCP is predominately a stepwise process, yielding 2-chlorophenol (2-CP) as the partially dechlorinated product, which is further converted to phenol and, ultimately, to cyclohexanone. The temporal dependence of product distribution is recorded and correlated to metal particle size/bulk solution pH changes. Structure sensitivity has been established where smaller palladium particles (≤5 nm) exhibit intrinsically higher specific activities. The HDC of 2,4-DCP has also been investigated under co...

Selective Gas Phase Hydrogenation of p-Chloronitrobenzene over Pd Catalysts: Role of the Support

Abstract: The gas phase (1 atm, 453 K) hydrogenation of p-chloronitrobenzene (p-CNB) over a series of laboratory-synthesized and commercial Pd (1–10% wt) supported on activated carbon (AC) and non-reducible (SiO2 and Al2O3) and reducible (ZnO) oxides has been examined. Reaction over these catalysts generated the target p-chloroaniline (p-CAN) (via selective hydrogenation) and nitrobenzene (NB)/aniline (AN) as a result of a combined hydrodechlorination/hydrogenation. A range of Pd nanoparticles with mean sizes 2.4–12.6 nm (from HRTEM and H2/CO chemisorption) were generated. Both the p-CNB transformation rate and H2 chemisorption increased with decreasing Pd size. Residual Mo (from the stabilizer used in the synthesis of Pd colloids) suppressed activity, but this was circumvented by the use of poly(N-vinyl-2-pyrrolidone) (PVP). Pd/AC generated p-CAN and AN as principal products, Pd on SiO2 and Al2O3 exhibited hydrodechlorination character generating AN and NB, and Pd/ZnO promoted the sole formation of p-CAN at all le...

Clean production of chloroanilines by selective gas phase hydrogenation over supported Ni catalysts

Abstract: We have established for the first time 100% selectivity in the continuous gas phase hydrogenation of p-chloronitrobenzene (p-CNB) to p-chloroaniline for reaction over a series of oxide and carbon supported Ni catalysts (6 ± 2%, w/w) under mild reaction conditions (T = 393 K, P = 1 atm). Catalyst activation by temperature programmed reduction (TPR) is addressed, BET area and H2 uptake measurements provided and mean metal particle sizes evaluated by transmission electron micrographic (TEM) analysis. The following activity sequence has been determined: Ni/Al2O3 > Ni/SiO2 > Ni/Activated Carbon > Ni/graphite. Pd/Al2O3, as an alternative catalyst, delivered an appreciably higher activity but with the production of nitrobenzene (principal product) and aniline (secondary product), i.e. hydrodechlorination with subsequent –NO2 reduction prevailed. Exclusive formation of the corresponding haloaniline is also demonstrated for the hydrogenation of o-chloronitrobenzene, m-chloronitrobenzene and p-bromonitrobenzene over Ni/Al2O3. A lower hydrogenation rate is established for p-CNB relative to nitrobenzene, consistent with a halogen substituent deactivation effect. While the Ni catalysts suffered a loss of activity with time-on-stream, exclusive selectivity to the haloamine product was maintained. These preliminary results can serve as a basis for the development of a cleaner, high throughput production of commercially important haloamines.

The effect of gold loading and particle size on photocatalytic hydrogen production from ethanol over Au/TiO2 nanoparticles

Abstract: Catalytic hydrogen production from renewables is a promising method for providing energy carriers in the near future. Photocatalysts capable of promoting this reaction are often composed of noble metal nanoparticles deposited on a semiconductor. The most promising semiconductor at present is TiO₂. The successful design of these catalysts relies on a thorough understanding of the role of the noble metal particle size and the TiO₂ polymorph. Here we demonstrate that Au particles in the size range 3-30 nm on TiO₂ are very active in hydrogen production from ethanol. It was found that Au particles of similar size on anatase nanoparticles delivered a rate two orders of magnitude higher than that recorded for Au on rutile nanoparticles. Surprisingly, it was also found that Au particle size does not affect the photoreaction rate over the 3-12 nm range. The high hydrogen yield observed makes these catalysts promising materials for solar conversion.