Ni-, Co- and Cu-TiO2

IX INSTM CONFERENCE, Bari, 30^th June - 3^rd July 2013

Ni-, Co- and Cu-TiO

catalysts for the steam reforming of ethanol: how the preparation method affects catalytic performance

J. Lasso,

I. Rossetti,

* G. Ramis,

E. Finocchio,

V. Nichele,

M. Signoretto,

A. Di Michele,

a Dip. Chimica, Università degli Studi di Milano, INSTM Unit Milano-Università and CNR-ISTM, via C. Golgi, 19, I-20133 Milano, Italy

b Dip. di Ingegneria Civile, Chimica e Ambientale, Università degli Studi di Genova, P.le J.F. Kennedy 1, I- 16129, Genova, Italy and INSTM Unit Genova

cDip. di Scienze Molecolari e Nanosistemi, Università Cà Foscari Venezia, Calle Larga S. Marta, 2137, Venezia, Italy and INSTM Unit Venezia

d Dip. di Fisica, Università degli Studi di Perugia, Via Pascoli, 06123 Perugia

*Corresponding author. +39-02-50314059, Fax +30-02-50314300, ilenia.rossetti@unimi.it

Concept

A set of Ni-, Co-, Cu-based catalysts supported over TiO2 for the steam reforming of ethanol were prepared by different procedures. For most of them the support was prepared by precipitation and calcined at 500°C or 800°C. Additional samples were prepared by flame pyrolysis, aiming at high metal dispersion coupled with synthesis at high temperature, which usually imparts a strong metal-support interaction, besides high thermal resistance. The samples were thoroughly characterised by AAS, XRD, N2 adsorption-desorption, TPR, SEM, TEM and FT-IR. Activity testing for the steam reforming of ethanol was performed after activation at 500°C or 800°C in H2 flow on a continuous micropilot plant, by feeding a 3:1 (mol/mol) mixture of water/ethanol. Testing has been carried out at 500°C for 8 h-on-stream.

Motivations and Objectives

Ni-based catalysts raised much interest for the present application [1-3]. Very high activity has been observed at high reaction temperature (>600°C), but it would be interesting to operate under milder conditions, in order to lower the energy input to the process and to improve H2 productivity by favoring the water gas shift reaction.

The major inconvenient for Ni-based samples is usually ascribed to coking, often due to the formation of carbon filaments over the active phase. This phenomenon is sometimes correlated also to catalyst deactivation and appearance of by-products. Indeed, if at high reaction temperature with excess steam carbon may be gasified, at operation at 500°C showed C balance often much lower than 100%, evidencing coke accumulation.

Results and Discussion

H2 productivity at 500°C seemed firmly dependent on the calcination and on activation temperature of the catalyst when Ni was supported over TiO2. When the sample was calcined and activated at 500°C, no H2

production was observed due to poor ethanol conversion, with selectivity mostly to acetaldehyde and poor carbon balance. By contrast, calcination of the sample at 800°C induced very high H2 productivity, higher C balance and negligible byproducts formation except some CH4 not reformed. These, results were attributed to the formation of a mixed oxide between Ni and the support during synthesis at high temperature, which keeps the metal well dispersed in spite of the high activation temperature. This leads to very fine Ni particles after activation, which demonstrated more active and most of all stable towards coking.

C balance was in general much higher for the Co- and Cu-containing samples than for the Ni-based ones. One may conclude that for most of these samples there is no additional coking on the catalyst due to the active phase.

However, they proved in general less active than Ni-based ones when tested at 500°C.

References

[1] I. Rossetti, A. Gallo, V. Dal Santo, C.L. Bianchi, V. Nichele, M. Signoretto, E. Finocchio, G. Ramis, G.

Garbarino, A. Di Michele, ChemCatChem, 5 (2013) 294.

[2] I. Rossetti, C. Biffi, C. Bianchi, V. Nichele, M. Signoretto, F. Menegazzo, E. Finocchio, G. Ramis, A. Di Michele, Appl. Catal. B, 117-118 (2012) 384.

[3] E. Finocchio, I. Rossetti, G. Ramis, Int. J. Hydrogen Energy, 38 (2013) 3213.

1

IX INSTM CONFERENCE, Bari, 30^th June - 3^rd July 2013

I contributi scientifici saranno soggetti ad approvazione del Comitato Scientifico del convegno. La selezione dei contributi scientifici sarà effettuata sulla base degli abstracts (1 pagina, in inglese) da inviare con deadline 29 marzo 2013 schiani@instm.it.

Gli autori sono invitati ad esprimere una preferenza all’interno del modulo di iscrizione, per comunicazione orale, presentazione breve orale o sessione poster.

Ogni partecipante registrato può presentare un solo contributo scientifico (invitato, comunicazione orale, presentazione breve orale o sessione poster) ma può naturalmente essere coautore di contributi presentati da altri partecipanti (invitato, comunicazione orale, presentazione breve orale o sessione poster). La selezione dei contributi scientifici sarà effettuata sulla base degli abstracts redatti secondo il formato richiesto - carattere Times new roman, dimensione carattere 11, max 1 pagina.

2