Journal of Molecular Catalysis A: Chemical 204–205 (2003) 673–681 Redox properties of a TiO 2 supported Cu-V-K-Cl catalyst in low temperature soot oxidation P. Ciambelli ∗ , V. Palma, P. Russo, S. Vaccaro Dipartimento di Ingegneria Chimica e Alimentare, Università di Salerno, via Ponte Don Melillo—84084, Fisciano, Salerno, Italy Received 15 October 2002; received in revised form 28 February 2003; accepted 13 March 2003 Dedicated to Professor Renato Ugo on the occasion of his 65th birthday Abstract Strong activity of a Cu-V-K-Cl/TiO 2 catalyst for soot oxidation was found by comparing results of constant temperature carbon oxidation tests in the presence and in the absence of catalyst. In addition, temperature programmed reductions (TPR) with different reductants (H 2 or soot) and re-oxidations (TPO) with air were carried out. Mass-spectrometric (MS) analyses of the gaseous products of the mentioned TPR and TPO processes were also performed on line. The aim was to investigate the behaviour of the catalyst under reducing and oxidising environments in order to draw indications on the role of the redox properties in the catalytic reaction mechanism. Results showed that the catalyst can be reduced and re-oxidised under proper environments. In particular, the catalyst delivers oxygen in the whole range of temperatures from 480 to 1000 K when carbon or H 2 are employed as reducing substances. The relevant differences between the two cases are the main products of the reductions (H 2 O with H 2 and CO 2 with soot) and the high HCl desorption in the case of reduction by H 2 . In addition, the temperature range within which the catalyst re-oxidises after such a reduction is practically coincident with those where soot catalytic oxidation occurs. © 2003 Elsevier Science B.V. All rights reserved. Keywords: Soot; Catalytic oxidation; Cu-V-K-Cl/TiO 2 catalyst; Redox properties 1. Introduction In the last 50 years catalysis has played a key role in the development of new and more advantageous routes for the manufacture of traditional and novel chemicals. More recently catalysis has been more and more ap- plied to carry out processes for solving environmental pollution problems [1]. The so called environmental catalysis has given a significant contribution to the re- duction of air pollution in many cases, such as, for ex- ∗ Corresponding author. Tel.: +39-089-964151; fax: +39-089-964057. E-mail address: pciambel@mail.unisa.it (P. Ciambelli). ample, NO x reduction from power plant flue gas [2], three way catalysts at the automotive engine exhaust [3], VOC oxidation [4]. The goal of abating the pollu- tants present at the exhaust of a diesel engine has not yet fully achieved, due to the specific feature of that exhaust, i.e. the presence of particulate matter, espe- cially as soot. Soot is the carbonaceous part of diesel particulate matter, which also contains other compo- nents, such as sulphates and heavy metals. Therefore, a diesel particulate matter removal process must in- clude: (i) soot filtration by a suitable filter medium, since the residence time in the exhaust pipe is not long enough for particulate conversion; (ii) soot combus- tion on a specific oxidation catalyst, since the exhaust 1381-1169/$ – see front matter © 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S1381-1169(03)00351-0