Photocatalytic performance of Li 1x Ag x VMoO 6 (0 6 x 6 1) compounds Lourdes Hurtado a , E. Torres-García b,⇑ , Rubí Romero a , A. Ramírez-Serrano c , Joseph Wood d , Reyna Natividad a,⇑ a Centro Conjunto de Investigación en Química Sustentable, UAEMex-UNAM, km 14.5 Toluca-Atlacomulco road, 50200 Toluca, Mexico b Instituto Mexicano del Petróleo, Lázaro Cárdenas 152, 07730 Mexico City, Mexico c Facultad de Química, Universidad Autónoma del Estado de México campus ‘‘El Cerrillo’’, 50200 Toluca, Mexico d Chemical Engineering Department, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK highlights The synthesis of Li 1x Ag x VMoO 6 (0 6 x 6 1) compounds with lamellar structure. The evaluation of mixed metal oxides Li 1x Ag x VMoO 6 (0 6 x 6 1) as photocatalysts. A comparison of Li 1x Ag x VMoO 6 (0 6 x 6 1) and TiO 2 Degussa P25. Ag does not improve Li 1x Ag x VMoO 6 (0 6 x 6 1) photocatalytic performance. Li 1x Ag x VMoO 6 (0 6 x 6 1) photocatalytic performance is superior to TiO 2 . graphical abstract LiVMoO6 Li0.8Ag0.2VMoO6 AgVMoO6 TiO2 Degussa P25 Photolisis 0 1 2 3 4 Catalyst -r BzOH 0 x10 6 (mol*kg -1 *s -1 ) 0 20 40 60 80 100 % Selectivity to benzaldehyde 0.3 0.6 0.9 1.2 0 10 20 30 LiVMoO 6 Experimental TiO 2 Degussa P25 Experimental LiVMoO 6 L-H model TiO 2 Degussa P25 L-H model -r BzOH 0 x10 6 (mol*kg -1 *s -1 ) C BzOH 0 (M) article info Article history: Received 9 April 2013 Received in revised form 19 August 2013 Accepted 21 August 2013 Available online 5 September 2013 Keywords: Mixed-metal oxides Selective oxidations Heterogeneous photocatalysis Benzyl alcohol TiO 2 Degussa P25 abstract In this work we report the influence of silver content on the structure and photocatalytic performance of Li 1x Ag x VMoO 6 compounds for the oxidation of benzyl alcohol under UV irradiation (k = 254 nm). Phot- ocatalysts were synthesized by solid state method and their structural and morphologic characterization was carried out by powder X-ray Diffraction, Raman Spectroscopy, SEM, TEM, UV–Vis diffuse reflectance spectroscopy and XPS. The effect of variables including silver content, temperature, catalyst concentra- tion and initial concentration of benzyl alcohol on photocatalytic performance were studied. Experimen- tation was also carried out with TiO 2 (Degussa P25) as reference. It was found that all tested Li 1x Ag x VMoO 6 (0 6 x 6 1) compounds exhibit higher photocatalytic efficiency than TiO 2 . However, among mixed oxides, silver was found to diminish their catalytic performance and selectivity towards benzaldehyde. The latter was affected in much less extent than activity (94%, 90% and 87% for LiVMoO 6 , Li 0.8 Ag 0.2 VMoO 6 and AgVMoO 6 , respectively). Kinetic modelling was carried out based on Langmuir–Hin- shelwood type expressions. Apparent activation energies were found to be 42 kJ mol 1 and 60.17 kJ mol 1 for LiVMoO 6 and TiO 2 , respectively. Ó 2013 Elsevier B.V. All rights reserved. 1. Introduction Over the last decades, photocatalysis has been extensively explored as a process to efficiently conduct oxidation of organic compounds, mainly pollutants. In this sense TiO 2 has been preferred by far over other materials as photocatalyst. Despite the proven efficiency of TiO 2 some issues still challenge the scien- tific community dedicated to photocatalysis. These issues are being addressed in order to improve the energetic efficiency of photocat- alytic processes and extend the applications and thus benefits of photocatalysis. In this context different approaches can be distinguished mainly based on type of catalyst and reactor. For in- stance, numerous attempts have been made to improve TiO 2 as a 1385-8947/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.cej.2013.08.091 ⇑ Corresponding authors. Tel.: +52 7222766610x7723 (R. Natividad), tel.: +52 5591758430 (E. Torres-García). E-mail addresses: etorresg@imp.mx (E. Torres-García), reynanr@gmail.com (R. Natividad). Chemical Engineering Journal 234 (2013) 327–337 Contents lists available at ScienceDirect Chemical Engineering Journal journal homepage: www.elsevier.com/locate/cej