Mesoporous catalysts based on Keggin-type heteropolyacids supported on MCM-41 and their application in thiophene hydrodesulfurization Franklin J. Méndez a,⇑ , Aura Llanos b , Marcel Echeverría a,b , Reynaldo Jáuregui a,b , Yanet Villasana a , Yraida Díaz a , Gustavo Liendo-Polanco c , Miguel A. Ramos-García d , Tamara Zoltan a , Joaquín L. Brito a,⇑ a Centro de Química, Instituto Venezolano de Investigaciones Cientíﬁcas, Apartado 20632, Caracas 1020-A, Venezuela b Departamento de Química, Instituto Universitario de Tecnología Dr. Federico Rivero Palacio, Caracas, Venezuela c Departamento de Química, Universidad de Oriente-Núcleo de Sucre, Cumaná, Venezuela d Unidad de Caracterización y Estructura de Materiales, Instituto Zuliano de Investigaciones Tecnológicas, Maracaibo, Venezuela highlights " Supporting the heteropolyacids increased the catalytic activities. " Surface acidity and calcination temperature related to HDS activity and stability. " Catalysts presented a good structural and morphological stability during reaction. graphical abstract article info Article history: Received 30 March 2012 Received in revised form 31 October 2012 Accepted 5 November 2012 Available online 5 December 2012 Keywords: 12-Molybdophosphoric acid 12-Tungstophosphoric acid Heteropolyacids Hydrodesulfurization MCM-41 abstract A series of tungsten and molybdenum catalysts supported on MCM-41 were prepared using Keggin het- eropolyacids (H 3 PM 12 O 40 , M = Mo or W) as active phase sources and compared with their analogues unsupported. The physicochemical characterization was carried out by, small angle and wide angle X-ray diffraction; thermogravimetric analysis/differential scanning calorimetry; ultraviolet–visible dif- fuse reﬂectance and Fourier transform infrared spectroscopies; N 2 physisorption and potentiometric titration with N-butylamine, for determination, respectively, of the structure; thermal stabilities; integ- rity of heteropolyacids; textural properties and superﬁcial acidity. The solids were tested in the thiophene hydrodesulfurization reaction at 400 °C, atmospheric pressure and weight hourly space velocity of 0.48 h 1 . In this study, it has been demonstrated the importance of supporting heteropolyacids to increase the catalytic activity. Furthermore, it was proved a correlation between surface acidity and calcination temper- ature with the activity and stability of these catalysts in the hydrodesulfurization reaction. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction Nowadays, the need to increase sulfur removal from fossil fuels by means of hydrodesulfurization (HDS) is stimulated by the new environmental legislations. In many countries, the production of ultra-clean diesel fuel with low sulfur content (less than 50 ppm) or even of sulfur-free diesel fuel (less than 10 ppm) is requested at the present time [1–3]. To meet these demands, different efforts 0016-2361/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.fuel.2012.11.021 ⇑ Corresponding authors. Tel.: +58 212 504 1321; fax: +58 212 504 1350. E-mail addresses: fmendez@ivic.gob.ve (F.J. Méndez), joabrito@ivic.gob.ve (J.L. Brito). Fuel 110 (2013) 249–258 Contents lists available at SciVerse ScienceDirect Fuel journal homepage: www.elsevier.com/locate/fuel