ORIGINAL ARTICLE Catalytic deoxygenation of C18 fatty acids over HAlMCM-41 molecular sieve F. C. M. Silva 1 & M. S. Lima 2 & C. O. Costa Neto 2 & J. L. S. Sá 2 & L. D. Souza 3 & V. P. S. Caldeira 3 & A. G. D. Santos 3 & G. E. Luz Jr 2 Received: 9 November 2016 /Revised: 25 April 2017 /Accepted: 1 May 2017 # Springer-Verlag Berlin Heidelberg 2017 Abstract The large demand for energy combined with eco- logical, economic, and social reasons encouraged the studies for alternative sources of fuel. The deoxygenation process of oils and fatty acids has emerged as a promising resource in obtaining fuels. This paper studied the deoxygenation process of oleic and stearic acids carried out in a distillation system, under the temperature of 450 °C over MCM-41, AlMCM-41- 41, and HAlMCM-41 molecular sieves, which were synthe- sized by direct hydrothermal synthesis method and character- ized by X-ray diffraction (XRD) spectroscopy in the infrared site (FTIR), adsorption and desorption of N 2 , and scanning electron microscopy (SEM). The products were analyzed by gas chromatography (GC) and acid-base titration. The results showed that stearic acid deoxygenates more than the oleic acid, and that the performance of HAlMCM-41 was superior to AlMCM-41, indicating that the total acidity positively in- fluenced the process. Furthermore, from the stearic acid deox- ygenation, it obtained mainly heptadecanes (C17:0) struc- tures, while the oleic acid produces heptadecenes (C17:1). Keywords Deoxygenation . HAlMCM-41 . Fatty acid . Pyrolysis . Biofuel 1 Introduction The growing demand for energy has promoted the develop- ment of research aimed at finding means which would con- tribute to supply this demand, which, when associated with environmental concerns, stimulated the production of fuels using biomass such as vegetable oils [1, 2]. Among biofuel production processes, the biomass cracking has proved promising in use since Second World War [2]. Since then, this process has aroused interest in many countries [3–6]. The pyrolysis or cracking is the breakdown of vegeta- ble oil molecules by heating at high temperatures (>350 °C), resulting in a mixture of chemical compounds with properties similar to diesel oil [7]. Many reactions are involved in this process, but the literature shows two distinct and successive stages [8, 9]. The first one, called primary cracking, which is basically thermal, consists of the formation of acid species, light hydrocarbons, and acrolein that are derived from the decomposition of triglyceride molecules. The second one, called secondary cracking, is influenced by the presence of a catalyst and that is where we can observe the deoxygenation of fatty acids derived from primary cracking, which leads to the formation of hydrocarbons with properties similar to those of petroleum products [8, 9]. Studies involving biomass cracking have focused on tri- glycerides and free fatty acids, but the thermal and thermal catalytic deoxygenation of these acids has received little atten- tion [10]. However, the carboxylic acids are available in nat- ural resources and are promising as renewable raw materials for the production of valuable chemicals and biofuel compo- nents [11, 12]. The fatty acid deoxygenation process can occur Electronic supplementary material The online version of this article (doi:10.1007/s13399-017-0263-9) contains supplementary material, which is available to authorized users. * G. E. Luz Jr geraldoeduardo@gmail.com 1 Department of Chemistry, Federal University of Piaui, Teresina, PI 64049-550, Brazil 2 GERATEC-PPGQ-CCN, State University of Piaui, João Cabral S/N, Teresina, PI 64002-150, Brazil 3 Department of Chemistry, FANAT, PPGCN, State University of Rio Grande do Norte, Mossoró, RN 59610-210, Brazil Biomass Conv. Bioref. DOI 10.1007/s13399-017-0263-9