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Received May 14, 2017; Accepted Aug 30, 2017
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1. Introduction
Catalytic supports are an important class of materials which, as their name implies, fix the active sites on the solids surface in order to improve their different physicochemical properties [1–3]. In general, supports are used, since they allow obtaining a high specific surface area, lead to adequate porosity, provide appropriate acidity and/or basicity, and tolerate elevated temperatures without suffering significant degradation (high thermal conductivity); such characteristics directly affect the catalytic performance (activity, selectivity, and stability) on certain specific reactions [4–8]. The catalytic supports most commonly used in the chemical industry are based on activated carbon, zeolites, molecular sieves, clays, alumina, and/or silica, among others [9–21].
The literature reports various methods for preparation of catalytic supports, such as conventional sol-gel [22, 23], polymeric precursor [21, 24], hybrid spheres [25, 26], and coprecipitation [27, 28]. Many of the existing techniques have a considerable cost and take significant time and typically use precursors from nonrenewable sources compared to the proteic sol-gel route proposed here, which uses gelatin from porcine skin as organic precursor (renewable source) and aluminum nitrate and/or tetraorthosilicate (TEOS) as inorganic precursors. It has given enough emphasis in the synthesis of metal oxides and alloys containing nanoparticles with interesting magnetic and optical properties using the proteic sol-gel route [29–33]; however, the synthesis of porous supported materials with potential applications in catalysis still needs to be studied from the gelatin precursor.
Gelatin is defined as partially hydrolyzed collagen, where the basic unit comprises a protein chain of about 1050 amino acids. The conversion of the collagen into gelatin requires the breaking of hydrogen bonds, stabilizing the triple helix, and thereby determining the random configuration of gelatin. The composition of the gelatin is essentially formed by 84–90% protein, 8–12% water, and...