Artigo:

This work aims the synthesis and study of ZSM-5 catalysts for the conversion of ethanol to light olefins, especially, using an alternative and inexpensive route. The ethanol emerges as a renewable source for the production of olefins. The ZSM-5 catalyst has important characteristics for this type of reaction such as acidity, surface area and particle size. The synthesis was carried out in hydrothermal treatment at 170 °C. Were performed two synthesis with templates, using n-butylamine and tetrapropylammonium hydroxide (TPAOH), and an alternative and novel way using a nucleating gel. The catalyst characterization was performed using several techniques (XRD, BET, SEM and TGA). The catalytic reaction studied the influence of temperature (250 to 450 °C) and SAR (Si/Al2 ratio). The products analysis was made with a gas chromatograph. The ethylene yield was above to 80 % for all catalysts. Lower SAR values obtain higher yields for propylene, around to 8 %. The temperature, SAR and template influenced in the selectivity. The nucleating gel method showed to be a viable and inexpensive alternative for ZSM-5 synthesis. 1. INTRODUCTION Nowadays, light olefins are in a growing demand since are used as feedstock for several polymeric products, and its production is manly as a byproduct of naphtha steam cracking and catalytic cracking of crude oil (Meng et al. 2012; Ouyang et al. 2009). The environmental issue regarding this type of process have made several researchers to explore for alternative and sustainable routes for olefins production, and following this tendency, ethanol show as a potential candidate for feedstock, in the ethanol to olefins (ETO) reaction (Inaba et al. 2007; Lu and Liu 2011). The use of ZSM-5 zeolite as catalyst for conversion of ethanol to light olefins become an option because of its characteristics such as acidity, structure and shape-selective. The textural properties of ZSM-5 zeolite, especially its framework Si/Al, which is related to the acidity of the catalyst, played a vital role in determining the nature of the product. In the ZSM-5 synthesis, templates are used for more structural stability and this substances can be neutral or charged, organic or inorganic and are used to induce crystallization and assist to define the structure (Fouad et al. 2006; Sang et al. 2004). Área temática: Engenharia de Reações Químicas e Catálise 1With the importance of find new methods for ZSM-5 synthesis, some studies are trying routes without the aid of templates (Cheng et al. 2008; Kalipçilar et al. 2007), and one of the synthesis in this work use a small portion of template in a attempt to find a alternative and inexpensive route for the ZSM-5 synthesis and consequently to the ETO reaction. Thus, the aim of this work was study and evaluate HZSM-5 catalysts for the ETO reaction. For that reason, catalysts where synthesized in two traditional methods with the aid of templates with the purpose of comparing with an a third and novel way using a nucleating gel containing a small concentration of template (Lam et al. 2006), all with three different SAR (Si/Al2 ratio) values (30, 60 and 100). In addition to that was studied, in the catalyst activity, the influence of the reaction