Synthesis and impregnation of silicoaluminophosphate WO₃ -NiO/SAPO-5

Full text: The increased concern about environment require industries seek faster chemicals processes without higher costs, efficient and do not harm the environment. The catalyst came to accelerate chemical reactions providing agility in chemical processes, low waste production, reducing the amount of raw material and energy costs for obtaining the expected product. The SAPO-5 is a member of the family of silicoaluminophosphates, is a microporous material with large pore and possess a variable silicon content, therefore a mild acidity. The SAPO-5 was synthesized by biphasic hydrothermal method and used as metal support. The combination of metals selected was NiO - WO₃ . The catalyst WO₃ -NiO/SAPO-5 with 10 wt.% WO₃ e 2 wt.% NiO, were prepared by incipient wetness impregnation of the materials with aqueous solution of Ni(NO₃)₂ .6H₂O and H₂WO₄ . The support and catalyst were analyzed by: XRD, EDX, FTIR. The results obtained by characterization indicated that crystalline SAPO-5 was obtained and after its calcination the material was more organized, or better crystallinity. The XRD of WO₃ -NiO catalyst showed a decrease of the characteristics peaks of SAPO-5. The EDX for the support showed the presence of silicon, aluminium and phosphorus and for the catalyst revealed that the SiO₂ content decrease considerably with the increase of WO₃ content. The FTIR analysis showed the region 1300-1500 cm^-1 corresponding to the links C - H vibrations caused by these triethylamine added in the synthesis of SAPO-5, and their intensity decreased in the calcined sample. It was possible to observe the symmetrical stretching of the links T - (T = Si, Al) in the region between 785-946 cm^-1, common in this materials. After impregnation of the SAPO-5 with tungsten trioxide was possible confirm bands between 1000-960 cm^-1 corresponding to P-OH bond, and the band between 700-800 cm^-1 can be assigned to links WO. The WO₃ -NiO/SAPO-5 catalyst had its surface properties affected by impregnation as expected. (author)