Avaliação de propriedades superficiais de catalisadores NiW suportados em SAPO-5 preparados por impregnação úmida.

Abstract

The fast industrial development and the increased concern about environment require industries seek faster chemicals processes without higher costs, efficient and do not harm the environment. Thus, catalysis, through 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 silicoaluminophosphates (SAPO's) are molecular sieves that generate great interest for their potential industry applicability. 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. It can be used as catalyst and as a supported metal catalyst, generating interest for their properties similar to those of zeolites. The SAPO-5 was used as metal support. The SAPO-5 support was synthesized by biphasic hydrothermal method. The combination of metals selected for the formation of the catalyst, expressed as oxides, was NiO - W03 . A series of catalysts NiW supported on SAPO-5, compositions with 5, 10 and 15 wt.% of W03 e 2 wt.% of NiO, were prepared by sequential incipient wetness impregnation of the materials with aqueous solution of Ni(N03)2.6H20 and H2W04 . The support and catalysts were analyzed by several techniques such as: XRD, EDX, SEM, FTIR, TG and BET. The results obtained by characterization indicated that crystalline SAPO-5 was obtained and after its calcination the material was more organized than before, what indicate better crystallinity. The XRD of NiW catalysts showed a decrease of the characteristics peaks of SAPO-5, it was found by SEM agglomerates impregnated oxides. The EDX revealed that the Si02 decrease considerably with increasing contente of W03 . The BET sample showed a decrease in pore volume and in pore diameter by impregnation of NiO and W03 . The SAPO-5/NiW catalyst had its surface properties affected by impregnation as expected.