Obtenção, caracterização e avaliação do desempenho catalitico de [alfa]-fosfatos de zirconio (IV) intercalados com Cu(II) ou Pt(II) na reação de HTS

AUTOR(ES)

Alexilda Oliveira de Souza

DATA DE PUBLICAÇÃO

2001

RESUMO

The a-zirconium (IV) hydrogenphosphate, usually refereed as a-ZrP, is one of the most extensively studied members of the group 4 layered metal phosphates. This compound has received great attention in the last years due to it s intercalation, ionic condutivity, ion exchange and catalytic properties. From the catalytic point of view, the a-ZrP is particularly attractive due to its thermal and chemical stability. This work reports ion exchange studies in samples of a-ZrP with copper(II) or platinum(II) seeking the application of such a material as catalyst in High Temperature Shift (HTS) reactions, a water gas shift reaction developed in the range of 350-420°C. This reaction is an important step in several industrial processes like ammonia synthesis and high purity hydrogen production. The catalysts were prepared under the following conditions: i) ion exchange reactions of the host (a-ZrP) with Cu or Pt and; ii) heat treatment of the ion exchanged a-ZrP in either reduced or inert atmospheres. The catalysts obtained were characterized by X-ray diffraction, infrared and Raman spectroscopies, surface area determination (BET), scanning electron microscopy, EXAFS and Chemissorcion. Catalytic activities were evaluated in a microreactor at 370°C and 1 atm. Although all materials obtained exhibited catalytic activity towards the HTS reaction, the most promising catalysts were those obtained under heat treatment in an inert atmosphere, these were stableunder the described reactional conditions and could be used for preventing the decay of activity often observed in industrial processes. The enhanced catalytic properties exhibited by the inert atmosphere heat treated catalyst is related to a better compromise between host structure organization and catalytic site accessibility displayed in these materials, and it s consequent reflexes in catalytic performance.

ASSUNTO(S)

metais de transição materiais celulas eletroliticas catalise

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