Reforma a vapor do etanol sobre catalisadores Cu-Ni/ZnO
Abstract
In this work copper, nickel and copper/nickel supported in zinc oxide catalysts
were prepared, characterized and tested in the steam reforming of ethanol to produce
hydrogen.
The support and the supported catalysts were prepared by precipitation and
impregnation methods, respectively, using aqueous solution of copper and nickel
nitrates. The supported catalysts were prepared by varying the nickel and copper
loading to obtain 15% weight of metals in the final solid.
After prepared and calcined, the solids were characterized by Inductively
Coupled Plasma Atomic Emission Spectroscopy (ICP-AES), X-Ray Diffraction
(XRD), Nitrogen Adsorption by B.E.T. method, and Temperature Programmed of
Reduction with H2 (TPR-H2). The results indicated that the preparation method and the
treatment conditions were appropriated to achieve the designed catalytic samples.
The catalytic tests were carried out in a range of temperature of 300 to 650oC
and water:ethanol molar feed ratio of 3:1 and 6:1. It was verified that the ethanol
conversions were higher then 80% in all range of temperature for all catalysts, including
the support, independently of water:ethanol molar feed ratio.
Other parallel reactions were observed, rather than steam reforming of ethanol,
at different conditions of operation, like dehydrogenation of ethanol to acetaldehyde and
hydrogen, decarbonylation of acetaldehyde to CH4 and CO, decomposition of ethanol to
CH4, CO and H2, water-gas shift and methane reforming at high temperatures.
It was also observed that the best combination between metal loading and
process parameters to produce hydrogen from steam reforming of ethanol was in the
temperature range of 450 to 550oC, 6:1 molar water:etanol feed ratio and bimetallic
catalysts with the composition Cu7,5Ni7,5ZnO.