A series of Co-Ni catalysts, prepared from hydrotalcite (HT)-like materials by co-precipitation, has been studied for the hydrogen production by ethanol steam reforming. The total metal loading was fixed at 40% and the Co-Ni composition was varied (40-0, 30-10, 20-20, 10-30 and 0-40). The catalysts were characterized using X-ray diffraction, N 2 physisorption, H 2 chemisorption, temperature-programmed reduction, scanning transmission electron microscope and energy dispersive spectroscopy. The results demonstrated that the particle size and reducibility of the Co-Ni catalysts are influenced by the degree of formation of a HT-like structure, increasing with Co content. All the catalysts were active and stable at 575°C during the course of ethanol steam reforming with a molar ratio of H 2 O:ethanol = 3:1. The activity decreased in the order 30Co-10Ni [ 40Co * 20Ni-20Co * 10Co-30Ni [ 40Ni. The 40Ni catalyst displayed the strongest resistance to deactivation, while all the Co-containing catalysts exhibited much higher activity than the 40Ni catalyst. The hydrogen selectivities were high and similar among the catalysts, the highest yield of hydrogen was found over the 30Co-10Ni catalyst. In general, the best catalytic performance is obtained with the 30Co-10Ni catalyst, in which Co and Ni are intimately mixed and dispersed in the HT-derived support, as indicated by the STEM micrograph and complementary mapping of Co, Ni, Al, Mg and O.

Sorption enhanced steam reforming of ethanol (SESRE), featured by yielding high purity of H(2) from one single reaction unit, is a new reaction process with a great potential for realizing sustainable H(2) production. The potential of such process with a CaO-based acceptor has been assessed by thermodynamic analysis and experimental demonstration. As predicted, ethanol can be reformed at relatively low temperatures (500-600 degrees C), still yielding high-quality H(2). Another major advantage of coupling CO(2) capture to the reforming process is predicted to be low risk in carbon formation. The SESRE reaction was carried out over a mixture of hydrotalcite-like material derived Co-Ni catalysts (Co-Ni/HTls) and calcined dolomite with a steam to carbon (S/C) ratio of 3 and temperatures ranging from 500 to 650 degrees C. The chosen reaction system was able to yield H(2) with purity fairly close to the theoretical prediction. Particularly, the best result was obtained over 40Ni and 20Co-20Ni/HTls at 550 degrees C, where the product gas had composition of more than 99 mol % H(2), ca. 0.4 mol % CH(4), 0.1 mol % CO, and 0.2 mol % CO(2). Special emphasis was put on the effect of steam on the stability of the CO(2) acceptor during the SESRE reaction. Hydration of CaO in the acceptor did not cause appreciable induction period, even at the low operating temperatures. However, different from a test under dry atmosphere (CO(2)/argon), the acceptor showed rapid deactivation in a multicycle operation of SESRE. A similar deactivation tend was given by a comparative test in a steam/CO(2)/Ar atmosphere.

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