Catalyst nickel/lanthana

Liguras et al. investigated autothermal reforming of ethanol over ruthenium and nickel catalysts on structured supports such as ceramic foams and monoliths [212,213]. Conditions chosen were an O/C ratio of 0.61 and an S/C ratio of 1.5. The reaction was performed at a very high pre-heating temperature of the monoliths and consequently substantial conversion occurred even upstream of the reactor, which created a hot spot of up to 950 °C in the monoliths. A ceramic monolith coated with 5 wt.% ruthenium formed in addition to carbon oxides methane as the main byproduct, but there were also small amounts of acetaldehyde, ethylene and ethane [212]. When the S/C ratio was increased to 2.0, the by-products could be suppressed. Increasing the O/C ratio had a similar effect and also suppressed the methane formation. The ruthenium catalyst showed stable conversion for a 75-h test duration. Nickel/lanthana catalysts containing 13 wt.% nickel on a lanthana carrier showed similar performances with respect to activity, selectivity and stability [213]. 

Nickel-based catalysts on various carriers such as alumina, lanthana, magnesia and zinc oxide have been studied intensively for ethanol steam reforming [196]. 

For nickel-based catalysts, Fatsikostas et al. reported that the alumina carrier promoted carbon formation, which was suppressed by the addition of lanthana [199,200]. Nickel, as the active species, promoted reforming to carbon dioxide but the also water-gas shift and methanation [199]. 

Chen et al. prepared a catalyst for pre-reforming of gasoline [236]. It was composed of 50 wt.% nickel oxide, 18 wt.% lanthana and the balance alumina. The catalyst was tested at a weight hourly space velocity of between 40 and 168 L (hgcai) at 5-bar pressure and 480 °C reaction temperature. The gasoline surrogate was composed of 74 wt.% isooctane, 20 wt.% xylene, 5 wt.% cyclo-hexane and 1 wt.% 1-octene (average... 

Other supports can be improved by lanthana, as was also observed by Xiancai et. al. [68] for dry reforming catalysts. They have found that the introduction of lanthanum to Ni/BaTiOs catalyst increased the specific surface area and the metal dispersion up to an optimum amoimt (1.5 % w) the excess of lanthanum caused the pore blockage decreasing the specific surface area. The catalytic activity in dry reforming was also improved due to lanthanum, a fact that was assigned to an increase of oxygen vacaneies, which help the reaction however, the catalytic activity had a decreasing tend with the increment of lanthanum amounts. In addition, lanthanum favored nickel reduction. 

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