Oxidative dehydrogenation of ethane to form ethylene was carried out over a platinum catalyst at short contact times. Alumina, zirconia, or silica reticulated foams were used as catalyst supports. The carbon selectivity to form ethylene was affected by the support material whereas the conversion of ethane was not affected to a large extent. The selectivity to form ethylene decreased from silica, to alumina, to zirconia. The temperature programmed desorption of ammonia carried out on the support materials showed that the zirconia support had a higher concentration of acid sites than either alumina or silica. After coating the supports, hydrogen chemisorption on the used catalyst showed metal dispersion was highest on silica and lowest on zirconia. The much higher selectivity on silica and alumina as compared to zirconia is explained by the lack of acid sites that catalyze the decomposition of ethylene to carbon. The higher dispersion of platinum on silica versus alumina will lead to a decrease in platinum metal costs of a real catalyst. The silica-supported catalyst achieved a yield close to that of a steam cracker without any attempt to optimize the system.
Three different ceria
containing catalyst supports and an alumina
(control) support have been deposited with rhodium and used in the
short contact time catalytic partial oxidation of methane. The goal
of this paper is to compare reactor performance from powder catalyst
studies to determine how they translate into structured high gas hourly
space velocity catalysts operating at millisecond contact times. The
supports were synthesized by 3-D printing of powders allowing for
the first time the use of a catalyst support in the form of a monolith
entirely composed of ceria. The ceria containing supports demonstrated
some of the enhanced activity demonstrated as powders and showed superior
methane conversion and hydrogen selectivity as compared to the alumina
support. The use of 3-D printing to translate powder catalysts into
structured supports is promising.
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