Catalysts for Selective Hydrocarbon Combustion in the Presence of CO

Abstract

Selective oxidation of hydrocarbons in the presence of CO goes against the relative reactivity of alkanes and CO. With the help of high throughput experimentation and hit amplification by selection, composition optimization and doping it was possible to develop new Cr-based mixed oxides, which selectively oxidize propane in the presence of CO. Heat of reaction, monitored by emissivity corrected IR-thermography, was chosen as screen, while conventional gas phase catalysis with product analysis by sensors was used for validation. Catalyst selection was based on validation experiments under conventional reaction conditions.

Catalysts for selective propane oxidation in the presence of carbon monoxide: Mechanistic aspects

“…This number shows that the reaction is catalytic under all circumstances. In our previous publications, it was shown that with a Pt/Rh/Al 2 O 3 catalyst under our standard reaction conditions, conversions of CO of 90% and propane of 60% have been obtained at 350°C, comparable to our best mixed oxide catalysts [7][8][9]. Catalyst stability had been tested with a Ti 50 Cr 30 Ce 20 O x catalyst for 7 days at 350°C with no significant loss of activity [7].…”

“…Since the oxygen content of such mixed oxides depends on O 2 partial pressure, synthesis recipe, precursors and calcination temperature as well as on feed gas composition and reaction temperature, the oxygen content of the catalysts used here is not specified, while the content of the metal ions is given as at.% of the overall cation content due to the amount used in synthesis. Among the above 5 starting oxides, Ti 62.5 Cr 37.5 O x had the highest activity with propane conversion of 39% at 350°C (42% in [7] confirms the reproducibility). The variation in synthesis parameters led to a slight increase in activity.…”

“…The cerium-containing catalyst could also be improved by variation in composition and recipe. Changing the synthesis method in the same way as done with Ti 62.5 Cr 37.5 O x (see above) and the addition of 2.5 at.% instead of 20 at.% Ce [7] resulted in a propane conversion of 89% with 100% selectivity at 375°C (see Fig. 5).…”

“…We have synthesized and tested over 2000 mixed oxides using high-throughput technologies. The powder samples were prepared with pipetting robots and for prescreening emissivity corrected infrared thermography (ecIRT) has been applied [7][8][9][10]. During the search, the ternary compound Ti 33.3 Cr 33.3 Ce 33.3 O x was discovered, which showed a propane conversion of 58% and CO conversion of 25% at 350°C in conventional tests.…”

High-throughput technology for novel SO2oxidation catalysts

“…A simple strategy of the catalyst design is provided by the directed evolution concept, which was applied to the development of noble-metal-free catalysts for the selective oxidation of CO in the presence of hydrogen [39]. Other successful examples are the development of hydrocarbon-selective oxidation catalysts in the presence of CO [40] and of CO-selective methanation catalysts in the presence of CO 2 [41]. Over the last 15 years, numerous sol-gel based recipes for a broad variety of compositions have been formulated by our group and summarized in the review [42].…”