High Selectivities to Ethylene by Partial Oxidation of Ethane

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Abstract
At least 85 percent selectivity to ethylene at greater than 70 percent conversion can be obtained by partial oxidation of ethane by adding large amounts of H 2 to the reaction mixture and using a platinum-tin catalyst operating at 950°C with a contact time of ∼10 −3 seconds. This system almost totally shuts off the reactions that form undesired CO and CO 2 , which fall from 20 percent without H 2 to 5 percent when H 2 is added. Although a 2/1 H 2 /O 2 mixture should be explosive at high temperatures, no flames or explosions occur in the presence of ethane. The successive reactions on the catalyst generate more H 2 than used in the feed, so with recycle no additional H 2 would be needed. These results are unexpected because ethylene is a nonequilibrium product and entropy considerations argue that all reaction channels open at high temperatures so the products should approach equilibrium, which predicts only a few percent ethylene. This process is promising for the replacement of steam cracking in the production of ethylene.