High selectivities to ethylene by partial oxidation of ethane

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 degrees C with a contact time of similar to 10(-3) seconds. This system almost totally shuts off the reactions that form undesired CO and CO2, 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

Pacioli and humanism: pitching the text in Summa Arithmetica

Despite the wide cross-disciplinary influence of Fra' Luca Pacioli's Summa de Arithmetica, Geometria, Proportioni et Proportionalita (Summa), it has been criticized as being both difficult to read and written in a mixture of bad Italian and bad Latin; but, paradoxically, intellectuals of Pacioli's day praised the style of writing in Summa. Can both viewpoints be correct? The answer to this question is sought by identifying what may have inspired Pacioli to write Summa in the manner he did. In doing so, the article considers the times in which he lived and, in particular, the impact that Renaissance Humanism and Humanist Education may have had upon his writing style. The article finds both views were correct in their own timeframes and contexts and that Pacioli's writing style was both an appropriate one with which to address a contemporary merchant society and one which would impress and gain the approval of his fellow humanist educators and patrons