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More than half of the bioethanol plants in operation today use corn or grains as raw materials. The downstream processing of mash after fermentation to produce ethanol and distiller grains is an energy-demanding process, which needs retrofitting for optimization. In addition, the fluctuation in the ethanol and grain prices affects the overall profitability of the plant. For this purpose, a process simulation was performed in Aspen Plus(®) based on an existing industrial plant located in Sweden. The simulations were compared using different scenarios including different concentrations of ethanol, using the stillage for biogas production to produce steam instead of distiller grains as a by-product, and altering the purity of the ethanol produced. Using stillage for biogas production, as well as utilizing the steam, reduced the overall energy consumption by 40% compared to the plant in operation. The fluctuations in grain prices had a high impact on the net present value (NPV), where grain prices greater than 349 USD/ton reached a zero NPV. After 20 years, the plant in operation producing 41,600 tons ethanol/year can generate a profit of 78 million USD. Compared to the base case, the less purified ethanol resulted in a lower NPV of 30 million USD.

Urea is a very attractive chemical raw material for large-scale production as it combines low cost with virtually unlimited supply and essentially no toxic effects. Here, we present a study on its use in the dehydration of trimethylolpropane with formation of 3-ethyl-3-(hydroxymethyl)oxetane. The reaction consists of carbonylation of trimethylolpropane and subsequent extrusion of carbon dioxide. The first step was run at a temperature of 120−160 °C at a pressure of approximately 300 mmHg for 1−5 h. Most likely, carbamates of TMP constitute the major product. In the latter step, the temperature was increased to 195−215 °C, the pressure was reduced to 10−50 mmHg, and the final product was isolated by distillation. A spiroorthocarbonate of TMP was formed as an unexpected by-product. The process has been demonstrated on a multikilogram scale. Toxicological screening revealed 3-ethyl-3-(hydroxy-methyl)oxetane to be irritating to eye but not to skin.

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