Scaling up a Gas-Phase Process for Converting Glycerol to Propane

It is of interest to study not only the fundamental behavior of catalysts and reactors but also to ensure that they can be scaled up in size. This paper investigates the scale-up of a glycerol-to-propane process starting from fundamental laboratory data from micro-reactor testing to the kilogram scale. The process is described in detail and consist of the use of design documents and computer simulations for determining the sizes of the unit operations involved. The final design included a vaporizer section for a glycerol/water mixture, four reactors in tandem with subsequent dehydration and hydrogenation reactions, a flash vessel to separate the excess hydrogen used, and a compressor for recycling the excess hydrogen with additional light components. The system was commissioned in a linear fashion, which is described, and operated for more than 3000 h and more than 1000 h in the final operating mode including recycle. The major results were that no catalyst deactivation was apparent aside from the slow build-up of carbonaceous material in the first dehydration reactor. That the system design calculations proved to be quite close to the results achieved and that the data generated is believed to be sufficient for up-scaling the process into the 1000 to 10,000 tonnes-per-annum range.

Ocean Acidification: Calcifying Marine Organisms

Rising atmospheric carbon dioxide (CO2) concentration leading to ocean acidification is a threat to marine ecosystems and organisms. As atmospheric CO2 rises, CO2 is driven into the ocean. When CO2 combines with seawater it makes carbonic acid. Carbonic acid then breaks down to form a hydrogen ion and a bicarbonate ion. Excess hydrogen ions building up over time result in decreased seawater pH. Furthermore, the excess hydrogen ions combine with carbonate ions in the water, resulting in fewer available carbonate ions for marine calcifiers. These carbonate ions are an essential element for marine calcifiers and their decreased availability is of increasing concern. The overall change in pH and available carbonate ions has been shown to have direct impacts on physiology, behavior, and calcification rates of marine organisms. Coastal Florida boasts an abundance and diversity of calcifying organisms that stand to be impacted by the altered carbonate chemistry resulting from increased atmospheric CO2 levels. This publication will focus on the impacts of ocean acidification on Calcification. Specifically focusing on how calcification in corals, bivalves, echinoderms and planktonic organisms are being impacte.