We conducted a comparative study of catalytic hydrodesulfurization of dibenzothiophene (DBT) with NiMo/Al2O3 at 673 K and 30 MPa, in various atmospheres (H2−SCW, CO−SCW, CO2−H2−SCW, and HCOOH−SCW), using a tube bomb reactor Higher conversion of DBT was obtained in CO−SCW, CO2−H2−SCW, and HCOOH−SCW than in H2−SCW These results clearly indicate that a water−gas shift reaction in supercritical water (SCW) produces species which can hydrogenate DBT more effectively than H2 gas We also conducted another experiment for the partial oxidation of a DBT−hexylbenzene mixture in SCW Even in the presence of oxygen, effective hydrogenation of DBT took place This result is probably because CO forms through the partial oxidation of hexylbenzene and converts to the hydrogenating species through a water−gas shift reaction We think the catalytic desulfurization of heavy oils in SCW will be a promising new technology, since even by introducing oxygen or air instead of hydrogen, an excellent hydrogenating atmosphere can

Catalytic hydrodesulfurization of dibenzothiophene through partial oxidation and a water-gas shift reaction in supercritical water

This paper deals with biodiesel production from corn oil as a feedstock via the transesterification and esterification reactions. To date, corn oil has not been considered a viable biodiesel feedstock because of its high edible value and relatively high price, but some industrial corn processing co-products, such as corn germ and dried distillers grains with solubles (DDGS), have potential for this application after the extraction of corn distillers oil (CDO). Here, after brief discussion of the issues related to corn botany, cultivation, and use, as well as the corn germ and oil composition, properties and use, the methods of corn processing for germ and DDGS recovery are presented. In addition, the mechanical and solvent extraction techniques for oil recovery from whole ground corn kernels, germs, and DDGS are considered. Furthermore, biodiesel production from corn oil, waste frying corn oil, and CDO is critically analyzed. It is expected that further investigation will be directed toward developing simpler, more effective and energy-saving technologies for biodiesel production from corn oil-based feedstocks, especially from CDO. The integration of biodiesel production directly into corn-based ethanol production will advance the overall economy of industrial plants. Furthermore, the fuel properties, performances and exhaust gas emissions of corn-based biodiesel and its blends with diesel fuel are discussed, taking into account the biodiesel quality standards. Finally, issues related to the environmental and socio-economic impacts of corn-based biodiesel production and use are also tackled.

Biodiesel production from corn oil: A review

Characteristics of polyethylene cracking in supercritical water compared to thermal cracking

Supercritical water upgrading (SCWU) of heavy oils reduces sulfur content and decreases average molecular weight, without rejecting carbon as coke products. Despite many years of industrial and academic scrutiny, many fundamental questions remain in the field: intrinsic reaction rates and mechanisms; the role of water; the need for catalysts; the importance of phase behavior and mixing. In 2009, MIT initiated a SCWU research program aimed at improving the understanding of the relevant physical, chemical, and catalytic phenomena. This overview summarizes the work performed at MIT within the historical context of SCWU with a particular focus on new kinetic rate measurements and modeling, reaction mechanism analysis, catalyst investigation, and combined mass/heat transport modeling of hydrocarbon/water mixtures. Kinetic rate measurements showed that sulfide decomposition during SCWU is consistent with a radical chain reaction pathway. Mechanistic studies and product distribution analysis identified that sulfide decomposition likely occurs via thioaldehyde and aldehyde intermediates and that water plays important roles in thioaldehyde hydrolysis (as a reactant) and aldehyde decarbonylation (as a catalyst). Catalytic investigation found that ZnO has potential to improve sulfur removal during SCWU, without addition of molecular hydrogen. Mixing studies revealed the complex dynamic processes that occur when hydrocarbons are injected into near or supercritical water. The article concludes with a summary of research needs and thoughts on the future of SCWU.

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Upgrading and desulfurization of heavy oils by supercritical water

The associated molecular nature of bituminous coal

Extraction of oil sand bitumens with supercritical water

Corn distiller’s dried grains with solubles (DDGS) is a byproduct of the ethanol industry and has potential as a source of valuable compounds. In this study, corn DDGS was extracted using supercritical carbon dioxide (SC-CO2) at 50–70 °C, 34.5–49.6 MPa, and constant CO2 flow rate of 1 L/min (measured at ambient conditions). The highest yield of total lipids (9.2%, w/w) was obtained at 49.6 MPa/70 °C. Apparent solubility of corn DDGS lipids ranged between 0.010 kg/kg CO2 at 34.5 MPa/50 °C and 0.026 kg/kg CO2 at 49.6 MPa/70 °C. The extract contained 107 mg/kg carotenoids, 1538 mg/kg tocochromanols, and 15904 mg/kg phytosterols at 49.6 MPa/70 °C. The Sovova model and Chrastil model were successfully used to describe the extraction of total lipids and apparent solubility of total and minor lipids, respectively. The study revealed that DDGS is a good inexpensive source of lipids and valuable minor lipid components and that SC-CO2 extraction can be used as a “green” process to add value to corn DDGS by recoveri...

Jaime Calderon

Papers

Extraction of oil sand bitumens with supercritical water

Supercritical carbon dioxide extraction of corn distiller's dried grains with solubles: experiments and mathematical modeling.

Some observations respecting reaction paths in coal liquefaction: 1. Reactions of coal-tetralin slurries

On “partial” coal conversion by extraction with supercritical H2O

Some observations respecting reaction paths in coal liquefaction: 3. Time and temperature effects in coal solubilization