Fuel | Year: 2014
Sulfur contamination of a bio-gasoline produced from very low sulfur soybean oil in a circulating pilot riser led to the investigation of the H 2S-olefin recombination pathway by which any sulfur source capable of producing H2S in the FCC riser could in principle produce all of the typical thiophenic species present in the FCC cracked naphtha. The H 2S-olefin recombination mechanism was confirmed in the laboratory by cracking ultra-low sulfur diesel spiked with 2 wt% dymethyl-dysulfide (DMDS) in a Short Contact Time Resid Test reactor to produce 60-80 ppm gasoline, in which the typical cracked naphtha sulfur species were major components. DMDS cracked to produce methyl-mercaptan and H2S as primary products, which continued to react with hydrocarbons derived from the diesel oil cracking to produce the intermediates and final products in the reaction pathway. When the reaction was repeated with catalyst containing 10% of a commercial gasoline sulfur reduction additive, the sulfur in gasoline was reduced by 40% and the sulfur in the spent catalyst went from very low levels, when no additive was used, to 0.5 wt% with the additive. The importance of the recombination pathway and the catalyst additive activity in interfering with the pathway by acting as an H2S scavenger may explain the functional mechanism of ZnO based gasoline sulfur reduction additives. © 2013 Elsevier Ltd. All rights reserved.
Bacellar Mendes L.B.,Petrobras |
Vermelho A.B.,Federal University of Rio de Janeiro
Biotechnology for Biofuels | Year: 2013
One of the main obstacles for continuous productivity in microalgae cultivation is the presence of biological contaminants capable of eliminating large numbers of cells in a matter of days or even hours. However, a number of strategies are being used to combat and prevent contamination in microalgae cultivation. These strategies include the use of extreme conditions in the culture media such as high salinity and high pH to create an unfavorable environment for the competitive organisms or predators of the microalgae. Numerous studies have explored the potential of naturally occurring bioactive secondary metabolites, which are natural products from plants and microorganisms, as a source of such compounds. Some of these compounds are herbicides, and marine and freshwater microalgae are a source of these compounds. Microalgae produce a remarkable diversity of biologically active metabolites. Results based on the allelopathic potential of algae have only been described for laboratory-scale production and not for algae cultivation on a pilot scale. The adoption of allelopathy on microalgal strains is an unexplored field and may be a novel solution to improve algae production. Here we present information showing the diversity of allelochemicals from microalgae and the use of an allelopathic approach to control microalgae cultivation on a pilot scale based on R&D activities being carried out in Brazil for biodiesel production. © 2013 Bacellar Mendes and Vermelho; licensee BioMed Central Ltd.
SPE Journal | Year: 2011
A model to calculate the theoretical critical flow rate of nitrogen (N 2) or natural gas through a Venturi gas lift valve is described herein. This new model considers real-gas effects not only in density calculations but also in other thermodynamic properties that are relevant during gas isentropic evolution. For the properties of N2, the Bennedict, Webb, and Rubin (BWR) equation of state and an accurate correlation for the ideal-gas isobaric heat capacity were used. For natural gas, the Dranchuic and Abou-Kassem equation, which reproduces the well-known Standing and Katz chart, was used, and, for the ideal-gas isobaric heat capacity, it was assumed that the natural gas was a mixture of methane and ethane only, their individual ideal-gas heat capacity being calculated by updated correlations. To validate the use of the proposed equations of state, a comparison of calculated with experimental or reference data on properties of N2 and natural gas (including pure methane and some relevant mixtures) was performed with very good results for N2 and for natural-gas compositions usual in gas lift operations (dry gas with very small amounts of contaminants). For natural gas with moderate amounts of N2 and carbon dioxide (C02), accurate results were obtained after correction of critical conditions and of ideal heat capacity. The model was also compared with other theoretical models found in the literature, which use compositional approaches for natural gas, with excellent results. Some experimental results obtained with commercial Venturi valves manufactured in Brazil are also presented. Copyright © 2011 Society of Petroleum Engineers.
Bioecon International Holding N.V. and Petrobras | Date: 2014-08-22
A process for converting cellulose to glucose, said process comprising the steps of: providing a hydrated molten salt; contacting the hydrated molten salt with a cellulose-containing material to form dissolved glucose; removing the dissolved glucose from the hydrated molten salt.
Process For Obtaining Nanocomposites, Nanocomposite, Method Of Capture And Retrieval Of A Solubilized And/Or Disperesed Material In Organic Or Inorganic Medium, Method Of Purification Of An Organic Or Inorganic Medium And Capture And Retrieval Kit For A Solubilized And/Or Dispersed Material In Organic Or Inorganic Medium
University of Sao Paulo and Petrobras | Date: 2015-06-11
The present invention lies in the fields of chemistry and nanotechnology and describes a nanocomposite to be used in the recovery of several compounds from inorganic or organic medium. Specifically, the invention presents a nanocomposite consisting of magnetic nanoparticles composed of Fe