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Le Duigou A.,CEA Saclay Nuclear Research Center | Miguet M.,Albi-Carmaux School of Engineering | Amalric Y.,CEA Saclay Nuclear Research Center
International Journal of Hydrogen Energy | Year: 2011

This study analyses the current industrial hydrogen markets in France on both a European and international scale, while endeavouring to assess future prospects by 2030. Hydrogen is produced either on purpose or unintentionally as a co-product. Intentional production of hydrogen, generally from natural gas, is classified as captive or merchant hydrogen. France produces about 920,000 metric tons of hydrogen annually. The producer and consumer industries are, in decreasing order of importance are: oil for refinery and petrochemicals, ammonia, iron & steel (co-production), chemicals, and chlorine (co-production). The intentional production of hydrogen from natural gas amounts to less than that co-produced: 40% compared with 60%. The amount of burned hydrogen is about 25% of the total. Production-related carbon dioxide emissions range between 1% and 2% of the total emissions in France. There is an increasing trend in the industrial hydrogen production, essentially due to the oil industry whereas a decline in production is expected in the ammonia industry. The annual production around 2030 should therefore be greater than 1 million metric tons (MMT) per year. If the iron & steel industry were to use hydrogen in every possible situation, it would double the total quantity of hydrogen produced and consumed in France. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. Source


Chitu T.M.,Albi-Carmaux School of Engineering | Oulahna D.,Albi-Carmaux School of Engineering | Hemati M.,ENSIACET
Powder Technology | Year: 2011

This study aims at better understanding the wet granulation process of a binary mixture composed of microcrystalline cellulose (water insoluble) and lactose (water soluble). It investigates the effect of formulation (proportion of the different components in the mixture) on the granule growth kinetics, the evolution of granule morphology during granulation, the wet mass consistency and dry granule strength of the end product. Additionally the influence of mixer design has been studied by up scaling the process from the 1.9. L Mi-pro high shear mixer used as the reference scale to a 6. L Diosna P1-6 high shear mixer. The scale-up rules investigated were constant impeller tip speed and constant Froude number. Our results allowed us to draw the following conclusions: -The increase in MCC content is found to increase the optimum binder requirement for granulation, wet mass consistency and dry granule strength. -Granule growth takes place in three distinct stages: wetting, nucleation and growth. These stages can be identified with the help of the recorded torque values during the granulation process or by the evolution of granule size and granule morphology. -The characterization of the starting materials by moisture sorption isotherms brings more insight to the role of each component during the granulation process. -The increase of the granulation scale has little influence on the observed growth mechanism. However bi-modality of the granule size distribution is increased, wet mass consistency and dry granule strength are decreased with increasing scale of operation. © 2010 Elsevier B.V. Source


Chitu T.M.,Albi-Carmaux School of Engineering | Oulahna D.,Albi-Carmaux School of Engineering | Hemati M.,ENSIACET
Powder Technology | Year: 2011

The effect of binder properties on torque curves, granule growth kinetics, wet mass consistency and dry granule strength has been investigated in this study. Granulation runs have been performed on a fine cohesive microcrystalline cellulose powder (Avicel 105, d 50=20μm) in two types of laboratory high shear mixers: a Mi-Pro high shear mixer using a 1.9L bowl and a 6L Diosna high shear mixer. Binders used included ultra-pure water and solutions of varying concentrations of PVP and HPMC allowing us to cover different values for parameters like viscosity and work of adhesion. Torque curves recorded during granulation are found to allow good control of the process. Optimum liquid requirement for granulation has been found to vary with binder type and decrease with increasing viscosity while granule growth kinetics has been found to be to be related to the work of adhesion for low viscosity binders. Granule strength has been evaluated for wet granules by the means of wet mass consistency measurements on a mixer torque rheometer and for dried granules by means of uniaxial compression tests on a Texture Analyser mechanical testing machine. For low viscosity binders both wet mass consistency and dry granule strength have been found to depend on the work of adhesion. For high viscosity binders higher wet mass consistencies but lower dry granule strengths have been observed. Granulating on the larger 6L scale has shown that constant impeller tip speed offers good agreement in terms of mean granule size however granule size distribution seems to be scale dependant. © 2010 Elsevier B.V. Source


Chitu T.M.,Albi-Carmaux School of Engineering | Oulahna D.,Albi-Carmaux School of Engineering | Hemati M.,ENSIACET
Powder Technology | Year: 2011

The effect of the main means of agitation in a high shear mixer has been investigated in this study. Granulation runs have been performed on a fine cohesive microcrystalline cellulose powder (Avicel 105, d 50=20μm) often used as a pharmaceutical excipient in tablet formulations in two bowls of a Mi-Pro® laboratory high shear mixer with a capacity of 0.9 and 1.9L, respectively. Torque curves recorded during granulation are found to allow good control of the process while increasing impeller speed is found to generally reduce granule size and the onset of breakage seems to occur for similar values of impeller tip speed. As a general rule, the chopper allows for better binder distribution in the Mi-Pro® and is found to be necessary for successful granulation at low to moderate impeller speeds. For high impeller speeds in excess of 4.4m/s with or without a chopper, similar granule sizes and growth mechanisms are observed. Granule roundness was found to increase with impeller speed up to a certain speed after which granule roundness has been found to decrease with increasing impeller speed most probably because of increased breakage of the granules. Dry granule strength has been found to increase with increasing impeller speed, presenting only a slight decrease at the highest impeller speed studied. © 2010 Elsevier B.V. Source


Carlier L.,Albi-Carmaux School of Engineering | Baron M.,Albi-Carmaux School of Engineering | Chamayou A.,Albi-Carmaux School of Engineering | Couarraze G.,University Paris - Sud
Tetrahedron Letters | Year: 2011

Many synthetic methods exist for dibenzoquinoxalines but only a few for dibenzophenazines and their aza derivatives and even less are 'green'. Some dibenzophenazines and dibenzopyridoquinoxaline have been efficiently obtained with good to excellent yield by a very simple method which does not require use of solvent or catalyst. Solid phase synthesis using co-grinding presents thus many advantages in developing greener synthetic organic pathways. © 2011 Elsevier Ltd. All rights reserved. Source

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