Complexes polymetalliques du cobalt et du fer a base de titane et de vanadium : synthese et reactivite

T 55895 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc

Activation et fonctionnalisation du propane en milieu superacide

SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : T 81810 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

A purification route of bio-acrylic acid by melt crystallization respectful of environmental constraints

International audienceBio-acrylic acid (AA) is produced from glycerol, a by-product of biodiesel production and oleochemistry. However, conventional purification techniques cannot purify this biobased AA owing to its impurity profile and the significant content of propionic acid (PA). The liquid–-solid phase diagram of the binary AA + PA shows that acrylic acid crystallizes ais a pure form from melts containing between 50 and 100% (mol/mol) of AA. Thus, a new falling film melt crystallization device has been developed and tested in which: – supercooling is limited by the use of a crystallization surface made of 316L stainless steel, – melt is thermostated, – visual observation of the crystal layer is possible, and – morphology of the crystal layer limits the retention of impure liquid. Purification tests in this falling film device show that AA is separated from the PA in reduced crystallization cycle times and high crystallization yields

Intensification of falling film melt crystallization process through micro and milli-structured surfaces

International audienceThis paper shows how falling film melt crystallization process can be intensified by using micro/ milli-structured surfaces. This work takes part in the development of purification techniques of bio-acrylic acid. The current acrylic acid synthesis is based on propylene, a petroleum derivative. Thus, a new production route of a bio-acrylic acid is developed, based on glycerol, a green by-product of oleochemistry and biofuel industry. However, the impurity profile of this bio-AA differs from that of propylene-based: crude bio-AA contains much more propionic acid (PA). Classical purification techniques do not allow the separation of these two chemicals whose structures are similar. [1] showed that falling film melt crystallization halves propionic acid contents in purified AA with yields reaching 60% and purification time less than five hours. Increasing the exchange surface between the cold surface and the melt to purify can improve heat transfer, decrease purification time and intensify melt crystallization process. Thus, micro/milli-structured crystallization surfaces have been designed and tested. Results show that these innovative surfaces can increase productivity by 84%. Heat transfer has been modeled during the crystallization process, and it clearly appears that thermal gradient is divided by ten with milli-structured surface compared to smooth surface.