Hydrothermal conversion of micro-algae as new biomaterials for pavement

Bitumen is a non-renewable petroleum-derived product whose market is under pressure due to the fossil fuel depletion and the environmental pollution concerns. It is therefore important to anticipate the replacement of this material, heavy fraction of petroleum distillation, used mostly in road construction as a matrix of an aggregate composite material. In that context, it is necessary to look for alternatives or substitution products and find processes that can valorize new renewable biomasses. Please click Additional Files below to see the full abstract

Development and characterization of bio-binder as an alternative to petroleum bitumen, produced from microalgae residues

L’objectif de ce travail consiste à produire un liant alternatif au bitume pétrolier à partir d’une biomasse renouvelable à fort potentiel : les résidus de microalgues. Le procédé de transformation chimique choisi est la liquéfaction hydrothermale (HTL). La première étape de cette étude avait pour but comprendre, d’une façon approfondie, la relation entre la composition chimique d’un bitume pétrolier conventionnel et ses propriétés physiques et rhéologiques. Pour ce faire, une procédure de fractionnement du bitume a été mise en place. Les quatre fractions ainsi obtenues ont été caractérisées et leur rôle dans le comportement thermo-rhéologique a été clairement identifié. En particulier, les fractions cristallisables et les agrégats d'asphaltènes semblent agir comme des structures moléculaires clés au sein de la phase huileuse continue. La deuxième partie du travail consistait à produire des bioliants à partir de la transformation de résidus de Spiruline sp., par HTL et en réacteur batch et à les caractériser. Les résultats ont montré que la température de liquéfaction et le taux de chargement du réacteur ont une influence directe sur les propriétés physicochimiques et rhéologiques des biobitumes alors que l’ajout d’un catalyseur lors de la HTL a très peu d’impact. L’influence de la nature de biomasse a été également étudiée: le comportement rhéologique du bioliant issu de Scenedesmus sp. se rapproche de celui d’un bitume standard alors que celui d’un bioliant issu de la Spiruline sp. est similaire à celui d’un liant fortement chargé en élastomères.The aim of this work is to produce an alternative road binder from a renewable biomass with high potential: microalgae residues. The chosen thermochemical transformation process is hydrothermal liquefaction (HTL). First, this requires a deep understanding of the chemical composition of standard bitumen and its physical properties, especially rheological ones. In that regard, a fractionation procedure on a petroleum bitumen has been developed. The four fractions obtained were characterized and their thermo-rheological behavior was clearly identified. In particular, crystallizable fractions and asphaltene aggregates seemed to act as key molecular structures in the continuous phase. The second part of the work consisted in producing biobinders from the HtL transformation of Spirulina sp. residues, in a batch reactor and then to study their chemical composition and their rheological properties. The results showed that the temperature and reactor loading during HTL have a direct influence on the physicochemical and rheological properties of biobinders whereas the use of a catalyst during the HTL process has little impact. The influence of the feed stock was also studied: the biobinder obtained from Scenedesmus sp. showed rheological properties similar to a petroleum-based bitumen while the biobinder obtained from Spirulina sp. presented a viscoelastic behavior similar to a bio-sourced binder loa

Synthesis of supported ZSM-5 nanoparticles

International audienceThe influence of the support on the nucleation of ZSM-5 nanoparticles has been studied for three supports: γ-alumina, zirconia and carbon nanotubes (CNT). While zeolite nucleation was suppressed in presence of alumina and strongly delayed in presence of zirconia, it occurred without delay in presence of CNT. These differences are explained by the partial dissolution of the support (for alumina and zirconia supports) that modify the composition of the zeolite nucleation solution. For the CNT/zeolite sample, the obtained composite contains about 60 wt% of zeolite and develops a surface area of 776 m 2 .g-1