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El uso de los plásticos se ha disparado en los últimos años, llegando a un potencial contaminante que podría llegar a ser aún más peligroso para un futuro cercano. La creación de este bioplástico es una de las varias propuestas con las que se quiere llegar a sustituir al plástico convencional. Formado por ingredientes naturales, se plantea como objetivo principal que obtenga algunas de sus propiedades, llegando a poder tener una aplicación real en algunos ámbitos, como en el envasado de productos.

Context and objectivesLight olefins (C2–C4) are key building-block chemicals mostly produced either by steam cracking or fluid catalytic cracking of oil resources, two highly energy-consuming processes. Among alternative processes, the syngas via methanol to olefins (SMTO) and the OX-ZEO single step processes are very promising since very high selectivity to light olefins can be reached. They combine one hydrogenating catalyst to synthesize either methanol or ketene and one acidic zeotype to convert the intermediate into light olefins. In both cases, the intermediate has to diffuse from the first catalyst to the other and their intimacy can significantly influence the catalytic performances.In this work, Cu/ZnO/Al2O3 or MnOx was used as hydrogenating catalyst and SAPO-34 as acidic zeotype The role of intimacy has been investigated by modulating the density of contact between the two functions in different bed arrangements and the distance through preparing MnO@SiO2 core shell structures or diluting the two catalysts in SiO2.Material and methodsCu/ZnO/Al2O3 was commercial catalyst while MnOx and MnOx@SiO2 were prepared from MnCO3 powder or monodispersed suspension by different routes. SAPO-34 powders with different acidities were prepared by hydrothermal method. The catalysts were characterized before and after reaction by various techniques, including ICP/XRF, BET, H2 and CO-TPR, NH3-TPD, XRD, SEM, STEM-HAADF, NMR as well as by in situ DRIFT and Raman spectroscopies. Catalytic performances were compared using a fixed-bed reactor with a feed H2/CO/N2:62/23/15 at 390-450 °C and 25 bar.Main resultsFor both catalytic systems, methanol was shown to be a key intermediate from catalytic data and from the in situ DRIFT observation and evolutions of formates (Fig. 1a) which are formed before methoxy species. The two catalytic systems were active and selective (>50%) to C2-C4 hydrocarbons with a low Olefin/Paraffin (O/P) ratio (

The main compounds present in the HTL micro-algal bio-oil were C16 and C18 carboxylic acids from triglycerides hydrolysis. Fatty amides, and cyclic aromatics nitrogen and oxygen compounds formed from the decomposition of carbohydrates and proteins were also found. The N and O content were, respectively 2.6 wt. % and 11.7 wt. %.The experiment performed with nickel phosphide showed the same conversion as an experiment without catalyst, indicating that, even though phosphides have been reported in the literature as a potential candidate to replace sulfide catalysts, more advances should be done to increase the activity of this active phase.However, the sulfide and nitride catalysts permitted to reduce the number of contaminants and improved the quality of bio-oil. The main compounds formed after the upgrading step were C15, C16, C17, and C18 from carboxylic acids hydrogenation (HDO) or decarboxylation/decarbonylation (DCO). More than 60% of upgraded bio-oil eluted on the diesel range, which corroborates the potential of microalgae as a feedstock for biofuel production. The degree of deoxygenation and denitrogenation were, respectively, 91% and 67% for sulfide catalyst, 93% and 46% for nitride catalyst, and 84% and 6% for phosphide. Therefore, NiWS/Al2O3 had a higher hydrodenitrogenation (HDN) ability than NiMoN and Ni2P/Al2O3 catalysts. GCxGC-MS/FID analysis revealed that fatty amides were first converted into nitriles and then in alkanes. The experiments performed over Ni2P/Al2O3 and without catalyst showed a family of nitriles that are completely converted with nitride and sulfide systems. Besides, it was also observed that NiWS/Al2O3 converted more cyclic nitrogen compounds, such as, pyrroles, indoles, and carbazoles than NiMoN which is associated with a higher hydrogenation ability of this catalyst, since these nitrogen molecules should be hydrogenated before the HDN reaction. These results were also corroborated by GPC-DAD analyses which indicate a lower absorbance for the upgraded bio-oil over sulfide catalyst which is associated with a lower degree of aromaticity of this sample.The HHV increased from 36 MJ/kg in the HTL micro–algal bio-oil to 47 MJ/kg in the upgraded bio-oil over sulfide catalyst, and the average molar mass reduced from 363 to 265 g/mol indicating that heavy molecules were converted during the upgrading step.

Microalgae seem to be a potential raw material for third-generation fuel production due to their high growth rate, the potential for CO2 fixation, and high lipids content which can provide a high biofuel yield. Hydrothermal liquefaction (HTL) is a thermochemical process that has been used for the conversion of microalgae in bio-oil. However, the HTL micro-algal bio-oil contains a high amount of heteroatoms such as N, O, and sometimes S which causes harmful emissions upon combustion and also reduced the quality of the fuel. Therefore, an upgrading step is required before the commercialization of this kind of biofuel to reach transportation fuel specifications. Being part of the Rafbioalg project (ANR-18-CE43-0009) that explores the production of biofuel from algae growth until fuel combustion with a LCA analysis of the all value chain, we investigated the catalytic upgrading step of the HTL algal oils. The whole algae, Chlorella Sorokiniana grew at CEA Cadarache, was converted to a bio-oil using a continuous reactor at 300 °C, under 10 MPa for 15 min at Liten laboratory in CEA Grenoble. The bio-oil was upgraded using a batch reactor at 375 °C under 10 MPa (H2), over NiWS/Al2O3, NiMoN, and Ni2P/Al2O3. The nitride and phosphide catalysts were prepared using a methodology described in the literature. The produced HTL and HDT oils were characterized by CHONS, XRF, ICP-OES, GPC–RID/DAD, 13C-NMR, SIMDIS, and GCxGC-MS/FID. The hydroconversion experiments performed with nickel phosphide showed the same conversion as an experiment without catalyst, indicating that, even though Ni phosphides have been reported in the literature as good candidate to replace sulfide catalysts, this active phase is not efficient for algal oil. However, the W sulfide and Mo nitride catalysts permitted to reduce O, N and S content and thus improved the quality of bio-oil. The main compounds formed after the upgrading step were C15, C16, C17, and C18 from carboxylic acids hydrogenation (HDO) or decarboxylation/decarbonylation (DCO). More than 60 wt% of upgraded bio-oil eluted on the diesel range, which corroborates fully the potential of microalgae as a feedstock for biofuel production. The degree of deoxygenation and denitrogenation were, respectively, 91% and 67% for sulfide catalyst, 93% and 46% for nitride catalyst, and 84% and 6% for phosphide. Therefore, NiWS/Al2O3 had a higher hydrodenitrogenation (HDN) ability than NiMoN and Ni2P/Al2O3 catalysts. GCxGC-MS/FID analysis revealed that fatty amides were first converted into nitriles and then in alkanes. The experiments performed over Ni2P/Al2O3 and without catalyst showed a family of nitriles that are completely converted with nitride and sulfide systems. Besides, it was also observed that NiWS/Al2O3 converted more cyclic nitrogen compounds, such as, pyrroles, indoles, and carbazoles than NiMoN which is associated with a higher hydrogenation ability of this catalyst, since these nitrogen molecules should be hydrogenated before the HDN reaction. The HHV increased from 36 MJ/kg in the HTL micro–algal bio-oil to 47 MJ/kg in the upgraded bio-oil over sulfide catalyst, and the average molar mass reduced from 363 to 265 g/mol indicating that heavy molecules were converted during the upgrading step.