Fast pyrolysis bio‐oils possess unfavorable physicochemical properties and poor stability, in large part, owing to the presence of carboxylic acids, which hinders their use as biofuels. Catalytic esterification offers an atom‐ and energy‐efficient route to upgrade pyrolysis bio‐oils. Propyl sulfonic acid (PrSO3H) silicas are active for carboxylic acid esterification but suffer mass‐transport limitations for bulky substrates. The incorporation of macropores (200 nm) enhances the activity of mesoporous SBA‐15 architectures (post‐functionalized by hydrothermal saline‐promoted grafting) for the esterification of linear carboxylic acids, with the magnitude of the turnover frequency (TOF) enhancement increasing with carboxylic acid chain length from 5 % (C3) to 110 % (C12). Macroporous–mesoporous PrSO3H/SBA‐15 also provides a two‐fold TOF enhancement over its mesoporous analogue for the esterification of a real, thermal fast‐pyrolysis bio‐oil derived from woodchips. The total acid number was reduced by 57 %, as determined by GC×GC–time‐of‐flight mass spectrometry (GC×GC–ToFMS), which indicated ester and ether formation accompanying the loss of acid, phenolic, aldehyde, and ketone components.

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A study of the production of fatty acid methyl and ethyl esters (FAMEs and FAEEs) to be used as biodiesel was carried with Nannochloropsis gaditana oil using three fungal lipases (from Thermomyces lanuginosus, Candida antarctica B and Mucor miehei) both free and immobilized in hexagonal (SBA-15 and MCM-41) and cubic (FDU-12 and SBA-16) mesoporous supports. The operating variables were optimized using free lipase (ethanol, 40°C, 24 h, 500:1 oil:lipase mass ratio and 8:1 ethanol:oil mass ratio).Higher FAEE yields were obtained with supported lipase than with free lipase due to the protection and stability given by the supports. The FAEE yields achieved were higher for lipase immobilized in hexagonal mesostructured materials since lipase molecules are more accessible than lipase immobilized in the three dimensional cubic supports. C. antarctica lipase B immobilized in functionalized SBA-15 showed the better performance and reusability among the biocatalysts used.

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Biomass from oleaginous microorganisms is an attractive source of materials used for the production of renewable fuels and industrial products due to its high productivity and the fact that it does not compete with human food. To ensure the economic feasibility and environmental sustainability of microbial biomass as feedstock, it is necessary to integrate its production and processing into the biorefinery concept. To achieve this goal, biodiesel production and fractionation of the whole biomass into different types of compounds (lipids, proteins, etc.) and further processing of each fraction must be performed. In the present work, the use of a microbial biomass source, the microalga Nannochloropsis gaditana, has been assessed as potential biorefinery feedstock.

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Quaternary ammonium surfactants with the hydrotris(1-pyrazolyl)borate anion as an unusual counterion were prepared and characterized. Dodecyl- (1a), tetradecyl- (1b), and hexadecyltrimethylammonium hydrotris(1-pyrazolyl)borate (1c), as well as didodecyldimethylammonium hydrotris(1-pyrazolyl)borate (2), were prepared by metathesis reactions with the corresponding quaternary ammonium bromides and potassium hydrotris(1-pyrazolyl)borate (4). Although the surfactants have limited stabilities in water at 23 degrees C, they were characterized by measurement of their Krafft temperatures and critical aggregation concentrations. (1)H NMR spectroscopy suggested that the single-chain surfactants 1 form small aggregates in water and revealed an association of the quaternary ammonium and hydrotris(1-pyrazolyl)borate ions above their critical aggregation concentrations. Cryo-etch high-resolution scanning electron microscopy indicated that 1a and 1b most likely form segregation patterns upon plunge-freezing and cryo-etching of their aqueous solutions, and a single-crystal X-ray diffraction study of 1a was performed.