• Energy Research

Abstract Carbon dioxide sequestration was studied by synthesizing diethyl carbonate (DEC) from ethanol and CO2 under supercritical conditions in the presence of potassium carbonate as a base. The co-reagent was ethyl iodide or a concentrated strong acid. This sequestration reaction occurs in two steps, which were studied separately and in a one-pot reaction. An organic–inorganic carbonate hybrid, potassium ethyl carbonate (PEC) is generated at the end of the first step. This intermediate was characterized and was found to be a target molecule for CO2 capture. Different co-reactants, such as ethyl iodide and concentrated strong Bronsted acid, were compared in the second step and used to investigate the reactivity of the hybrid. With ethyl iodide as the co-reactant, one-pot DEC synthesis gave higher yields (46%) than two-step production. The supercritical CO2 acts as a swelling solvent and compatibilizing agent in the reaction medium, favoring interactions between ethanol and CO2 and between PEC and ethyl iodide. The use of a phase transfer catalyst (PTC) increased DEC production (yield 51%) without increasing the amount of diethyl ether (DEE) produced as a by-product (yield 2%).

Abstract Procedures and operating conditions optimized in laboratory scale for the production of ethyl biodiesels from non-edible vegetable oils (NEVOs) were successfully transferred at pilot scale, with implementation of separation and purification stages. The three NEVOs candidates are Balanites aegyptiaca (BA), Azadirachta indica (AI), and Jatropha curcas (JC), converted into BAEEs, AIEEs and JCEEs respectively via homogeneous catalysis. Quality specifications of the produced biofuels were used to explain pollutant emissions and engine performance observed via a power generator. Under the same conditions, blends of petrodiesel with crude BA or JC oil (50 wt.%) were also investigated. The selected overall methodology “feedstock-conversion-engine” led to the proposal of a sustainable alternative fuel. The candidate NEVO is BA oil to which the proposed alkali route should lead to a low cost biodiesel production process thanks to easy operating conditions, associated with a two-stage procedure (glycerol recycling) and a dry-purification method (rice husk ashes). Glycerol addition should be carried out at ambient temperature to play positively at phenomena occurring in the reacting medium (chemical kinetics, chemical equilibrium, phase equilibrium). Tests on power generator demonstrated that BAEEs led to cleaner combustion than petrodiesel, particularly for the most harmful emissions (light carbonyls and ultrafine particulate matter).

AbstractThe substitution of conventional solvents, in line with regulation changes, requires the use of appropriate methodologies able to generate candidate molecules. Starting from the widely used trial and error approach, we developed two improved, time‐ and cost‐saving methodologies, involving the prediction of molecule properties and reverse design. Reverse design is an innovative methodology to design biosolvents through a virtual laboratory: stages of generation of molecular structures and properties prediction are integrated into a computer‐aided molecular design tool providing solutions that meet targeted specifications. These two substitution methodologies were applied in a case study aiming at replacing acetone and methyl ethyl ketone for the solubilization of epoxy resin prepolymers. The generation of performing biosolvents was carried out from furfural as a bio‐based platform molecule, thanks to the prediction of different relevant properties (physico‐chemical, safety, and environmental characteristics). The reverse design succeeded in ranking these solvent candidates according to their capacity to match the required specifications.

Many analytical procedures have been developed to determine the composition of reaction mixtures during transesterification of vegetable oils with alcohols. However, despite their accuracy, these methods are time consuming and cannot be easily used for on-line monitoring. In this work, a fast analytical method was developed to on-line monitor the transesterification reaction of high oleic sunflower oil with ethanol using Near InfraRed spectroscopy and a multivariate approach. The reactions were monitored through sequential scans of the reaction medium with a probe in a one-liter batch reactor without collecting and preparing samples. To calibrate the NIR analytical method, gas chromatography-flame ionization detection was used as a reference method. The method was validated by studying the kinetics of the EtONa-catalyzed transesterification reaction. Activation energy (51.0 kJ/mol) was also determined by considering a pseudo second order kinetics model.

Biodiesel can be produced from vegetable oils, animal fats, and waste cooking oils by transesterification with ethanol (also called ethanolysis) in order to substitute fossil fuels. In this work, the batch ethanolysis of high oleic sunflower oil was transferred into a continuous microstructured device, which induces a better control of heat and mass transfers. Various parameters were studied, notably the initial ethanol to oil molar ratio. An innovative method using NIR spectroscopy was also developed to on-line monitor the transesterification reaction of high oleic sunflower oil with ethanol in microreactors (circular PFA tube 1/1600 OD, 0.0200 ID). The reactions were monitored directly in the microreactors through sequential scans of the reaction medium by the means of an adequate probe. The asset of the method is that no sample collection or preparation is necessary. Partial Least Squares regression was used to develop calibration and prediction models between NIR spectral data and analytical data obtained by a reference method (gas chromatography with flame ionization detection, GC–FID). This method is fast, safe, reliable, nondestructive and inexpensive contrary to conventional procedures, such as gas chromatography and high performance liquid chromatography generally used to determine the composition of crude transesterification medium.

In a context of dwindling oil reserves and environmental pressures, the chemical industry needs to innovate by developing new processes for producing bioproducts from raw plant materials. Unsaturated fatty acids from vegetable oils constitute a highly promising renewable resource that can be used to diversify productions, decreasing reliance on petroleum. A starting material rich in oleic acid has been obtained through the selection of high-oleic sunflower varieties and enzymatic hydrolysis of the oil they produce. The double bonds of this unsaturated raw material have been cleaved in green oxidizing conditions involving a biphasic lipophilic-aqueous system including hydrogen peroxide as an oxidant and a peroxo-tungsten complex Q3 {PO2[WO(O2)2]4} as a phase-transfer catalyst (PTC) and co-oxidant. This PTC efficiently transferred oxygen to the substrate in the lipophilic phase. A mono-acid (pelargonic acid) and a di-acid (azelaic acid), with shorter, unusual hydrocarbon chains not present in the natural state, were synthesized and purified through an intensive process. Pelargonic acid was then formulated as an environmentally friendly biocontrol agent for weeds. We extended this green process of oxidative scission to other fatty acids and derivatives, to obtain other short-chain acids with diverse potential applications. This production chain (crops, reaction and purification processes, products, applications) is based on a sustainable development strategy.