Green cosmetics via bio-oil

The refining of crude vegetable oil results in an unused sidestream, the oil deodorizer distillate (ODD). Thisdistillate contains valuable ‘minors’, like squalene, tocopherols and sterols, which have applications in thecosmetic, pharmaceutical and nutrition industry. Therefore, their successful separation from this sidestream increases the viability of a refinery. The separation is achieved by supercritical esterification and supercritical CO2 extraction. The objective of this study is to simulate the process with Aspen® and model the kinetics with AVS®. Different ODD are investigated with HT soybean giving the highest yield. Additionally, an economic analysis is performed to estimate the process profitability

A combined modeling and experimental study on low- and high-temperature oxidation chemistry of OME3 as novel fuel additive

International audienceThe present research focuses on combined modeling and experimental work on the com-bustion of oxymethylene ethers (OMEs). OMEs are promising synthetic fuels which can beproduced in a carbon-neutral manner starting from captured CO2 and renewable energy.Moreover, blending them with conventional diesel reduces soot emissions because of the ab-sence of carbon-carbon bonds. This results in less harmful emissions and contributes to amore sustainable transport sector as aimed by the Paris climate agreement objectives. Topromote the use of these kind of molecules as fuel additive, it is important to understand theirlow- and high-temperature combustion kinetics. The development of detailed microkineticmodels provides this fundamental insight and enables predictive simulations for combustionapplications.During the last decade, great progress has been made in the construction of reliable kineticmodels for numerous technologically important radical chemistry processes. The resultingmodels typically contain hundreds of species, and several thousands of associated reactions.The manual generation of microkinetic models would be a tedious, error prone and oftenincomplete process. To prevent this, automatic kinetic model generation routines have beendeveloped to systematically develop models, such as Genesys at the Laboratory for Chemi-cal Technology (Ghent University). A kinetic model for both oxidation and pyrolysis hasbeen developed for OME3 based on first principles using Genesys.A prerequisite for the generation of detailed kinetic models is the availability of accuratethermodynamic and kinetic data for species and reactions respectively. Ideally, these pa-rameters are available from experiments or high-level quantum chemical calculations. Sincethese methods are expensive and time-consuming, Genesys instead often relies on approxi-mation methods such as group additivity and rate rules. In this work, thermodynamic andkinetic parameters are obtained from quantum chemical calculations at the CBS-QB3 levelof theory for important reaction pathways for both low- and high- temperature oxidation ofOME3. The results of these calculations are extrapolated to be valid for long-chain OMEsby regression of new group additive values and rate rules.Within Genesys, the possible reactions are generally defined in terms of reaction families,e.g. hydrogen abstraction by molecular oxygen from a secondary carbon atom. Reactionfamilies from earlier studies on smaller oxymethylene ethers such as dimethoxy methaneare taken over and applied for the OME3 model. The outcome is a model containing thechemistry for OME3. To include the chemistry of smaller (oxygenated) hydrocarbons in thefinal model, the Genesys model is merged with the AramcoMech 1.3 base model.Both at ame burner and rapid compression machine experiments have been performedwith OME3 for validation of the combustion model. The ame experiments are performedat 0.053 bara and with a fuel composition of 20 mol% OME3 and 80 mol% CH4. Some mea-sured concentration profiles in function of the height above burner (HAB) of small species(i.e. OME3, CH2O, CH3OH, H2, CO2 and CO) are shown in Figure 1. Other impor-tant species which are observed include ethane, ethylene, dimethyl ether, methyl formate,dimethoxy methane and methoxymethyl formate.Ignition delay times have been measured via rapid compression at 5 bara for and to ad-ditionally validate the low-temperature section of the model. Samples were taken to identifythe reactants and products, including OME3, methyl formate, methoxymethyl formate andmethoxymethoxymethyl formate. Similarly, pyrolysis experiments are performed for OME3in a bench-scale steam cracker setup over a broad range of temperatures (723 K - 1073 K)to validate both the primary and secondary chemistry of the pyrolysis model

Oxymethylene ethers as fossil fuel alternative to reach carbon neutrality

More than a quarter of the global greenhouse gas emissions are related to the transportation sector and, therefore, a major revamp of this sector is required to comply with the Paris Climate Agreement objectives. Our research focuses on combined modeling and experimental work on combustion of oxymethylene ethers (OMEs). These molecules form a promising family of synthetic fuels, which can be produced starting from CO2 via carbon capture and utilization technology with renewable electricity, so-called e-fuels. OMEs consist of alternating carbon and oxygen bonds in the backbone saturated with hydrogen (structural formula CH3O(CH2O)nCH3), instead of alternating carbon-carbon bonds in the case of fossil-based fuels. OMEs are compatible with the current generation of diesel engines and blending them with conventional diesel fuels reduces the soot emissions significantly because of the absence of carbon-carbon bonds. As such, OMEs and OME-diesel blends result in less harmful emissions and can contribute to a more sustainable transportation sector on the short term due to the transition towards a circular carbon economy. To promote the use of these molecules, it is important to understand their low- and high-temperature combustion chemistry. Detailed microkinetic models have been developed systematically with in-house developed automatic kinetic model generation code `Genesys' to gain fundamental insight into the decomposition chemistry. Quantum chemical calculations are performed on the HPC to unravel the OME decomposition pathways, and to obtain both accurate thermodynamic and kinetic parameters for species and reactions, respectively. New experimental data is obtained from a variety of experimental units to validate the constructed models under a broad set of conditions. Our kinetic models will enable predictive simulations to optimize the combustion and allow global deployment in heavy-duty transportation for which electrification is unfeasible

The secondary chemistry of synthetic fuel oxymethylene ethers unraveled : theoretical and kinetic modeling of methoxymethyl formate and formic anhydride decomposition

Replacing fossil fuels by oxymethylene ethers (OMEs) produced from renewable resources could help to reduce the rising CO2 levels. In this work, the thermal decomposition chemistry of methoxymethyl formate (CH3O-CH2OCHO) and formic anhydride (OCHOCHO) is investigated by means of a combination of quantum chemical calculations and kinetic modeling. The latter compounds are two important intermediates formed during the thermal decomposition chemistry of synthetic fuel OMEs. Two detailed kinetic models are developed based on first principles to describe the radical decomposition chemistry of methoxymethyl formate and formic anhydride, which are ultimately incorporated into the OME-2 model from De Ras et al. (Combustion and Flame, 2022). This newly obtained kinetic model describes experimental measurements for pyrolysis from literature significantly better than the model from the original study, without any fitting of thermodynamic or kinetic parameters. More particularly, some minor compounds are now satisfactorily reproduced within the experimental uncertainty margin of 10 mol% relative. Methoxymethyl formate and formic anhydride are found to be more reactive compared to OMEs. Both a reaction pathway analysis and sensitivity analysis reveal the important decomposition pathways under pyrolysis conditions

Automatic kinetic model generation : a novel modelling approach for liquid-phase processes

Current societal trends push for innovation and optimization of existing large-scale processes in the pursuit of a sustainable chemical industry. In the last decade, a substantial amount of progress has been made for predictive first principles-based models for numerous gas-phase processes. This is in contrast to the liquid phase, for which the construction of such detailed models has proven to be more challenging. As a case study, the liquid-phase oxidation of cyclohexane to cyclohexanol and cyclohexanone is investigated since it is an industrially relevant process to produce nylon-6 and nylon- 6,6. A new program is developed to aid liquid-phase model development, called ALKIMO, standing for ``Automatic Liquid-phase Kinetic Modeller''. The purpose is to transform a gas-phase kinetic model into a liquid- phase model by adding additional phenomena present in the liquid phase. Two effects are considered, the (de)stabilizing effect of dissolution and the diffusional limitations present in condensed phases. The effect of dissolution is modelled using the Gibbs free energy of solvation. This is calculated using the Volume- Translated Peng-Robinson Equation of State, which can be calculated using available group contribution methods. The predicted solvation energies in cyclohexane are compared with the experimental results of the CompSol database, resulting in a root mean square deviation of 1.23 kJ/mol. Diffusional limitations were also calculated based on empirical equations and group contribution methods. These proved to play a significant factor in the liquid-phase oxidation of cyclohexane as a substancial percentage (~21\%) of the reactions are diffusion limited. Bringing all these advancements together will enable to construct a new reliable microkinetic model to describe the liquid-phase oxidation of cyclohexane