Laboratoire de Sécurité des Procédés Chimiques

The epoxidized group, also known as the oxirane group, can be considered as one of the most crucial rings in chemistry. Due to the high ring strain and the polarization of the C–O bond in this three-membered ring, several reactions can be carried out. One can see such a functional group as a crucial intermediate in fuels, polymers, materials, fine chemistry, etc. Literature covering the topic of epoxidation, including the catalytic aspect, is vast. No review articles have been written on the catalytic synthesis of short size, intermediate and macro-molecules to the best of our knowledge. To fill this gap, this manuscript reviews the main catalytic findings for the production of ethylene and propylene oxides, epichlorohydrin and epoxidized vegetable oil. We have selected these three epoxidized molecules because they are the most studied and produced. The following catalytic systems will be considered: homogeneous, heterogeneous and enzymatic catalysis.

Abstract Production of epoxidized vegetable oils becomes more and more important because they are renewable, nontoxic, and biodegradable chemicals. At the industrial scale, the Prileschajew oxidation is used to produce epoxidized vegetable oils from the corresponding vegetable oils. This oxidation uses an oxygen carrier, which is a percarboxylic acid produced in situ in the aqueous phase, to epoxidize the unsaturated groups on the vegetable oils. One of the main drawbacks of this method is the presence of side reactions: ring‐opening reactions of the epoxide group. To minimize the ring‐opening reactions and to find the most suitable reactor configuration, it is essential to investigate deeply the different ring‐opening reactions. For this work, epoxidation of cottonseed oil by peracetic acid in a batch reactor was studied. By developing a suitable modeling strategy, the kinetic constants for the ring‐opening reactions by water, hydrogen peroxide and acetic and peracetic acids were estimated. It was found that ring opening by acetic and peracetic acids was faster than by water and hydrogen peroxide. Based on this model, it was found that a semibatch reactor where hydrogen peroxide and sulfuric acid were added is the most suitable configuration.

Nowadays, industrial symbiosis is a key concept of industrial ecology, which studies material and energy exchange flows in the local industrial systems to reduce the costs, e.g., the wastes treatment cost, and to reduce the pollution, e.g., greenhouse gas emissions. An industrial park is a set of manufacturing businesses producing different products and by-products located at the same place (city, region, etc.). As the concept of this model encourages the development of synergy and leverage of resource networks, to the advantage of all of the enterprises present in an industrial park, a general mathematical model has been proposed. The aims of this general model are: to maximize total quantity of exchanges flows, to maximize total economic benefice of an industrial park, and to reduce relative environmental pollution, industrial waste treatment cost and delivery cost. This model can assure a win-win situation for industries and environment. There are rigorous mathematical models for specific ecological industrial parks [1]. To the best of our knowledge, there is no currently other general mathematical model for designing and optimizing an ecological industrial park. In addition, there is no currently complete ecological industrial park in France.

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Abstract Dielectric barrier discharge (DBD) plasma technology is a promising method for producing methanol from CO 2 hydrogenation as the reaction can be run at atmospheric pressure and temperatures below 100 °C. The choice of the catalyst is crucial and has to be made not only according to its activity and selectivity towards the desired product, but its effect on plasma properties. In this work, the influence of several important catalytic properties of DBD plasma such as the dielectric constant of the catalyst and ionic conductivity is studied. The effects of the catalyst support and the addition of promoters on CO 2 hydrogenation under DBD plasma are also studied. To this end, Cu and Cu–ZnO catalysts supported on γ -Al 2 O 3 and a template-free seedless ZSM-5 (Si/Al molar ratio of 23) were prepared to study their catalytic performance on CO 2 hydrogenation into methanol under DBD plasma. These catalysts were fully characterized by XRD, SEM, N 2 physisorption, temperature programmed reduction and in situ FTIR CO adsorption. The relative complex permittivity of the catalysts was measured and the ionic conductivity was estimated using a modified Debye model. In this paper, the role of the ionic conductivity of the catalyst was identified as a crucial parameter in plasma-assisted CO 2 hydrogenation. It was found that the lower the value of the ionic conductivity, the better the CO 2 conversion. Indeed, high ionic conductivity reduces the density of the plasma and decreases the dissociation of CO 2 . The highest CO 2 conversion value (34.0%) was observed for the nonconductive alumina support, whereas the highest methanol yield (0.5%) was observed for the zeolite-supported Cu–ZnO catalyst.

Microwave energy is used in zeolite sorption process intensification and more specifically in the desorption step. To optimize a microwave process, the knowledge of dielectric properties of the used materials is required. The complex permittivities of several zeolites (NaA, NaK-LSX, NaX, NaY, and DAYs) were measured and interpreted using phenomenological models. Permittivities are linked to the various properties of the zeolites such as structures (LTA and FAU), number of exchangeable cations, silanols density, and hydration level. Three phenomena have been proven to occur: two relaxation processes and one ionic conductivity contribution. Rotational polarization of water molecules adsorbed is revealed, as well as interfacial polarization of charges in intercrystalline void and orientational polarization of water molecules adsorbed on hydroxyl sites. Water loading strongly affects the charge carriers mobility and improves the conductivity phenomenon observed for low and intermediate silica zeolites. Cation location is also of main importance in the involved mechanisms.

This article describes a kinetic study of the perhydrolysis of propionic acid with sulfuric acid at various molar reactant ratios (PA-H2O2 from 0.4 to 2.05), reaction temperatures (from 30 to 60 °C), and catalyst concentrations (from 0 to 1.41 M). The influence of water and acidic catalysts were taken into account to develop a suitable kinetic model. The system is nonideal, mainly due to the presence of the strong electrolyte (i.e., H2SO4), and a parameter was introduced to describe the nonideality. The kinetic and thermodynamic parameters determined by nonlinear regression analysis were statistically well identified. The standard enthalpy change of reaction was estimated to −4.17 kJ·mol-1, and the activation energy of the reaction was estimated to 44.2 kJ·mol-1.

Biomass can be converted into energy/fuel by different techniques, such as pyrolysis, gasification, and others. In the case of pyrolysis, biomass can be converted into a crude bio-oil around 50-75% yield. However, the direct use of this crude bio-oil is impractical due to its high content of oxygenated compounds, which provide inferior properties compared to those of fossil-derived bio-oil, such as petroleum. Consequently, bio-oil needs to be upgraded by physical processes (filtration, emulsification, among others) and/or chemical processes (esterification, cracking, hydrodeoxygenation, among others). In contrast, hydrodeoxygenation (HDO) can effectively increase the calorific value and improve the acidity and viscosity of bio-oils through reaction pathways such as cracking, decarbonylation, decarboxylation, hydrocracking, hydrodeoxygenation, and hydrogenation, where catalysts play a crucial role. This article first focuses on the general aspects of biomass, subsequent bio-oil production, its properties, and the various methods of upgrading pyrolytic bio-oil to improve its calorific value, pH, viscosity, degree of deoxygenation (DOD), and other attributes. Secondly, particular emphasis is placed on the process of converting model molecules and bio-oil via HDO using catalysts based on nickel and nickel combined with other active elements. Through these phases, readers can gain a deeper understanding of the HDO process and the reaction mechanisms involved. Finally, the different equipment used to obtain an improved HDO product from bio-oil is discussed, providing valuable insights for the practical application of this reaction in pyrolysis bio-oil production.

Biomass valorization processes are being used more frequently in industry. These processes are greener because they use some renewable and biodegradable raw materials, but are they safer? We propose to study the thermal stability of different epoxidized and carbonated vegetable oils. The severity of the thermal risk, i.e., adiabatic temperature rise, was determined by using differential scanning calorimetry tools. The probability of the thermal risk, i.e., time-to-maximum rate under adiabatic conditions, was determined by using an accelerating rate calorimeter. By analyzing these safety criteria, we have found that the thermal risk, essentially during storage and reactor loading, can be assumed to be negligible.

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Thermogravimetric analysis was employed to investigate the combustion characteristics of flax shives, beech wood, hemicellulose, cellulose, lignin, and their chars. The chars were prepared from raw materials in a fixed-bed reactor at 850 °C. In this study, the thermal behavior based on characteristic temperatures (ignition, maximum, and final temperatures), burnout time and maximum rate was investigated. The kinetic parameters for the combustion of different materials were determined based on the Coats-Redfern approach. The results of our study revealed that the combustion of pure pseudo-components behaved differently from that of biomass. Indeed, principal component analysis showed that the thermal behavior of both biomasses was generally similar to that of pure hemicellulose. However, pure cellulose and lignin showed different behaviors compared to flax shives, beech wood, and hemicellulose. Hemicellulose and cellulose chars had almost the same behaviors, while being different from biomass and lignin chars. Despite the difference between flax shives and beech wood, they showed almost the same thermal characteristics and apparent activation energies. Also, the combustion of the hemicellulose and cellulose chars showed that they have almost the same structure. Their overall thermal and kinetic behavior remained between that of biomass and lignin.

Cyclic carbonates are important platform molecules with relevant industrial applications such as polymers precursors, fuel additives and solvents. They can be obtained from epoxidized vegetable oils via a carbonation reaction with carbon dioxide. This process is typically performed using homogenous catalyst or co-catalyzed systems, requiring of a homogenous specie. At the present moment very little have been reported regarding fully heterogeneous catalysts applied to the carbonation of epoxidized vegetable oils. In this study, the carbonation of epoxidized methyl oleate was investigated with various heterogeneous catalysts. Diverse nucleophilic organic salts were supported on silica gel and SBA-15 and screened as single component heterogeneous catalysts for the carbonation of epoxidized methyl oleate as a model compound of vegetable oils. The effect of some textural features of the catalytic materials such as the average pore size and surface area were investigated. An improved catalytic performance was observed as the catalytic species were supported on a mesoporous material. The addition of weak Lewis acidity to the support was found to play an important role in the opening of the oxirane ring and its further conversion to a cyclic carbonate, by providing a source of hydrogen bond donor (HBD) to activate the oxirane ring. The methyl esters of oleic acid, tall oil and cottonseed oil were investigated as substrates. A plausible reaction mechanism was proposed.

Biochar, an organic, porous, and carbon-rich material originating from biomass via pyrolysis, showcases compelling attributes and intrinsic performances. Its appeal as a reinforcement material for biocomposites, as well as its auspicious electrical properties, has gained more attention, and makes biochar a versatile candidate for applications ranging from energy storage to catalytic devices. This scientific review undertakes a comprehensive exploration of biochar, spanning production methodologies, physicochemical intricacies, and critical process parameters. The focus of this paper extends to optimization strategies for biochar properties tailored to specific applications, with a dedicated inquiry into diverse production methods and activation strategies. This review’s second phase delves into a meticulous analysis of key properties within biochar-based composites, emphasizing limitations and unique performance characteristics crucial for diverse applications. By synthesizing a substantial body of research, this review aims to catalyze future investigations by pinpointing areas that demand attention in upcoming experiments, ultimately emphasizing the profound potential of biochar-based materials across technical and scientific domains.

Oxidized starch is important for paper coating because of its good mechanical and sizing properties. Traditionally, starch oxidation is performed by different heavy metals as catalysts and chlorites or chlorines as oxidizing agents. In this study, an environmentally friendly method was developed, utilizing iron tetrasulfophthalocyanine as a catalyst only in small amounts and hydrogen peroxide as a clean oxidant. It has been previously shown that the method works well, but analysis of the kinetic data as well as catalyst deactivation was difficult because of the semibatch operation mode. In this study, hydrogen peroxide was employed in a batch mode, allowing more simple analysis methods for determining the degree of substitution, starch degradation, and hydrogen peroxide decomposition kinetics. Additionally, the effect of adding the catalyst continuously into the solution, as well as the influence of ultrasound treatment on starch prior to oxidation, was studied. The batch-mode results showed DSCOOH = 0.73 for 100 anhydroglucose units at 52 °C and pH 10, whereas adding the catalyst continuously increased DSCOOH to 1.62. An increased DSCOOH was obtained with the ultrasound-treated starch, which shows that ultrasound is a promising method for enhancing the reaction performance.

Comprehensive gas chromatography (GC) has emerged in recent years as the technique of choice for the analysis of volatile and semivolatile compounds in complex matrices. Coupling it with high-resolution mass spectrometry (MS) makes a powerful tool for identification and quantification of organic compounds. The results obtained in this study showed a significant improvement by using GC×GC-EI-MS in comparison with GC-EI-MS; the separation of chromatogram peaks was highly improved, which facilitated detection and identification. However, the limitation of Orbitrap mass analyzer compared with time-of-flight analyzer is the data acquisition rate; the frequency average was about 25 Hz at a mass resolving power of 15.000, which is barely sufficient for the proper reconstruction of the narrowest chromatographic peaks. On the other hand, the different spectra obtained in this study showed an average mass accuracy of about 1 ppm. Within this average mass accuracy, some reasonable elemental compositions can be proposed and combined with characteristic fragment ions, and the molecules can be identified with precision. At a mass resolving power of 7.500, the scan rate reaches 43 Hz and the GC×GC-MS peaks can be represented by more than 10 data points, which should be sufficient for quantification. The GC×GC-MS was also applied to analyze a cellulose bio-oil sample. Following this, a highly resolved chromatogram was obtained, allowing EI mass spectra containing molecular and fragment ions of many distinct molecules present in the sample to be identified.

This paper presents an experimental study on zeolite NaX dehydration under microwave irradiation at a laboratory scale. Dehydration rates vary linearly with the absorbed power and show no influence with the purge gas flowrate. A pulsed mode of irradiation enhances dehydration due to higher temperatures reached and improved mass transport rates. A thermal balance model is developed in order to assess the maximum temperature reached in the adsorbent bed and the use of the dissipated energy inside the solid is discussed. From these results, this paper evaluates the economic interest in a microwave regeneration process and discusses the technical feasibility at an industrial scale.

Heterogeneous catalysts are widely used in the chemical industry. Compared with homogeneous catalysts, they can be easily separated from the reaction mixture. To design and optimize an efficient and safe chemical process one needs to calculate the energy balance, implying the need for knowledge of the catalyst’s specific heat capacity. Such values are typically not reported in the literature, especially not the temperature dependence. To fill this gap in knowledge, the specific heat capacities of commonly utilized heterogeneous catalytic supports were measured at different temperatures in a Tian–Calvet calorimeter. The following materials were tested: activated carbon, aluminum oxide, amberlite IR120 (H-form), H-Beta-25, H-Beta-38, H-Y-60, H-ZSM-5-23, H-ZSM-5-280, silicon dioxide, titanium dioxide, and zeolite 13X. Polynomial expressions were successfully fitted to the experimental data.

Abstract The complexity of composition of bio‐oil from biomass makes it difficult to produce upgraded bio‐oil via hydrodeoxygenation. In this paper, acetone is thus considered as a model compound of the ketones family abundant in pyrolysis bio‐oil. Results showed that high conversion rates of acetone between 86.6% and 91.9% were observed with the use of HZSM‐5, 5% Ni 2 P/HZSM‐5, and 10% Ni2P/HZSM‐5 catalysts. In most cases, CO 2 , C 2 H 6 , C 3 H 6 , and C 3 H 8 were the dominant non‐condensable gas products. For liquid phase, the selectivity was evaluated for different catalysts relative to ethanol, acetaldehyde, and aromatic hydrocarbons. A lower temperature favoured the formation of acetaldehyde and methyl isobutyl ketone with the 5% Ni 2 P/HZSM‐5 catalyst, while higher temperatures increased the proportion of aromatic hydrocarbons. The principal influencing parameters of acetone HDO were temperature and contact time followed by reaction pressure and H 2 partial pressure. Optimal conditions give a selectivity of 49% of aromatics (benzene, toluene, and xylene) with the use of the 5% Ni 2 P/HZSM‐5 catalyst. The pathway of the main reactions of acetone HDO was also proposed. MIK and aromatic hydrocarbons were formed by a multiple step aldol condensation reaction of acetone molecules followed by further hydrogenation.

Abstract BACKGROUND For many chemical systems, it is of great importance to find a durable, active and efficient catalyst that improves the process performance. Epoxidation of oleic acid with peracetic acid (Prilezhaev oxidation) was carried out in an isothermal loop reactor in the presence of heterogeneous catalysts. The kinetic experiments conducted under microwave heating (MW) were compared with identical experiments carried out under conventional (conductive/convective) heating. Extensive screening of heterogeneous catalysts was conducted and the influence of microwave irradiation on the reaction kinetics was studied. Several ion exchange resins were screened to explore their applicability and activity in the epoxidation of oleic acid. The perhydrolysis reaction (peracetic acid formed in situ from acetic acid and H 2 O 2 ) was promoted with the use of various solid acid catalysts: Amberlite IR‐120, Amberlyst 15, Smopex®, Dowex 50x8‐100, Dowex 50x8‐50, Dowex 50x2‐100 and Nafion™. RESULTS From the selected group of catalysts, Dowex 50‐x8100 and Dowex 50x8‐50 produced the highest yield of epoxidized oil. Only minor differences in the reactant conversion and the product yield were found in the experiments carried out under microwave exposure compared to the conventionally heated experiments in the presence of several ion exchange resins. CONCLUSIONS The catalytic effect was much more prominent than the microwave effect, because the solid acid catalysts enhanced the slow step of the process, the perhydrolysis of acetic acid. The catalytic effect was very dominant and a considerable improvement of the oleic acid conversion and the epoxide yield was observed in the presence of the top‐performing catalysts. © 2019 Society of Chemical Industry

This study investigates the green synthesis of zinc oxide nanoparticles (ZnO NPs) using leaf extract as a natural reducing agent, evaluating their antimicrobial and photocatalytic properties. The nanoparticles were annealed at 320 °C and 500 °C, and the effects of leaf extract concentration and annealing temperature on their structural, morphological, and electronic properties were systematically explored. X-ray diffraction (XRD) analysis confirmed the hexagonal wurtzite structure of ZnO, with crystallite size and defect density being influenced by the concentration of the extract. Scanning electron microscopy (SEM) revealed the formation of smaller, spherical particles, with increased aggregation observed at higher extract concentrations. Fourier-transform infrared spectroscopy (FTIR) identified key functional groups, such as hydroxyl groups, C–O bonds, and metal–oxygen vibrations. UV–Vis spectroscopy showed a reduction in band gap energy and an increase in Urbach energy as the extract concentration and annealing temperature were increased. The antimicrobial activity of the ZnO NPs was evaluated against Gram-positive and Gram-negative bacteria as well as Candida albicans, demonstrating significant antibacterial efficacy. Photocatalytic degradation studies of methylene blue dye revealed a superior efficiency of up to 74% for the annealed samples, particularly at 500 °C. This research highlights the potential of green-synthesized ZnO NPs for a wide range of applications, including antimicrobial agents, water purification, and environmental catalysis. It contributes to the advancement of sustainable nanotechnology, offering promising solutions for both technological and ecological challenges.