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CO2 hydrogenation toward gaseous and liquid hydrocarbons has been experimentally studied over a Fe–K/Al2O3 catalyst in a fixed-bed reactor. At 15 bar, 300 °C, 2080 N mL/gcat/h, and H2/CO2 ratio of 3, the catalyst is able to convert CO2 to an extent of 30% and with a CO selectivity around 10%. Among hydrocarbons, linear short olefins C2–C4 are the most abundant product, but linear paraffins and alcohols are also formed and chains until 30 carbon atoms are detected. Operating parameters were varied (T between 250 and 300 °C, total pressure between 10 and 25 bar, H2/CO2 ratio between 3 and 24, and GHSV between 832 and 7059 N mL/gcat/h) in order to study their effects on the catalyst activity and selectivity. It was observed that the H2/CO2 inlet molar ratio is a very important parameter, and a large excess of H2 at the reactor inlet could lead to a significant increase of the CO2 conversion, with a minimization of the CO formation. Moreover, a semiempirical macrokinetic model for this reaction was developed. The model is able to describe with good accuracy the CO2 conversion and CO selectivity, as well as hydrocarbons distribution according to their C number and their chemical nature. The model is able to predict the experimental data within an error of 20% and with a MARR lower than 5% in the experimental domain considered.

Herein, we describe an efficient and recyclable catalytic system based on metal triflates capable of converting highly concentrated feeds of furfuryl alcohol (30−40 wt %) to alkyl levulinates in excellent yields (>90%). This constitutes a unique and important advance in the field. Indeed, the dilution of feedstocks represent one of the major bottlenecks in catalysis for the industrial deployment of biobased fuels and chemicals in our society. The impact of water in the metal triflates catalytic performances is also discussed. A comparison with a commercialized process (SFOS) shows that this catalytic route is in line with industrial requirements in terms of yield, selectivity, reactor productivity, and capacity. In particular, unprecedented space time yields up to 200 kg m −3 h −1 were obtained.

Cet article fait partie du dossier thématique ci-dessous publié dans la revue OGST, Vol. 70, n°2, et téléchargeable ici D o s s i e rOil & Gas Science and Technology -Rev. IFP Energies nouvelles, Vol. 70 (2015), No. 3, Copyright © 2015, IFP Energies nouvelles > Editorial -Towards the Laboratory of the Future for the Factory of the FutureÉditorial -Vers le laboratoire du futur pour construire l'usine du futur Abstract -By using a steric approach, it is possible to design templates matching closely with an inorganic framework. Herein, the design, synthesis and successful application of several di(azacrown ether) templates to direct the formation of EMC-1 zeolite (FAU-type) are reported. Following a high throughput experiment design, the synthesis gel composition was optimized to obtain well-crystallized materials. Taking into account their respective crystallization rates, their textural and morphological properties were comparable to their counterparts, typically structured by 15-crown-5 ether.Re´sume´-L'utilisation d'agents structuraux originaux pour la synthe`se de ze´olithe EMC-1 -En utilisant une approche « ste´rique », il est possible de concevoir des agents structurants qui s'adaptent bien a`la porosite´de la charpente mine´rale. Ici, la conception, la synthe`se et l'application re´ussie de plusieurs agents structurants de type di(aza-e´ther-couronne) pour diriger la formation de ze´olithe EMC-1 de type FAU sont reporte´s. Suite a`des synthe`ses a`haut-de´bit, la composition du gel de synthe`se a e´te´optimise´e pour obtenir des mate´riaux bien cristallise´s. Compte tenu de leurs taux de cristallisation respectifs, leurs proprie´te´s texturales et morphologiques sont comparables a`leurs homologues, ge´ne´ralement synthe´tise´s en pre´sence du 15-e´ther-couronne-5.

Liquid organic hydrogen carriers (LOHCs) are an interesting alternative for hydrogen storage as the method is based on the reversibility of hydrogenation and dehydrogenation reactions to produce liquid and safe components at room temperature. As hydrogen storage involves a large amount of hydrogen and pure compounds, the design of a three-phase reactor requires the study of gas and liquid-phase kinetics. The gas-phase hydrogenation kinetics of LOHC γ-butyrolactone/1,4-butanediol on a copper-zinc catalyst are investigated here. The experiments were performed with data, taken from the literature, in the temperature and pressure ranges 200–240 °C and 25–35 bar, respectively, for a H2/γ-butyrolactone molar ratio at the reactor inlet of about 90. The best kinetic law takes into account the thermodynamic chemical equilibrium, is based on the associative hydrogen adsorption and is able to simulate temperature and pressure effects. For this model, the confidence intervals are at most 28% for the pre-exponential factors and 4% for the activation energies. Finally, this model will be included in a larger reactor model in order to evaluate the selectivity of the reactions, which may differ depending on whether the reaction takes place in the liquid or gas phase.

The synthesis of an original compound consisting of an azacrown ether interconnected with a diazacrown ether bearing an alkyl chain is described herein. This derivative is promising for numerous applications.

Mechanistic kinetic models have been developed for the CO2 hydrogenation reaction with the aim to provide insights into the mechanism followed for the formation of CO, linear alkanes and alkenes containing up to 20 carbon atoms, and alcohols and acids containing up to six carbon atoms over an Fe–K/Al2O3 catalyst in a continuous fixed-bed reactor. On the basis of a redox mechanism for the reverse water-gas shift reaction, an alkyl mechanism to explain the chain-growth mechanism and the formation of linear hydrocarbon chains, and a CO insertion mechanism to explain the formation of oxygenate products, the kinetic rates for the compounds considered are derived according to the Langmuir–Hinshelwood–Hougen–Watson method. Two models are proposed: the first one considers the existence of only one site for the FT step, where all of the products are formed; the second model is based on the hypothesis that two different active sites exist, one for the formation of hydrocarbons and the other for the formation of oxygenates. Mathematical optimization via least-squares methods allowed estimation of the kinetic parameters for the two models. The models were validated against the available experimental data. Globally, both models give good predictions of the experimental data, with mean average relative residuals <5%. However, the monosite model shows a better fit of the experimental data and has a lower statistical error. Nevertheless, it is not able to accurately predict the formation of oxygenates, giving a value of the chain-growth probability that is significantly far from the experimental value. An improved description of oxygenates is provided by the multisite model, but it has larger confidence intervals and suffers from a high number of kinetic parameters. This study globally provides a first investigation of the mechanism of CO2 hydrogenation, including the formation of hydrocarbons and oxygenates. It has been shown that a complex mechanism is involved that includes chain-growth via an alkyl mechanism combined with a CO insertion mechanism to form the oxygenate products.