Sulfur compounds reactivity in the ODS of model and real feeds on W-SBA based catalysts

International audienceW based catalysts were synthesized by dry impregnation of SBA-15 mesoporous silica with phosphotungstic acid (HPW) solution with W contents between 5 and 20%, the HPW compound being preserved after calcination. The catalysts performance and the reactivity of various sulfide compounds were evaluated in the oxidative desulfurization (ODS) of model solutions and of real diesels, with sulfur contents ranging from 50 to 2000 ppm. The reactivity of benzothiophene and dibenzothiophene compounds was different in the ODS of model solutions but globally identical in the ODS of SRGO. The monitoring of the concentration of a range of alkyl DBT compounds (with alkyl groups from C2 to C5) in LGO confirmed the importance of the steric hindrance of alkyl substituents in the 4,6 position near the S atom, as well as of the size of the alkyl groups. Among the xW/SBA series, the catalyst with the highest loading showed the best performance in the ODS of LGO and SRGO while the catalysts efficiency could not be discriminated in the ODS of model solutions. In the ODS of both model solutions and real feeds, the W/SBA catalyst was found to be much more efficient than a catalyst obtained by impregnation of a commercial silica with similar loading, highlighting the beneficial use of a mesoporous support with high surface area and pore volume that allowed well-dispersed tungsten species to be obtained. The quantity of sulfones precipitated and/or retained on the catalyst depended on the feed and was found to be higher in the ODS of model solution than in the ODS of real feeds. The precipitated/retained sulfones on the support may induce catalyst deactivation, which highlights the importance of the textural properties of the support. This detailed study points out the difficulty of extrapolating results obtained in the ODS of model solution to the ODS of real feeds

W-SBA based materials as efficient catalysts for the ODS of model and real feeds: Improvement of their lifetime through active phase encapsulation

International audienceIncorporated W-SBA based catalysts were prepared by a direct synthesis method involving phosphotungstic acic (HPW) together with mixed structure directing agents, and by incipient wetness impregnation for comparison purpose. In the oxidative desulfurization CODS) of dibenzothiophene (DBT, 500-1500 ppmS) and of a Straight Run Gas Oil (SRGO, 2000 ppmS) in batch reactor, the impregnated solids showed higher efficiency than the incorporated ones, which was attributed to a better accessibility of the active phase present at the surface of the support in the impregnated catalysts. However, in continuous evaluation using a fixed bed reactor, the incorporated catalyst showed a stable conversion in the ODS of SRGO 2000 ppmS for 9 days while within 24 h the impregnated solid was almost completely deactivated. Higher interaction of the active phase with the support in incorporated catalysts was evidenced by Time-of-Flight Secondary Ions Mass Spectrometry (ToF-SIMS) analysis, which can be at the origin of less leaching of tungsten species during reaction and thus explain their better resistance towards deactivation. The lower efficiency of incorporated catalysts compared to impregnated ones in ODS reaction carried out in a batch reactor is clearly compensated by their resistance towards leaching of the active phase in a continuous test. These results highlight the importance of evaluating not only the catalysts performance but also their lifetime in conditions more representative of industrial ones

Conversion of Biogas to Syngas via Catalytic Carbon Dioxide Reforming Reactions: An Overview of Thermodynamic Aspects, Catalytic Design, and Reaction Kinetics

International audienceBiogas production has continuously increased worldwide during the last decades. Nowadays, heat, electricity, and biomethane production are the main utilization of biogas at large-scale industrial processes. The research and development on biogas valorization is currently related to synthesis gas production via reforming process, since syngas allows obtaining various chemicals and fuels of high-added value. However, biogas reforming is a complex process, which implies various reactions in parallel, and needs high temperature (>800 °C) to obtain high methane conversion. The development of a highly-performing catalyst, which must be active, selective, thermally stable, and resistant to solid carbon formation on its surface, is crucial. This chapter is devoted to an update of the thermodynamic aspect of biogas reforming under different conditions. This chapter also reviews recent significant works related to catalyst design as well as kinetic and mechanistic studies of biogas reforming processes

Immobilized Furanone Derivatives as Inhibitors for Adhesion of Bacteria on Modified Poly(styrene- co

The ability of brominated furanones and other furanone compounds with 2(3H) and 2(5H) cores to inhibit bacterial adhesion of surfaces as well deactivate (destroy) them has been previously reported. The furanone derivatives 4-(2-(2-aminoethoxy)-2,5-dimethyl-3(2H)-furanone and 5-(2-(2-aminoethoxy)-ethoxy)methyl)-2(5H)-furanone were synthesized in our laboratory. These furanone derivatives were then covalently immobilized onto poly(styrene-co-maleic anhydride) (SMA) and electrospun to fabricate nonwoven nanofibrous mats with antimicrobial and cell-adhesion inhibition properties. The electrospun nanofibrous mats were tested for their ability to inhibit cell attachment by strains of bacteria commonly found in water (Klebsiella pneumoniae Xen 39, Staphylococcus aureus Xen 36, Escherichia coli Xen 14, Pseudomonas aeruginosa Xen 5, and Salmonella tymphimurium Xen 26). Proton nuclear magnetic resonance spectroscopy (1H NMR), electrospray mass spectroscopy (ES-MS), and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) were used to confirm the structures of the synthesized furanones as well as their successful immobilization on SMA. To ascertain that the immobilized furanone compounds do not leach into filtered water, samples of water, filtered through the nanofibrous mats were analyzed using gas chromatography coupled with mass spectroscopy (GC-MS). The morphology of the electrospun nanofibers was characterized using scanning electron microscopy (SEM)