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Context. Carbonaceous chondrites are sources of information on the origin of the Solar System. Their organic content is conventionally classified as soluble (SOM) and insoluble organic matter (IOM), where the latter represents the majority. Aims. In this work, our objectives are to identify possible relations between soluble and insoluble organic matter generated in laboratory experiments and to extrapolate the laboratory analog findings to soluble and insoluble organic matter of meteorites to test their connection. Methods. Using laboratory experiments, processes possibly linking IOM analog (IOMA) to SOM analog (SOMA) precursors are investigated by assuming that dense molecular ices are one of the sources of organic matter in the Solar System. Each organic fraction is analyzed by laser desorption coupled to a Fourier transform ion cyclotron resonance mass spectrometer on a comprehensive basis. Results. SOMA and IOMA significantly differ in their chemical fingerprints, and particularly in their aromaticity, O/C, and N/C elemental ratios. Using an innovative molecular network, the SOMA–IOMA transition was tested, revealing connection between both classes. This new network suggests that IOMA is formed in two steps: a first generation IOMA based on precursors from SOMA, while a second IOMA generation is formed by altering the first IOMA generation. Finally, using the same analytical technique, the molecular content of IOMA and that of the Paris IOM are compared, showing their molecular similarities for the first time. The molecular network application to the Paris SOM and IOM demonstrates that a possible connection related to photochemical ice processing is present, but that the overall history of IOM formation in meteorites is much more complex and might have been affected by additional factors (e.g., aqueous alteration). Conclusions. Our approach provides a new way to analyze the organic fraction of extraterrestrial material, giving new insights into the evolution of organic matter in the Solar System.

International audience; The rich diversity and complexity of organic matter found in meteorites is rapidly expanding our knowledge and understanding of extreme environments from which the early solar system emerged and evolved. Here, we report the discovery of a hitherto unknown chemical class, dihydroxymagnesium carboxylates [(OH)(2)MgO2CR](-), in meteoritic soluble organic matter. High collision energies, which are required for fragmentation, suggest substantial thermal stability of these Mg-metalorganics (CHOMg compounds). This was corroborated by their higher abundance in thermally processed meteorites. CHOMg compounds were found to be present in a set of 61 meteorites of diverse petrological classes. The appearance of this CHOMg chemical class extends the previously investigated, diverse set of CHNOS molecules. A connection between the evolution of organic compounds and minerals is made, as Mg released from minerals gets trapped into organic compounds. These CHOMg metalorganic compounds and their relation to thermal processing in meteorites might shed new light on our understanding of carbon speciation at a molecular level in meteorite parent bodies.

International audience; SBA-15 with a 2D hexagonal mesoporous structure exhibiting a narrow pore size distribution and commercial AEROSIL380 silica were used as supports for the dispersion of Ni, Co or Fe metal oxide particles. After reduction at 973 K, catalytic properties of these materials were evaluated for ethanol conversion to H-2 and carbon nanotubes (CNTs). The reduced composites were selective for hydrogen production as follows: iron (45-55%) < cobalt (55-70%) < nickel (70-80%) regardless of the type of silica used as support. The nickel-based catalysts appeared to be the most active for the production of hydrogen and also generate carbon nanotubes in large amounts, independently of the support porosity. HRTEM micrographs showed a generally well-defined morphology and a quite uniform outer diameter of CNTs produced using the Ni composites. The texture of the silica support had however a particular influence on the catalytic properties of the cobalt-based catalysts. Both Ni and Co supported on SBA-15 silica generate a mixture of CNTs and carbon nanofibers (CNFs) with a wider size distribution compared with that of the CNTs produced over Ni/Aerosil. This lack of selectivity was attributed to the expelling of Co particles from the SBA-15 mesoporous channels upon reduction. All Fe/silica materials proved the least active and selective. Along the major carbon fibers, they generate a few poorly defined multi-walled CNTs with small diameter. TG analysis indicated that all CNTs exhibit a relative high stability in an oxidizing atmosphere.

International audience; MCM-41 and SBA-15 micelle-templated silicas are ideal reference materials to study the effect of surface roughness on pore size measurement by mercury intrusion, as the inner surface of the mesoporous channels is much rougher in the case of SBA-15 than MCM-41. In the case of MCM-41, the pressure of mercury intrusion is related to the pore size by the classical Washburn-Laplace law while, in the case of SBA-15, the pressure of intrusion is much higher than expected and classical models underevaluate the size of the channels. Defects on the pore surface of SBA-15 affect the mercury intrusion in a similar way as the deviation from cylindrical geometry does for the pores of sponge-like silica glasses. The results vindicate the models of Wenzel and Kloubek on the effect of surface defects on the mercury contact angle, which is significantly larger for a rough surface than for a plane surface. The surface defects of SBA-15 does not affect the evaluation of the mesopore size by nitrogen adsorption, as they are filled at an early stage of the adsorption and do not interfere with capillary condensation.

MCM-41 and SBA-15 micelle-templated silicas are ideal reference materials to study the effect of surface roughness on pore size measurement by mercury intrusion, as the inner surface of the mesoporous channels is much rougher in the case of SBA-15 than MCM-41. In the case of MCM-41, the pressure of mercury intrusion is related to the pore size by the classical Washburn−Laplace law, while in the case of SBA-15, the pressure of intrusion is much higher than expected and classical models underevaluate the size of the channels. Defects on the pore surface of SBA-15 affect the mercury intrusion in a similar way as the deviation from cylindrical geometry does for the pores of spongelike silica glasses. The results vindicate the models of Wenzel and Kloubek on the effect of surface defects on the mercury contact angle, which is significantly larger for a rough surface than for a plane surface. The surface defects of SBA-15 does not affect the evaluation of the mesopore size by nitrogen adsorption, as they are fi...

This study is aimed at exploring the ability of very small sized N-bearing molecules to generate and stabilize microporous aluminophosphates. Two new AlPO 4 - n materials, called IST-1 and IST-2, have been obtained in aqueous media using, as main template, methylamine (MA), directly added, or generated in situ from methylformamide (MF) degradation. While IST-1 topology proved to be novel, IST-2 appears structurally related to AlPO 4 -53(A). The obtained materials were characterized by powder XRD, TG/DSC, SEM and solid-state NMR. Tetraalkylammonium (TEA) cations were used as potential co-templates but only MA and water were found incorporated in the pore volumes of both structures, which argues for their true templating role. In IST-1, 13 C solid-state NMR studies showed that half of MA species, presumably protonated, is H-bonded to framework oxygens while the other half surprisingly bonds directly to framework Al atoms. 13 C NMR showed that only protonated MA occurs in IST-2 channels. TEA + cations definitely do not play any specific template role. They indirectly favor the crystallization of IST-1 or IST-2 devoid from other crystalline or amorphous side phases, by interacting with part of the Al and P in solution and forming soluble [AlPO 4 (OH)]–[TEA,HMA] complexes, substantially modifying the compositions of gels precursors to each phase during nucleation and/or growth steps. While both IST-1 and IST-2 crystallize from gels of similar initial compositions, it was demonstrated that the new MA/T ratio (T = Al or P) obtained after in situ complexation was the key parameter that specifically governs the crystallization of each phase.

A series of binary Cu-Al surfactant-assisted mesoporous precursors have been prepared through direct synthesis and catalytically evaluated in the selective hydrogenation of conjugated α,β-unsaturated aldehyde (cinnamaldehyde) to the corresponding unsaturated alcohol in the liquid phase. The resulting material consists in a mesoporous alumina substrate involving a ripple sheet type-texture onto which Cu hydroxynitrate domains of uniform size were dispersed. After calcination, these particles yield sub-nanometer (< 1 nm) and larger (20-40 nm) CuO particles. An original model implying a homogeneous temperature-induced particle accretion is proposed to explain this bimodal dispersion. A specific re-evaluation of some synthesis parameters allowed us to optimize the relative size, dispersion and final stabilization of these particles. Upon reduction, CuO yields sub-nanometric Cu 2 O and metallic Cu particles of relatively uniform size. The remarkable selectivity (70%) of the binary mesoporous samples towards the hydrogenation of the carbonyl group of cinnamaldehyde is due to the presence of Cu 2 O particles that are probably in relatively strong interaction with the alumina pore walls. By contrast, solids involving Cu nitrate impregnates on either mesoporous and commercial (bulky) γ-alumina performed poorly towards the formation of cinnamyl alcohol, arguing for a fundamental difference in the electronic states of the various supported Cu particles with respect to those generated on samples by direct synthesis.

A highly crystalline cobalt-substituted aluminophosphate with an AEN topology, labeled CoIST-2, has been synthesized and characterized by powder XRD, TG/DSC, diffuse reflectance UV-vis spectroscopy, FTIR, EPR spectroscopy, and cyclic voltammetry. Both water and methylamine were shown to play a complementary role as dual template and space-filling agents during the hydrothermal synthesis of this material. The spectroscopic (EPR, UV-vis, and FTIR) and electrochemical characterization of the as-synthesized and calcined CoIST-2 material revealed the presence of two structurally different Co(II) species incorporated in its crystalline framework. The redox behavior and acidity was found to be different for these two Co(II) species. While one of these cobalt species corresponded to Bro¨nsted Co(OH)P acid sites, the other seemed to be associated with the presence of Lewis acid sites (Co0P type species). UV-vis spectra, typical of divalent cobalt in tetrahedral coordination, along with FTIR, demonstrated that only a fraction of the Co(II) ions undergo a reversible oxidative process after calcination in air and that some extraframework CoxOy type species are also generated through oxidation. The presence of divalent Co(II) in a slightly distorted tetrahedral coordination, both in the as-synthesized and calcined phase, was also detected with use of EPR data. The electrochemical oxidation of the two different framework Co(II) species and their further reduction could be evaluated semiquantitatively by cyclic voltammetry. The redox ability of CoIST-2 was also compared with that of two other cobaltsubstituted aluminophosphates involving different pore structures, namely CoAPO-40 and CoAPO-37, by using FTIR of adsorbed NO. It was found that the most readily oxidized ions were present in the more dense AEN topology, followed by the more open AFR and FAU structures, thereby emphasizing how the redox properties of transition metal ions in porous aluminophosphates are intimately linked to both the structure type/density of the host lattice and framework positions of the heteroelement.

Highly crystalline CoAPSO-40 and ZnAPSO-40 have been synthesized and characterized by powder XRD, TG/DSC, SEM, EDX, 27Al, 31P and 29Si solid-state NMR, diffuse reflectance UV–VIS spectroscopy, FT IR and catalytic tests using the m-xylene isomerization and n-heptane cracking as model reactions. The simultaneous incorporation of silicon and a divalent metal in the framework of the AFR structure results in the generation of Bronsted acid sites similar to those found in SAPO-40 and MeAPO-40. The catalytic activity of the samples for acid catalyzed reactions is higher than that of SAPO-40 with a homogeneous framework silicon distribution. The framework incorporation of cobalt or zinc results in a decrease of the thermal and hydrothermal stability of the metal bearing AFR framework, when compared with AlPO4-40 and SAPO-40.

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