SEIS: Insight’s Seismic Experiment for Internal Structure of Mars

By the end of 2018, 42 years after the landing of the two Viking seismometers on Mars, InSight will deploy onto Mars’ surface the SEIS (Seismic Experiment for Internal Structure) instrument; a six-axes seismometer equipped with both a long-period three-axes Very Broad Band (VBB) instrument and a three-axes short-period (SP) instrument. These six sensors will cover a broad range of the seismic bandwidth, from 0.01 Hz to 50 Hz, with possible extension to longer periods. Data will be transmitted in the form of three continuous VBB components at 2 sample per second (sps), an estimation of the short period energy content from the SP at 1 sps and a continuous compound VBB/SP vertical axis at 10 sps. The continuous streams will be augmented by requested event data with sample rates from 20 to 100 sps. SEIS will improve upon the existing resolution of Viking’s Mars seismic monitoring by a factor of ∼ 2500 at 1 Hz and ∼ 200 000 at 0.1 Hz. An additional major improvement is that, contrary to Viking, the seismometers will be deployed via a robotic arm directly onto Mars’ surface and will be protected against temperature and wind by highly efficient thermal and wind shielding. Based on existing knowledge of Mars, it is reasonable to infer a moment magnitude detection threshold of Mw ∼ 3 at 40◦ epicentral distance and a potential to detect several tens of quakes and about five impacts per year. In this paper, we first describe the science goals of the experiment and the rationale used to define its requirements. We then provide a detailed description of the hardware, from the sensors to the deployment system and associated performance, including transfer functions of the seismic sensors and temperature sensors. We conclude by describing the experiment ground segment, including data processing services, outreach and education networks and provide a description of the format to be used for future data distribution

High efficiency CoSn/ZnO catalysts for the hydrogenation of methyl oleate

International audienceThe hydrogenation of methyl oleate (methyl cis-9-octadecenoate) to oleyl alcohol (methyl cis-9-octadecen-1-ol) was studied in the presence of a bimetallic CoSn supported over zinc oxide catalyst in a stainless steel batch reactor at 270 degrees C and 8.0 MPa of hydrogen. The active species in the reduction of methyl oleate into unsaturated alcohols was CoSn2. In order to increase the amount of these active species the nature of the precursor salts was studied. These results have shown that the carbonyl cobalt precursor is the optimum salt for the hydrogenation of methyl oleate into unsaturated alcohol since the selectivity to unsaturated alcohol reached 55% at 80% of conversion. Moreover, the selectivity is governed by the reduction of the heavy esters (oleyl oleate and oleyl stearate) formed, which can occur in the presence of small Co-Sn-2 particles, well dispersed on the catalyst surface and with a high surface content

Bifunctional Hydrogenating/Acid Catalysis: Quantification of the Intimacy Criterion

International audiencen-Alkane hydroisomerisation over Pt-tridimensional large pore Hzeolite catalysts was shown to be determined by only two parameters, easy to be quantified: the hydrogenating/acid balance and the number of acid steps undergone by olefinic intermediates during their diffusion between Pt sites, this last one being related to the Weisz's intimacy criterion

Study of physisorbed carbon dioxide on zeolites modified by addition of oxides or acetate impregnation

International audienceFundamental study of carbon dioxide (CO2) physisorption and chemisorption is investigated with the NaX zeolite modified by addition of magnesium oxide (mechanical mixtures) or by impregnation of magnesium acetate (impregnated zeolites). Defined by their textural properties, these samples are characterized using the CO2 adsorption and desorption. Complementary results are obtained with infrared experiments. This study enabled to conclude that the addition of small amounts of magnesium oxide improved the interactions of physisorbed CO2 with the materials without noticeable increase of the chemisorption. The CO2 desorption energies are increased when small magnesium amounts are added. As shown with the deconvolution of the thermal desorption curves, all the "high" temperatures physisorbed species (300-400 K) are improved at the expense of the intermediate ones when the samples are modifie

Réaction d’isomérisation de l’oléate de méthyle et de l’alcool oléique en présence de catalyseurs bimétalliques CoSn supportés

Les composés naturels sont en majorité dans la configuration cis mais au cours de leur transformation ils peuvent facilement s’isomériser en composés trans qui pourraient être à l’origine de certaines maladies cardio-vasculaires. L’objectif de notre étude est de suivre la réaction d’isomérisation cis-trans de l’oléate de méthyle et de l’alcool oléique sous azote et hydrogène en présence de catalyseurs CoSn supportés sur alumine et préparés par différentes techniques (sol-gel ou co-imprégnation). Cette étude a montré que les catalyseurs monométalliques ne permettent pas l’isomérisation cis-trans de l’ester ou de l’alcool sous atmosphère d’azote ou d’hydrogène. En revanche, l’association du cobalt et de l’étain favorise l’isomérisation cis-trans de l’ester méthylique lorsque la réaction est réalisée en milieu hydrogénant, l’activité initiale étant très augmentée lorsque la pression d’hydrogène passe de 1 à 80 bar. La présence de cobalt métallique semble favoriser la réaction d’isomérisation, puisque les systèmes CoSn préparés par voie sol-gel et exempts d’espèces métalliques s’avèrent moins isomérisants. Toutefois, l’ajout d’étain limite la réaction d’isomérisation par recouvrement des espèces cobalt en inhibant l’adsorption et l’activation de l’hydrogène. L’alcool oléique seul est préférentiellement déshydraté en présence du système CoSn mais il peut aussi s’isomériser sous forte pression d’hydrogène

Comparison Between SBA-15 and MCM-41 Structure on the Stability and the Selectivity of Basic Catalysts in Oligomerization of Glycerol

International audienceThe oligomerization of glycerol to di- and triglycerol is an attractive reaction because these products find many applications in cosmetics, food industry and polymer industry. To control the oligomerization degree, it is necessary to develop a selective catalyst. In this work, two cesium mesoporous silica (MCM-41 and SBA-15) are compared in the selective oligomerization of glycerol into di- and triglycerol. The catalysts were prepared by incipient-wetness impregnation. The results showed that the stability and the activity of catalysts depend on the support nature. The use of SBA-15 support instead of MCM-41 leads to a more stable catalyst without changing polyglycerols selectivity. Different characterizations showed that it is due to the larger wall thickness of SBA-15. This study also showed that the nature of catalyst could influence the diglycerol isomers distribution. In fact the glycerol activation inside or outside the pores can strongly modify the selectivity to linear or branched diglycerol isomers

Réaction d’isomérisation de l’oléate de méthyle et de l’alcool oléique en présence de catalyseurs bimétalliques CoSn supportés

Les composés naturels sont en majorité dans la configuration cis mais au cours de leur transformation ils peuvent facilement s’isomériser en composés trans qui pourraient être à l’origine de certaines maladies cardio-vasculaires. L’objectif de notre étude est de suivre la réaction d’isomérisation cis-trans de l’oléate de méthyle et de l’alcool oléique sous azote et hydrogène en présence de catalyseurs CoSn supportés sur alumine et préparés par différentes techniques (sol-gel ou co-imprégnation). Cette étude a montré que les catalyseurs monométalliques ne permettent pas l’isomérisation cis-trans de l’ester ou de l’alcool sous atmosphère d’azote ou d’hydrogène. En revanche, l’association du cobalt et de l’étain favorise l’isomérisation cis-trans de l’ester méthylique lorsque la réaction est réalisée en milieu hydrogénant, l’activité initiale étant très augmentée lorsque la pression d’hydrogène passe de 1 à 80 bar. La présence de cobalt métallique semble favoriser la réaction d’isomérisation, puisque les systèmes CoSn préparés par voie sol-gel et exempts d’espèces métalliques s’avèrent moins isomérisants. Toutefois, l’ajout d’étain limite la réaction d’isomérisation par recouvrement des espèces cobalt en inhibant l’adsorption et l’activation de l’hydrogène. L’alcool oléique seul est préférentiellement déshydraté en présence du système CoSn mais il peut aussi s’isomériser sous forte pression d’hydrogène

Comparison Between SBA-15 and MCM-41 Structure on the Stability and the Selectivity of Basic Catalysts in Oligomerization of Glycerol

RAFFINAGE+LRA:CLOThe oligomerization of glycerol to di- and triglycerol is an attractive reaction because these products find many applications in cosmetics, food industry and polymer industry. To control the oligomerization degree, it is necessary to develop a selective catalyst. In this work, two cesium mesoporous silica (MCM-41 and SBA-15) are compared in the selective oligomerization of glycerol into di- and triglycerol. The catalysts were prepared by incipient-wetness impregnation. The results showed that the stability and the activity of catalysts depend on the support nature. The use of SBA-15 support instead of MCM-41 leads to a more stable catalyst without changing polyglycerols selectivity. Different characterizations showed that it is due to the larger wall thickness of SBA-15. This study also showed that the nature of catalyst could influence the diglycerol isomers distribution. In fact the glycerol activation inside or outside the pores can strongly modify the selectivity to linear or branched diglycerol isomers

Synthesis of hierarchical zeolite templated carbons

International audienceThe achievement of hierarchical zeolite templated carbons (ZTCs) is firstly reported through the use of mesoporous zeolites as sacrificial scaffolds. The achieved hierarchical ZTCs feature both tailored microporosity and high degree of mesoporosity and allow hence to bridge the gap between classical ZTCs and CMK-like materials. Mesoporosity from steamed zeolites was meticulously transcribed to the ZTC particles. The use of zeolites featuring surfactant-templated mesoporosity allowed for achieving a ZTC with a very high mesopore volume (0.85 cm 3 g −1). The rearrangement of surfactant-templated mesoporosity could be evidenced through nitrogen physisorption and transmission electron microscopy on ultramicrotomed samples. The rearrangement of mesoporosity during ZTC formation has been found to impact coherent crystal size and the lattice strain of the zeolite template. The combination of data from X-ray diffraction and nitrogen physisorption allowed further to reveal that the thickness of the ZTC skeleton is impacted by the degree of intracrystalline mesoporosity in the template zeolite. Through comparing the textural characteristics of the zeolite templates and of the achieved hierarchical ZTCs, important evidence was found that the surfactant-templating of USY zeolite leads to the development of a secondary amorphous phase and that the reduction of the microporous volume during this process is merely apparent