Reactivity of crotonaldehyde and propene over Au/Pd(111) surfaces

The surface chemistry of crotonaldehyde and propene, primary and secondary reaction products in the aerobic selective oxidation of crotyl alcohol, has been studied by temperature-programmed reaction over Au/Pd(111) surface alloys. Gold strongly promotes desorption versus reaction at mole fractions ≥0.3 (crotonaldehyde) and ≥0.8 (CH); only ∼5% of the chemisorbed aldehyde or alkene react over Au-rich alloys. Surprisingly, co-adsorbed oxygen strongly suppresses crotonaldehyde decomposition over both clean Pd(111) and alloy surfaces, while CH combustion, an important undesired side-reaction over unpromoted Pd(111), is also moderated by Au. © the Owner Societies.

La presse d'extreme droite face au revisionnisme en France 1978-1990

Between 1978 and 1990 five newspapers close to Jean-Marie Le Pen's Front National had the choice of defining their stand on so-called révisionnisme which in its extreme form denied the existence of the Shoah, considering it to be the fabrication of a Jewish conspiracy. Within révisionnisme, a négationniste discourse affirmed that the gas chambers never existed, while a relativiste discourse denied that the Shoah was an act of genocide. However, most of the extreme-right newspapers did not adopt the cause of révisionnisme, even if they sometimes evinced an indulgence towards it. Only the weekly Rivarol and the militant François Brigneau who worked for Minute, Présent and National Hebdo and wrote the most on the subject openly espoused révisionnisme. The reasons for their stance included neo-fascist views, belief in a Jewish conspiracy. Their stance was in keeping with ideas commonly expressed in French neo-fascist circles that made for a révisionnisme of exculpation. On the other hand, the French Catholic intégriste milieu close to the Front National, which is represented by the newspapers Présent and Aspects de la France, was not generally révisionniste, notwithstanding the occasionnal expressions of relativisme by persons in the schismatic lefebvriste movement or close to Présent. This rejection of révisionnisme by Catholics on the extreme right was conditioned by various factors: the nature of Maurras's nationalisme intégral and anti-Semitism transmitted by I' Action française; the Catholic Church's modified position on the Jews; and the (offensive) atheism of the upholders of révisionnisme. This same révisionnisme extended beyond latter-day Nazi sympathisers. In its French version, it served to unite elements of the extreme right and the extreme left, as witness the role played by La Vieille Taupe, the extreme left group which was (and is) the leading publisher in France of tracts favouring révisionnisme.

New insights in the deactivation of sulfonic modified SBA-15 catalysts for biodiesel production from low-grade oleaginous feedstock

Arenesulfonic-acid functionalized SBA-15 materials have been used in the production of biodiesel from low grade oleaginous feedstock. These materials display an outstanding catalytic activity, being able to promote the transformation of crude palm oil with methanol into fatty acid methyl esters with high yield (85%) under mild reaction conditions. However, high sensitivity of the catalyst against poisoning by different substances has also been detected. Thus, alkaline metal cations, such as sodium or potassium exert a negative influence on the catalytic activity of these materials, being necessary amounts around 500 ppm of sodium in the reaction media to decrease the catalytic activity of these materials to a half of its initial value in just two reaction runs. The deactivation of arenesulfonic acid functionalized SBA-15 materials seems to occur in this case by ion exchange of the acid protons at the sulfonic groups. Organic unsaponifiable compounds like lecithin or retinol also induce a negative influence in the catalytic activity of these sulfonic acid-based materials, though not so intense as in the case of alkaline metals. The deactivating mechanism associated to the influence of the organic compounds seems to be linked to the adsorption of such substances onto the catalytic acid sites as well as on the silica surface. The accumulation of lecithin in the surface of catalyst, observed by means of thermogravimetric analysis, suggest the creation of a strong interaction, probably by ion pair, between this compound and the sulfonic acid group.