Process for the partial hydrogenation of a nitrile compound containing two or more nitrile groups

Process for the preparation of a mixture of an aminonitrile and an amino compound containing two or more amino groups through partial hydrogenation of a nitrile compound containing two or more nitrile groups using hydrogen in the presence of a Raney catalyst, hydroxide base and water, the hydroxide base/catalyst weight ratio being more than 0.05 and the water/catalyst weight ratio being less than

Process to continuously prepare an aqueous mixture of epsilon-caprolactam and epsilon-caprolactam precursors

Process for preparing an aqueous mixture of ε-caprolactam and 6-aminocaproic acid and/or 6-aminocaproamide which involves as the reductive amination step, contacting 5-formylvaleric acid and/or an alkyl 5-formylvalerate in water as solvent with hydrogen and an excess of ammonia in the presence of a ruthenium on carrier as a catalyst, wherein the carrier is titanium oxide or zirconium oxide, graphite or carbon and the catalyst contains at least one of the metals of group 8-11, or a compound of these metals. The aqueous mixture can be used to prepare ε-caprolacta

Process to continuously prepare an aqueous mixture of ε-caprolactam and ε-caprolactam precursors

This continuous process for preparing an aqueous mixture of epsilon-caprolactam and 6-aminocaptoic acid and/or 6-aminocaproamide which involves as the reductive amination step, continuously contacting 5-formylvaleric acid or an alkyl 5-formylvalerate in water as solvent with hydrogen and an excess of ammonia in the presence of a ruthenium on carrier, as a catalyst, wherein the carrier is at least one of titanium oxide or zirconium oxide. The aqueous mixture can de used to prepare ε-caprolactam

The role of carbonaceous deposits and support impurities in the selective hydrogenation of ethyne

In order to elucidate the role of carbonaceous deposits, the hydrogenation of ethyne over silica supported Pt and Pd catalysts has been studied in a micro-pulse reactor. When a pure silica support (Aerosil) was used, the conversion decreased with an increasing number of ethyne pulses led over the reactor. Simultaneously, the selectivity towards ethene increased. When less pure silica (Kieselgel) was used as a support, the opposite effect was observed. These results are explained by assuming that the carbonaceous deposits are not active, but influence the selectivity of the uncovered metal surface by diminishing the average ensemble size available for the reaction. Impurities in the support can alter the behaviour of the catalysts

Process for the preparation of a mixture of epsilon-caprolactam and/or epsilon-caprolactam precursors

Process for the preparation of a mixture of ε-caprolactam and/or ε-caprolactam precursors from 5-formylvalerate ester and/or 5-formylvaleric acid, ammonia and hydrogen in the presence of a hydrogenation catalyst, wherein the process is conducted in a reactor of which the internal wall material is an inert material

Selective reduction of acetic acid to acetaldehyde on iron oxides

The selective reduction of acetic acid to acetaldehyde on iron oxides has been studied in various pressure ranges. A good selectivity towards acetaldehyde could be achieved with molecular hydrogen continuously present in the gas phase and on a prereduced catalyst containing both a metal phase (zero-valent metal) and an oxidic phase. The pressure of acetic acid appears to influence the formation and the kind of by-products. At low pressures of acetic acid (0.015 mbar) ketene (CH2CO) is the most important (by-)product, while at high pressures (25 mbar) ketene has never been observed and acetone is the main (by-) product. Reaction mechanisms have been proposed for the selective reduction to acetaldehyde and for the formation of the (by-)products. Presumably the reduction to acetaldehyde occurs on the vacancy-rich oxidic layer, while hydrogen is dissociated on the zero-valent metal sites. The by-products are most likely formed via a common ketene-like intermediate

Reactions of carboxylic acids on oxides:1. selective hydrogenation of acetic acid to acetaldehyde R. Pestman,

Acetic acid has been used as a model compound in the selective\u3cbr/\u3ehydrogenation of aliphatic acids, which contain ®-hydrogen atoms,\u3cbr/\u3eto their corresponding aldehydes. In contrast to what the literature\u3cbr/\u3epredicts, it appeared to be possible to produce acetaldehyde directly\u3cbr/\u3efrom acetic acid. The appropriate catalyst consists of an oxide with\u3cbr/\u3ean intermediate metal–oxygen bond strength. Addition of platinum\u3cbr/\u3eto the catalyst enhances selectivity and activity. A mechanism is\u3cbr/\u3eproposed, based on the involvement of lattice oxygen (viz., a Mars\u3cbr/\u3eand Van Krevelen mechanism) and the spill-over of activated hydrogen\u3cbr/\u3efrom the platinum to the oxide. The most important side\u3cbr/\u3ereaction is the formation of acetone from two molecules of acetic\u3cbr/\u3eacid (ketonization), but this reaction is suppressed completely by\u3cbr/\u3ethe addition of platinum to the catalyst

Insight into the rate-determining step and active sites in the Fischer-Tropsch reaction over cobalt catalysts

\u3cp\u3e Most studies on the Fischer-Tropsch reaction assume that the dissociation of the C-O bond is crucial in determining the overall reaction rate. However, recent experimental results show that a hydrogenation step is crucial in the overall kinetics. At low pressures, which are typically used in academic research, the structure-independent termination by hydrogenation dominates the reaction rate. This is reflected in a particle-size- and structure-independent apparent activation energy and is confirmed by kinetic modeling of transient experiments. At higher (i.e., industrially more relevant) pressures, both the availability of appropriate dissociation sites and the removal of adsorbates by hydrogenation appear to limit the rate. This results in comparable degrees of rate control for CO dissociation and hydrogenation. At low pressures, the locus of termination by hydrogenation has been studied by selective site blocking of planar sites with graphene and by using nanoparticles exposing specific crystal planes. It is found that the termination runs mainly on planar surfaces, while corrugated surfaces contribute to chain growth, which follows the ASF distribution. Migration of CH \u3csub\u3ex\u3c/sub\u3e species between these two sites is foreseen. A shortage of stepped sites needed for monomer formation limits the yield of both methane and longer hydrocarbons. We propose that as long as the number of stepped CO dissociation sites is sufficient, the overall rate is dominated by the structure-insensitive hydrogenation. Otherwise, the turnover frequency follows the occurrence of CO dissociation sites. \u3c/p\u3