Mechanism of Carbon–Nitrogen Bond Scission on Unsupported Transition Metal Sulfides

Mechanism of carbon?nitrogen bond scission in the presence of H2S on Pt Supported catalysts

“…The substituted amines were the same as in reference [9], namely neo-pentylamine (2H a and no H b ) n-pentylamine (2H a and 2H b ) and tert-pentylamine (no H a and 8 H b ). Their transformation was carried out in the vapour phase at atmospheric pressure similarly to [9].…”

“…Overall amine conversion and product distribution were determined after a period of at least 15 h on stream, which was enough for reaching stable conversions. The acidity of the catalysts was evaluated by hydrocracking of 2,2,4-trimethylpentane (isooctane) [17,9]. The reaction was carried out at 523 K at atmospheric pressure, with an isooctane partial pressure of 1.7 kPa, a hydrogen flow rate of 0.67 mL/s and a catalyst weight 0.05-0.75 g. No deactivation was observed during the experiments.…”

“…Since the reactivity of the different amines varies in a wide range, the activities were measured at 523 K with different amounts of catalyst or feed flow rates in order to keep the conversion below 20% (except for tert-pentylamine conversion on NiMoP, which reached 46%). The other experimental conditions were the following ones: amine partial pressure 0.329 kPa (standard conditions), total reactant flow $2.2 mL/s, catalyst weight 0.025/0.080 g. The H 2 S concentation was varied from 83 to 333 vol ppm (instead of 0.4%, 0.395 kPa, for [9]). Table 2 presents the reactants used in this study.…”

“…Their transformation was carried out in the vapour phase at atmospheric pressure similarly to [9]. Since the reactivity of the different amines varies in a wide range, the activities were measured at 523 K with different amounts of catalyst or feed flow rates in order to keep the conversion below 20% (except for tert-pentylamine conversion on NiMoP, which reached 46%).…”

“…The knowledge of mechanism of C-N bond cleavage on sulfide catalysts was thoroughly improved by studying the reactivity of a series of amines with different structures and different numbers of hydrogen atoms on the carbon atoms in the a and b positions with respect to their nitrogen atom (H a and H b , respectively). These amines were previously studied on unsupported transition metal sulfides [9] or Mo or Nb carbides and MoS 2 /SiO 2 [10] or phosphides (MoP, WP) on silica [11]. It was shown that the reaction mechanism depended both on the structure of the amine to be converted (steric hindrance around the carbon bearing the NH 2 group and number of hydrogen atoms in the b position) and on the sulfide (or carbide) properties.…”