Predictor displays: The application of human engineering in process control systems

Influence of feed components on the activity and stability of cobalt molybdenum alumina metathesis catalyst

“…The results agree with literature reports that polar compounds such as H 2 O, which might be present as an impurity in reactant(s) are catalyst poisons [5,15,16]. Water might deactivate the catalyst via destruction of propagation active centres (for example, oxidation of carbenes to carbonyl compounds) or by bonding strongly to the metal centre, preventing coordination of the alkene [4]. Stencel et al, investigated the effect of exposing calcined molybdenum based catalysts to H 2 O by Raman spectroscopy [17].…”

“…The impurities in the feed, which act as poisons seem to quench the metal carbene, while others retard the metathesis reaction through competitive adsorption on the metal centre [3][4][5]. Typical heterogeneous catalysts for the metathesis reaction are WO 3 /SiO 2 , CoO/MoO 3 /Al 2 O 3 , MoO 3 /Al 2 O 3 and Re 2 O 7 / Al 2 O 3 .…”

“…Typical heterogeneous catalysts for the metathesis reaction are WO 3 /SiO 2 , CoO/MoO 3 /Al 2 O 3 , MoO 3 /Al 2 O 3 and Re 2 O 7 / Al 2 O 3 . Silica-based catalysts for example WO 3 /SiO 2 , when deactivated by feed impurities can regain their original activity when the impurity is removed from the feed [4,6]. This is due to the high operating reaction temperature of between 300 and 500 8C for WO 3 /SiO 2 catalyst system and inherent slow reductive elimination of metal carbene species with tungsten systems.…”

“…Alkene metathesis catalysts are reported to be sensitive to certain feed impurities [3][4][5]. The impurities in the feed, which act as poisons seem to quench the metal carbene, while others retard the metathesis reaction through competitive adsorption on the metal centre [3][4][5].…”