Rules of chemical promotion

Electrochemical promotion of Pt impregnated catalyst for the treatment of automotive exhaust emissions

“…3 and 4) may be attributed to a decrease in H 2 O coverage (electron donor species, which is initially strongly adsorbed on the catalyst surface), since as already mentioned, a decrease in catalyst potential to the Pt electrode increased the coverage of electron acceptor species (O 2 and N 2 O) at the expense of electrondonor species (C 3 H 6 , H 2 O) [4,6,14]. This promotional effect is in good agreement with the recently identified rules of chemical and electrochemical promotion [4,30], as the effect of addition of a promoter on the catalytic activity depends on the initial coverage of the different molecules that participate in the reaction. The observed promotional effect under wet reaction conditions opens a new alternative to decreasing the adverse effect of poisons on the behaviour of a catalyst under real exhaust emissions.…”

Thiophene as Internal Promoter of Selectivity for the Liquid Phase Hydrogenation of Citral Over Ru/KL Catalysts

“…In addition, taking into account the shape of the graphs in Fig. 2, the hydrogenation of citral in presence of thiophene can be considered a volcano-type reaction, in agreement with the rules of electrochemical promotion established by Brosda et al [27] i.e., citral and thiophene are strongly adsorbed on supported ruthenium. Although in this competitive process thiophene deactivates the surface metal sites on which adsorbs and probably hydrogenolyses, as a consequence an electron deficient field over the neighboring metal atoms may be originated [9] and then catalytic properties are greatly affected.…”

Electrochemical Promotion of NO Reduction by C2H4 in Excess O2 Using a Monolithic Electropromoted Reactor and Pt–Rh Sputtered Electrodes

“…it is enhanced both with positive (anodic) and negative (cathodic) potential. In view of the recently established rules of promotion and electrochemical promotion [13,21,[34][35][36][37], these results imply that at lower temperatures the coverage of O is much higher than the coverages of NO and C 2 H 4 and thus O poisons both the reduction of NO and the oxidation of C 2 H 4 , thus leading to electrophobic behaviour for both reactions [13,21,34,35]. At higher temperature (380°C) the coverage of O remains relatively high, thus C 2 H 4 oxidation remains electrophobic, but the coverages of both NO and C 2 H 4 are quite low, thus leading to inverted volcano behaviour for the reduction of NO [13,21,34,35].…”