Electrochemical promotion of Pd for the hydrogenation of C2H2

Abstract

Abstract. The effect of Non-Faradaic Electrochemical Modification of Catalytic Activity, or insitu controlled promotion, was investigated during Acetylene selective hydrogenation on Pd films deposited on 13"-A1203, a Na + conductor, at temperatures from 60 to 100 ~ and GHSVs from 103 to 104 h -1, i.e., under conditions similar to those used in industrial processes. It was found that both acetylene conversion and hydrogenation selectivity can be affected by means of externally applied potentials, i.e., by supplying or removing sodium ions to or from the catalyst surface. Electrochemical sodium supply to the Pd catalyst surface was found to supress both the rate of acetylene hydrogenation and, to a larger extent the rate of ethylene hydrogenation to ethane. Consequently electrochemical sodium supply was found to enhance the selectivity to ethylene. Thus, 13"-A1203 can act as an active catalyst support causing enhanced performance of the Pd catalyst. Acetylene conversion and hydrogenation selectivity values up to 90 % and 95 %, respectively, were obtained.

Hydrogen Spillover and Its Relation to Hydrogenation: Observations on Structurally Defined Single‐Atom Sites**

“…We may ascribe those differences in reactivity to the change in oxidation state of Pd, as reflected by a shift in XPS binding energies of Pd from initially 337.6 eV to 337.1 eV as hydrogen spillover progressed (Figure S11), as well as by Bader charge analysis of PMo 11 O 39 Pd 1 as a function of H coverage (Table S1). This reactivity trend is consistent with previous reports on the drop in C=C bond hydrogenation activity when the oxidation state of Pd was reduced [24] . We further found that a catalyst not exhibiting hydrogen spillover (PW 11 O 39 Pd 1 ) was significantly more active in the hydrogenation of vinyl acetate (Figure S35).…”

“…This reactivity trend is consistent with previous reports on the drop in C=C bond hydrogenation activity when the oxidation state of Pd was reduced. [24] We further found that a catalyst not exhibiting hydrogen spillover (PW 11 O 39 Pd 1 ) was significantly more active in the hydrogenation of vinyl acetate (Figure S35).…”

Electrochemical promoted catalysis: Towards practical utilization

“…While electrochemical promotion has mostly applied to oxidation reactions, there is a plethora of studies on hydrogenation and hydrogenation reactions [1,[28][29][30][31]. Among these studies, CO 2 and CO hydrogenation for the production of alcohols and other oxygenated products appear to be of a considerable technological interest.…”

Μελέτη Του Φαινομένου Της Ηλεκτροχημικής Ενίσχυσης Σε Αντιδράσεις Βιομηχανικού Ενδιαφέροντος

“…Nasicοn [54], ιόντων Η + όπως CsHSO4 [26] και CaZr0.9In0.1O3-a [55], ιόντων Κ + όπως Κ2ΥΖr(PO4)3 [56] ιόντων Fόπως CaF2 [57] καθώς και μικτοί αγωγοί όπως TiO2 [21] και CeO2 [54]. Εκτός από αντιδράσεις πλήρους ή μερικής οξείδωσης όπου αρχικά εμφανίστηκε το φαινόμενο [2,9], έχουν γίνει μελέτες και σε αντιδράσεις αφυδρογόνωσης [11], υδρογόνωσης [58,59] και διάσπασης [29,56,[60][61][62]. Στον Πίνακα 1.1 παρουσιάζονται συνοπτικά τα καταλυτικά συστήματα που έχουν μελετηθεί με το φαινόμενο NEMCA καθώς και τιμές βασικών παραμέτρων που χαρακτηρίζουν το φαινόμενο αυτό, οι οποίες συνοψίζονται και περιγράφονται στη συνέχεια.…”