Sulfur as a catalyst promoter or selectivity modifier in heterogeneous catalysis

Recent advances in selective acetylene hydrogenation using palladium containing catalysts

“…The group of Anderson investigated the adsorption of organic sulfur [46][47][48][49] and phosphorous [48][49][50] modifiers on acetylene hydrogenation. Diphenylsulfide and triphenylphosphine were adsorbed onto a Pd/TiO 2 catalyst by impregnation from a hexane solution.…”

CO induced surface segregation as a means of improving surface composition and enhancing performance of CuPd bimetallic catalysts

“…The industrial process typically takes place at low temperature (313-393 K) over a PdAg 'skin' or egg-shell catalyst [25] where Pd is the active metal. The role of Ag is to dilute Pd ensemble size [23] and limit palladium hydride formation [26] which has been shown to be detrimental for achieving high alkene selectivity [27][28][29][30][31][32], although a similar effect may be achieved by using organic sulfur [33][34][35][36] and phosphorous modifiers [33,37]. Several other monometallic [38][39][40], bimetallic [41][42][43][44], trimetallic [45] and metal-free catalysts [46,47] have been shown to offer high alkene selectivity, although they typically require activation and/or use at elevated temperatures.…”

Cu/Al 2 O 3 catalysts modified with Pd for selective acetylene hydrogenation

“…New approaches to improving selectivity in Pd based catalysts include alloying with Ga [16,17] or the adsorption of molecules which act as a selectivity modifier. Examples include sulphur and phosphorous containing molecules such as diphenyl sulfide [18][19][20] and triphenylphosphine [21] with selectivity varying depending on the ligand structure suggesting the effect has yet to be fully optimised [22].…”