Influence of triphenylphosphine on the activity of heterogeneous iridium, rhodium and platinum containing catalysts for the dehydrogenation of saturated hydrocarbons

Triphenylphosphine: a ligand for heterogeneous catalysis too? Selectivity enhancement in acetylene hydrogenation over modified Pd/TiO2 catalyst

“…41 Despite the fact that triphenylphosphine is one of the most commonly employed ligands in homogeneous catalysis, 43 reports of its use in heterogeneous systems are rare 44 beyond cases where it forms part of an anchored complex. [45][46][47] In this paper we report characterisation of triphenylphosphine modified Pd/TiO 2 as well as evaluation of catalytic performance at atmospheric pressure (as commonly reported in the academic literature). In addition, catalyst performance and stability under high pressure conditions (as applied in industry) is investigated for longer periods on stream than previously reported, and in the absence of CO.…”

Poison or Promoter? Investigating the Dual-Role of Carbon Monoxide in Pincer-Iridium-Based Alkane Dehydrogenation Systems via Operando Diffuse Reflectance Infrared Fourier Transform Spectroscopy

“…[7][8] A common approach, as opposed to generating complexes on the surface of the support used, has been to support or immobilize organometallic complexes on high surface area inorganic supports. [9][10][11][12][13][14][15][16][17][18][19][20][21][22] These strategies frequently work, but only in a narrow range of operating conditions, usually at low temperature, outside of which ligand loss contributes to particle agglomeration and at which point the unique benefits of the ligand field such as enhanced selectivity and active site uniformity are also lost. 10,20,23 CHARACTERIZATION ACTIVITY SELECTIVITY HANDLING HETEROGENEOUS X X HOMOGENEOUS X X TETHERED X X X X…”

In Situ Formation of a Sub-Nanometer Iridium Phosphide Catalyst from Supported Organometallic Species

“…It has been previously shown that the dehydrogenation activities of various, seemingly unrelated, iridium catalysts toward dehydrogenation at temperatures above 300 °C are strongly correlated to the number of equivalents of tertiary phosphine present in the system, whether loaded initially or pulsed while on stream. [54][55][56] This was in spite of the fact that the phosphine ligands and/or additives used were observed to decompose, and even though these past experiments were performed in open, continuousflow systems which would allow for volatile phosphorus products to be removed from the catalyst bed. 54,55 This is consistent with the phosphorus becoming "trapped" on the surface in an iridium phosphide phase, much like the one observed in this work.…”

“…[54][55][56] This was in spite of the fact that the phosphine ligands and/or additives used were observed to decompose, and even though these past experiments were performed in open, continuousflow systems which would allow for volatile phosphorus products to be removed from the catalyst bed. 54,55 This is consistent with the phosphorus becoming "trapped" on the surface in an iridium phosphide phase, much like the one observed in this work. The serendipitous precatalyst deconstruction observed here resulted in nanoparticles with an average size of 0.8 -0.9 nm in diameter that proved to be stable against agglomeration at temperatures up to 440 °C, even under non-oxidative dehydrogenation conditions.…”