13815-17-3Relevant academic research and scientific papers
Propylene epoxidation with hydrogen peroxide over palladium containing titanium silicalite
Laufer,Meiers,Hoelderich
, p. 215 - 221 (1999)
The epoxidation of propylene to propylene oxide with H2O2 was studied over palladium impregnated and reduced titanium silicalite (TS-1), over merely impregnated titanium tilicalite and over untreated titanium silicalite. The use of such catalytic systems in the epoxidation of propylene with a H2-O2 mixture motivated us to assess the influence of operating conditions and the effect of the Pd loading on the epoxidation capability of the titanium silicalite catalyst. Concerning the operating conditions TS-1 was found to be very active even at temperatures as low as 10°C. Lowering the H2O2 concentrations to only 2 wt.% of H2O2 caused the PO yield to increase slightly over TS-1 and 1% Pd/TS-1. TS-1 catalysts that were merely impregnated with [Pd(NH3)4]Cl2 were less active than the catalysts that were reduced after impregnation, though the latter is more active in the decomposition of H2O2. The deactivation of TS-1 after impregnation with [Pd(NH3)4]Cl2 was probably caused by the blocking of the Ti sites by ammonia, since the impregnation with PdCl2 did not cause any decrease in activity. Reducing the catalyst removes the ammonia and improves the catalytic performance of the Pd loaded catalyst.
Synthesis and Structure of [Pd(NH3)4][cis-Pd(NH 3)2(SO3)2][Pd(NH3) 3(SO3)]·H2O
Mulagaleev,Soloviev,Blokhin,Kirik
, p. 256 - 260 (2003)
A new palladium compound [Pd(NH3)4][cis-Pd(NH 3)2(SO3)2][Pd(NH3) 3(SO3)]·H2O (I) was synthesized and its structure was studied by X-ray powder diffraction method. In the course of the synthesis, the initial trans-diamminesulfite anionic complex is transformed into the cis-configuration. Further heating in aqueous solution results in isomerization of a substance into a neutral complex [Pd(NH3) 3(SO3)]. Crystals I are triclinic: a = 10.3297(2) A, b = 14.1062(3) A, c = 6.8531(1) A, α = 101.36(0)°, β = 92.74(0)°, γ = 92.71(0)°, space group P1. Structure I consists of the columns with alternating cis-[Pd(NH 3)2(SO3)2]2- and [Pd(NH3)3(SO3)] complexes and [Pd(NH 3)4]2+ ions between the columns.
Solid-State Thermal Transformations in a Mixture of Palladium Tetraammine Dichloride with Ammonium Chromate
Fesik,Buslaeva,Mel’nikova,Tarasova
, p. 1299 - 1307 (2018)
Abstract—: Solid-state transformations of a 3[Pd(NH3)4]Cl2 + (NH4)2CrO4 mixture at temperatures from 40?to 550°C in various media have been studied by thermal analysis and mass spectrometry. The results demonstrate that the solid thermolysis product obtained in an argon atmosphere consists of a single phase: palladium-based Pd1?–?xCrx solid solution isostructural with palladium and having a unit-cell parameter a = 3.897(2) ?. Its formation proceeds through the formation of metallic Pd and Cr, as evidenced by the absence of chromium oxide phases in all of the solid intermediate thermolysis products. The solid thermolysis product obtained in air consists of the phases Pd and PdO. A model has been proposed for the transformations of the 3[Pd(NH3)4]Cl2 + (NH4)2CrO4 mixture through the formation of metallic palladium and chromium.
Immobilization of palladium in mesoporous silica matrix: Preparation, characterization, and its catalytic efficacy in carbon-carbon coupling reactions
Jana, Sreyashi,Dutta, Buddhadeb,Bera, Rajesh,Koner, Subratanath
, p. 5512 - 5520 (2008)
Palladium(0) has been immobilized into the silica-based mesoporous material to develop catalyst Pd(0)-MCM-41, which is found to be highly active in carbon-carbon coupling reactions. [Pd(NH3)4]2+ ions have been incorporated into the mesoporous material during synthesis of MCM-41 and subsequently upon treatments with hydrazine hydrate Pd2+ ions present in mesoporous silica matrix were reduced to Pd(0) almost instantaneously. The catalyst has been characterized by small-angle X-ray diffraction, N2 sorption, and transmission electron microscopy (TEM). TEM and surface area measurements clearly demonstrate that the immobilization of Pd(0) into the mesoporous silica has a significant effect on pore structure of the catalyst. Nevertheless, after immobilization of palladium the meso-porosity of the material is retained, as evidenced in the nitrogen sorption measurement. The TEM micrograph shows that both MCM-41 and Pd(0)-MCM-41 have similar types of external surface morphology; however, Pd(0)-MCM-41 was less ordered. Pd(0)-MCM-41 showed high catalytic activity toward carbon-carbon bond formation reactions like Heck and Sonogashira coupling, as evidenced in high turn-over numbers. In contrast to many other Pd-based catalysts reported so far, Pd(0)-MCM-41 acts as a truly heterogeneous catalyst in C-C coupling reactions. Notably, the new heterogeneous catalyst is found to be efficient in the activation of arylchloride to give impressive conversion in cross coupling (15-45% for Heck and 30% for Sonogashira) reactions under mild conditions.
Gallic acid-assisted synthesis of Pd uniformly anchored on porous N-rGO as efficient electrocatalyst for microbial fuel cells
Wu, Xiao-Tong,Li, Jie-Cheng,Pan, Qiu-Ren,Li, Nan,Liu, Zhao-Qing
, p. 1442 - 1450 (2018)
The sluggish kinetic rate-limiting oxygen reduction reaction (ORR) at the cathode remains the foremost issue hindering the commercialization of microbial fuel cells (MFCs). Utilization of the effect of micromolecule conjugation and the synergistic effect between Pd nanoparticles and N-rGO (nitrogen-doped reduced graphene oxide) to stabilize a precious metal onto carbon materials is a promising strategy to design and synthesize highly efficient cathode catalysts. In this study, gallic acid is used to facilitate the coupling of palladium (Pd) with N-rGO to form GN@Pd-GA via a simple hydrothermal process. Notably, the as-synthesized GN@Pd-GA as a cathode catalyst shows an approximately direct four-electron feature and demonstrates a high ORR performance in 0.1 M KOH. Furthermore, the stability and methanol tolerance of GN@Pd-GA are superior to those of the commercial Pt/C catalysts. In addition, a maximum power density of 391.06 ± 0.2 mW m-2 of MFCs equipped with GN@Pd-GA was obtained, which was 96.2% of the power density of MFCs equipped with a commercial Pt/C catalyst.
The influence of the dispersion of metals on the activity of Pt/C and Pd/C catalysts in the dehydrogenation of perhydroterphenyl
Tarasov,Kirichenko,Tolkachev,Mishin,Kalenchuk,Bogdan,Kustov
, p. 1122 - 1126 (2010)
The activity of Pt/C and Pd/C catalysts in the dehydrogenation of perhydroterphenyl was studied at conversions lower than 30% depending on the dispersion of platinum and palladium metals, which was estimated by two independent methods (adsorption of CO an
Synthesis of ruthenium(iii) and rhodium(iii) tris-acetylacetonates and palladium(ii) bis-ketoiminate using microwave heating
Chimitov,Zherikova,Mikheev,Zharkova,Morozova,Igumenov,Arzhannikov,Tumm
, p. 2236 - 2242 (2012)
Preparation of ruthenium(iii) and rhodium(iii) tris-acetylacetonates and palladium(ii) bisketoiminate (Pd(i-acac)2) under microwave irradiation using different synthetic conditions, both in the solid-phase and in solution, was studied with precise control of parameters. In the solid-phase systems, the preparation of the target product was hindered. The efficiency of the microwave heating increased when liquid phases of the reagent mixtures were used. For Pd(i-acac)2, the highest yield was achieved under elevated temperature of the process, with the reaction time decreasing to several minutes. A laboratory procedure for the microwave synthesis of ruthenium(iii) and rhodium(iii) tris-acetylacetonates and palladium(ii) bis-ketoiminate in aqueous solutions was developed, which allowed us to obtain them in 85, 55, and 80% yields, respectively. These yields are higher than those reported in the literature, with the process becoming considerably less time consuming and laborious.
Copper-free heterogeneous catalysts for the Sonogashira cross-coupling reaction: Preparation, characterisation, activity and applications for organic synthesis
Rollet, Patrick,Kleist, Wolfgang,Dufaud, Véronique,Djakovitch, Laurent
, p. 39 - 51 (2008/10/09)
Heterogeneous copper-free catalysts supported on microporous ([Pd(NH 3)4]2+/NaY) and mesoporous materials ([Pd]/SBA-15) have been prepared, characterised and evaluated in the Sonogashira coupling reaction of aryl halides w
