The Ru-based catalysts, including Ru/AC (activated carbon), TPAP (tetrapropylammonium perruthenate)/AC, TPAP/AC-HNO3, and TPAP/AC-HCl, were prepared and assessed for the direct synthesis of vinyl chloride monomer. The results indicate that the TPAP/AC-HCl catalyst exhibits the best performance with the conversion falling from 97% to 91% in 48 hours’ reaction under the conditions of 180 °C, a GHSV(C2H2) of 180 h−1, and the feed ratioVHCl/VC2H2of 1.15. The substitution of RuCl3precursor with high valent TPAP species leads to more ruthenium oxides active species in the catalysts; the acidification treatment of carrier in TPAP/AC catalyst can produce an enhanced interaction between the active species and the modified functional groups on the carrier, and it is beneficial to inhibit the carbon deposition and sintering of ruthenium species in the reaction process, greatly increase the adsorption ability of reactants, and further increase the amount of dominating active species in the catalysts, thus improving the catalytic performance. This also provides a promising strategy to explore high efficient and economic mercury-free catalysts for the hydrochlorination of acetylene.Keywords:tetrapropylammonium perruthenate;acetylene hydrochlorination;Ru catalysts
Tongtong Liu,Hengyu Guo,Yanan Chen,Zhengping Zhang,Feng Wang
Pyrochlore ruthenate (Y 2 Ru 2 O 7–δ ) is highlighted as a promising oxygen evolution reaction (OER) catalyst for water splitting in polymer electrolyte membrane electrolyzers. However, an efficient electronic modulation strategy for Y 2 Ru 2 O 7–δ is required to overcome its electrochemical inertness. Herein, a surface manipulation strategy involving implanting MoO x moieties on nano Y 2 Ru 2 O 7–δ (Mo–YRO) using wet chemical peroxone method is demonstrated. In contrast to electronic structure regulation by intramolecular charge transfer (i.e., substitutional strategies), the heterogeneous Mo−O−Ru micro-interfaces facilitate efficient intermolecular electron transfer from [RuO 6 ] to MoO x . This eliminates the bandgap by inducing Ru 4 d delocalization and band alignment rearrangement. The MoO x modifiers also alleviate distortion of [RuO 6 ] by shortening Ru−O bond and enlarging Ru−O−Ru bond angle. This electronic and geometric structure tailoring enhances the OER performance, showing a small overpotential of 240 mV at 10 mA cm −2 . Moreover, the electron-accepting MoO x moieties provide more electronegative surfaces, which serve as a protective “fence” to inhibit the dissolution of metal ions, thereby stabilizing the electrochemical activity. This study offers fresh insights into the design of new-based pyrochlore electrocatalysts, and also highlights the versatility of surface engineering as a way of optimizing electronic structure and catalytic performance of other related materials.
The sulfur-doped yttrium ruthenate pyrochlore catalysts was synthesized by simple hydrothermal method and exhibits excellent OER activity and stability under acidic conditions. Remarkably, the Y 2 Ru 2 O 7 S-0.17 catalyst reaches a current density of 10 mA cm −2 with only 237 mV and remains stable during 30 hours of electrolysis. In contrast, the original Y 2 Ru 2 O 7 and commercial RuO 2 require 282 mV and 365 mV, respectively. The introduction of sulfur into the internal lattice, replacing a portion of oxygen ions, creates vacancies that enhance the surface adsorption of oxygen. Furthermore, density functional theory calculations expose that S-doping alters the hybridization between the Ru 4d center and O 2p orbitals, significantly decreasing the energy barrier of the rate-determining step of the OER (O*--OOH*). Consequently, the intrinsic activity of the catalyst is greatly enhanced.
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