9002-86-2Relevant academic research and scientific papers
Phosphine-oxide organic ligand improved Cu-based catalyst for acetylene hydrochlorination
Li, Wei,Liu, Yawen,Wang, Bao,Zhang, Haiyang,Zhang, Jinli,Zhang, Tiantong
, (2021/12/08)
Considering the disadvantages of Cu-based catalyst for acetylene hydrochlorination, such as poor dispersion, severe carbon deposition and insufficient active sites, supported Cu-complex catalysts were synthesized by using phosphine-oxide organic compounds as ligands. A local active domain was successfully constructed based on the complexation of Cu atom to heteroatomic structure in meticulously selected ligands, in which the phenyl group acts as an electron donor to change the CuCl2 active site electronic structure. The density functional theory calculation proved the existence of a strong interaction between triphenylphosphine oxide and CuCl2, and synchronously, electrons on the benzene ring were transferred to the Cl atom in CuCl2, stabilizing the Cu species. This superior activity may be attributed to the heightened adsorption of HCl and weakened C2H2 and vinyl chloride adsorption by the constructed local active domain, which impedes the carbon deposition that promotes the continuous exposure of active sites. Under the reaction conditions: T = 180 ℃, GHSVC2H2 = 180 h?1 and VHCl/VC2H2 = 1.2, the C2H2 conversion of 15%Cu7%TPPO/AC reaches 88%, which was over 30% higher than 15%Cu/AC catalyst. The significantly improved activity and stability of the proposed catalyst provides a reference for green and sustainable production of vinyl chloride.
Acetylene hydrochlorination over supported ionic liquid phase (SILP) gold-based catalyst: Stabilization of cationic Au species via chemical activation of hydrogen chloride and corresponding mechanisms
Fang, Zheng,Feng, Feng,Guo, Lingling,Jin, Chunxiao,Li, Xiaonian,Lu, Jinyue,Pan, Zhiyan,Pang, Xiangxue,Wang, Bolin,Wang, Saisai,Yue, Yuxue,Zhao, Jia
, p. 334 - 346 (2020/07/25)
The activation of HCl by cationic Au in the presence of C2H2 is important for the construction of active Au sites and in acetylene hydrochlorination. Here, we report a strategy for activating HCl by the Au-based supported ionic liquid phase (Au–SILP) technology with the [N(CN)2?] anion. This strategy enables HCl to accept electrons from [N(CN)2?] anions in Au–[N(CN)2?] complexes rather than from pure [Bmim][N(CN)2], leading to notable improvement in both the reaction path and the stability of the catalyst without changing the reaction triggered by acetylene adsorption. Furthermore, the induction period of the Au–SILP catalyst was shown to be absent in the reaction process due to the high Au(III) content in the Au(III)/Au(I) site and the high substrate diffusion rate in the ionic liquid layer. This work provides a facile method to improve the stability of Au-based catalysts for acetylene hydrochlorination.
Sustainable Synthesis of Bimetallic Single Atom Gold-Based Catalysts with Enhanced Durability in Acetylene Hydrochlorination
Kaiser, Selina K.,Clark, Adam H.,Cartocci, Lucrezia,Krumeich, Frank,Pérez-Ramírez, Javier
, (2021/01/15)
Gold single-atom catalysts (SACs) exhibit outstanding reactivity in acetylene hydrochlorination to vinyl chloride, but their practical applicability is compromised by current synthesis protocols, using aqua regia as chlorine-based dispersing agent, and their high susceptibility to sintering on non-functionalized carbon supports at >500 K and/or under reaction conditions. Herein, a sustainable synthesis route to carbon-supported gold nanostructures in bimetallic catalysts is developed by employing salts as alternative chlorine source, allowing for tailored gold dispersion, ultimately reaching atomic level when using H2PtCl6. To rationalize these observations, several synthesis parameters (i.e., pH, Cl-content) as well as the choice of metal chlorides are evaluated, hinting at the key role of platinum in promoting a chlorine-mediated dispersion mechanism. This can be further extrapolated to redisperse large gold agglomerates (>70?nm) on carbon carriers into isolated atoms, which has important implications for catalyst regeneration. Another key role of platinum single atoms is to inhibit the sintering of their spatially isolated gold-based analogs up to 800 K and during acetylene hydrochlorination, without compromising the intrinsic activity of Au(I)-Cl active sites. Accordingly, exploiting cooperativity effects of a second metal is a promising strategy towards practical applicability of gold SACs, opening up exciting opportunities for multifunctional single-atom catalysis.
Carbon-supported copper–organic framework as active catalysts for acetylene hydrochlorination
Han, Yong-Jun,Li, Fu-Xiang,Li, Qing-Bin,Li, Song-Tian,Ma, Yao,Wu, Yi-Bo
, p. 812 - 820 (2021/10/05)
In this work, activated carbon supported Cu-MOF was used as an acetylene hydrochlorination catalyst to manufacture vinyl chloride. Cu-MOF/AC with 15 wt. % Cu-MOF content has the initial acetylene conversion of 99.2% and vinyl chloride selectivity of 98.5% at 200 °C. By combining steady-state experiments and physical–chemical characterization results (XPS, BET, H2-TPR, C2H2-TPD, XRD, and HCl adsorption experiments), Cu–O–C is shown to slow the reduction of Cu2+, improve the reactants adsorption, and strengthen the anti-coking ability of Cu-based catalysts. According to the previous studies and the Eley–Rideal mechanism, it is proposed that Cu2+ first adsorbed C2H2 to generate transition states in acetylene hydrochlorination catalysis.
Waste cigarette butt-derived nitrogen-doped porous carbon as a non-mercury catalyst for acetylene hydrochlorination
Feng, Hongbin,Hao, Yalei,Hu, Jiapeng,Jin, Xin,Li, Xingyun,Liu, Chengxiang,Song, Yujiang,Zhou, Yuxin,Zhu, Yan
, p. 19358 - 19363 (2021/11/09)
The development of advanced carbon materials as metal-free catalysts holds great importance for mercury catalyst replacement in acetylene hydrochlorination. In this paper, we transform discarded cigarette butts into a porous nitrogen-doped carbon material (N-CB-800), exhibiting characteristics of high specific surface area, large N doping amount, defective structure and strong C2H2 chemical adsorption ability. These unique features endow N-CB-800 with a high catalytic performance with an acetylene conversion of 71.8% at 220 °C and an acetylene space velocity of 100 h-1, making it one of the most active metal-free catalysts. This work will be of great value for the recycling of living waste and provide meaningful guidance for the development of non-mercury catalysts for acetylene hydrochlorination.
Effect of transition metal oxide doping on catalytic activity of titania for the oxidation of 1,2-dichloroethane
Zhang, Xing,Liu, Yuxi,Deng, Jiguang,Jing, Lin,Yu, Xiaohui,Han, Zhuo,Dai, Hongxing
, p. 623 - 634 (2019/12/27)
Transition metal oxides (MOx; M = Cr, Mn, Fe, Ni, Cu)-doped titania solid solution catalysts (10 wt% MOx–TiO2, denoted as 10MOx–TiO2) were prepared by the coprecipitation method. The techniques of XRD, TPR, TPD, XPS, TPSR, and in situ DRIFTS were used to characterize physicochemical properties of the materials, and their catalytic activities were evaluated for the oxidation of 1,2-dichloroethane (1,2-DCE). The introduction of MOx enhanced adsorption and activation of oxygen molecules, mobility of surface lattice oxygen, and low-temperature reducibility. The 10MOx–TiO2 catalysts showed good performance, with 10CrOx–TiO2 exhibiting the highest catalytic activity (reaction rate = 2.35 × 10?7 mol/(gcat s) and apparent activation energy (Ea) =35 kJ/mol at space velocity = 40,000 mL/(g h)) and good resistance to chlorine poisoning, The mechanism of 1,2-DCE oxidation over 10CrOx–TiO2 was also discussed based on the results of TPSR and in situ DRIFTS characterization. It is concluded that strong acidity and redox ability, high adsorbed oxygen species concentration, and strong interaction between TiO2 and CrOx were accountable for the good performance of 10CrOx–TiO2.
Nitrogen-Doped Carbon-Assisted One-pot Tandem Reaction for Vinyl Chloride Production via Ethylene Oxychlorination
Chen, De,Chen, Qingjun,Fuglerud, Terje,Ma, Guoyan,Ma, Hongfei,Qi, Yanying,Rout, Kumar R.,Wang, Yalan
supporting information, p. 22080 - 22085 (2020/10/02)
A bifunctional catalyst comprising CuCl2/Al2O3 and nitrogen-doped carbon was developed for an efficient one-pot ethylene oxychlorination process to produce vinyl chloride monomer (VCM) up to 76 % yield at 250 °C and under ambient pressure, which is higher than the conventional industrial two-step process (≈50 %) in a single pass. In the second bed, active sites containing N-functional groups on the metal-free N-doped carbon catalyzed both ethylene oxychlorination and ethylene dichloride (EDC) dehydrochlorination under the mild conditions. Benefitting from the bifunctionality of the N-doped carbon, VCM formation was intensified by the surface Cl*-looping of EDC dehydrochlorination and ethylene oxychlorination. Both reactions were enhanced by in situ consumption of surface Cl* by oxychlorination, in which Cl* was generated by EDC dehydrochlorination. This work offers a promising alternative pathway to VCM production via ethylene oxychlorination at mild conditions through a single pass reactor.
High performance of supported Cu-based catalysts modulated via phosphamide coordination in acetylene hydrochlorination
Hu, Yubing,Wang, Yan,Wang, Yulian,Li, Wei,Zhang, Jinli,Han, You
, (2020/01/08)
In order to develop a cut-price, high-efficiency non-mercuric catalyst for acetylene hydrochlorination reaction, several kinds of supported Cu-based catalysts containing phosphoramide ligands have been synthesized by wet impregnation method. The outstanding catalytic activity was obtained over 15 %Cu10 %HMPA/SAC catalyst with acetylene conversion of 87.25 % in the test conditions of T =180 °C, GHSV(C2H2) =180 h?1 and V(HCl): V(C2H2) = 1.2. The catalyst with optimal HMPA ligand also exhibited splendid stability in 100 h lifetime test. The analysis for XRD, TEM, TGA, ICP, H2-TPR and XPS indicated that HMPA ligand can improve Cu species dispersion, restrain coke deposition, suppress loss of loading Cu, and stabilize valence state of active Cu species. Due to electron transfer mechanism, steady coordination structure between Cu and HMPA led to favorable properties of Cu-based catalyst, which was further proved by FT-IR, Raman spectra, O 1s XPS spectra integrated with DFT calculations.
Boron-doped carbon nanodots dispersed on graphitic carbon as high-performance catalysts for acetylene hydrochlorination
Yue, Yuxue,Wang, Bolin,Wang, Saisai,Jin, Chunxiao,Lu, Jinyue,Fang, Zheng,Shao, Shujuan,Pan, Zhiyan,Ni, Jun,Zhao, Jia,Li, Xiaonian
supporting information, p. 5174 - 5177 (2020/05/26)
Boron-doped carbon nanodot materials, comprising evenly distributed BC3-nanodots in a layered carbon matrix, are prepared through a pre-assembly assisted carbonization synthetic strategy. The prepared materials are endowed with high electron affinity and distortion resistance, which provides a stable framework while generating affinity to substrates.
In situ K-edge X-ray absorption spectroscopy of the ligand environment of single-site Au/C catalysts during acetylene hydrochlorination
Aramini, Matteo,Freakley, Simon J.,Gianolio, Diego,Gibson, Emma K.,Hutchings, Graham J.,Johnston, Peter,Kondrat, Simon A.,Malta, Grazia,Morgan, David J.,Thompson, Paul B. J.,Wells, Peter P.
, p. 7040 - 7052 (2020/07/23)
The replacement of HgCl2/C with Au/C as a catalyst for acetylene hydrochlorination represents a significant reduction in the environmental impact of this industrial process. Under reaction conditions atomically dispersed cationic Au species are the catalytic active site, representing a large-scale application of heterogeneous single-site catalysts. While the metal nuclearity and oxidation state under operating conditions has been investigated in catalysts prepared from aqua regia and thiosulphate, limited studies have focused on the ligand environment surrounding the metal centre. We now report K-edge soft X-ray absorption spectroscopy of the Cl and S ligand species used to stabilise these isolated cationic Au centres in the harsh reaction conditions. We demonstrate the presence of three distinct Cl species in the materials; inorganic Cl-, Au-Cl, and C-Cl and how these species evolve during reaction. Direct evidence of Au-S interactions is confirmed in catalysts prepared using thiosulfate precursors which show high stability towards reduction to inactive metal nanoparticles. This stability was clear during gas switching experiments, where exposure to C2H2 alone did not dramatically alter the Au electronic structure and consequently did not deactivate the thiosulfate catalyst.
