Pyrrolidone ligand improved Cu‐based catalysts with high performance for acetylene hydrochlorination

Abstract

A series of Cu-pyrrolidone/spherical activated carbon (SAC) catalysts were prepared via a simple incipient wetness impregnation method and then assessed in acetylene hydrochlorination, and the catalytic evaluation result indicated that the 1-methyl-2-pyrrolidinone (NMP) ligand was found to be the most effective one to significantly improve the activity and stability of Cu catalyst. The catalyst with the optimal molar ratio of NMP/Cu = 0.25 showed 94.2% acetylene conversion at 180 C and an acetylene gas hourly space velocity of 180 h −1. Moreover, the acetylene conversion of Cu-0.25NMP/SAC remained stable over 99.1% for about 220 h under the industrial condition. Transmission electron microscopy (TEM) analyses proved that NMP ligand improved the dispersion of Cu species. In addition, hydrogen temperature-programmed reduction (H 2-TPR), X-ray photoelectron spectra (XPS), thermogravimetric analysis (TGA), and Brunner-Emmet-Teller (BET) indicated that the additive of NMP was preferential to stabilize the catalytic active Cu + and Cu 2+ species and inhibit the reduction of Cu α+ to Cu 0 during the preparation process and reaction, hence restraining the coke deposition. Furthermore, the steady coordination structure between Cu and NMP was confirmed by Fourier-transform infrared spectra (FT-IR) and Raman combining with density functional theory (DFT) calculation, which could effectively lower the adsorption energy of catalyst for C 2 H 2 and inhibit the serious carbon deposition caused by excessive acetylene self-accumulation. Our findings suggest that the efficient, well-stabilized cost-effective, and environmentally friendly Cu catalyst has great potential in acetylene hydrochlorination.

Controllable Synthesis of Vacancy-Defect Cu Site and Its Catalysis for the Manufacture of Vinyl Chloride Monomer

“…The acetylene hydrochlorination activities of the Cu SAC series were investigated in a continuous-flow fixed-bed microreactor (SI, Figure S1). Notably, the vinyl chloride monomer (VCM) was the only product detected in all tests, which was commonly reported commonly for acetylene hydrochlorination catalyzed by Cu-, Au-, Pt-, Pd-, and Ru-based systems in previous studies. − A volcanic curve was presented for the three series of Cu SACs, and CuCl 2 V–N SAC showed the highest TOF value of 409 h –1 (Figure a), suggesting the vacancy-defect Cu sites facilitate the catalytic activity. As reference, the respective supported CuCl 2 precursor and Cu–N ([PrMIM + -Cl – ] and N , N -dimethylformamide) catalysts without thermal treatment, named as Cu/ACF and Cu–N/ACF, were synthesized and evaluated under the same conditions.…”

“…Two fitting peaks could be observed at 931–936 eV (Figure c). The position of the first main peak centered at ∼933.0 eV could be ascribed to Cu + or Cu 0 species, whereas the second peak at ∼935.1 eV was assigned to Cu 2+ species. − In the curves of the Cu LMM Auger spectra (SI, Figure S6), three different peaks could be fitted, including one main peak with a kinetic energy of 915.2 eV assigned to Cu + species, and two small peaks at ∼918.4 and 910.0 eV attributed to the Cu 0 species and a different Cu transition state, respectively. − The corresponding deconvolution results showed 26.2%, 24.9%, and 25.1% Cu 2+ for CuCl 3 –N SAC, CuCl 2 V–N SAC, and CuN 4 SAC, respectively. The atomic dispersion of Cu entries and their precise coordination structure were further explored by X-ray absorption fine structure spectroscopy (XAFS).…”

“…In this regard, low-priced copper (Cu)-based catalysts would be highly promising alternatives from an industrial perspective, if an efficient and durable Cu active site could be developed soon. However, the research of Cu-based catalysts in this field has not attracted enough attention, − due to the limitations of their extremely low catalytic activity and durability. The identification of Cu active sites and the determination of the corresponding reaction mechanism are still obstacles to develop Cu-based catalysts.…”

Hollow Carbon Nanospheres Decorated with Abundant Pyridinic N+O– for Efficient Acetylene Hydrochlorination

“…It is also widely used in construction, agriculture, daily necessities, and other fields due to its electrical insulating characteristics, flame retardancy, and corrosion resistance . Vinyl chloride can be synthesized by the calcium carbide acetylene process, ethane process, or petroleum ethylene process, , among which the calcium carbide acetylene process is popular in areas with rich coal resources; however, the use of volatile and highly toxic mercury chloride catalyst makes the reaction process antithetical to “green” concepts. , Therefore, it is important to identify environmentally friendly catalysts for the hydrochlorination of acetylene to replace the HgCl 2 catalyst. , For decades, researchers have focused on the selection and optimization of metal catalysts, especially Au-, − Ru-, , Cu-, − and Pd-based catalysts, which usually exhibit excellent catalytic performance; however, these metal catalysts have several shortcomings, including high prices, easy agglomeration, loss, etc . Compared with metal catalysts, environmentally friendly carbon materials with features of high surface area, tunable pore structure, mechanical/chemical strength, etc.…”

Advances in Enhancing the Stability of Cu-Based Catalysts for Methanol Reforming

“…On the contrary, the aggregation of copper particles reduces the active sites, resulting in reduced catalyst activity. Researchers usually analyze the dispersion of Cu-based catalysts by XRD, N 2 O pulse titration, TEM, and H 2 temperatureprogrammed reduction (H 2 -TPR) [67]. The factors that affect the sintering and aggregation of copper particles are also different.…”