Effect of Cu+/Cu2+ Ratio on the Catalytic Behavior of Anhydrous Nieuwland Catalyst during Dimerization of Acetylene

Abstract

Abstract:The relative contents of Cu + and Cu 2+ in solutions of anhydrous Nieuwland catalyst and CuCl 2 -added anhydrous Nieuwland catalyst were detected by X-ray photoelectron spectroscopy (XPS). Results indicated that Cu + could be transformed into Cu 2+ during the process of acetylene dimerization into monovinylacetylene, leading to deactivation of the catalyst. Moreover, the addition of Cu 2+ inhibited the oxidation of Cu + into Cu 2+ and enhanced the performance and lifetime of the catalyst. The optimum molar ratio of Cu + to Cu 2+ was approximately 2:1; at this ratio, up to 40% acetylene conversion may be achieved.

Ultrathin Cu-TCPP MOF nanosheets: a new theragnostic nanoplatform with magnetic resonance/near-infrared thermal imaging for synergistic phototherapy of cancers

“…Figure 2 B shows the Cu 2p spectrum for Cu-TCPP. The binding energy at 944.0 eV was assigned to the shake-up satellite peak of Cu 2+ ; a Cu 2p 3/2 (934.8 eV) peak and a Cu 2p 1/2 (954.7 eV) peak as well as two shakeup satellites in the Cu 2p spectrum confirmed the coexistence of two copper valence states, Cu 2+ and Cu + 27 . The relative atomic percentages of Cu 2+ and Cu + were determined by XPS to be 63% and 37%, respectively.…”

Effect of Iminodiacetic Acid-Modified Nieuwland Catalyst on the Acetylene Dimerization Reaction

“…Han et al reported that the addition of DL-alanine to the Nieuwland catalyst can reduce the activity of acetylene dimerization and improve the MVA selectivity [25]. We also found that the addition of SrCl 2 [26], ZnCl 2 [27], PEGs [28], and CuCl 2 [9] can improve the selectivity of MVA or the lifetime of the catalyst. However, these modified catalysts can only improve either the acetylene conversion or MVA selectivity, and simultaneous improvements in conversion and selectivity have not been reported in the literature.…”

“…However, our previous studies found that Cu 2+ also plays an important role in the acetylene dimerization reaction, and the deactivation of the anhydrous NC was caused by the transformation of Cu + to Cu 2+ [9]. Hence, valence changes for copper species in fresh and used NC and L1-NC were evaluated via high-resolution XPS, and the results are shown in Figure 9 and Table 4.…”

“…Because of the practical importance and the long history of the Nieuwland catalyst, recent studies on the reaction mechanism [1, [6][7][8][9], catalyst structure [10,11], and factors affecting the catalytic performance [11][12][13][14][15][16][17][18][19] have attracted significant attention. In general, it catalyzes a homogenous transition metal-catalyzed organic transformation; the addition of a second metal and ligand/additive results in changes in the electronic structure of the active metal, thus causing change in the performance of the catalyst; the change in the electronic structure of the active metal may be due to an electron transfer between the active metal and second metal or ligand/additive.…”

Effects of Coordination Ability of Nitrogen-Containing Carboxylic Acid Ligands on Nieuwland Catalyst

“…It is well known that Cu + is the main active component of the Nieuwland catalyst, and it has been reported in our previous work that the content of Cu + is related to the activity of the anhydrous Nieuwland catalyst [20]. Therefore, we investigated the valence charges of copper species using high-resolution XPS.…”