In Situ DRIFTS Investigation During the Adsorption of 1-Pentyne and Catalytic Performance of Pd–Ni Bimetallic Catalysts for Olefinic Purification

In Situ DRIFTS Analysis during Hydrogenation of 1‐Pentyne and Olefin Purification with Ag Nanoparticles

“…A negative signal of −OH groups of alumina at 3730 cm −1 is evidenced on Al and AlMg supports, which is attributed to the formation of hydrogen bonds with 1‐pentyne with OH groups [32,46,47] . Furthermore, a signal at 3940 cm −1 is observed on Al, AlMg and Ca supports with different intensity, associated to the formation of a complex between OH groups and 1‐Pentyne due to the dissociative adsorption; which are consistent with previous studies [29] . In Figure 6 are schematically represented the species of 1‐Pentyne adsorbed over Al (1 – 3) , AlMg (1 – 4) and Ca (5) supports [32,46] …”

“…The peaks evidenced over Ag/Ca and Ag/RX3 at 3337 and 650 could be considered as hydrocarbon species with the role of spectators or related species to the growth process of oligomers formations during the hydrogenation processes [29,33,45,47] …”

“…In previous works of our group, during the selective hydrogenation of alkynes and the purification of alkyne/alkene mixtures with Pd catalysts, it was found that the use the different supports had electronic and geometric effects that improved the activity of Pd catalysts [7,11,29] . However, the effect of the acidity, surface properties and intermediate species over Ag catalysts with different supports has not been investigated in detail for selective hydrogenation of medium/long chain alkynes neither for the purification of alkene/alkyne mixtures.…”

“…On the other hand, in the last decade Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) has become a very popular method for the characterization of catalysts and it has been applied quite extensively to the identification of all adsorbed species on the surface, and consequently can contribute to the identification of reaction intermediates [28] . Recent works of catalytic systems using infrared spectroscopy to study the adsorption of alkynes and alkenes over supported metal catalysts and single crystals, have been published [14,16,29–34] …”

“…[28] Recent works of catalytic systems using infrared spectroscopy to study the adsorption of alkynes and alkenes over supported metal catalysts and single crystals, have been published. [14,16,[29][30][31][32][33][34] There are very few researches over the use of heterogeneous Ag catalysts during the selective hydrogenation of pure alkynes at mild operational conditions, neither regarded the purification or alkene/alkyne mixtures. Besides, to optimize the performance of Ag catalysts, it is essential to understand the effect of the support over the catalytic activity during the selective hydrogenation processes.…”