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

Yanhe You,Bin Dai,Jianwei Xie,Juan Luo

doi:10.3390/catal7120394

Yanhe You, Bin Dai + Show 2 more

Open Access

https://doi.org/10.3390/catal7120394

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Abstract

The iminodiacetic acid-modified Nieuwland catalyst not only improves the conversion of acetylene but also increases the selectivity of monovinylacetylene (MVA). A catalyst system containing 4.5% iminodiacetic acid exhibited excellent performance, and the yield of MVA was maintained at 32% after 24 h, producing an increase in the yield by 12% relative to the Nieuwland catalyst system. Based on a variety of characterization methods analysis of the crystal precipitated from the catalyst solution, it can be inferred that the outstanding performance and lifetime of the catalyst system was due to the presence of iminodiacetic acid, which increases the electron density of Cu+ and adjusts the acidity of the catalytic solution.

Highlights

The catalytic performances of NC and L-NC were tested under fixed reaction conditions, and the results are shown in Figure 1 and Table 1
For MVA selectivity, all the L-NCs exhibited good selectivity in the range of 76–87%, whereas there was only 76% MVA selectivity for NC. This was surprising given the previous findings that a higher acetylene conversion resulted in lower MVA selectivity
The results of the effect of the amount of L1 showed that an optimal catalytic performance for acetylene dimerization was achieved when 4.5% of L1 was used, which is shown in Figure 2 and Table 2

Summary

Catalytic Activities of NC and L-NC

The catalytic performances of NC and L-NC were tested under fixed reaction conditions (space velocity of acetylene = 105 h−1, reaction temperature = 80 ◦C, L: CuCl = 0.03:1), and the results are shown in Figure 1 and Table 1. For MVA selectivity, all the L-NCs exhibited good selectivity in the range of 76–87%, whereas there was only 76% MVA selectivity for NC This was surprising given the previous findings that a higher acetylene conversion resulted in lower MVA selectivity. L1 is the most efficient ligand in this reaction with 29.3% acetylene conversion and 84.6% MVA selectivity. The results of the effect of the amount of L1 showed that an optimal catalytic performance for acetylene dimerization was achieved when 4.5% of L1 was used, which is shown in Figure 2 and Table 2. IR spectra of the crystal A (a), crystal B and L1 (b)

Action of the Ligand

Relationship between the Valence of Copper and Catalytic Activity

Conclusions