Abstract
The in situ formed Cu+ species serve as active sites in the ethynylation of formaldehyde. The key problem that needs to be solved in this process is how to avoid excessive reduction of Cu2+ to inactive metallic Cu, which tends to decrease the catalytic activity. In this work, Cl−-modified Cu2O catalysts with different Cl content were prepared by co-precipitation. The characterization results demonstrated that Cl− remained in the lattice structure of Cu2O, inducing the expansion of the Cu2O lattice and the enhancement of the Cu–O bond strength. Consequently, the reduction of Cu+ to Cu0 was effectively prevented in reductive media. Moreover, the activity and stability of Cu2O were significantly improved. The Cl− modification increased the yield of 1,4-butynediol (BD) from 73% to 94% at a reaction temperature of 90 °C. More importantly, the BD yield of Cl− modified Cu2O was still as high as 86% during the ten-cycle experiment, whereas the BD yield of Cu2O in the absence of Cl− decreased sharply to 17% at the same reaction conditions. This work provides a simple strategy to stabilize Cu+ in reductive media.
Highlights
Catalytic ethynylation of formaldehyde is an important initial process for mass production of high-value intermediates, such as 1,4-butynediol (BD), propynol (PO), and downstream chemicals, such as 1,4-butanediol (BDO), 3-butene-1-alcohol (BTO), tetrahydrofuran (THF), poly glycol (PTMEG), γ-butyrolactone (GBL), polybutylene succinate (PBS), and polybutylene terephthalate (PBT)
Based on the combination of characterization results, we speculate that the fundamental reason for different catalytic activity and stability is the difference in the reduction performance caused
Based oncatalytic the combination of characterization results, weinspeculate the fundamental reason for different activity and stability is the+difference the Cu2Othat reduction performance caused by the Cl−−catalytic modification
Summary
Catalytic ethynylation of formaldehyde is an important initial process for mass production of high-value intermediates, such as 1,4-butynediol (BD), propynol (PO), and downstream chemicals, such as 1,4-butanediol (BDO), 3-butene-1-alcohol (BTO), tetrahydrofuran (THF), poly (tetramethylene ether) glycol (PTMEG), γ-butyrolactone (GBL), polybutylene succinate (PBS), and polybutylene terephthalate (PBT). These compounds are in high demand in various industries, such as pharmaceutical, textile, military, electrical/electronics, automotive manufacturing, and others [1,2,3,4,5,6,7,8]. Literature mainly reports introducing Bi2 O3 to inhibit over-reduction of Cu2+ [15,19,20]
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