The preparation of CuM/SiO2 (M=Bi, Mg, Mn) catalysts applied in ethynylation of formaldehyde for 1,4‑butynediol synthesis: the positive interface effect of CuO and Bi2O3

The ethynylation of formaldehyde reaction catalyzed by Cu-based catalysts is an important synthesis method for 1,4-butynediol relating to high value-added chemicals. In this work, a series of CuM/SiO2 ( M=Bi, Mg, Mn ) catalysts were prepared by a deposition-precipitation method and applied in the ethynylation reaction. The effects of different promoters ( Bi, Mg, Mn ) on the catalytic activity were investigated. The relationship between catalyst structure and performance is systematically studied using XRD, TEM, SEM mapping, N2 low- temperature adsorption/desorption, FT-IR, XPS, and TG-DTA characterization analysis. The results show that 30Cu2Bi/SiO2 exhibits the highest 1,4-butynediol yield (70%) and selectivity (97%) after the ethynylation reaction for 7 h. Furthermore, compared with the commercial catalyst, 30Cu2Bi/SiO2 shows similar cyclic stability, 47% yield, and 98% selectivity for 1,4-butynediol after 8 times about 60 h. It is attributed that small CuO particles are uniformly dispersed in 30Cu2Bi/SiO2 with the biggest specific surface area (446.37 m2/g). What’s more, the Cu-Bi interface existing in 30Cu2Bi/SiO2 plays an important role in stabilizing cuprous, not excessively reduced to metallic Cu. Therefore, during the ethynylation reaction, 30Cu2Bi/SiO2 has the most active Cu2C2 and the least polyacetylene by-products. In addition, the richest oxygen vacancies arose in 30Cu2Bi/SiO2 also contribute to the ethynylation of the formaldehyde reaction.