In situ FTIR study of low-pressure hydroformylation of 1-hexene catalyzed by ultrafine cobalt nanoparticles

Abstract

The hydroformylation of 1-hexene in syngas (CO:H 2 = 1) under 2–3 MPa at 100 °C was catalyzed using 2.8 nm ultrafine cobalt nanoparticles and investigated by in situ Fourier transform infrared spectroscopy (FTIR). A group of bands observed in the in situ FTIR spectra at 2071, 2041, and 2022 cm −1 are assigned to terminal CO adsorptions distributed over different Co sites. A band at 2054 cm −1 is attributed to the intermediate, RCH 2 CH 2 COCo, which has been observed for the first time. Through this intermediate, the catalytic reaction proceeds via the elimination of RCH 2 CH 2 COCo to leave a single H atom on the surface of each 2.8-nm Co nanoparticle. 利用原位透射红外光谱研究了2.8 nm超细钴纳米粒子在2 ∼ 3 MPa合成气(CO:H 2 = 1:1)和100 °C条件下催化的1-己烯氢甲酰化反应. 结果表明, 在反应中出现与Co 2 (CO) 8 类似的红外吸收峰(2071, 2041和2022 cm −1 ), 被证明是不同Co位点端式吸附CO. 首次观测到了位于2054 cm −1 处吸收峰处的物种, 可能归属为RCH 2 CH 2 COCo. 通过此中间物种，产物醛可以在钴催化剂表面经由结合一个氢原子脱除反应而获得. An in situ FTIR observation of the hydroformylation reaction conducted using a Co nanoparticle-based system suggests that some of the observed bands in the FTIR spectrum are similar to those of the original Co complex. The unique absorption band at 2054 cm −1 corresponds to terminal CO adsorptions bound to different cobalt sites.