Branched Regioselectivity in the Heterogeneous Hydroformylation of Terminal Olefins: A “Two-Step Process” Method and Kinetic Optimization

Hydroformylation of olefins to aldehydes is an important reaction in the chemical industry. The development of heterogeneous catalysts has attracted much attention due to their ease of separation and environmental friendliness. Although researchers have focused more on linear products, branched aldehydes also have wide applications, serving as important chemical products or intermediates in fragrance, pharmaceutical, and other fields. In this work, we propose a tandem “two-step process” method to obtain high regioselectivity of branched aldehydes with the same catalyst, even when using terminal olefins as the reactants. The method includes the isomerization process of the terminal olefins to internal olefins and the subsequent heterogeneous hydroformylation process, converting internal olefins to branched aldehydes. The kinetic model of heterogeneous hydroformylation of internal olefins is also established, and the predicted b/l ratio under different reaction conditions is consistent with the experimental results. After the optimization of reaction conditions, the highest b/l ratio of the ″two-step process” for 1-octene reaches 33.34, which is 39 times higher than that obtained by direct hydroformylation and surpasses all branched regioselectivities reported in other literature, to the best of our knowledge. This work not only deepens the mechanistic understanding of heterogeneous hydroformylation of both terminal and internal olefins but also provides inspiration and practical guidance for the industrial production of branched aldehydes.