To address the low linear aldehyde selectivity in the hydroformylation of long-chain olefins and the insufficient utilization of conventional heterogeneous Rh catalysts, Rh was encapsulated in a highly dispersed state within the channels of MFI-type zeolite via a ligand-protected in situ hydrothermal method and a dry gel conversion strategy. The results show that the calcination atmosphere can tune the pore microenvironment: air calcination removes the template and opens the pores but leads to low regioselectivity; N₂/CO₂ calcination retains residual carbon, slightly narrows the micropores, and suppresses the branched transition state through steric hindrance, thereby significantly increasing the n/iso ratio of the aldehyde products. Rh@S-1 was synthesized by the dry gel conversion (DGC) method, which avoids Rh leaching in conventional hydrothermal synthesis. The matching effect between calcination temperature and Rh loading was investigated. At low Rh loading, atomically dispersed Rh calcined at a relatively low temperature exhibits excellent activity, whereas high-temperature calcination causes deactivation due to the formation of irreducible rhodium silicate through strong metal–support interactions. At high Rh loading, high-temperature calcination forms Rh nanoparticles accessible on the external surface, which weaken CO adsorption and promote CO insertion, thus increasing the TOF. Selective thiol poisoning experiments indicate that Rh sites at the pore mouths and on the external surface are important sources of the nonselective branched pathway; poisoning the pore mouths can greatly enhance linear selectivity at the expense of partial conversion. This work provides a useful basis for the design of efficient supported noble metal catalysts.

hydroformylation; rhodium; zeolite; regioselectivity