Hydroformylation of 1-butene on Rh catalyst

Kinetics of homogeneously catalyzed hydroformylation of 1-butene was studied in a pressurized semibatch autoclave reactor. Kinetics was determined for a reaction mixture, which consisted of 1-butene, carbon monoxide, hydrogen, a rhodium-based catalyst, and 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate as a solvent. The following reaction parameters were investigated: temperature (70-100°C), total pressure (1-3 MPa), catalyst concentration (100-200 ppm), catalyst (Rh)-to-ligand ratio, and the initial ratio of the synthesis gas (hydrogen and carbon dioxide) components. The solubility of 1-butene, carbon monoxide, and hydrogen in the solvent was determined by precise pressure and weight measurements and modeled mathematically. The main reaction products were pentanal (P) and 2-methylbutanal (MB), while trace amounts of cis-2- and trans-2-butene were detected as reaction intermediates. The ratio of the main products (P and MB) was practically independent of temperature, but the ligand-to-Rh ratio affected considerably the product distribution: an increasing ratio preferred the formation of pentanal (P). Increasing total pressure diminished the yield of pentanal (P). On the basis of the experimentally recorded kinetic data, a stoichiometric scheme was constructed and simplified. The kinetic data were combined with solubility models, and the parameters of an empirical power-law rate model were determined by nonlinear regression analysis. The kinetic parameters were well identified and physically reasonable being in accordance with qualitative observations.