Improvement of Homogeneous Catalysts for Methanol Carbonylation to Acetic Acid: Effects of Three-Ethyl Phosphine and Three-Phenyl Phosphine as Ligands

The carbonylation of methanol is a catalytic homogeneous process that has been expanded for industrial applications. The metal-organic complexes utilized as homogeneous catalysts for acetic acid production encompass Co, Ru, Ir, Ni, and Rh-based catalysts. While conventional Rh-complex continue to be employed in the industry today, significant efforts are underway to enhance them, particularly by incorporating ligands that can boost their activity. Introducing ligands can result in an increased reaction rate, while stability concerns frequently restrict this approach. Recent developments in creating appropriate ligands, primarily derived from phosphorus-based systems, enable the production of highly effective and reliable Rh catalyst. In this study, the effects of three-ethyl phosphine and three-phenyl phosphine as a ligand in rhodium three iodide have been detected and compared with Rh3I. The study depicts the measurement of yield and comparison of solubility, as well as the survey of chain reaction and intermediate components in Monsanto reactions. Furthermore, it demonstrated that when 3PP was utilized instead of iodide in the rhodium catalyst, the rate of reactions increased. After 12 hours, methanol finished the catalyst with 3PP raised the rate of the reactions, and was more soluble compared with Rh-3EP, and Rh3I. Solubility of Rh-3PP catalyst during 12 hr raised from 0.0 to 138 ppm. On the other hand, 3EP depicted more activity for acetic acid production. The yield per hour of three ethyl phosphines was 4.62. Furthermore, the yield for Rh-3PP and Rh3I was 3.46, and 2.91 respectively.