Mass Transfer in Catalytic Depolymerization: Serendipitous Processivity in Stagnant and Stirred Melts

Concentration profiles in stagnant and stirring medium.

Scientific Achievement

Developed expressions for external mass transfer effects and transport induced β€œserendipitous” processivity for catalysts in stagnant and stirred melts.  Also derived theory to predict rate of polymer chain-end insertion into pore mouth.  

Significance and Impact

The study predicts the effects of diffusion limitations on co-reactant transport to the catalyst and on chain egress after scission.  We emphasize that studies should report stirring rates and catalyst particle sizes, with analyses illustrated herein, to ensure mass transfer effects are insignificant.  

Research Details

  • Co-reactant diffusion limitations: hext = (1+ k(Pe))-1
  • Processivity from chain egress limits: npro = 1+ k(Pe)
  • Results for stagnant and stirred melts: Pe = R2g/D, k = ksd/D, d = 2R/Sh(Pe), and π‘†β„Ž(𝑃𝑒)=2+0.514𝑃𝑒^(1/2)+…
  • Predicted pore-mouth insertion rate: π‘—_𝑒=πœ‹π‘…_π‘π‘œπ‘Ÿπ‘’^2 [𝑒] 𝐷_𝑒/𝐿_π‘π‘Ÿπ‘œπ‘‘π‘’π‘π‘‘

J. Ge and B. Peters, Chem. Eng. J., 2023, 466 143251. https://doi.org/10.1016/j.cej.2023.143251