For gas phase reactions, such as cracking or methanol-to-olefins, the introduction of mesopores (2 - 50 nm) and/or macropore (>50 nm) into zeolite structure leads to the occurence of Knudsen diffusion mechanism since diffusion relies on wall collisions to direct molecular flow.
Does this diffusion also occur when hierarchical zeolite used as catalyst in liquid phase reaction, i.e. self condensation of cylohexanone??
Please refer me to articles or books regarding the diffusion of organic liquid phase reaction in hierarchical zeolites.
Thank you
Diffusion controlled and chemically controlled reactions (and distinguishing between them) are a feature of all catalysis, not just zeolites. Read a general text book such as Bond's Heterogeneous Catalysis.(Oxford University Press, 1974) - I believe the first chapter.
If you mean Knudsen diffusion then it applies mostly in gas phase. The fluid diffusion in liquid phase is even more problematic. As the arrangement of molecules in liquid phase is more packed so the probability for inter-molecules collision is higher leading to more, i would say, molecular diffusion instead of Knudsen diffusion (requiring a longer free mean path and direct collision between the pore wall and molecule). Or neither Knudsen nor molecular diffusion can precisely describe the condition. Other alternative books that might help you: Elements of Chemical Reaction Engineering (Fogler) and Fundamentals of Chemical Reaction Engineering (Mark E Davis & Robert Davis) but i cant remember precisely which chapter it is.
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Materials Science
- Materials Chemistry