Location: WUR Building 316, room C7
Aim of the seminar series is informing people about nanotechnology research in Wageningen and other institutions in the Netherlands by Pieter Stroeve.
Programme
13.30: Pieter Stroeve: Environment
14.30: Jos Keurentjes, Process Development Group, Eindhoven University of Technology: Micellar Systems for Nanoscale Engineering of Reaction and Separation Processes.
The 21st century will require the development of a sustainable process industry. This asks for processes that generate a minimum amount of waste, efficiently use raw materials and energy, and in which no net consumption of auxiliary fluids (solvents) occurs. This lecture will discuss two applications of “soft” nanotechnology for the development of novel process concepts for reaction and separation.
In many processes scaling by precipitation of divalent metal ions (e.g. calcium and barium) represents a serious problem. We have developed antiscalants that can easily be recycled by applying a moderate temperature shift. These are based on polymeric surfactants of the Pluronic type (PEO-PPO-PEO triblock copolymers), modified with carboxylic acid groups. Above the critical micelle formation temperature (CMT) these surfactants are present as micelles, in which carboxylic acid groups present on different polymer chains are located relatively close to each other, thus allowing for metal binding. After concentration by nanofiltration or reverse osmosis, a decrease in temperature to a value below the CMT induces the micelle to fall apart into the single surfactant molecules. As the carboxylic acid groups on one single surfactant are too far apart for metal binding, the metal ions are released and can easily be precipitated from the concentrated solution.
A second example describes the development of a clean process for the production of propylene oxide using hydrogen peroxide as the oxidant. A microheterogeneous environment is created by immobilizing various apolar homogeneous catalysts in the core of micelles dissolved in water. This increases the reaction selectivity as compared to heterogeneous catalysts, an effect that is even more pronounced due to in-situ extraction of the polar product towards the surrounding water phase. Various catalysts and surfactants have been evaluated for this purpose. Based on the reaction kinetics a process has been designed, in which the catalyst containing micelles can effectively be recycled using an ultrafiltration membrane.
Process Development Group, Eindhoven University of Technology