Within the project ‘Testing and Evaluation of Nanofiltration Membranes in Industrial Processes‘ (TENMIP) it was evaluated if nanofiltration can replace energy intensive distillation.
Two industrial partners (Shell and Huntsman) selected five industrial processes for which the separation is difficult and/or energy intensive. Five membrane developers (Univ. Twente, KU Leuven, ECN part of TNO, VITO and SolSep) selected five membrane composition concepts within their own range of expertise that could potentially be suitable for the proposed cases.
The difficulty lays in small differences in size, shape, polarizability and complexity of the compounds to be separated. Also, the low molecular weight cut-off of less the 300 Da needed for these separations and the high process temperatures (>100°C) are a challenge.
Proven membranes types screened first on model mixtures and tailored to optimize the performance for the selected cases. In this way over 100 screening experiments were done on varying membrane types, cases and/or conditions. The best preforming membranes were selected per case and tested for the process mixtures.
It was shown through tests with model mixtures that it is possible to obtain good separation with a good permeate flow with some membrane types. However, the results could not be reproduced using the actual process mixtures or under actual process conditions. This was probably due to specific differences in composition between the industrial process mixtures and model feeds.
The economics of OSN separation for the five industrial processes were calculated, using an excel based calculation tool, and when possible compared to the existing process. It was found that two membranes tested in the model mixtures meet the required separation demand as set by the end-user.