Method for on-line prediction of conjunct polymer concentration in a hydrocarbon conversion process

A method for predicting a concentration of conjunct polymer concentration in a spent ionic liquid of unknown conjunct polymer concentration, during a continuous hydrocarbon conversion process, the method comprising:

• (a) separating an effluent from a reaction zone into a light fraction and a heavy fraction, the heavy fraction comprising spent ionic liquid of unknown conjunct polymer concentration;
• (b) acquiring an infrared spectrum for each of a plurality of samples of the spent ionic liquid using an in-line infrared spectrometer configured with a measurement cell to allow the spent ionic liquid to flow therethrough;
• (c) separately determining a concentration of conjunct polymer in the spent ionic liquid by acquiring an infrared spectrum for each of a plurality of samples using an off-line infrared spectrometer;
• (d) analyzing the infrared spectra acquired in (b) and (c) using a multivariate chemometric technique to provide a training data set;
• (e) generating a predictive model for conjunct polymer concentration based on the training data set;
• (f) applying the predictive model to the infrared spectra acquired in (b);
• and thereafter
• (g) quantitatively predicting the conjunct polymer concentration in the spent ionic liquid during the continuous hydrocarbon conversion process.