Influence of Cross-Linking at Low Polymer Content
Fig. 8.16 shows the effective reaction rate for the synthesis of MTBE for three catalyst samples with different cross-linking and a low polymer content of 11 %. More cross-linking shifts the expected maximum of the MTBE reaction rate to lower methanol concentrations. In general, with more cross-linking the ratio of the polar compound to the non-polar reactant will rise. For MTBE synthesis this means that a high cross-linked resin contains more methanol. In the kinetics of MTBE synthesis methanol has a negative reaction order, resulting in reaction rate curves with a maximum [11, 17]. In addition, high cross-linking results in low swelling of the polymer. This causes larger pores and higher porosity compared with less cross-linked resins. Large pores limit methanol transport less. This behavior is observed for the new catalyst also, but only at low polymer loading. For the activity in the catalytic reaction this means that cross-linking is a parameter that can be used to adjust the catalytic activity in MTBE synthesis for a given bulk fluid composition. However, this parameter influences selectivity. The main side
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