Titania 1-hexene incorporation, inhibition

FIGURE 102 Inhibition of 1-hexene incorporation by the addition of titania on Cr/silica catalyst. 

Figure 103 is a plot of branch profiles obtained from three different Cr/silica-titania cogels which contained various amounts of titania. Each was activated at 700 °C. The addition of titania inhibited 1-hexene incorporation in the shortest chains, where the Ti-associated sites contribute. The catalyst with the highest titania loading provided the flattest branch... 

A similar experiment was conducted without 1-hexene added to the reactor and those results are also listed in Table 36. The same effect on MW distribution was observed. The incorporation of 1-hexene increased significantly when the titania-associated sites were selectively poisoned. This is another indication that titania inhibits branching in the low-MW side. Table 36 shows the drop in the polymer density, and the rise in the amount of 1-hexene incorporated, when the catalyst was treated in CO at only 100 °C. 

FIGURE 44 Properties of polymers made (at 95 °C and 0.7 mol 1-hexene L ) with Cr/silica-titania in the presence of various amounts of methanol showing the inhibition of comonomer incorporation by methanol. 

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