Effect of Magnesium Oxide on the Performance of FCC Catalyst

1. The effect of the amount of magnesium oxide added on the content of magnesium oxide in the FCC catalyst

It is the comparison between the amount of magnesium oxide added and the content of magnesium oxide in the FCC catalyst. Magnesium oxide addition does not have a linear relationship with the magnesium oxide content in the catalyst, and when the magnesium oxide addition is less, the magnesium oxide content in the catalyst increases faster: when the magnesium oxide addition is more, the magnesium oxide content in the catalyst increases slowly. This may be because the surface of the catalyst contains a certain number of acidic centers that can react with magnesium oxide to produce acid-base reactions. When the acidic active centers on the catalyst surface react with magnesium oxide to reach saturation, it is difficult for magnesium oxide to enter the pores and react with the internal acidic active centers. The magnesium oxide content in the catalyst increases slowly.

2. Effect of magnesium oxide content on acid type and acid amount of FCC catalyst

The acid type and acid content of magnesium oxide modified FCC catalyst were determined by infrared spectroscopy, and the acid content was obtained by integrating the peak area. The FCC catalyst modified by magnesia contained L acid and B acid, and the acid content first increased and then decreased with the increase of magnesia content, and reached the maximum when the magnesia content was about 1.50% (D). The overall acid strength of magnesia modified FCC catalysts is dominated by weak acids (peak around 150°C). The acid strength at around 150°C increases first and then decreases. When the MgO content reaches 1.50%, the acid strength on the surface of the catalyst reaches the maximum value, indicating that adding an appropriate amount of magnesium to the FCC catalyst can increase the acid strength on the surface of the FCC catalyst.

Since the main forms of magnesium are MgO, Mg2+Mg(OH)*Mg(OH)2, etc., its existing forms will directly affect the acid content and micro-reaction activity of the molecular sieve surface. Introduction of magnesium element into FCC catalyst Magnesium element may interact with the active center on the surface of the catalyst to form a new compound. The acidity of the hydroxyl group in this compound may be stronger than that of the silicon-aluminum hydroxyl group, thereby increasing the acidity of the FCC catalyst. Due to the limited number of acid centers on the surface of the FCC catalyst, the amount of acid on the surface of the catalyst will not increase when the MgO content reaches a certain value.

3. The effect of magnesium oxide content on the micro-reaction activity of FCC catalyst

The microreaction activity of FCC catalyst increases…

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