捕钒剂对不同FCC分子筛催化剂的钝钒效果

研究了在ＲＥＹ、ＲＥＨＹ、ＵＳＹ三类常用的ＦＣＣ分子筛催化剂中加入捕钒剂组分（对催化剂基体进行化学改性）对钝化重金属钒污染的作用效果。结果表明，碱土金属类捕钒剂ＡＢＯ３对ＲＥＹ、ＵＳＹ类ＦＣＣ催化剂有良好的钝化效果，属于酸碱反应的钝化机理。但碱土金属类捕钒剂，如ＡＢＯ３、ＭｇＴｉＯ３、ＭｇＯ和ＣａＳｎＯ３等，与ＲＥＨＹ分子筛不匹配，非但没有钝化重金属，反而对ＲＥＨＹ分子筛的质子酸中心有破坏作用，使分子筛酸性活性中心数目减少、强度下降，导致催化剂的裂化活性急剧下降。在ＲＥＨＹ分子筛催化剂基体中加入ＭＯ金属氧化物作为捕钒剂，通过Ｖ５＋与金属离子发生在ＭＯ的（１０１）晶面上的晶格取代来得到良好的钝钒效果。

EFFECT OF VANADIUM TRAPPING AGENTS ON DIFFERENT FCC ZEOLITE CATALYSTS

The performances of vanadium trapping agents incorporated into the catalyst matrixes combining with the USY, REY and REHY zeolite active components to form three kinds of FCC catalysts are investigated. The experiment shows that the alkaline earth metal oxide ABO 3 is an effective vanadium trap compoud for the USY and REY zeolite FCC catalysts following the acid base reaction mechanism, but the alkaline earth metal oxides (such as ABO 3, MgTiO 3, MgO and CaSnO 3) are harmful to the vanadium trapping in the REHY zeolite FCC catalysts, because the basicities of these oxides are too strong to match the REHY zeolite catalysts. The Bronsted acid sites on the REHY zeolite surface decreased with increasing basicities of the trap agents. However, the new type of vanadium trapping agent MO (metal oxide) added into matrixes of the REHY zeolite catalysts indicates the satisfactory passivation efficiency based on the principle of the crystalline substitution between V 5 ions and M metal ions on the 101 crystal plane of MO crystal.