铝对流化催化裂化催化剂的钝镍机理

以Ａｌ为钝镍组分，利用ＣＨＺ－２平衡催化裂化催化剂考察了不同原子比（钝化剂原子／重金属原子）对钝镍效果的影响。同时采用Ｘ光衍射（ＸＲＤ）物相检测、程序升温还原（ＴＰＲ）等实验方法研究了Ａｌ的钝镍机理。结果表明，在适当的原子比和一定的条件下，Ａｌ有一定的钝镍效果，其机理是沉积在催化剂上的ＮｉＯ与活性氧化铝生成镍铝尖晶石（ＮｉＡｌ２Ｏ４）结构的稳定化合物，使镍处于高价态的Ｎｉ２＋而难以被还原成低价态的Ｎｉ＋和Ｎｉ０，从而减少了镍的脱氢活性，降低了催化剂上的积炭量。

MECHANISM OF PASSIVATION OF NICKEL ON FCC CATALYSTS BY PASSIVATOR ALUMINUM/

The passivation effect of Al on the FCC equilibrium catalysts CHZ-2 containing 1.0% nickel under the condition of different atomic ratios of passivator Al to heavy metal element nickel is investigated by using XRD and TPR methods. The experiment results show that the passivation of nickel by taking Al as passivator exhibits a satisfactory effect under the condition of proper atomic ratio of Al to Ni, calcinating temperature and time. It is concluded that the favorite passivation efficiency is based on the principle of forming the stable crystalline compound (NiAl 2O 4) between NiO and Al 2O 3, which is difficult to be reduced by hydrogen. When valence of nickel is controlled in the form of high valence state ( Ni 2 ), the dehydrogenation activities of nickel decreased. Moreover, the longer the time of calcinating Al compound with Ni loading on catalyst surface is, the more the nickel aluminium spinel is produced.