| The main contents of this paper are to study the straight-run gasoline isomerization reactions overnanosized ZSM-5. ZSM-5、β zeolite、mordenite, and Y molecular sieve are tested in straight-run gasolineisomerization reaction. Different modification methods for nanosized HZSM-5catalytic straight-rungasoline are given.Nanoscale ZSM-5has short channels, multi-orifice secondary pores, large external surface area, thelarge amount of acid and strong stability characteristics. Compared with micro sized ZSM-5，the acidicamount of nanosized ZSM-5is higher while the strength of the strong acid sites is lower. The external acidsites on nanosized ZSM-5are about30%of the total acidic amount and the external area is about30%ofthe total specific area.Nanometer ZSM-5shows better performance in straight-run gasoline isomerization thanmicro sized ZSM-5. The concentration of n-alkanes in the product is greatly reduced, while isomericalkanes and cycloalkanes and aromatics increase significantly. In addition, the activity and stability of NHZwas better than MHZ. The best performance of NHZ is shown when the temperature is320℃-360℃andspace velocity is1h-1.,The isomerization reaction mainly occurs in the weak acidic sites, whereas the aromatization reactionmainly occurs in the strong acid sites. After vapor treatment at550℃, the acid strength and the weak acidare bigger while the strong acid strength increased slightly and the amount of it significantly reduced. Aftera load of nitrate salts, the strength of weak acid significantly increased while the strong acid strengthsignificantly reduced. The best results can be get with the load of ferric nitrate1%and550℃watertreatment when operated in the suitable conditions (reaction temperature320℃,space velocity of1h-1,pressure of0.2-0.3MPa).In this paper, a variety of composite modification methods is studied. It gives better performance whenthe ferric nitrate loaded as the main, nickel nitrate loaded as the auxiliary than the nickel nitrate loadedalone. |
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