Hβ/HZSM-5 Composite Carrier Supported Catalysts for Olefins Reduction of FCC Gasoline Via Hydroisomerization and Aromatization

Abstract

In order to develop a novel catalyst system that has excellent olefin reduction ability for FCC gasoline without loss in research octane number (RON), different catalysts supported on single-and binary-zeolite carriers consisting of Hb or/and HZSM-5 were prepared and their catalytic performances for FCC gasoline upgrading were assessed in the present investigation. Acidity measurements by pyridine-adsorbed Fourier transformed infrared spectroscopy (FTIR) showed that hydroisomerization and aromatization activities were closely related to the density of acid sites and the ratios of medium Lewis acidity and strong Bro¨nsted acidity to total acidity. Compared with the single HZSM-5 supported catalyst, the single Hb supported catalyst was found to have much better olefin reduction performance, but the product RON still suffered from a loss of 1.6. Compared to the single-zeolite supported catalysts, the binary-zeolite Hb/HZSM-5 supported catalysts with the mass ratio of Hb to HZSM-5 at 6.6 offered much more stable activity and selectivity to arene, which played an important role in preserving gasoline RON.

A Six-Lump Kinetic Model for Olefin Hydrogenation, Hydroisomerization and Aromatization in FCC Gasoline Hydro-Upgrading

“…This is because: (1) previous experimental results [12][13][14][15] had confirmed that the n-paraffins and i-paraffins are less active in FCC gasoline hydro-upgrading, as reflected by the great increases in their contents resulting from the olefin conversion; (2) it is known that the adsorption of olefins on bifunctional catalysts is much easier than that of paraffins, and thus the presence of olefins in the feedstock can remarkable restrain the adsorption of paraffins and their subsequent conversion [16,17]; (3) the presence of excess hydrogen also inhibits the paraffin dehydrogenation on non-noble metal sites, namely the first step in the paraffin conversion [18].…”

“…Unlike FCC gasoline secondary reactions and FCC gasoline aromatization in the absence of hydrogen, coke formation in FCC gasoline hydro-upgrading can be greatly depressed in the presence of hydrogen [12][13][14]. In view of the very high liquid yield ([98 wt%) of the FCC gasoline hydro-upgrading process [4,12,13], the dry gas and LPG yields are likewise neglectable.…”

“…Low temperature favors the hydroisomerization of n-olefins and the hydrogenation of i-olefins and n-olefins and thus leads to the high iparaffin and n-paraffin yields, in accordance with the exothermal nature of the two reactions. With the increasing temperature, the three kinds of olefins are prone to form aromatics due to the promoted cyclization and dehydrogenation of n-olefins and i-olefins as well as the greatly enhanced dehydrogenation of cyclo-olefins [14], so the aromatics yield increases and the i-paraffin and n-paraffin yields decrease. According to the specification of Euro IV clean gasoline, the olefin and aromatics contents should be lower than 18 and 35%, respectively.…”

Self-Etherification Process for Cleaner Fuel Production

“…Conversions of olefins in FCC gasoline by hydroisomerization and aromatization have been recently investigated by many researchers [59][60][61][62][63]. The loss of octane number from olefin reduction was compensated by the formation of iso-paraffins and aromatics.…”

The Effect of Lanthanum and Niobium on Additives for Olefins Reduction of FCC Gasoline

“…It has been found that by means of operation optimization of FCC units and use of novel olefins reduction FCC catalysts [5][6][7] the olefins content can be decreased to around 35 vol.% [8], which is still much higher than the upper value 18 vol.% as regulated by Europe III vehicle standard of unleaded gasoline. Several selective hydrogenation routes have been proposed and some of them have been put into pilot-scale operations, but none of them enables satisfactory olefins control with acceptable loss in both gasoline research octane number (RON) and yield [8]. Therefore, it is urgent to develop a novel technique that can preserve the octane value while reducing the olefins content of gasoline.…”