No abstract

Paraffins in the cracked naphtha can be transformed into aromatics and isoparaffin to improve the octane number. In this article, a series of Ni/HZSM-5 bifunctional catalysts were prepared and were characterized by temperature-programmed desorption of NH 3 (NH 3 -TPD), FT-IR analysis with adsorbed pyridine as well as by x-ray powder diffraction analysis. The monolayer dispersion threshold value of Ni on HZSM-5 was determined and the cracking and aromatization activities of the catalysts were investigated in the transformation of n-heptane. The experimental results show that the catalyst with a monolayer dispersion threshold value of Ni shows the best aromatization and isomerization activity. The products selectivity of n-heptane over different catalysts was analyzed and it was revealed that low hydrogen pressure can reduce the conversion of n-heptane, but at the same time accelerate the production of aromatics. The aromatization activity of the catalysts increases with the elevation of the reaction temperature, and the incorporation of metal in HZSM-5 decreases the cracking reaction on the catalysts, while at the same time increases the reactions that may result in the production of aromatics.

Thiols in RFCC naphthas produced in two refineries in China have been separated and characterized with GC/FPD. The identification results show that there are more than 20 kinds of thiols, including C 3 -C 8 normal thiols, isothiols, thiophenol and methylthiophenol presenting in presweetening RFCC naphthas, while in sweetened RFCC naphthas, only have the isothiols and C 7 -C 8 normal thiols been detected. The content of C 7 -C 8 thiols and isothiols is higher in RFCC naphthas than that in FCC naphthas.