DEVELOPMENT OF Pt-Zn/Al2O3 CATALYST FOR n-OCTANE REFORMING
DEVELOPMENT OF Pt-Zn/Al2O3 CATALYST FOR n-OCTANE REFORMING
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Date
2015-01
Authors
OLOWORISHE, FEMI,
JOHN
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Abstract
Six different platinum and zinc gamma-alumina supported catalysts were developed by impregnation method. Five of the catalysts consist of 1.0% wt of Zn and varying amounts of Pt (0, 0.5, 1.0, 1.5, 2.0% wt) while the sixth catalyst was chlorinated gamma-alumina, having no active metal(s) serving as the control sample. The catalysts were characterized using X-ray diffractometer (XRD), Brunauer-Emmett-Teller (BET), and scanning electron microscope (SEM) techniques. The catalytic performances of these catalysts were evaluated with respect to n-octane reforming in a packed tubular reactor. The XRD patterns show that the chlorinated support (γ-Al2O3) is amorphous as its diffractograph was characterized by low intensity counts and broad peaks. The other catalysts had similar Bragg angles. The textural properties determined by the BET analyses were: specific surface area ranging from 44m2/g to 78m2/g, pore volume ranging from 0.02cm3/g to 0.04cm3/g, and pore size ranging from 2.00nm to 2.10nm. The catalytic performances of the catalysts for n-octane reforming were determined at varying reactor temperatures (4300C, 4550C, 4800C, 5050C, and 5300C). The results showed low reformate yield at low reactor-temperatures (430-4550C) when the reactor was packed with the chlorinated gamma-alumina. Nonetheless, a significant improvement in the reformate yield was observed at higher temperatures (T ≥ 4550C). When the Zn/Al2O catalyst was used, the reformate yield increases from a minimum of 46% at 4300C to a maximum of 83% at 5300C. The set of four Pt-Zn/Al2O3 catalysts (with 0.5, 1.0, 1.5, 2.0%wt Pt) showed similar trends in reformate yields with changes in temperature, showing minimum yield of about 25% at 4300C and maximum yield of 84% at 4800C. Beyond this point (4800C), the yields pattern became erratic. The selectivity of all the catalysts for aromatics were quite impressive. The chlorinated support had high selectivity for iso-paraffins, while the metal dispersed catalysts favor formation of
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aromatics. Technically, the 1.5%wt Pt-Zn/Al2O3 catalyst demonstrated the best performance, but economic consideration may support preference for 0.5%wt Pt-Zn/Al2O3 catalyst.
Description
An MSc. Thesis submitted to the School of Postgraduate Studies, Ahmadu Bello University, Zaria, In partial fulfillment of the requirements for the award of Master of Science Degree in Chemical Engineering
Keywords
DEVELOPMENT,, Pt-Zn/Al2O3, CATALYST,, n-OCTANE,, REFORMING