Synthesis of Cobalt and Tungsten catalysts for Cracking in a Fischer-Tropsch model using Triisopropylbenzene and Dodecane as Chemical Probes

Badawy, Wala; M. Dessouky, S.; M.Aboul-Fotouh, Tarek; Betiha, Mohamed A.; A. El-Shafie, Masoud

doi:10.21608/ejchem.2021.95522.4483

Synthesis of Cobalt and Tungsten catalysts for Cracking in a Fischer-Tropsch model using Triisopropylbenzene and Dodecane as Chemical Probes

Document Type : Original Article

Authors

¹ Egyptian petroleum research institute

² Production Department, Egyptian Petroleum Research Institute (ERRI), B. O. 11727, Cairo, Egypt

³ Mining and Petroleum Engineering Department, Faculty of Engineering, Al-Azhar University, Cairo, Egypt

10.21608/ejchem.2021.95522.4483

Abstract

In this paper, three different catalysts based on the effective element concentration, cobalt substituted heteropoly acid (H8P2W17O61Co(H2O). 16 H2O), were impregnated on mesoporous silica with different concentrations of Cobalt High Performane Alloy (CoHPA). The concentrations of these catalysts were as following: 5%CoHPA, 10%CoHPA, and 15%CoHPA. Mesoporous silicate is manufactured from silica that extracted from rice husk. The three catalysts have been characterized using low and high X-Ray Diffractometer (XRD), Brunauer–Emmett–Teller (BET), temperature-programmed desorption of ammonia (NH3-TPD), pyridine-FTIR and Fourier- Transform Infrared Spectroscopy (FTIR). Triisopropylbenzene (TIPB) and dodecane (as a Fischer-Troupsch product) were used as chemical probes to identify the type of acid sites and the thermal catalytic cracking. Based on the hydrogen acceptor or hydrogen donor number (brønsted and Lewis acid sites) on the surface of the CoHPA catalyst, it was found that CoHPA catalysts have good progress in catalytic cracking by enriching catalyst surface with active acid sites. Although the catalyst already contains both acid sites, the amount of Lewis acidity increases with the increase in the tolerance of the active phase (cobalt substituted phosphotungstic acid). The results of this research work showed that the 15% CoHPA catalyst achieve a TIPB cracking capacity of 51.79%. Also, the formation of moderate carbon on this catalyst's surface (2.6%) occurred within the good selectivity of propene by enriching the surface with Brønsted acid site. The 10%CoHPA catalyst achieved a dodecane cracking (89.3 %) at 550 °C with high selectivity to olefins (ethylene, propylene, and butene).

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