Characterization of Pt-Sn/Al2O3 catalyst and coke formation during propane dehydrogenation / Ho Kah Sing

Project paper (Bachelor of Chemical Engineering) -- Universiti Malaysia Pahang – 2013

Bibliography : p. 63-67

The problems faced in propane dehydrogenation, PDH process are lack of information on the commercially obtained Pt-Sn/Al2O3 catalyst and formation of coke. Therefore, this research deals with characterization of regenerated Pt-Sn/Al2O3 catalyst obtained from PDH plant and coke formation during propane dehydrogenation process at different temperature. Analyses of these characteristics were performed using nitrogen adsorption method, X-Ray Diffraction, Field Emission Scanning Electron Microscopy, X-Ray Photoelectron Spectroscopy and Fourier Transform Infrared Spectroscopy. Effect of temperatures on coke formation is identified by studying the fraction of products formed over the catalyst using Temperature Programmed Reaction. XPS was able to pick up traces of carbon in regenerated catalyst with percentage of atomic composition of 7.750%. FTIR had suggested that most of the carbon exist in the form of alkane and alkene where ethylene and methane records the highest fraction of side products formed by TPR. The regenerated Pt-Sn/Al2O3 catalyst has a surface area of 103.554 m2/g and mean pore radius of 12.695 nm with highest crystallite sizes of 20.0 nm. As for the effect of temperature towards coke formation, more carbon precursors were produced at higher temperature suggesting that more coke will be formed on the catalyst resulting in less propylene formed at higher temperatures. Spent catalyst yields a lower surface area of 78.943 m2/g and means pore radius of 10.151 nm compared to regenerated catalyst. Besides, the coke formed on the catalyst forms a crystal which was detected by XRD with its size of 25.7 nm. The increment of carbon content in the spent catalyst was traced by XPS where the percentage of atomic concentration increased to 31.75%.