AVS 53rd International Symposium
    Surface Science Tuesday Sessions
       Session SS-TuP

Paper SS-TuP47
Nickel-rich Bimetallic Phosphide Hydrotreating Catalysts

Tuesday, November 14, 2006, 6:00 pm, Room 3rd Floor Lobby

Session: Surface Science Poster Session
Presenter: A.W. Burns, Western Washington University
Authors: A.W. Burns, Western Washington University
M.E. Bussell, Western Washington University
Correspondent: Click to Email
Our research group is interested in the design of novel transition metal phosphide catalysts to be used for the removal of sulfur from petroleum feedstocks. Hydrodesulfurization (HDS) is a process in which sulfur is catalytically removed from fossil fuels. This project focuses on the development and properties of nickel-rich bimetallic phosphide catalysts. Nickel phosphide (Ni@sub 2@P) has been found to exhibit high HDS activity as well as excellent stability under reaction conditions. By incorporating another metal such as Co or Fe, we are investigating the properties of bimetallic phases in order to optimize the nickel phosphide-based catalysts. Therefore, we have prepared a series of oxide-supported Co@sub x@Ni@sub 2-x@P catalysts, where x varies between 0 and 1. Our results show an increase in HDS activity with increasing Ni (decreasing Co) compositions. Interestingly, for Co@sub x@Ni@sub 2-x@P compositions where x is small but not zero, the HDS activity is higher than that of pure Ni@sub 2@P. As will be described, different results are observed for a series of Fe@sub x@Ni@sub 2-x@P catalysts. X-ray diffraction (XRD) is used to confirm the identity of the crystalline phosphide phase(s) present, to determine the average crystallite size, and to observe the transition from the Co@sub 2@P-like phase to the Ni@sub 2@P-like phase. BET surface area and O@sub 2@ chemisorption capacity measurements are used to determine the surface area and the number of active sites for the oxide-supported catalysts. Together with the results of elemental analysis and x-ray photoelectron spectroscopy (XPS) measurements, the surface area and chemisorption data are used to describe how the HDS activity is influenced by the surface properties of these catalysts. In this manner, we are determining the optimal composition for Ni-rich bimetallic phosphide catalysts for the HDS process.