Development of Noble Metal Phosphide Hydrotreating Catalysts
EMSL Project ID
34892
Abstract
High impurity levels in heavy and unconventional crude oils present major challenges to the petroleum industry at a time that environmental regulations in the United States, Japan and in many European countries are dramatically lowering allowable sulfur levels in transportation fuels. Hydrodesulfurization (HDS) catalysis is a critical process in the petroleum industry, selectively removing sulfur from organosulfur compounds found in crude oil. While metal sulfide-based catalysts are widely used in industrial hydrotreatment of crude oils, noble metal catalysts are attracting interest for deep HDS applications because of their excellent hydrogenation properties. However, noble metals are susceptible to deactivation by sulfur and, therefore, can be used only for feeds with low S contents, accomplished via use of a second-stage HDS reactor. The goal of the research described in this proposal is to develop highly active and S resistant hydrotreating catalysts based on noble metal phosphides. The properties of the noble metal phosphide catalysts are being tailored for deep HDS of alkyl-substituted dibenzothiophenes in either single- or two-stage reactor systems in which higher hydrogen sulfide partial pressures can be tolerated. The proposed research is motivated by findings that early transition metal phosphide catalysts exhibit high HDS activities and excellent resistance to S incorporation. Monometallic and bimetallic phosphide catalysts of noble metals are being prepared using the temperature-programmed reduction (TPR) method, in which oxidic precursors are reduced in flowing hydrogen to give metal phosphide particles dispersed on high surface area silica. The HDS activities of the phosphide catalysts will be evaluated under industrially relevant conditions using 4,6-dimethyldibenzothiophene (4,6-DMDBT) as the model compound for alkyl-substituted dibenzothiophenes present in crude oil feedstocks.
The catalysts are characterized with a variety of bulk and surface sensitive physicochemical techniques that are available in the PI's laboratory and elsewhere. Building upon previous collaborations, we propose to continue characterization studies at the EMSL user facility. X-ray photoelectron spectroscopy (XPS) provides information concerning the surface composition of the metal phosphide particles as well as the oxidation states of surface species. Transmission electron microscopy (TEM) permits us to probe the morphology and size of the metal phosphide and support particles, and to determine the crystallinity of phosphide particles below the size limit detectable by powder X-ray diffraction (XRD). The analysis of powder XRD patterns acquired at WWU is aided by staff expertise and software available at EMSL.
The outcome of this research will be the development and detailed evaluation of highly active, noble metal phosphide hydrotreating catalysts, and an understanding of the roles of the phosphide composition and S resistance in determining the catalytic properties of these materials.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2009-10-05
End Date
2012-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Bowker RH, MC Smith, M Pease, KM Slenkamp, L Kovarik, and ME Bussell. 2011. "Synthesis and Hydrodeoxygenation Properties of Ruthenium Phosphide Catalysts." ACS Catalysis 1(8):917-922. doi:10.1021/cs200238v
Gaudette AF, AW Burns, JR Hayes, MC Smith, RH Bowker, T Seda, and ME Bussell. 2010. "Mössbauer Spectroscopy Investigation and Hydrodesulfurization Properties of Iron–nickel Phosphide Catalysts." Journal of Catalysis 272(1):18-27. doi:10.1016/j.jcat.2010.03.016
Hayes JR, RH Bowker, AF Gaudette, MC Smith, CE Moak, CY Nam, TK Pratum, and ME Bussell. 2010. "Hydrodesulfurization Properties of Rhodium Phosphide: Comparison with Rhodium Metal and Sulfide Catalysts." Journal of Catalysis 276(2):249-258. doi:10.1016/j.jcat.2010.09.013