Spongy chalcogels of non-platinum metals act as effective hydrodesulfurization catalysts

Abstract

Aerogels are low-density porous materials, made mostly of air, for which hundreds of applications have been found in recent years. Inorganic oxide-based aerogels have been known for a long time, carbon aerogels were discovered in the early 1990s and sulfur- and selenium-based aerogels (chalcogels) are the most recent additions to this family. Here we present new aerogels made of Co(Ni)-Mo(W)-S networks with extremely large surface areas and porosity. These systems are formed by the coordinative reactions of (MoS(4))(2-) and (WS(4))(2-) with Co(2+) and Ni(2+) salts in non-aqueous solvents. We show that these low-density sponge-like networks can absorb conjugated organic molecules and mercury ions, and preferentially adsorb CO(2) over H(2), which illustrates their high potential as gas-separation media. The chalcogels are shown to be twice as active as the conventional sulfided Co-Mo/Al(2)O(3) catalyst for the hydrodesulfurization of thiophene.

Summary Report for the Development of Materials for Volatile Radionuclides

“…Other catalysts can be used in conjunction with GeCh gels, i.e., Zn. After further literature review, alternate chemistries were studied and proposed for FY2011 and include (Mo,W)-S-(Ni,Co) and (Mo,W)-Se-(Ni,Co) systems, also studied by Bag et al,(2009) which will reduce costs even further. We aim to investigate potentially chemistry changes that could improve the thermal stability of these chalcogels.…”

“…Bag and Kanatzidis also demonstrated a wide variety of uses for these materials, in which they can be used as sorbents with selective affinity for heavy metals (e.g., Hg vs. Zn) (Bag et al 2007) and selective sorbents or catalysts for gas separation, e.g. hydrodesulfurization (Bag et al 2009), to name a few applications.…”

“…Figure 8 shows how iodine is adsorbed into the network of a Ge-S-c chalcogel. Bag and Kanatzidis demonstrated the wide compositional flexibility of these chalcogels in which the properties, i.e., surface area per unit mass (10-528 m 2 /g) (Bag et al 2009;Bag et al 2007), band gap (2.0-0.8 eV) (Bag et al 2007), selective affinity (i.e., liquids, vapors), etc., can be "tuned" by changing the metal and chalcogen precursors.…”

Summary Report on the Volatile Radionuclide and Immobilization Research for FY2011 at PNNL

“…• Sn-S-X gels, e.g., X = Sn, Sb, Zn (Oh et al 2011;Bag et al 2007;Kanatzidis and Bag 2008;Bag and Kanatzidis 2010) • Ge,Sn-S gels (Bag and Kanatzidis 2010;Ruffolo and Boolchand 1985) • Mo,W-S-X gels, e.g., X = Co, Ni, Pb, Cr, Bi (Bag et al 2009) …”

“…Adding Ge to Sn gels decreases the density, thereby decreasing the volumetric waste loading. These glasses and chalcogel formulations are to be investigated in FY2012 with a combination of experiments involving Ge-S precursor [(CH 3 ) (Bag et al 2009;Kanatzidis 2011). However, these materials do not have high thermal stability and tend to show measureable mass-loss (~30 mass%) at T ≈ 200°C for NiMoS 4 (Bag et al 2009).…”