The goal of this project is to develop a methodology to remove sulfur in refined fuels to ultralow levels of below 30 parts per million (ppm).
Brookhaven National Laboratory (BNL)
Argonne National Laboratory (ANL)
During 2002, BNL developed a synthesis procedure that would allow convenient and reproducible preparation of nanocatalytic materials. A newly emerging sonochemical synthesis technique was utilized to synthesize nanoparticles (mean particle diameter <30 nanometers, or nm) of several molybdenum sulfate (MoS2)-based complexes for use as hydrodesulfurization (HDS) catalysts used in refining. Sonolysis in hexadecane solvent produced cavitation that successfully resulted in the production of nano-sized MoS2 in greater than 90% yields. This project continued the work by focusing on characterization of nano-sized materials that have been synthesized for evaluation as potential HDS catalysts.
The methods developed in this project will allow efficient removal of sulfur compounds from refined fuels and thereby reduce air contamination from vehicles.
The objective of the proposal is to use evolving sonolysis techniques and synthesize nano-sized particles of MoS2. The focus of this study was to understand the interaction of sterically hindered organic sulfur compounds with size-dependent MoS2.
The unique aspect of this approach is to use nano-sized MoS2 particles for two reasons: 1) Nanosizing increases surface area and therefore the number of "active-edge sites" per unit catalyst volume, and 2) amorphous nanoparticles may overcome steric resistance in sulfur-containing large aromatic molecule,s making the rings susceptible to catalytic attack during HDS. This approach has three aspects: 1) characterization of sterically hindered organic sulfur compounds that are typically present in crudes but resistant to conventional HDS catalysts, 2) reaction behavior of these sterically hindered sulfur compounds with nano-sized MoS2, and 3) formulation and evaluation of supported nano MoS2-based system for ultradeep catalytic HDS of heavy oils and distillates.
The sonolysis unit was customized to produce nanoparticles. This included a jacketed reaction flask to control reaction temperature during sonolysis. After shake-down of the sonolysis unit, the sonolysis technique was further refined with a goal to synthesize 10-100 grams of nano MoS2 . Previous studies showed that a high surface area of unsupported nanometer particles of Fe, Mo, and MoS2 was produced in quantitative yields by sonolysis of Fe(CO)5, Mo(CO)6, and Mo(CO)6/S, respectively. During the study, several hydrocarbons were evaluated as solvents to optimize "cavitation" that is critical to produce nano Mo metal particles by decomposition of molybdenum hexacarbonyl.
The synthesis of supported and bimetallic systems that are potential HDS catalysts was successfully completed. With a known ratio of Co2(CO)8/Mo(CO)6, the method produced nano Co/MoS2. Sonolysis of Mo(CO)6 in the presence of ?-Al2O3 produced supported nano Mo, i.e., nano MoS2/?-Al2O3. The yields of all nano-sized materials were >90% based on the starting Mo(CO)6. Each material has been produced in several-gram quantities.
The project has been completed.
$90,000 (24% of total)