Investigation on the active site location, structure and ultra-deep desulfurization performance of CuY zeolite

Y zeolites modified with Cu are promising sorbents for adsorption desulfurization due to their cost-effectiveness. Only the supercage, which is larger than thiophene molecule, is the potential location of active sites for thiophene removal. However, numerous copper species cannot serve as effective active sites due to their inability to be located in the supercages. Based on this consideration, two strategies to regulate Cu location in Y zeolite to address the aforementioned challenges were explored. One is to adjust the molecular size of copper -ammonia ligands through pH value of cuprammonia solution, and the other is to prevent the migration of copper to small cages by heat treatment. The results showed that these two strategies could effectively regulate the location of copper active sites in Y zeolite. During heat treatment, Cu could transfer into supercages from sodalite cages at 350 C-degrees. More effective copper would be targeted to be located in the supercages in the process of adjusting pH. For the best Cu10.74Y350 sorbent, which was prepared at 350 C-degrees under pH of 10.74, the Cu content in the supercages was the highest (25 %), and thus it has an excellent desulfurization efficiency of 82.3 %.