Pd/SiO₂ Aerogel Composite Adsorbents with High Desulfurization Performance

Abstract

Pd/SiO2-n aerogel composites with different Si/Pd mole ratios (n(Si/Pd)) were synthesized by a sol–gel method followed by drying in the atmosphere to adsorb thiophenic compounds from model oils. For Pd/SiO2-n, doping Pd species in SiO2 aerogels led to the appearance of weak Lewis acidic sites on the surface. The adsorption capacity of Pd/SiO2-n was significantly higher than that of pure SiO2, owing to the π-complexation, S–M bonding, and acid–base interaction between Pd2+ and thiophenic compounds. Among them, the capacity of Pd/SiO2-318 was the highest, 4.76 mg S/gads (i.e., 9.37 μmol S/μmol Pd), which was obviously higher than that of sorbents reported such as Pd/activated carbon and Pd/Al2O3, based on the amount of thiophene adsorbed per unit active centers. In the presence of aromatics and olefins, the selectivity of Pd/SiO2 for thiophene was higher than that of Ag/SiO2 and Cu/SiO2 reported, attributed to the stronger S–Pd bonding than the S–Ag and S–Cu bonding. The equilibrium adsorption data of thiophene onto Pd/SiO2-318 were well simulated with the Langmuir and Freundlich models. Combined with thermodynamic results, it can be found that the low temperature was favorable for the adsorption of thiophene. Pd/SiO2 exhibited a good regeneration performance after solvent washing.

Investigation of palladium catalysts in mesoporous silica support for CO oxidation and CO2 adsorption

“…Achieving high palladium dispersion within a silica-based support is challenging due to many factors, including high hydrophobicity and poor ion exchange capacity. Research in this area could aid the development of future heterogeneous Pd catalysts for a wide range of reactions besides CO oxidation [ 32 ]. We recently reported mesoporous silica aerogel-supported palladium catalyst (Pd/SiO 2 ) for low-temperature CO oxidation under ignition/extinction cycles with excellent stability [ 12 ].…”

Iridium–Nickel Nanoparticle-Based Aerogels for Oxygen Evolution Reaction

“…After consideration of these drawbacks in the development of electrocatalysts, aerogel remains as a very attractive structure to be applied as an electrocatalyst. Aerogel has been used in various applications such as sensing, − adsorbents, , insulators, etc. − Recently, it has been in the spotlight as a catalyst owing to its attractive properties. − First, aerogel exhibits a self-standing three-dimensional (3D) structure, which has no need to be supported by other materials. It can prevent cell degradation possibly caused by the dissolution of additional materials and instead use the volume more efficiently.…”

“…After consideration of these drawbacks in the development of electrocatalysts, aerogel remains as a very attractive structure to be applied as an electrocatalyst. Aerogel has been used in various applications such as sensing, 25−27 adsorbents, 28,29 insulators, 30 etc. 31−33 Recently, it has been in the spotlight as a catalyst owing to its attractive properties.…”

High‐performance adsorptive desulfurization by ternary hybrid boron carbon nitride aerogel

“…In recent years, aerogel with a three‐dimensional interconnected porous network, assembled by coherent nanoparticles or polymer molecules, 34 has been receiving considerable attention because of its high surface area and flexible porous structure, which endow this kind of material with abundant active sites and high adsorption rate for a variety of adsorption applications. SiO 2 aerogel with a uniform pore structure is the widely investigated material for adsorptive desulfurization in the past few years 35‐39 . However, it shows weak surface interactions with aromatic sulfur compounds, which greatly restrict its ADS performance.…”