Nanomaterials and Nanocomposites for Adsorptive Desulfurization

Desulfurization (removal of S compounds) of fuels is an important research topic in recent years. Several techniques have been reported to remove the sulfur-containing compounds in fuels. One of these techniques is adsorptive desulfurization (removal based on chemisorption and physisorption), which has received much attention because of low energy consumption and facile operation condition. This chapter discusses the methods employed under this technique and the types of nanocomposites and hybrid materials (adsorbents) that have been investigated as potential adsorbents. The strategies to enhance sulfur adsorption capacity and main challenges will be discussed.

Mesoporous Adsorbents for Desulfurization of Model Diesel Fuel: Optimization, Kinetic, and Thermodynamic Studies

Mesoporous alumina-based adsorbents consisting of a π-electron acceptor complexing agent (2,7-dinitro-9-fluorenone) were synthesized and characterized. Adsorbents were screened for the removal of sulfur compounds from a model ultra-low-sulfur diesel fuel via a charge transfer complex (CTC) mechanism. The sulfur adsorption isotherms and kinetics were examined. The kinetics of sulfur adsorption followed a pseudo-second-order model with the CTC adsorbents. Among the three adsorbents screened, a commercial γ-Al2O3 CTC adsorbent showed the highest desulfurization in a short-run period. The regeneration of spent adsorbent was studied with three different polar solvents, namely chloroform, dichloromethane, and carbon tetrachloride. Dichloromethane was found to be the most suitable solvent for extracting a major portion of sulfur compounds occupied in the pores of the spent adsorbent. γ-Al2O3 CTC adsorbent can be reused after regeneration. Thermodynamic parameters such as Ea, ΔG, ΔH, and ΔS provided a better insight into the adsorption process.

Nanomaterials and Nanocomposites for Adsorptive Desulfurization

Desulfurization (removal of S compounds) of fuels is an important research topic in recent years. Several techniques have been reported to remove the sulfur-containing compounds in fuels. One of these techniques is adsorptive desulfurization (removal based on chemisorption and physisorption), which has received much attention because of low energy consumption and facile operation condition. This chapter discusses the methods employed under this technique and the types of nanocomposites and hybrid materials (adsorbents) that have been investigated as potential adsorbents. The strategies to enhance sulfur adsorption capacity and main challenges will be discussed.

Effect of sulfate removal in a high sulfate volumetric loading micro-aerobic bio-reactor and study of subsequent bio-sulfur adsorption by iron-modified activated carbon

Removal of sulfide from a micro-aerobic bio-reactor was studied at 10 000 mg L−1 chemical oxygen demand (COD) of inlet water, with the sulfate volumetric loading 0.75, 1.0, 1.5 and 2.0 kg (m−3 d−1), respectively.

The Relation of Ni/ZnO Nano Structures With Properties of Reactive Adsorption Desulfurization

Ni/ZnO nano-sorbent systems have been extensively used in the reactive adsorption desulfurization (RADS) of gasoline steams, especially in China, to meet the more rigorous regulation on the sulfur content. The apparent advantage of RADS is that most of the olefins are kept in the product with low consumption of hydrogen and little loss of octane. The authors discussed in this chapter the relation of catalytic properties with components and structures of Ni/ZnO sorbent. Based on detailed characterization and reaction results, they revealed the dynamic change of Ni/ZnO sorbents during RADS, the mechanisms of desulfurization, and the sulfur transfer and sulfur adsorption. Apart from the RADS of Ni/ZnO nano-sorbent for cleaner gasoline production, they also presented other potential applications.

Assessment of Ag Nanoparticles Interaction over Low-Cost Mesoporous Silica in Deep Desulfurization of Diesel

Chemical interactions between metal particles (Ag or Ni) dispersed in a low-cost MCM-41M produced from beach sand amorphous silica and sulfur compounds were evaluated in the deep adsorptive desulfurization process of real diesel fuel. N2 adsorption-desorption isotherms, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM) and scanning transmission electron microscopy coupled to energy-dispersive X-ray spectroscopy (STEM-EDX) were used for characterizing the adsorbents. HRTEM and XPS confirmed the high dispersion of Ag nanoparticles on the MCM-41 surface, and its chemical interaction with support and sulfur compounds by diverse mechanisms such as π-complexation and oxidation. Thermodynamic tests indicated that the adsorption of sulfur compounds over Ag(I)/MCM-41M is an endothermic process under the studied conditions. The magnitude of ΔH° (42.1 kJ/mol) indicates that chemisorptive mechanisms govern the sulfur removal. The best fit of kinetic and equilibrium data to pseudo-second order (R2 > 0.99) and Langmuir models (R2 > 0.98), respectively, along with the results for intraparticle diffusion and Boyd’s film-diffusion kinetic models, suggest that the chemisorptive interaction between organosulfur compounds and Ag nanosites controls sulfur adsorption, as seen in the XPS results. Its adsorption capacity (qm = 31.25 mgS/g) was 10 times higher than that obtained for pure MCM-41M and double the qm for the Ag(I)/MCM-41C adsorbent from commercial silica. Saturated adsorbents presented a satisfactory regeneration rate after a total of five sulfur adsorption cycles.