Design of Lewis Acid Centers in Bundlelike Boron Nitride for Boosting Adsorptive Desulfurization Performance

New Adsorption Materials for Deep Desulfurization of Fuel Oil

In recent years, due to the rapid growth of mankind's demand for energy, harmful gases (SOx) produced by the combustion of sulfur-containing compounds in fuel oil have caused serious problems to the ecological environment and human health. Therefore, in order to solve this hidden danger from the source, countries around the world have created increasingly strict standards for the sulfur content in fuel. Adsorption desulfurization technology has attracted wide attention due to its advantages of energy saving and low operating cost. This paper reviewed the latest research progress on various porous adsorption materials. The future challenges and research directions of adsorption materials to meet the needs of clean fuels are proposed.

Atomically Dispersed Aluminum Sites in Hexagonal Boron Nitride Nanofibers for Boosting Adsorptive Desulfurization Performance

The exploitation of highly efficient and cost-effective selective adsorbents for adsorptive desulfurization (ADS) remains a challenge. Fortunately, single-atom adsorbents (SAAs) characterized by maximized atom utilization and atomically dispersed adsorption sites have great potential to solve this problem as an emerging class of adsorption materials. Herein, aiming at improving the efficiency of ADS performance via the economical and feasible strategy, the desirable SAAs have been fabricated by uniformly anchoring aluminum (Al) atoms on hexagonal boron nitride nanofibers (BNNF) via an in situ pyrolysis method. Remarkably, Al-BN-1.0 exhibited a superior adsorption capacity of 46.1 mg S/g adsorbent for dibenzothiophene, with a 45% increase in adsorption capacity compared to the pristine BNNF. Additionally, it demonstrated excellent adsorption of other thiophene sulfides. Moreover, the ADS mechanisms have been investigated through special adsorption experiments combined with density functional theory (DFT) calculations. It was demonstrated that the superior ADS performance and selectivity of Al-BN-1.0 originate from the sulfur-aluminum (S-Al) and π-π interactions cooperating synergistically. This work would cast light on a novel fabrication strategy for the SAAs based on the two-dimensional material with a tunable metal site configurations and densities for varied selective adsorption and separation.

Heteropolyacid Ionic Liquid-Based MCF: An Efficient Heterogeneous Catalyst for Oxidative Desulfurization of Fuel

A new type of catalyst was synthesized by immobilizing heteropolyacid on ionic liquid-modified mesostructured cellular silica foam (denoted as MCF) and applied to the oxidative desulfurization of fuel. The surface morphology and structure of the catalyst were characterized by XRD, TEM, N₂ adsorption-desorption, FT-IR, EDS and XPS analysis. The catalyst exhibited good stability and desulfurization for various sulfur-containing compounds in oxidative desulfurization. Heteropolyacid ionic liquid-based MCF solved the shortage of the amount of ionic liquid and difficult separation in the process of oxidative desulfurization. Meanwhile, MCF had a special three-dimensional structure that was not only highly conducive to mass transfer but also greatly increased catalytic active sites and significantly improved catalytic efficiency. Accordingly, the prepared catalyst of 1-butyl-3-methyl imidazolium phosphomolybdic acid-based MCF (denoted as [BMIM]₃PMo₁₂O₄₀-based MCF) exhibited high desulfurization activity in an oxidative desulfurization system. The removal of dibenzothiophene could achieve levels of 100% in 90 min. Additionally, four sulfur-containing compounds could be removed completely under mild conditions. Due to the stability of the structure, sulfur removal efficiency still reached 99.8% after the catalyst was recycled six times.

Synthesis, characterization and application of organoclays for adsorptive desulfurization of fuel oil

The present study encompasses the application of cost effective, organo-modified bentonite material for efficient desulfurization of model oil and real fuel. For the adsorptive desulfurization of oil, dibenzothiophene (DBT) was used as model compound. Various experimental parameters (time, temperature, adsorbent-amount and DBT concentration) were thoroughly investigated. The synthesized material was characterized via X-ray diffraction (XRD), X-ray Fluorescence (XRF), Scanning electron microscopy (SEM), Energy dispersive x-ray (EDX), Thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FT-IR). The modification exhibits the increase in interlayer spacing of clay as confirmed from XRD and modified material shows interesting morphology as compared to unmodified bentonite. The results showed that > 90% of DBT removal was achieved under optimized conditions for B-BTC, B-BTB and B-DSS and > 80% for B-BEHA, for model fuel oil which are greater than unmodified clay (< 45%). Additionally, the findings from desulfurization of real fuel oil declare that 96.76% and 95.83% removal efficiency was achieved for kerosene and diesel oil respectively, at optimized conditions and fuel properties follow ASTM specifications. The obtained findings well fitted with thermodynamic, isothermal (Langmuir) with adsorption capacity (70.8 (B-BTC), 66 (B-BTB), 61.2 (B-DSS) and 55.2 (B-BEHA) in mg/g) and pseudo-second-order kinetics. In thermodynamic studies, negative sign ([Formula: see text] specifies the spontaneity whereas, [Formula: see text] endothermic and positive sign [Formula: see text] show randomness after DBT adsorption onto organoclay.

Cu-Doped Boron Nitride Nanosheets for Solid-Phase Extraction and Determination of Rhodamine B in Foods Matrix

Cu-doped boron nitride nanosheets (Cu-BNNS) were first reported as promising adsorbents for the solid-phase extraction and determination of rhodamine B (RhB) dye in a food matrix. Different characterizations, including XRD, FTIR, XPS, SEM, and TEM, were performed to confirm the formation of the adsorbent. Then, the adsorption performance of Cu-BNNS was investigated by adsorption kinetics, isotherms, and thermodynamics. Multiple extraction parameters were optimized by single-factor experiments. Under optimized conditions, the recoveries in the food matrix were in the range of 89.8–95.4%, with the spiked levels of 100 ng/mL and 500 ng/mL, respectively. This novel system was expected to have great potential to detect RhB in a wide variety of real samples.

Adsorption desulfurization performance of PdO/SiO2@graphene oxide hybrid aerogel: Influence of graphene oxide

Preparation of PdO/SiO₂@graphene oxide (GO) hybrid aerogels were carried out sol-gel method combined with atmospheric drying technology to study their adsorption performance for thiophenics and compared with PdO/SiO₂. Scanning electron microscope (SEM), N₂ adsorption-desorption isotherms, X-ray diffraction (XRD) analysis, X-ray photoelectron spectroscopy (XPS), and fourier transformation infrared spectroscopy (FT-IR) for samples were performed. The adsorption performance of PdO/SiO₂@GO for thiophene were better than that of PdO/SiO₂, attributed to that incorporation of GO increased the specific surface area and the Pd incorporation rate, where Pd²⁺ ions acted as the π-complexation and sulfur-metal (SM) bond adsorption active centers, as well as GO adsorbed thiophene by the π-π stacking effect. The adsorption capacities of PdO/SiO₂@GO-1.0 for thiophene (TH), benzothiophene (BT) and dibenzothiophene (DBT) were 8.89, 9.3 and 12.6 mg-S/g_ads, respectively. The addition of GO in aerogels could improve the inhibition effect of toluene, cyclohexene and pyridine while decreased the inhibition effect of MTBE and H₂O for the adsorption of thiophene, due to the π-π stacking effect and the hydrophobicity of GO, respectively. The adsorption process was spontaneous and exothermic, be well fitted by the apparent second-order kinetic model and dominated by chemical interaction. Pd/SiO₂@GO-1.0 had a good solvent elution regeneration performance.

Defect Engineering on Boron Nitride for O2 Activation and Subsequent Oxidative Desulfurization

The rational design of highly active hexagonal boron nitride (h-BN) catalysts at the atomic level is urgent for aerobic reactions. Herein, a doping impurity atom strategy is adopted to increase its catalytic activities. A series of doping systems involving O, C impurities and B, N antisites are constructed and their catalytic activities for molecular O₂ have been studied by density functional theory (DFT) calculations. It is demonstrated that O₂ is highly activated on O_N and B_N defects, and moderately activated on C_B and C_N defects, however, it is not stable on N_B and O_B defects. The subsequent application in oxidative desulfurization (ODS) reactions proves the O_N and C-doped (C_B , C_N ) systems to be good choice for sulfocompounds oxidization, especially for dibenzothiophene (DBT). While the B_N antisite is not suitable for such aerobic reaction due to the extremely stable B-O^* -B species formed during the oxidation process.

Desulfurization on Boron Nitride and Boron Nitride-based Materials

Combustion of liquid fuels containing sulfur compounds is highly unfavorable due to the adverse effects caused by the resultant SO_x emission. Consequently, catalytic and adsorptive materials having the capacity to eliminate the sulfur compounds from liquid fuels are very attractive. Hexagonal boron nitride (BN), with its interesting chemical and physical properties, finds applications in diverse fields, especially in energy and environmental applications. Recently, BN and BN-based materials have gained significant interest in emerging desulfurization processes such as oxidative desulfurization and adsorptive desulfurization. In this review, BN and BN-based materials are elaborately discussed in the context of their use in various desulfurization techniques. A brief description about the different desulfurization processes is provided at the outset. The relationship between the characteristics (the defects, morphology, porosity and surface area) of BN and desulfurization efficiency is also summarized. Furthermore, the mechanistic insights regarding the action of BN materials in the desulfurization processes are discussed. With this review, the synthetic strategies for designing the novel BN-based catalysts/adsorbents for the effective desulfurization of liquid fuels can be grasped.

Synthesis of porous carbon via a waste tire leavening strategy for adsorptive desulfurization

Adsorptive desulfurization is an effective technology for removing harmful sulfur under mild conditions. Carbon materials have many advantages and are often used in adsorption desulfurization research, but until now have been synthesized using complicated methods and have shown limited adsorption capacity. Using an NaHCO3-assisted leavening method, waste tires were in the current work used as raw materials to produce hierarchically porous carbon that exhibits a high specific surface area and abundant oxygen-containing functional groups. In contrast to the sulfur removal by the carbon material prepared using a commonly used method, the as-prepared carbon material shows excellent adsorption performance, and was able to achieve an ultra-deep desulfurization of pentanethiol, specifically removing up to 99.7% of the sulfur from a model fuel with an initial sulfur concentration of 28 ppm. Therefore, we have provided a simple method for synthesizing adsorbents with high adsorption performance, and we expect these adsorbents to be used for industrial adsorptive desulfurization.