Yanhong Chao

Few-layered graphene-like boron nitride induced a remarkable adsorption capacity for dibenzothiophene in fuels

Metal-free graphene-like boron nitride (BN) samples were prepared and applied as adsorbents for removing dibenzothiophene (DBT) in model oil. The results showed that the graphene-like BN exhibited a remarkable adsorption performance. The adsorption capacity could reach 28.17 mg S g−1 adsorbent. Experiments have been carried out to investigate the effects of the number of BN layers, DBT initial concentration, and temperature on DBT adsorption. Langmuir and Freundlich isotherm models were used to study the adsorption of DBT on BN. The kinetic results showed that the adsorption process was best described by the pseudo-second-order kinetic model. Density functional theory (DFT) was employed to prove that the Lewis acid–base interaction plays an important role in removing DBT over graphene-like BN.

Fenton-like ionic liquids/H2O2 system: one-pot extraction combined with oxidation desulfurization of fuel

The extraction desulfurization (EDS) and extraction combined with oxidation desulfurization (EODS) for the removal of dibenzothiophene (DBT), benzothiophene (BT), and 4,6-dimethyldibenzothiphene (4,6-DMDBT) in a model oil were carried out in Fenton-like ionic liquids, such as [Et3NHCl]FeCl3, [Et3NHCl]CuCl2, [Et3NHCl]ZnCl2, [Et3NHCl]CoCl2, [Et3NHCl]SnCl2 and [Et3NHCl]CrCl3. The deep desulfurization could be achieved in [Et3NHCl]FeCl3 for only 5 min at room temperature. The reaction conditions such as temperature, the molar ratio of H2O2 and DBT and the amount of ionic liquid (IL) were investigated in the EODS system. By controlling the way of adding H2O2 into the desulfurization system, the sulfur content in the model oil could decrease from 500 mg L−1 to less than 10 mg L−1 at the IL/oil volume of 1 : 5. The oxidation reactivity of the different sulfur-containing compounds was found to be in the order of DBT > BT > 4,6-DMDBT. Moreover, the EODS system could be recycled ten times with a slight decrease in activity to model oil. EODS process was applied to prehydrotreated gasoline and the sulfur content could decrease from 150 to 15 mg L−1 after two rounds of reaction.

A template-free solvent-mediated synthesis of high surface area boron nitride nanosheets for aerobic oxidative desulfurization

Hexagonal boron nitride nanosheets (h-BNNs) with rather high specific surface area (SSA) are important two-dimensional layer-structured materials. Here, a solvent-mediated synthesis of h-BNNs revealed a template-free lattice plane control strategy that induced high SSA nanoporous structured h-BNNs with outstanding aerobic oxidative desulfurization performance.

Carbon-doped porous boron nitride: metal-free adsorbents for sulfur removal from fuels

Novel carbon-doped porous boron nitride (C-BN) has been successfully prepared by using 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF4) as a soft template and the carbon source via calcination under N2 atmosphere. Multiple techniques were applied to investigate the structure, morphology, and adsorptive desulfurization performance. The metal-free porous C-BN displayed enhanced adsorption performance for dibenzothiophene (DBT) than pure BN materials and exhibited one of the highest adsorption capacities reported up to now (49.75 mg S g−1 adsorbent according to the Langmuir isotherm model, 35.2 mg S g−1 adsorbent for 500 ppm sulfur model oil). After three times recycling, the adsorption capacity slightly decreased from 35.2 to 27.2 mg S g−1 adsorbent. The excellent adsorption performance of porous C-BN was attributed to the more exposed atoms along the edges of the pores and the stronger Lewis acid–base interactions between DBT and carbon-doped porous BN. Moreover, it is believed that this strategy to control the structure and composition of BN can be extended to incorporate other heteroatoms and control the pore size for BN materials by changing the anion or cation of the ionic liquids.

Controlled Gas Exfoliation of Boron Nitride into Few‐Layered Nanosheets

The controlled exfoliation of hexagonal boron nitride (h-BN) into single- or few-layered nanosheets remains a grand challenge and becomes the bottleneck to essential studies and applications of h-BN. Here, we present an efficient strategy for the scalable synthesis of few-layered h-BN nanosheets (BNNS) using a novel gas exfoliation of bulk h-BN in liquid N2 (L-N2 ). The essence of this strategy lies in the combination of a high temperature triggered expansion of bulk h-BN and the cryogenic L-N2 gasification to exfoliate the h-BN. The produced BNNS after ten cycles (BNNS-10) consisted primarily of fewer than five atomic layers with a high mass yield of 16-20 %. N2 sorption and desorption isotherms show that the BNNS-10 exhibited a much higher specific surface area of 278 m(2)  g(-1) than that of bulk BN (10 m(2)  g(-1) ). Through the investigation of the exfoliated intermediates combined with a theoretical calculation, we found that the huge temperature variation initiates the expansion and curling of the bulk h-BN. Subseqently, the L-N2 penetrates into the interlayers of h-BN along the curling edge, followed by an immediate drastic gasification of L-N2 , further peeling off h-BN. This novel gas exfoliation of high surface area BNNS not only opens up potential opportunities for wide applications, but also can be extended to produce other layered materials in high yields.

Controllable Fabrication of Tungsten Oxide Nanoparticles Confined in Graphene-Analogous Boron Nitride as an Efficient Desulfurization Catalyst

Tungsten oxide nanoparticles (WOx NPs) are gaining increasing attention, but low stabiliity and poor dispersion of WOx NPs hinder their catalytic applications. Herein, WOx NPs were confined in graphene-analogous boron nitride (g-BN) by a one-step, in situ method at high temperature, which can enhance the interactions between WOx NPs and the support and control the sizes of WOx NPs in a range of about 4-5 nm. The as-prepared catalysts were applied in catalytic oxidation of aromatic sulfur compounds in which they showed high catalytic activity. A balance between the W loading and the size distribution of the WOx NPs could govern the catalytic activity. Furthermore, a synergistic effect between g-BN and WOx NPs also contributed to high catalytic activity. The reaction mechanism is discussed in detail and the catalytic scope was enlarged.

Photocatalytic oxidative desulfurization of dibenzothiophene catalyzed by amorphous TiO2 in ionic liquid

Three types of TiO2 were synthesized by a hydrolysis and calcination method. The catalysts were characterized by X-ray powder diffraction (XRD), diffuse reflectance spectrum (DRS), Raman spectra, and X-ray photoelectron spectroscopy (XPS). The XRD and Raman spectra indicated that amorphous TiO2 was successfully obtained at 100 °C. The results indicated that amorphous TiO2 achieved the highest efficiency of desulfurization. The photocatalytic oxidation of dibenzothiophene (DBT), benzothiophene (BT), 4,6-dimethyldibenzothiophene (4,6-DMDBT) and dodecanethiol (RSH) in model oil was studied at room temperature (30 °C) with three catalysts. The system contained amorphous TiO2, H2O2, and [Bmim]BF4 ionic liquid, ultraviolet (UV), which played vitally important roles in the photocatalytic oxidative desulfurization. Especially, the molar ratio of H2O2 and sulfur (O/S) was only 2: 1, which corresponded to the stoichiometric reaction. The sulfur removal of DBT-containing model oil with amorphous TiO2 could reach 96.6%, which was apparently superior to a system with anatase TiO2 (23.6%) or with anatase — rutile TiO2 (18.2%). The system could be recycled seven times without a signicant decrease in photocatalytic activity.

A large number of low coordinated atoms in boron nitride for outstanding adsorptive desulfurization performance

h-BN has been demonstrated to be able to exhibit adsorptive desulfurization from fuel. In order to further optimize the adsorption capacities to meet the potential industrial applications, tuning the nanostructure of BN was taken into account. In this work, we demonstrated that cyanamide, dicyandiamide, and melamine as different nitrogen precursors for synthesizing BN could tune the BN nanoarchitectures. The high performance BN prepared with melamine presented a ribbon-like structure which was assembled with porous nanosheets. This kind of nanoarchitecture with exposed BN sharp edges and a porous structure can be constructed on the BN surface. The large number of low coordinated atoms at the exposed sharp edges and along the edges of the pores could build powerful interaction with sulfide, which was believed to be responsible for the advanced adsorption capacity. The prepared BN with melamine as nitrogen precursors displayed remarkable adsorption performance for DBT (40.2 mg S per g adsorbent for 500 ppm sulfur model oil and 57.5 mg S per g adsorbent according to the Langmuir isotherm model). To the best of our knowledge, it is the highest adsorption capacities reported so far for the adsorptive desulfurization. It is also noteworthy to mention that even for refractory sulfur compound 4,6-DMDBT, the prepared BN still showed high adsorption performance.

Application of a self-emulsifiable task-specific ionic liquid in oxidative desulfurization of fuels

A tungsten-containing task-specific ionic liquid (IL) [(C6H13)3PC14H29]2W6O19 was synthesized and applied in the desulfurization process of a dibenzothiophene-containing model oil with aqueous hydrogen peroxide. In the desulfurization process, a novel aqueous hydrogen peroxide-in-IL emulsion catalytic system was found. The task-specific IL not only acted as extraction media for the organo-sulfur compounds and served as a catalyst for the hydrogen peroxide but also provided an oxidation micro-environment for the conversion from sulfur compounds to sulfones by forming IL emulsions. The self-emulsifiable IL played two roles in the emulsification process: the surfactant and the dispersion medium.

Graphene-Analogues Boron Nitride Nanosheets Confining Ionic Liquids: A High-Performance Quasi-Liquid Solid Electrolyte.

Solid electrolytes are one of the most promising electrolyte systems for safe lithium batteries, but the low ionic conductivity of these electrolytes seriously hinders the development of efficient lithium batteries. Here, a novel class of graphene-analogues boron nitride (g-BN) nanosheets confining an ultrahigh concentration of ionic liquids (ILs) in an interlayer and out-of-layer chamber to give rise to a quasi-liquid solid electrolyte (QLSE) is reported. The electron-insulated g-BN nanosheet host with a large specific surface area can confine ILs as much as 10 times of the hosts weight to afford high ionic conductivity (3.85 × 10(-3) S cm(-1) at 25 °C, even 2.32 × 10(-4) S cm(-1) at -20 °C), which is close to that of the corresponding bulk IL electrolytes. The high ionic conductivity of QLSE is attributed to the enormous absorption for ILs and the confining effect of g-BN to form the ordered lithium ion transport channels in an interlayer and out-of-layer of g-BN. Furthermore, the electrolyte displays outstanding electrochemical properties and battery performance. In principle, this work enables a wider tunability, further opening up a new field for the fabrication of the next-generation QLSE based on layered nanomaterials in energy conversion devices.