Adsorptive Desulfurization By Boron Nitride Prepared With Melamine Method

Combustion of sulfur compounds in transportation fuels which release SOx,NOx pose serious threats to the air,water,and environment.Controlling or reducing the emission of SOx has becoming an important global concern.It is easy and efficient to remove sulfide,thiol,and thiophene with conventional HDS in the industry.However,it requires higher operating temperature,pressure and a large amount of expensive hydrogen to remove the sulfur compounds from the diesel because the sulfur compounds are dibenzothiophene(DBT)and its derivative.Moreover,the stringent operating conditions can cause the quality of the fuel reduced and make the cost increased.To meet the demanding specifications,many other desulfurization technologies have been explored to compliment the current HDS technology.Adsorptive desulfurization(ADS)technology has been considered to be one of the promising technologies due to its low-energy consumption and mild operating conditions.In this work,a series of metal-free BN adsorbents has been designed to remove the sulfur compounds from the fuel.In this work,melamine(C3H6N6),dicyandiamide(C2H4N4),and cyanamide(CH2N2)were chosen as different nitrogen precursors to tune the BN nanoarchitectures.Among these,BN prepared by melamine possessed a ribbon-like structure which was assembled with porous nanosheets and exhibited high desulfurization performance.The kind of nanoarchitecture with exposed BN sharp edges and porous structure could form large number of low coordinated atoms which could build powerful interaction with sulfide,and thus the adsorptive desulfurization performance was improved greatly.The adsorption capacities of BN prepared by melamine for DBT achieved 40.2 mgS·g-1 adsorbent(500 ppm sulfur model oil).Additionally,the BN prepared by melamine showed high adsorption performance for refractory sulfur compound 4,6-DMDBT.Based on the previous work,the heteroatoms with high electronegativity introduced to the BN could enhance the interaction with DBT.The BN used boric acid and melamine as precursor which exhibited high adsorptive desulfurization performance has been proved.In this study,P123 as soft template was introduced.A novel BN mesoporous nanowire material with doped oxygen atoms has been controlled and prepared successfully.The structure,morphology,surface feature,and electronic structure of BN mesoporous nanowire have been characterized by multiple techniques.The synthesized BN mesoporous nanowire was applied to adsorptive desulfurization for the first time.The experimental data demonstrated that BN mesoporous nanowire displayed outstanding adsorptive desulfurization activity for DBT(65.4 mgS·g-1 adsorbent according to the Langmuir isotherm model),which was much higher than that of commercial BN and graphene-like BN.It was noteworthy that the BN mesoporous nanowire exhibited good stability and excellent adsorption performance for the 4,6-DMDBT(33.2 mgS·g-1 adsorbent for 400 ppm sulfur model oil).Compared with commercial BN and graphene-like BN,the significant enhancement of adsorption desulfurization performance of BN mesoporous nanowire was ascribed to the doped oxygen atoms,which could cause an interaction with DBT.The BN with doped oxygen atoms possessed high interaction with DBT.However,the adsorption desulfurization performance of BN with doped oxygen atoms could not meet the demand of current sulfur contant standard.Aiming at the latest standard of sulfur contant,activated metal-free BN adsorbent has been prepared by a surfactant assisted regulation strategy.The adsorptive desulfurization of BN was further optimized by tuning the variety of surfactants(such as P123,PVP,F127),usage and reaction temperature.The optimized activated BN-P123 adsorbent displayed porous structure with high surface area about 1185 m2·g-1.The adsorption capacities of BN-P123 could achieve 45.7 mgS·g-1 adsorbent for DBT(500 ppm sulfur model oil),which was comparable or even superior to the state-of-the-art adsorbent.Additionally,the activated BN-P123 could realize the ultra-deep desulfurization through adsorptive process to reach the latest international standard(less than 10 ppm).Considering the nontoxic metal-free feature and the excellent adsorption performance,the obtained activated BN-P123 may be a powerful candidate to meet the requirements of potential industrial applications.