Preparation Of Cu（Ⅰ）,B₂O₃ Modified Two-dimensional Black Phosphorus Nanosheets For Adsorption Desulfurization From Model Fuel

The emission of sulfur oxides will cause a series of environmental problems such as acid rain and smog.Many countries have strengthened the limit on the concentration of sulfur compounds in fuel.Therefore,it is urgent to develop an efficient and environmentally friendly desulfurization method.Adsorption desulfurization technology is considered to be the most promising desulfurization method in the future because of its low energy consumption,low equipment requirements and easy operation.In this paper,black phosphorus(BP)was used as a precursor,and two-dimensional adsorbents of Cu(Ⅰ)modified black phosphorus nanosheets(BPNSs)and B2O3 modified BPNSs were developed by a ball-mill method for adsorption desulfurization from fuel.Firstly,three methods of mineralization,solvothermal and ball-mill were used to prepare crystal BP.Then the crystal BP with a layered structure was exfoliated into twodimensional nanosheets by ball-mill,and the active components were anchored on the nanosheets to synthesize adsorbents.Finally,the adsorption desulfurization performances of the adsorbents were evaluated by the static adsorption method.The Cu(Ⅰ)/BPNSs adsorbents prepared by wet-mill are composed of nanosheets with a lateral size of 100～1000 nm and a thickness of 3.0～6.0 nm.Each phosphorus atom has a pair of unbonded lone pairs of electrons,which endows BP with high reducibility.In the preparation process,BP can reduce Cu(Ⅱ)to Cu(Ⅰ),and Cu-P interaction occurs between Cu(Ⅰ)and BPNSs,so Cu(Ⅰ)species have been anchored on the surface of BPNSs,which significantly improves the Cu(Ⅰ)dispersibility.As the active center of the adsorbent,Cu(Ⅰ)can adsorb sulfur-containing compounds by forming a πcomplexation with the aromatic compounds in the fuel to achieve the purpose of desulfurization.The particles size of the B2O3/BPNSs adsorbent prepared by the dry-mill method are mostly concentrated in 100 nm,and the thickness is 6～8 nm.Compared with the Cu(Ⅰ)/BPNSs prepared by the wet-mill method,the size is smaller and the thickness is larger.As an electron-deficient compound,B2O3 can be combined with electron-rich BPNSs.It can not only enhance the stability of BPNSs,but also interact with sulfurcontaining compounds to complete adsorption desulfurization.The adsorption capacity of Cu(Ⅰ)/BPNSs increases with the molar ratio of Cu to P.However,when the doping amount of Cu is too high,Cu2+ will cause severe oxidation of BPNSs,resulting in a decrease in the yield of the adsorbent.When the molar ratio of Cu to P is 0.15,the relationship between the adsorption capacity and the yield of the adsorbent can be effectively balanced.Under the condition,the saturated adsorption capacities of the adsorbent for benzothiophene and dibenzothiophene are 18.02 and 13.16 mg S/g,respectively.The adsorption capacity of B2O3/BPNSs adsorbent increases first and then decreases with the increase of the molar ratio of B2O3 to P.The adsorption capacity is the highest when the molar ratio is 0.10,and the saturated adsorption capacities for benzothiophene and dibenzothiophene are 5.71 and 4.20 mg S/g,respectively.The adsorption experimental data of Cu(I)/BPNSs and B2O3/BPNSs accord well with the characteristics of the quasi-second-order kinetic equation.Both adsorbents can be recycled through the thermal regeneration,and their saturated adsorption capacities can still maintain more than 75%of the initial capacities after four cycles.