Preparation Of Boron-based Metal-free Materials For Oxygen Activation In Ultra-deep Desulfurization

Organic sulfides are commonly existent in fuel oil.However,SO_x would be released in the combustion of sulfides in fuel oil,leading to a series of serious weather,such as the acid rain and haze,which would corrode the buildings and endanger the health of animals or plants.Currently,hydrodesulfurization is the most important desulfurization technology in refineries,while the operating conditions of high temperature,high pressure,and high consumption of hydrogen limit the perpetual and steady development of industrialization.Thus,the oxidative desulfurization（ODS）technology,with the mild reaction conditions and high efficiency,attracted extensive attention of the researchers.In this paper,focused on the topic of“Preparation of boron-based metal-free materials for oxygen activation in ultra-deep desulfurization”,metal-free boron-based heterogeneous catalysts were successfully designed via the special properties of boron elements for enhanced the activation abilities of O₂.The catalysts are analyzed by XRD,FT-IR,Pyridine FT-IR,Raman,NH₃-TPD,XPS,SEM,TEM,and other characterizations.In the aerobic oxidative ultra-deep desulfurization system,the removal ability,rules of desulfurization for different sulfides in fuel oil were studied,the catalytic process of the deep oxidative desulfurization system was also discussed.The research results obtained in this paper are as follows:1.Cubic boron carbides（B₄C）,as a metal-free ceramic catalyst,has been fabricated by a facile mechanical exfoliation method.B₄C nanosheets,with the lower height,the smaller particle size,and the higher defects level,are obtained by an up-bottom approach for the first time.In the ODS system,the effects of exfoliation time,catalysts purity,reaction temperature,and recycle times on sulfur removal performance are discussed.At the suitable reaction conditions,the DBT removal performance of B₄C catalysts is up to 99.5%and higher than 87.5%after recycling 17 times.The sulfur removal performance of B₄C-5 to various sulfides are DBT>4,6-DMDBT>4-MDBT.Herein,the possible reaction process of the B₄C desulfurization system is proposed,the current method may path the way to a potential application of the mechanical ball-milling exfoliation in the preparation of the catalysts,as well as a prospect of the B₄C applied in the oxidation field.2.Boron-doped graphite（B-G）has been prepared by a one-step calcination method,B-G nanosheets with redistributed electron structure are obtained according to a series of characterization.In the ODS system,the effects of boron amount,atmosphere,reaction temperature,and recycle times on sulfur removal performance are discussed.At the suitable reaction conditions,the DBT removal performance of B-G nanosheets is up to 99%,the sulfur removal performance of B-G to various sulfides are DBT>4-MDBT>4,6-DMDBT.Herein,the possible reaction process of the B-G desulfurization system is proposed,this strategy may provide a new strategy of the carbon materials for the activation of O₂ molecules.3.Boron-doped graphene-analogous carbon nitride（B-C₃N₄）has been prepared and applied to remove 4,6-DMDBT.Detailed characterizations show that B atoms have been doped into the framework of carbon nitride,which redistributes the electron structures and appears enhanced Lewis acidity.In the ODS system,the effects of boron doping,reaction temperature,sulfur concentration,and recycle times on sulfur removal performance are discussed.At the suitable reaction conditions,the 4,6-DMDBT removal performance of B-C₃N₄ is up to 100%,the sulfur removal performance of B-C₃N₄ to various sulfides are 4,6-DMDBT>4-MDBT>DBT.Herein,the possible reaction process of the B-C₃N₄ desulfurization system is proposed,the current method provides a potential strategy for the removal of 4,6-DMDBT in fuels.