Preparation Of Fibrous Boron-based Catalyst For Oxidative Dehydrogenation Of Propane

With the gradual increase in the production of natural gas and shale gas,as well as the continuous increase in the demand for propylene in China,the production of propylene from propane as a raw material has attracted more and more attention.Among them,the oxidative dehydrogenation of propane（ODHP）to propylene has attracted much attention due to its advantages of low reaction temperature,no thermodynamic equilibrium restriction,and no carbon deposition.As emerging ODHP catalysts,boron-based catalysts have the advantages of high selectivity and suppression of excessive oxidation.Therefore,the research and preparation of high-activity boron-based catalysts is a current research hotspot.One-dimensional fibrous nanomaterials have attracted much attention in the field of catalysis due to their highly active phase loading potential and their ability to promote mass transfer.In this study,a new type of one-dimensional supported boron-based catalyst was prepared by electrospinning.The effects of different boron species doping,active species loading amount,and calcination temperature on the morphology,structure,and ODHP reaction performance of the catalyst were investigated.The research results are as follows:Hexagonal boron nitride/silicon dioxide（h-BN/Si O₂）nanofiber catalysts were prepared by electrospinning.Dispersing ball-milled h-BN in silica sol to obtain a uniform spinning solution was the key to the success of electrospinning.The diameter of the nanofiber catalyst could be adjusted in the range of 150～300 nm by calcination temperature and h-BN loading.When the obtained h-BN（7 wt%）/Si O₂ catalyst was calcined at 600°C and used in the oxidative dehydrogenation of propane,the conversion rate of propane was 12.4%,the selectivity to propylene was 85.1%,and the olefins productivity was 24.9 g_olefins·g _BN^-1·h^-1,which was more than 5 times higher than that of bulk ODHP catalysts reported to date.Meanwhile,the reaction test for 500 min showed that the catalyst had good stability.Boron phosphate/silicon dioxide（BPO₄/Si O₂）nanofiber catalysts were prepared by using the above successful method where boron phosphate was used as the active component.The influence of BPO₄ loading and calcination temperature on the structure of the product were mainly investigated.The SEM characterization results showed that the BPO₄/Si O₂ catalysts had one-dimensional fibrous structure.When the BPO₄ loading was 7 wt%,the fibrous catalyst obtained after calcination at 600°C stabilized the conversion rate of propane at 14.8%within500 min,and the selectivity of propylene and ethylene at 79.1%and 7.7%,respectively,which indicated that the catalyst also has good stability.