Preparation Of H-BN Nanoparticles And BN-Based Composite Catalysts Study On Catalytic Performance

Boron nitride nanosheets?BNNS?hold the similar two-dimensional structure as graphene and unique properties complementary to graphene,which makes it a promising candidate in the field of catalyst carrier,water pollution treatment and hydrogen storage materials.The exfoliation of boron nitride still remains challenge and hindersthe applications of BNNSs.Compared with graphene,the boron nitride is more difficult to be intercalated and exfoliated than graphite.This may attribute to the ionic characteristic of the bonding between neighboring boron nitride layers,which is stronger than the weak Uan der Waals force between graphene layers.Therefore,it is particularly necessary to find a moderate,eco-friendly and large scale chemical engineering process to fabricate excellent BNNSs.In this paper,a low residue and low cost BNNSs exfoliation technology was developed by using ultrasonic assisted supercritical carbon dioxide method with the original h-BN as the precursor.By controlling the rate of mechanical agitation and adjusting the shear force,controllable,large scale materials suitable for using as catalyst carriers were obtained.The exfoliated BNNSs retained a more complete six-party crystal structure with a diameter of about 50-200nm.This method is easy to operate and is friendly to the environment,which presents a promising method for exfoliating layered materials even with strong interlayer bonds.Using BNNSs exfoliated by supercritical CO₂ fluid technology as carrier and Co nanoparticles as catalytic active component.X%Co/BNNSs?X=1,5,10,15?catalyst with different Co content was prepared by a hydrothermal synthesis method.At a control,Co/h-BN catalyst was obtained in same way.The reaction of p-nitrophenol reduced to p-aminophenol is used to evaluate the catalytic performance.The catalytic activity of the Co/BNNSs catalyst after exfoliation is much greater than that of the unpeeled Co/h-BN,especially the Co/BNNSs catalyst with 10wt%content has the highest catalytic activity.After5 cycles of application,it still shows good catalytic activity and cycling stability.Therefore,BNNSs is a good support for the preparation of heterogeneous catalysts.The surface modification of h-BN powder was treated with a strong oxidant at high temperature,and the modified h-BN was used as the carrier to prepare the composite catalyst of nano cobalt,nickel and cobalt nickel alloy?M/h-BN?,which was used to catalyze the hydrolysis dehydrogenation of the borane.The three catalysts showed good catalytic activity,in which the catalytic performance of the bimetallic CoNi/h-BN catalyst is the best.The activation energy of the experiment is Ea 29.14 kJ mol^-1.This is due to the electronic effect and synergy produced by bimetallic,which effectively improves the catalytic activity,and have a certain catalytic stability.