Density Functional Theory Study On The Mechanism Of Non-metal Catalyzed Propane Dehydrogenation Reaction

Propylene is an important basic chemical raw material for the production of three major synthetic materials such as plastics,rubber and fibers.Because of the wide range of applications and high product yield of propylene derivatives,the demand for propylene is increasing year by year,leading to the fact that the traditional propylene production technology can no longer meet the market demand,and therefore a new propylene preparation process is needed to replace the traditional propylene production technology.Propane dehydrogenation process is considered to be a very promising method for propylene preparation due to its high selectivity,cheap and easily available feedstock.However,the platinum-based and chromium-based catalysts currently used in the propane dehydrogenation process are expensive and polluting to the environment.In order to make the further promotion of propane dehydrogenation process,the development of an efficient catalyst that is environmentally friendly and inexpensive is the first problem to be solved.In this paper,the reaction mechanism and catalytic performance of different structures of BN nanomaterials(0D B12N12 nanoclusters,1D BN nanotubes,2D BN nanosheets),nonmetallic single-atom(C,O,P,S)doped BN nanosheets,and nonmetallic single-atom(N,O,P)doped graphene for prop0ane dehydrogenation catalytic reaction were explored by density flooding theory(DFT)method.This provides a theoretical basis for the design of novel nonmetallic catalysts for propane dehydrogenation.Through theoretical calculations,the following research results were obtained in this paper:(1)In the first chapter,the effect of different structured nonmetallic BN nanomaterial catalysts on the direct dehydrogenation reaction of propane was investigated using density flooding theory(DFT)and the reaction mechanism was analyzed.The computational results show that the catalytic performance characteristics of different structured nonmetallic BN nanomaterial catalysts in the direct dehydrogenation reaction of propane vary considerably.In the PDH reaction,the energy required to activate the C-H bond on propane was in the order of BNNT>BNNS>B12N12NC from high to low.this indicates that the 0-dimensional B12N12NC catalyst has the best catalytic activity for the C-H bond,while both the 1dimensional BNNT and the 2-dimensional BNNS catalysts are less effective.(2)Based on the study in Chapter 1,the 2-dimensional BN nanosheets were modified.The modification of BN nanosheet catalysts with different nonmetallic single atoms(C,O,P,S)doping was investigated by DFT,followed by exploring the effect of the modified catalysts on the direct dehydrogenation reaction of propane and analyzing the reaction mechanism.The results show that the BN nanosheet catalysts after modification with carbon atoms and the increased electron transfer within the C-atom doping sites enhance the ability to activate the C-H bond on propane,which is a potential nonmetallic propane dehydrogenation catalyst.(3)In Chapter 3,the effects of different non-metallic single-atom-doped graphene catalysts on the direct dehydrogenation reaction of propane were investigated by DFT and the reaction mechanism was analyzed.The calculation results showed that the catalytic performance characteristics of different non-metallic single-atom-doped graphene catalysts in the direct dehydrogenation reaction of propane were very different.The comparative analysis revealed that among the non-metallic single-atom(N,O and P)doped graphene catalysts,the P-PG catalyst is the most promising catalyst in catalytic PDH.