Research On Doping Of Mo-V-Te-Nb-O Catalyst For Selective Oxidation Of Propane To Acrylic Acid

Acrylic acid is one of the most important basic raw material and intermediate for modern chemical industry.At present,the acrylic acid is mainly synthetised from propylene and is obtained by two-step oxidation.The relatively expensive price of propylene leads to high production cost of acrylic acid.However,propane is abundant,cheap and easy to be available.Therefore,the research of acrylic acid synthesis has been focusing on the propane used as the substitute for propylene in this field.According to the patent report,The metal oxide catalyst of Mo-V-Te-Nb-O composite for the selective oxidation of propane to acrylic acid is of excellent catalytic performance,the yield of acrylic acid can reach 48%,but so far the industrial application have not been achieved because of the catalytic stability.Therefore,further modifying the catalyst is still the focus of research.At the same time,it is also of great significance to find suitable carriers for catalyst loading and exploring reaction conditions suitable for industrial applications.In order to further study the Mo-V-Te-Nb-O catalyst of selective oxidation of propane to acrylic acid which is more excellent in performance and has industrial application prospects,this research has mainly engaged in the following two aspects based on the previous studies in the laboratory.Firstly,the characteristics like the acidity of element P,the oxidative dehydrogenation promoted by element of Sb,the increase of lattice oxygen donor and the improvement of structural stability of the catalyst phase are used to conduct element doping studies to explore the influence of the introduction of P and Sb elements on the catalytic performance of the catalyst so as to lay the foundation for better catalytic performance.Secondly,the carrier loading study is carried out to investigate the effects of factors such as carrier type,loading mode and carrier content on the catalytic performance of supported catalysts in order to lay a foundation for better industrial application.The main results of this research are as follows:(1)Based on the Mo1Vo.3Teo.23Nbo.12O catalyst,the doping of P and Sb elements was carried out.The experimental results indicated that the doping of the appropriate amount of P element(P/Mo?0.02(mol))and Sb element(Sb/Mo=0.01(mol))could improve the catalytic performance of the catalyst to some extent.The acrylic acid yield of Mo1Vo.3Teo.23Nbo.12Po.02O catalyst is 45.8%,and the acrylic acid yield of Mo,V0.3Te0.23Nb0.12Sb0.01O catalyst is 48.5%,both of which are higher than that of undoped catalyst(42.4%).(2)The doping of P and Sb elements reduces the content of Mo6+and V5+species on the catalyst surface.The relative content of the active phase structure of the catalyst,M1 and M2,changes.The oxidation activity and the surface acidity decline.As a result,the conversion rate of propane decreases,and the selectivity of acrylic acid increases.(3)A MoiV0.3Te0.23Nbo.i2O@HZSM-5 catalyst with good stability was prepared.It was found by loading HZSM-5 molecular sieve that the loading of the carrier reduces the content of the active phase structure of the catalyst to a certain extent,thereby reducing its catalytic activity.However,the stability of the catalyst is well.