Visual Study Of The Effect Of Catalyst Particles On Catalytic Cracking

At present,our country’s oil refining capacity is overcapacity,coupled with the impact of the development of "dual carbon" and new energy technologies,the demand for oil products has declined.However,our country’s basic chemical products are in short supply and rely on imports,and refining and chemical integration is an inevitable trend.Catalytic cracking technology is one of the important production processes for oil production of chemical raw materials,which can solve the dual problems of heavy oil production and refining and chemical integration in my country at the same time.Studies have shown that the adjustment of the reactor structure will affect the internal oil contact and thus the reaction performance.Therefore,it is of great significance to explore the relationship between the catalyst distribution in the reactor and the reaction performance.Particle agglomeration often occurs due to the small particle size of the catalyst and the fast fluidization rate in the reaction.However,the current research on the effect of particle agglomeration only stays in the perspective of numerical simulation,and lacks experimental confirmation.Therefore,it is very important to quantitatively determine the influence of catalyst agglomeration by means of experiments,which can also provide theoretical guidance for the design of the reactor and the improvement of the reaction performance.This topic mainly focuses on the research on the influence of catalyst particle distribution on the reaction under different reaction conditions.A new system for the visualization of catalytic cracking is built to realize the visualization of the reaction process.The study simulates particle agglomeration and dispersion in large-scale devices by changing the catalyst arrangement state,and investigates the effect of agglomeration on the reaction of different catalyst particles and reaction conditions.The research results show that under the same reaction conditions,catalyst particle agglomeration will reduce the reaction conversion rate and target product ethylene selectivity,and increasing the reaction temperature and space velocity can reduce the adverse effects of catalyst agglomeration on both.The difference of NTO-19 conversion rate gradually decreased from 11.2 wt% at 450 °C to 2.0 wt% at 600 °C,and from 7.6 wt% at 1 m L/min to 2.0 wt%at 4 m L/min.The difference in the conversion rate of DMMC-2 gradually decreased from2.3 wt% at 450 °C to 0.2 wt% at 600 °C,and from 1.4 wt% at 1 m L/min to 0.1 wt% at 4m L/min.The catalyst composition and reaction conditions will affect the choice of the optimal distribution state of the catalyst.The optimal distribution state of the two catalysts with ethylene as the target product is the catalyst dispersion state,while the optimal distribution state of the catalyst with propylene as the target product varies with the type of catalyst.In order to improve the yield of the target product in actual production,the optimal distribution state of the catalytic reaction of the catalyst should be comprehensively considered and selected.In addition,the reduction of the catalyst particle size will promote the progress of the reaction,but if the particle size is too small,the dispersion degree of the catalyst in the reactor will also be affected,and the reaction effect will be deteriorated.In the actual production operation,the distribution of the catalyst in the reactor can be changed by adjusting the experimental conditions,changing the catalyst feeding method and reforming the structure of the reactor according to the properties of the catalyst used and the demand of the target product.Through the observation and photography of the macroscopic and microscopic experimental process,it is found that the catalyst particles have obvious agglomeration phenomenon,and a large amount of dry gas is generated when the single particle agglomerates at the microscopic level.This confirms the common occurrence of catalyst particle agglomeration in the cracking process,and fills the gap in the current capture of particle agglomeration in the catalytic cracking reaction process.