Study On Magnetic Rhodium Catalyst For Hydroformylation Of FCC Light Gasoline

Due to the increasingly strict quality standards of national automotive gasoline and the attention of human beings to environmental protection,reducing the olefin content of gasoline to produce high-quality clean oil has become a hot research topic.Traditional methods of reducing olefins,such as hydrogenation and aromatization,are easy to reduce the octane number of gasoline.Therefore,this paper proposes to use hydroformylation to convert olefins in gasoline to aldehydes,and then further hydrogenate to produce alcohols,in order to achieve olefin reduction while keeping the octane number does not decrease.At present,the industrial hydroformylation catalyst is homogeneous rhodium catalyst,which needs to be recycled by distillation separation.In order to achieve the separation of low energy consumption,a series of magnetic rhodium catalysts are designed and prepared in this paper,in order to realize the simple separation of catalyst by magnetic field,by optimizing the catalyst structure,slowing the loss of rhodium,and providing data reference for the industrial application of supported hydroformylation catalyst.First of all,in this paper,Rh/Fe₃O₄ and Fe₃O₄@Rh catalysts were prepared by hydrothermal method and surface modification method,which was intended to screen out better catalyst preparation method.In the doped magnetic catalyst Rh/Fe₃O₄ prepared by hydrothermal method,by changing the molar ratio of Rh:Fe,the resulting catalyst particle size distribution is not uniform,and the particle size is relatively large,up to 6?m.The catalyst evaluation results show that with the increase of the rhodium-iron ratio,the reaction conversion rate decreases and the maximum conversion rate does not exceed10%,indicating that the rhodium atom utilization rate is extremely low.The second method uses the surface modification method to load rhodium nanoparticles on Fe₃O₄ to prepare Fe₃O₄@Rh catalyst,changing the rhodium loading to 1%?4%,the resulting catalyst particles are uniformly distributed and the size is around 200nm.The catalyst evaluation results show that with the increase of the rhodium loading,the reaction conversion rate decreases.When the rhodium loading is 1%,the highest conversion rate is 35.23%.It can be seen that the Fe₃O₄@Rh activity prepared by the surface modification method and the rhodium atom utilization rate are superior to the Rh/Fe₃O₄ prepared by the hydrothermal method,but the rhodium active component of the Fe₃O₄@Rh catalyst is easily lost,and the conversion rate after the second reaction is reduced to 8.34%.After screening out the catalyst with the best catalytic effect,1%Fe₃O₄@Rh,in order to improve the stability of its cycle reaction,the catalyst was structurally optimized.After encapsulating a layer of Si O₂ on the outer layer of Fe₃O₄@Rh catalyst,it was etched with NaOH solution.The controlled variable method was used to explore the etching time and the etching concentration.The experimental results showed that the etching time of NaOH was 50min and the etching concentration of NaOH is 0.05g/m L,the Fe₃O₄@Rh@Si O₂catalyst has the best cycle performance and the conversion rate is 27.78%and 11.61%after four cycles.Finally,after a series of experiments on the direct hydrogenation of glutaraldehyde and the series connection of olefin aldehyde and alcohol,it is concluded that the concentration of phosphine ligand and the waiting time after hydroformylation have an important effect on the reaction.After that,gasoline aldehyde alcohol series reaction was carried out.The results showed that the conversion of hydroformylation was 38.02%in the first step and the conversion of hydrogenation was 88.32%in the second step.