| Hydrogenated nitrile rubber（HNBR）has become one of the strategic materials in my country due to its good oil resistance,chemical resistance and mechanical properties.However,expensive metal catalysts such as Pd,Rh and Ru need to be used in the preparation of hydrogenated nitrile rubber.In addition,the noble metal catalysts remaining in HNBR will also have a certain impact on the performance of HNBR.In order to solve this problem,researchers start from the preparation and removal of the catalyst.（1）After the hydrogenation is completed,the heterogeneous catalyst can be separated by centrifugation,etc.,and can be reused after post-treatment.The activity and selectivity are lower than those of homogeneous catalysts.（2）The catalyst remaining in the HNBR glue solution is removed by methods such as adsorption method and precipitation method.Usually,the catalyst removal is not complete,and eluents such as HCl need to be used.The reuse of the catalyst leads to waste of the catalyst.Metal-organic frameworks（MOFs）are used as supports and adsorbents for heterogeneous catalysts due to their high specific surface area,open metal sites,and good porosity.Aiming at the above problems,this paper uses MOFs as the carrier of heterogeneous catalyst to carry out catalytic hydrogenation of NBR,and uses MOFs as adsorbent to adsorb the adsorbent remaining in the HNBR glue solution,and finally realizes the reuse of the catalyst and reduces the HNBR.preparation cost.The main research contents are as follows:1.Several different metal-organic frameworks（MOFs）were developed,and their structures and specific surface areas were characterized by X-ray powder diffraction（XRD）and N2 physical adsorption.The results showed that Ui O series MOFs had larger specific surface areas.The MOFs were further modified to introduce sulfonic acid groups,urea groups and benzene rings,and the specific surface area of MOFs decreased after modification.The Pd@MOFs catalyst was prepared by impregnation method.The effect of different MOFs-loaded Pd on the catalytic hydrogenation activity of nitrile rubber was investigated,and the shedding of active components during the hydrogenation process was investigated.The catalytic hydrogenation has high activity and less catalyst shedding,and the hydrogenation degree is 92.0%under the optimal process conditions.2.Using the adsorption of highly active carrier MOFs,the Pd residual in the HNBR solution was recovered and reused.The effects of additives and process conditions on the recovery of Pd were studied,and the recovered catalyst was hydrogenated to NBR again.The results show that the addition of acetic acid is beneficial to improve the recovery of Pd by MOFs,and under the optimal process conditions,the recovery rate of Pd reaches 95.8%.After the catalyst is reused 4 times,the hydrogenation degree is still above 80%.Catalyst recycling and reuse. |
