Preparation Of Copper-Based Catalyst And Study On HPA Hydrogenation Performance

As an important intermediate and organic synthesis material in modern chemical industry,neopentylene glycol is widely used in medicine and resin production.In recent years,due to the increasing demand for neopentylene glycol downstream products such as ibuprofen and high quality coatings,its market prospects have become increasingly broad.At present,disproportionation method,as a backward production process,can no longer adapt to the concept of green development in today’s society.Condensation hydrogenation method has the advantages of 100%atomic utilization rate and environmental friendliness,and is gradually becoming the preferred process for the production of neopentylene glycol.Catalyst is one of the key factors restricting the progress of condensation hydrogenation technology.In view of the problems of low hydrogenation performance and short life of existing commercial copper based catalysts,the development of high-performance HPA selective hydrogenation catalyst was carried out in this paper.The preparation process of copper based catalyst was optimized and modified,the influence of catalyst synthesis method on its performance and structure was investigated,and the structure-activity correlation between catalytic activity and structure was discussed combined with related characterization,which provided the basis for the development of similar high performance catalysts.The main research work of this paper is as follows:Firstly,the effect of the synthesis method on the catalytic performance of selective hydrogenation of HPA was investigated.Normal,reverse and parallel-flow precipitation methods were used to prepare the catalysts,and the optimal preparation method was selected according to the catalytic reaction performance.Then,the precipitation p H and calcination temperature were investigated.The results showed that the selective hydrogenation performance of Cu,Zn and Al catalysts prepared by stepwise coprecipitation method was better than that of positive and negative addition.The catalytic activity of the catalysts prepared by calcination at p H=7 and 550℃was the highest.Under the reduction temperature of 300℃and reduction time of 12h,the catalytic activity remained stable after continuous operation for 60h.XRD,SEM and TG&DTG were used to analyze the effect of different preparation conditions on the structure of catalyst.Secondly,the precipitation agent in the preparation process of catalyst was optimized and improved,and the traditional sodium carbonate precipitation agent was replaced by composite precipitation agent.The prepared catalyst showed the best conversion rate of hydroxy-neopentalaldehyde and the selectivity of neopentalglycol.Under the conditions of reaction system pressure of 3.5MPa,reaction temperature of110℃,hydrogenal ratio（molar ratio）of 10:1 and liquid space velocity of 6h^-1,the conversion of HPA can reach 95.4%and the selectivity of NPG is 90.3%.XRD shows that the introduction of proper amount of sodium bicarbonate is conducive to the formation of more malachite phase structure in the precursor and the dispersion of Cu species on the catalyst surface.The catalyst with 7%sodium bicarbonate added to the precipitator has the smallest Cu O grain size.H₂-TPR spectra showed that with the increase of sodium bicarbonate content in the double precipitator,the reduction peak of the catalyst shifted to low temperature and then to high temperature.When sodium bicarbonate content was 7%,the catalyst had the best reduction performance.The characterization of XPS-AES showed that the double precipitator could adjust the distribution of Cu⁰ and Cu⁺on the surface of the reduced catalyst,so as to regulate the activity of the catalyst.Finally,the effect of the change of aluminum source on the hydrogenation performance of hydroxyl tervalaldehyde was investigated.XRD characterization shows that different aluminum sources have a great influence on the crystal structure of catalyst precursor and the dispersion of active components on the catalyst surface after calcination.The results show that the catalytic performance can be significantly improved when the aluminum sol is used as the source of the catalyst.