Preparation And Catalytic Performance Of HPA Hydrogenation Catalyst

Neopentyl glycol is an important organic chemical raw material,which is widely used in the production of environmentally friendly coatings,medicines,and resins.In recent years,with the continuous development of neopentyl glycol application fields and its downstream products,the domestic neopentyl glycol market is in short supply,and it is urgent to increase its production capacity.Hydrogenation has become the mainstream method for the production of neopentyl glycol in industry due to its advantages of environmental protection,less by-products,and high product purity.Although this process has achieved large-scale industrialization in my country,the industrial catalyst used in the hydrogenation of hydroxypivalaldehyde still has many problems,such as low activity,poor selectivity,and short life.In view of the above problems,this article improves the catalyst of the reaction system for the hydrogenation of hydroxypivalaldehyde to neopentyl glycol by optimizing the preparation conditions and the addition of additives（silicon and gallium）.Using XRD,TPR,SEM,XPS and other characterization methods,the effects of the active components,structure and additives of the catalyst were discussed in depth.First,the effects of the precipitation method,precipitation p H,aging time and other preparation conditions on the performance of the Cu/Zn O/Al₂O₃ catalyst were investigated.The results show that the activity of the stepwise precipitation catalyst is better than that of one step co-precipitation.After calcination at p H=7,precipitation temperature 70℃,aging 80min,and 550℃,a catalyst with excellent HPA hydrogenation performance can be obtained.Secondly,a Cu-based catalyst modified by non-metallic promoters was prepared by a step-by-step co-precipitation method.The catalyst prepared when introduced in the co-precipitation process showed good catalytic activity and selectivity for the hydrogenation of hydroxypivalaldehyde to neopentyl glycol.The XRD characterization of the catalyst showed that the introduction of an appropriate amount ofβpromoter is beneficial to the dispersion of the active component Cu O.The H₂-TPR characterization shows that the addition of additives makes the catalyst easy to reduce.Combining the calculation results of the particle size of the catalyst,we infer that the introduction ofβcan adjust the interaction between the copper oxide and other components in the catalyst and improve the reducibility of the catalyst.Finally,this article also investigated the influence of the introduction of the metallic promoter on the hydrogenation performance of the copper-based catalyst hydroxypivalaldehyde.The step-by-step co-precipitation method introduces before aging to prepare a gallium-modified Cu/Zn O/Al₂O₃ catalyst.It was found that the introduction ofγsignificantly improved the hydrogenation performance of the catalyst.When the added amount ofγwas 2wt%,theγ-modified Cu/Zn O/Al₂O₃ catalyst had the highest catalytic activity.Under the reaction pressure of 3.5 MPa,the reaction temperature of 110℃,the ratio of hydrogen to aldehyde（molar ratio）10:1,and the liquid hourly space velocity of 18 h^-1,the HPA conversion rate and NPG selectivity reached 88%and 62.72%,respectively.The XRD and XPS-AES characterizations showed that the addition ofγimproved the dispersibility of copper and increased the ratio of Cu⁺on the catalyst surface.By controlling the amount of additives added,the ratio of Cu⁺:Cu⁰ on the catalyst surface can be adjusted.