Preparation And Reactivity Of Hydroxyl Neopentaldehyde Hydrogenation Catalyst

Neopentyl glycol（NPG）is an important basic chemical raw material in modern industry,which is widely used in high-grade paint and powder coating industry.However,due to the shortage of production capacity in China and the long-term dependence on imports,neopentyl glycol produced by hydrogenation method has few impurities and high purity,so it has a good market prospect.The research and development of hydrogenation catalyst is the key technology for the synthesis of neopentyl glycol.The copper based NPG catalyst has a relatively low price and a simple preparation method.Based on the above problems,the study of Cu/ZnO/Al2O3 catalyst was carried out in this paper.1.Firstly,the raw material hydroxyl neopentaldehyde was synthesized,and the synthesis conditions were optimized.Combining with the requirements of raw materials in the reaction process,the synthesis process of hydroxyl neopentaldehyde was determined as follows:the catalyst was triethylamine,the raw material ratio was n（FA）:n（IBD）:n（TEA）=1.2:1:05,the reaction temperature was 75℃,and the reaction time was 2.5h.The selectivity of hydroxyl neopentaldehyde reached 92.13%.Cu/ZnO/Al₂O₃ catalyst was prepared by positive addition,reverse addition and co-precipitation.The microscopic properties of catalysts synthesized by different preparation methods were studied by XRD,low-temperature N₂ adsorption-desorption and H₂-TPR,etc.The characterization results showed that Cu/ZnO/Al₂O₃ catalyst prepared by co-precipitation method had good dispersion,large specific surface area,pore volume and pore diameter.The hydrogenation performance of Cu/ZnO/Al₂O₃catalyst was evaluated in a pressurized fixed bed reactor and the process parameters were optimized.The products were detected by gas chromatograph and analyzed by external standard curve method.The optimized process conditions were as follows:reaction temperature 110℃,reaction pressure 3.0MPa,hydro-aldehyde ratio 10:1,liquid/air speed 1.0h^-1,HPA conversion rate and NPG selectivity reached 100%and 83.3%respectively.2.In the Cu/ZnO/Al₂O₃ catalyst prepared by cocurrent coprecipitation method,the catalyst was modified by the introduction of auxiliary agent B.The experimental results show that adding B after aging can significantly improve the catalytic performance of Cu/ZnO/Al₂O₃ catalyst,and the conversion of hydroxyl neopentaldehyde and the selectivity of neopentyl glycol have reached 100%and 96.7%respectively.The characterization results showed that the addition of adequate amount of B was conducive to the reduction of grain diameter,the increase of the specific surface area of the catalyst,the more uniform dispersion of the active components,and the improvement of the selectivity of neopentyl glycol.Through the hydrogenation experiment of hydroxyl neopentyl aldehyde,it was found that when the optimal addition amount of B was0.5wt%,the conversion rate of hydroxyl neopentyl aldehyde was 100%,and the selectivity of neopentyl glycol was 96.7%.The selectivity of neopentyl glycol was improved by the addition of B.3.In order to improve the stability of B-Cu/ZnO/Al₂O₃ catalyst,silica sol was added to modify the catalyst.The evaluation results showed that the best way to add silica sol was to add it into the mixed salt solution by parallel flow coprecipitation.The best amount of silica sol was 1.5wt%.The catalyst still has high activity in 100h.