Microstructure-controlled Synthesis And Performance Comparison Of Nickel-based 1,4-butynediol Hydrogenation Catalyst

1,4-Butanediol(BDO)is a key material for preparing degradable plastics.In recent years,there is a huge demand for BDO in China and even the whole world.Among all of the BDO synthesis methods,the most effective selective hydrogenation of 1,4-butynediol(BYD)is an effective synthesis strategy.However,BYD hydrogenation is a complex reaction,since its substrates involves many functional groups such as C≡C,C=C,COH,C=O,etc.In the hydrogenation process,there are many side reactions such as parallel isomerization and hydrogenolysis,which are easy to produce by-products,thus reducing the purity of BDO.Therefore,it is of great urgent to develop a suitable catalyst,which effectively reduce the side reaction.The common catalysts for BYD hydrogenation are noble metal catalysts and Ni-based catalysts,the former is difficult to realize largescale industrial investment due to their high cost,while the latter ones are prone to deactivation due to poor interaction between metal and carrier.Based on above,the Ni-based core-shell catalyst with phyllosilicate structure was constructed in this project and applied to BYD hydrogenation.Because of its unique layered structure,phyllosilicate core-shell catalyst has excellent regional limiting effect,which can improve the resistance to isomerization of intermediates and achieve excellent BDO selectivity.Phyllosilicate is divided into 1:1 type(1:1 Ni-phy)and 2:1 type(2:1 Niphy)structure,the difference in structure units will affect the hydrogenation performance of BYD.This thesis explores the impact of different types of phyllosilicate structure on BYD selective hydrogenation performance,and the main research contents are as follows:1.Phyllosilicate core-shell catalysts with different structural types were prepared by deposition-precipitation,hydrothermal and ammonia evaporation method.The effects of different layered silicate structures on the hydrogenation performance of BYD were analyzed by various characterization.The results show that the catalyst with 1:1 Ni-phy structure prepared by deposition-precipitation method has excellent localized structure and strong metal support interaction,and its active sites are highly dispersed and rich in acid sites.With the synergistic effect of acid sites and Ni active sites,it shows the best BYD conversion and BDO selectivity.2.In order to better realize the hydrogenation performance of phyllosilicate core-shell catalyst,the microstructure of the optimal deposition-precipitation catalyst was further adjusted.A series of Ni-phy catalysts with different Ni-O-Si binding forces were obtained by changing the reflux temperature during the preparation process,and their structures were analyzed by various characterization.The results show that the Si layer and Ni layer react more easily at the interface when the reflux temperature is at 120 ℃,and the obtained catalyst has the most regular phyllosilicate morphology.Its rich petal-like phyllosilicate structure can provide cross channels,and form a stronger confinement effect,both of which greatly improves the dispersion of metal active sites and achieve stronger hydrogenation capacity for better BYD conversion and better BDO selectivity.