Preparation And Properties Of Multicomponent And Hydrophilic Catalysts For Dehydrogenation Of Diethanolamine To Iminodiacetic Acid

After the ban on paraquat,glyphosate is the most sold and used herbicide in China,and one of the most used pesticides in the world.The production methods of glyphosate include the traditional method and the iminodiacetic acid（IDA）method.The IDA method has high product purity and less pollution.It is a green and environmentally friendly production method,but the catalyst reuse effect of this method is poor.In order to improve the catalyst performance and increase the economic effect of production,this paper modified the Cu-based catalyst in the diethanolamine dehydrogenation method:on the one hand,the synergistic effect of the bimetallic catalyst was used to introduce Ni to prepare the bimetallic catalyst to improve the reaction efficiency;on the other hand,the hydrophilicity of the catalyst is strengthened,and the hydrophilic catalyst is prepared by doping with the hydrophilic metal oxide La₂O₃to improve the life of the catalyst;at last,granulating the catalyst,study its performance after granulation.First,the metal oxide Ni was introduced into the CuO-ZrO₂catalyst precursor by co-precipitation method,and the bimetallic catalyst Cu-Ni/ZrO₂was obtained by calcination reduction.The effect of the ratio of catalyst on the conversion of feedstock and product yield.The experimental results show that when Cu:Ni:Zr=1:1:2,The experimental results show that when Cu:Ni:Zr=1:1:2,the reaction time is shortened from 3h to 1h,the conversion rate of diethanolamine is up to 95%,and the yield of iminodiacetic acid is up to 93%..Secondly,the hydrophilic metal oxide La₂O₃was doped with the CuO-ZrO₂catalyst precursor,and the hydrophilic catalyst Cu-La₂O₃/ZrO₂was obtained by a hydrothermal method.The effect of different molar ratios of catalysts on the conversion of feedstock and product yield.The experimental results show that when Cu:La:Zr=2:1:4,the reaction time is the same as that of the Cu-ZrO₂catalyst,the conversion rate of diethanolamine is increased to 97%,and the yield of product iminodiacetic acid is increased to 94%.It is believed that the doping of hydrophilic carrier La₂O₃enhances the interaction between hydrophilic sites and active metals,which is conducive to the high dispersion of active metal Cu on the surface of the carrier,inhibits the free migration and agglomeration of active metals,and prevents catalyst sintering;the surface is hydrophilic It will also significantly affect the boiling heat transfer.The continuous water film formed on the hydrophilic surface can delay the formation of the vapor film in boiling water,thereby improving the critical heat flux and heat transfer coefficient.The hydrophilic surface can play a role in strong exothermic reactions.The effect of protecting the catalyst increases the life of the catalyst.Finally,granulating the catalyst and applied to the continuous process of diethanolamine,the granulation conditions were changed,exploring the best conditions.the results showed that the catalyst particles with the powder-to-water ratio of 1.25 and the addition of silica sol as the binder had the best performance,and the yield of IDA was 32%.