Study On The Preparation And Performance Of Cu-Zn-Al-Zr And Cu-Mo-Zr Catalyst For The Dehydrogenation Of Diethanolamine

Iminodiacetic acid is mainly used for the synthesis of herbicide glyphosate, alsoin the rubber, surfactants and the pharmaceutical industry has important applicationvalue. This article is mainly study on the copper-based catalyst for thedehydrogenation reaction of diethanolamine, preparation of the Cu-Zn-Al-Zr andCu-MO-Zr two different dehydrogenation catalysts, and through experimentsdiscussed the two catalysts about the preparation conditions，the catalytic performancetest, and characterization.Cu-Zn-Al-Zr catalyst (the mole ratio was Cu:Zn:Al:Zr=3:1:1:5) were preparedby coprecipitation method, under the effect of precipitation agent sodium hydroxide,the optimal preparation conditions were as follows: precipitation end-point pH of10.0,precipitation at room temperature4h, after filtering and washing, drying12h under110℃, after grinding by roasting4h under500℃,hydrogen reduction of4h under230℃. The optimal reaction conditions of Cu-Zn-Al-Zr catalyst were that n(NaOH):n(Diethanolamine)=2:1(mole ratio), reaction temperature160℃, reaction pressure1.0MPa, reaction time4h, the conversion of diethanolamine can be reached100%,and the yield of iminodiacetic acid can be reached95.61%. Via using Cu-Zn-Al-Zrcatalyst for repeating10times, the average yield of iminodiacetic acid was92.85%,the result show that Cu-Zn-Al-Zr catalyst has good stability and catalytic activity. TheBET and XRD characterization results indicated that Cu-Zn-Al-Zr catalyst into whichZn and Al were simultaneously added change its physical and chemical properties,Cu-Zn-Al-Zr catalyst has a big specific surface area and an amorphous structure.Cu-MO-Zr catalyst (the mole ratio was Cu: MO:Zr=3:5:2) were prepared bycoprecipitation method, the optimal preparation conditions were as follows:precipitation end-point pH of12.0, drying10h under120℃, roasting5h under500℃,hydrogen reduction of4h under258℃. The optimal reaction conditions of Cu-MO-Zrcatalyst were that n(NaOH): n(Diethanolamine)=2.5:1(mole ratio), reactiontemperature165℃, reaction pressure0.5MPa, reaction time4h, the conversion ofdiethanolamine can be reached100%, and the yield of iminodiacetic acid can bereached96.3%. Cu-MO-Zr catalyst reused12times, the conversion of the catalystdecreased by5.0%, show that Cu-MO-Zr catalyst has good catalytic performance andstability. The BET, XRD and TPR characterization results indicated that moderate MO content promoted the reduction of CuO，and increased the surface area and porevolume of the catalysts，and significantly decreased the reduction temperature of thecatalysts，and improved the catalytic performance of catalysts.Analysis of diethanolamine dehydrogenation product can be used highperformance liquid chromatographic method and potentiometric titration method.Compared the two methods, potentiometric titration method has operationaladvantages when do not have the condition of instruments, but it has complicatedsteps, the analysis reproducibility is poor and big error. And high performance liquidchromatographic method has simple analysis steps, the analysis reproducibility isgood, but there are higher requirements for instrument.