Nitrotoluene Catalytic Hydrogenation Of M-toluidine Process

This dissertation studied the appliance of catalytic hydrogenation technology to the preparation of m-toluidine from m-nitrotoluene, including liquid catalytic hydrogenation and gas phase catalytic hydrogenation.Three different catalysts were used in the process of liquid catalytic hydrogenation. It has been found that the Raney Ni catalyst which was prepared on the condition that m(NaOH):m(Al-Ni)=1.7 has the best performance. Under the condition that m(catalyst): m(m-nitrotoluene) =6:100, methanol as solvent, reaction time was 1h, reaction pressure was 1MPa, reaction temperature was 80##, the conversion of m-nitrolotuene reached 100%. Ni-B amorphous alloy catalyst which was prepared on the condition that BH₄^-/Ni²⁺=2 has the best performance. Under the condition that m(catalyst): m(m-nitrotoluene)= 3:10, anhydrous ethanol as solvent, reaction time was lh, reaction pressure was 1MPa, reaction temperature was 100℃, the conversion of m-nitrolotuene reached 100%. And the Ni-B amorphous alloy was characterized by TEM. The urushibara nickel catalyst which was prepared on the condition that m(Zn):m(NiCl₂·6H₂O)=3:2 and acetic acid as the developing agent has the best performance. Under the condition that m(catalyst): m(m-nitrotoluene)=5:3 ,methanol as solvent, reaction time was 1.5h and hydrogen velocity was about 15 mL/min ,the conversion of m-nitrolotuene reached 100%. Fresh catalyst's performance just declined after a week's time and the catalyst was not obviously deactivated after being used for 10 cycles.The fixed-bed reactor was used as the device where m-toluidine was prepared from m-nitrotoluene by gas phase catalytic hydrogenation. The effect of different contents of copper and supports, such as Ni, Co and Cr in Cu/SiO₂ catalyst was examined.It has been found the optimum catalyst was composed of 20% of copper and 0.8% Cr. And then we study the technological conditions of gas phase catalytic hydrogenation.The optimum technology was as follows, activation temperature 240℃,reaction temperature 270℃,oil-hydrogen ratio 9:1～11:1,LHSV 1.1 mL/h·mL-cat, conversion of m-nitrotoluene was 100%.