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1,3-Bis(aminomethyl)cyclohexane (1,3-BAC) is an important chemical intermediate with a reactive β-dicarbonyl structure that finds wide applications in organic compounds. It is used in cosmetics, pharmaceuticals, pesticides, and more. Foreign manufacturers include Mitsubishi Gas and BASF. However, there are fewer domestic manufacturers, and the demand for 1,3-BAC as a substitute for meta-xylylenediamine (MXDA) has sharply increased since it was classified as a toxic chemical.
A method for hydrogenating meta-xylylenediamine to produce 1,3-Cyclohexanebis(methylamine) involves catalytic hydrogenation in a fixed-bed reactor. The catalyst is loaded, and a solution is prepared by dissolving meta-xylylenediamine and a co-catalyst in isopropanol. The solution is then pumped into the fixed-bed reactor under the conditions of temperature 100-200°C, pressure 4-7 MPa, liquid hourly space velocity 0.5-2 h-1, and hydrogen to meta-xylylenediamine molar ratio of 5-10:1. After the hydrogenation reaction, 1,3-Cyclohexanebis(methylamine) is obtained. The co-catalyst can be sodium nitrate, potassium nitrate, sodium nitrite, or potassium nitrite, with an addition amount of 0.012-0.02% of the material mass.
The catalyst composition consists of 0.5-3% ruthenium by mass, 0.2-2% co-catalyst by mass, and the rest is alumina support. The co-catalyst can be Mn, Co, or Mg. The catalyst has a specific surface area of 120-200 m2/g, pore volume of 0.15-0.45 mL/g.
The catalyst preparation method includes:
1. Preparation of the support: Alumina nitrate solution is prepared and added to a reaction vessel. Ammonia solution is slowly added to neutralize and precipitate the solution. The neutralization time is 15-30 minutes, and the pH is adjusted to 7.0-8.0. After aging for 20-40 minutes, the precipitate is filtered to obtain a filter cake. The filter cake is dried, crushed, and then shaped with stearic acid and carboxymethyl cellulose pore-forming agent. The shaped material is calcined at 700-900°C for 2-5 hours to obtain catalyst support A.
2. Impregnation of the active component: A solution is prepared by dissolving hydrated ruthenium trichloride and co-catalyst soluble salts, which is then sprayed onto support A. After initial drying in a constant temperature air dryer to achieve 10-20% moisture content, the sample is moved to a microwave heating furnace for further processing to obtain semi-finished catalyst C.
3. Activation of the catalyst: Semi-finished catalyst C is reduced with 10% hydrogen/nitrogen at 200-300°C for 2-4 hours to obtain the final catalyst product.
CN110090641B
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