Method for synthesizing o-phenylenediamine from ortho-nitroaniline by virtue of catalytic hydrogenation

The invention provides a method for synthesizing o-phenylenediamine from ortho-nitroaniline by virtue of catalytic hydrogenation. The method comprises the following steps: firstly, adding ortho-nitroaniline and a palladium-carbon catalyst into a high-pressure reaction kettle, introducing nitrogen to exhaust air in the kettle, and then introducing hydrogen to exhaust nitrogen in the kettle; secondly, heating and introducing hydrogen, performing catalytic hydrogenation reduction reaction under the conditions that the temperature is 110 DEG C and the pressure is 1.0MPa, reacting for 7-8 hours, then stopping introducing hydrogen, water-cooling, then filtering to recycle the catalyst, and collecting a filtrate after filtration to obtain o-phenylenediamine. According to the method provided by the invention, a raw material namely ortho-nitroaniline is subjected to direct hydrogenation without using a solvent, so that the consumption of the solvent can be greatly reduced, the after-treatment energy consumption can be saved, and large-sized solvent steaming equipment can be saved; and by adopting the method, a separation process can be simplified, the equipment investment, separation energy consumption, material consumption and environmental pollution can be reduced, and the system productivity and production safety can be improved.