High pressure reactor (hydrogenation) use experience brief talk

Here are some experience exchanges for high-pressure hydrogenation reaction which has been done for many years, hoping to play a role of throwing out a brick to attract jade. High-pressure autoclave is generally used for reducing hydrogenolysis. It is very easy to occur safety accidents under the conditions of high pressure, flammability, spontaneous combustion and simultaneous existence of oxygen, which will cause lifelong regret for operators. Therefore, the matters needing attention and operating procedures for the use of high-pressure autoclave are recorded as follows.

1. Precautions

1. When the initial high-pressure autoclave operator is operating, at least one person who has mastered the highpressure reactor operation must be present.

2. Personnel operating on-site must wear cotton gloves and shoes without iron nails.

3. Do not bring phones, lighters, MP3 players, etc., which are easily explosive and self-ignitable items, into the hydrogenation work area. 4. When near the hydrogenation, personnel should handle tools and parts with care, avoiding rigid impacts that could produce sparks. 5. When depressurizing the tail gas the high-pressure reaction, it is best to use a rubber tube to vent it outdoors or inside a fume hood.

2. Operating Procedures

A complete operation procedure for a high-pressure autoclave reaction is divided into five processes:

installation, hydrogenation, sampling, dehydrogenation, and unloading.

(a) Installation

1. Check whether there are flammable or explosive items inside and outside the kettle, and whether there are items that are not conducive to air circulation. If so, please remove them.

2. Check whether the valves and inside the kettle are clean. If not, please clean them.

3. Close all valves, except for the vent valve. Start adding materials. After adding materials, cover the kettle lid. Note that when rotating the screw cap, the force should be uniform to ensure that the two screws on the diagonal line are tightened against each other to prevent gas leakage after tightening.

4. Close the vent valve.

(b) Check the airtightness of the apparatus

　　Close all valves and cover the kettle lid, taking care to the screws evenly to ensure that the diagonal screws are tightened against each other to prevent leakage after tightening. Open the intake valve to introduce nitrogen to 1MPa, close the valve, observe the pressure change, and confirm whether the apparatus is leaking.

　　(c) Hydrogenation

　　1. Check whether each valve is closed tightly

　　2. Point the exhaust flexible tube in an open and well-ventilated place.

　　3. Connect the hydrogen pressure valve, taking care that the thread the hydrogen pressure valve is left-handed. For the nitrogen pressure valve, after connecting it, check with soapy water whether there is any leakage. If there is any leakage, re-connect it.

　　4. Use a vacuum to remove the air from the surface of the liquid at the exhaust port.

　　5. Open the intake of the kettle, open the nitrogen pressure valve to fill the kettle with nitrogen to make the pressure in the inner kettle P=0.2Mpa, then close nitrogen pressure valve, close the intake valve, keep it for about 2 minutes to see if the pressure gauge pressure drops, and also listen to the valves and kettle lid to if there is any leakage. If there is no leakage, slowly open the exhaust valve to exhaust the pressure inside to 0.01Mpa, then close the exhaust valve.

　　6. Repeat step 5 once.

　　7. Open the intake valve, open the hydrogen pressure valve, fill in hydrogen to the required pressure, close intake valve, close the hydrogen pressure valve, and then adjust other parameters to the required state and let it react.

       (d) Control Sampling

        1. Observe the data every half hour to see if it is normal. If the pressure decreases it is necessary to replenish hydrogen.

        2. The hydrogen in the hydrogen cylinder cannot be completely discharged. It is necessary to ensure a certain pressure. When P ≈0.01 Mpa, it should be discarded and replaced with a new bottle.

        3. Sampling. Slowly open the exhaust valve, set the pressure in kettle to 0.2 Mpa, close the exhaust valve, slowly open the sampling valve until there is reaction liquid coming out, close the sampling valve to sample, then the sampling port, and do not let flammable substances remain.

 

        (e) Discharge Hydrogen Confirm that the reaction has ended, slowly discharge the hydrogen it is all gone, pay attention to close the exhaust valve when there is a little pressure inside, to prevent oxygen from entering, open the intake valve, fill in nitrogen until .2 Mpa, close the intake valve, then slowly open the exhaust valve, release the mixed gas inside, when it is almost gone, re-input nitrogen, so change gas three times, then use the vacuum pump to pump out the gas on the liquid surface, open the exhaust valve, sampling valve, and start to discharge from the bottom valve. that there are substances that are prone to spontaneous combustion when exposed to oxygen, such as Pa/c, RaneyNi, inside, so it is absolutely forbidden to spill over the. If there is any spill, please immediately wipe it out with a wet towel and put it into a bucket of water, and then use a small amount of dilute acid to it. After discharging, immediately close the bottom valve.

         (f) Unloading

          After the reactor is emptied, it should be cleaned immediately. Before cleaning, the following steps should be followed:

          1. Fill the reactor with reaction solvent from the vent valve, clean away most of the residue, and then inject water halfway into the reactor for stirring for 10 minutes Only then can the reactor cover be opened to clean the inner wall of the reactor.

           2. When cleaning, it is necessary to clean the reactor cover and the sampling valve and at the same time, slightly fill the reactor with nitrogen when there is water in the reactor.

          3. For temporarily unused reactors, it is best to add 7 volumes of clean anhydrous ethanol to the reactor for soaking, and the screws do not need to be tightened.