Homogeneous catalytic distillation

Is the catalyst a solid? If the catalyst is solid, it can’t be called homogeneous catalysis, right? Is it the catalyst that enters the condenser along with the liquid droplets? If so, it should be removed, and at the same time, should the operating conditions be changed to reduce foam entrainment?

The catalyst is dissolved in the feed – isn’t the load a bit high?

The last edit to this post was made by luoli519 on 2016-5-24 at 20:31. I think what the original poster meant was that he dissolved the liquid catalyst in the preheated liquid feed and added it to the reactor； The by-products generated by the reaction may be gas phase or low-boiling vapor, carrying some unreacted liquid feedstock and catalyst droplets; these substances distill out from the top of the reactor and then enter the condenser. After cooling, the catalyst turns into a liquid state or even precipitates as a solid, remaining in the tubes of the heat exchanger, which may lead to poor discharge or even blockages. The poster hopes for a solution to minimize the amount of catalyst entering the cooler. If my understanding above is correct, the poster’s reaction is very similar to the experiments I have conducted. I believe the following suggestions are available for the original poster’s reference: 1. First, install a G50 type fan-type anti-clogging high-efficiency gas-liquid demisting and defoaming separator on the inside of the gas outlet at the top of the reactor/distillation tower, in order to remove as much liquid droplet as possible from the gas stream and return it to the reaction system. Because the liquid droplets carried in the gas phase, which contain catalysts, tend to precipitate within the cooler. After the gas phase liquid droplets are removed using a G50 type feather-leaf high-efficiency gas-liquid demister, only trace amounts of liquid droplets and catalyst remain in the gas stream, which **reduces the amount of catalyst that enters the condenser. Even if a very small amount of catalyst precipitates in the cooler, it will be dissolved by the large amount of material condensate and carried away from the heat exchange tubes. Traditional aperture-blocking type demisters, such as mesh demisters, are not suitable for use. The main reasons are: (1) When the system temperature fluctuates, the catalyst tends to precipitate and clog the wire mesh demister ； (2) The volumetric velocity of the gases or low-boiling substances released as by-products fluctuates significantly as the reaction progresses, especially in batch reactors. Traditional barrier-type demisters, such as mesh demisters, have very limited operational flexibility; even slight changes in gas flow can cause flooding in the demister, thereby deteriorating the performance of the pre-separation tower. (3) Screen-type demisters are prone to causing wire erosion and breakage in the gas phase, which not only reduces the demisting efficiency but also allows the broken wire fragments to flow back into the reaction vessel along with the material, thereby leading to operational failures in the material circulation pumps used in industrial production. 2. Appropriately increase the height of the pre-distillation tower to improve distillation efficiency, thereby **reducing** the content of raw material in the overhead vapor stream. 3. Appropriately reduce the temperature control at the top of the reactor’s pre-distillation column; if possible, use direct internal reflux for temperature control at the top of the column, thereby minimizing the cooling and reflux load outside the column. If the top temperature of the pre-fractionation tower can be maintained below the catalyst precipitation temperature, the solubility of the catalyst in the liquid foam can be reduced. The amount of catalyst that escapes from the G50 type vane-type gas-liquid demisting and defoaming separator will be significantly reduced. However, this may require an increase in the reactor’s heating power as a trade-off. 4. Appropriately increase the outlet temperature of the process material from the external tower cooler. If the outlet temperature of the condenser process stream can be maintained above the catalyst precipitation temperature, not only will catalyst precipitation be prevented, but energy consumption for cooling will also decrease. The above suggestions stem from my own experiences. I hope this will be helpful to the original poster.