Does the injection of a terminator cause thermal runaway of the catalyst?

First, understand what thermal collapse means: it is the phenomenon in which water vaporizes rapidly when it comes into contact with a high-temperature catalyst, causing the catalyst particles to break apart. It is mainly related to the regeneration temperature, the water content in the fresh material fed into the regenerator, the steam quality in the reverse regeneration system, or the dilute phase in the regenerator. This higher temperature is relative to the regeneration temperature! If it cannot even withstand normal reaction temperatures, then the hydrothermal stability of this catalyst is extremely poor

It is unlikely, for the following reasons: Early amorphous aluminum silicate catalysts had very poor hydrothermal stability, and catalysts with a higher aluminum content (Al2O3 25%) performed slightly better than those with a lower aluminum content (Al2O3 13%). Deactivation accelerates above 650°C, and it occurs rapidly at 750°C. The hydrothermal stability of the zeolite catalysts currently used is superior to that of those without a stabilizer, as NaY already possesses high stability; after rare earth exchange, cations with 5+ charges (with an additional hydrogen bond –H on oxygen) are formed within the framework structure, thereby increasing the stability of REY. The crystal collapse temperatures of NaY and REY determined by thermogravimetric analysis were 850–860°C and 870–880°C, respectively. Ultra-stable zeolites have an even higher stability, reaching 950–980°C.

Acidic water inevitably causes thermal degradation of the catalyst, but the benefits outweigh the drawbacks

I don’t agree with what was said on the second floor. Firstly, it can only be said that the place where thermal collapse is most likely to occur is when the fresh agent enters the regenerator. However, I believe that some risk of thermal collapse is inevitable at the point where the reactor comes into contact with the terminator. The reason for this is probably as follows: the moisture contained in the fresh agent may exist within the agent itself (I don’t know whether it is in a crystalline state, adsorbed state, or some other form on the catalyst), and when exposed to high temperatures, this moisture vaporizes, causing the catalyst to crack from within ； However, the sudden cooling of the high-temperature catalyst in the reactor should also cause cracking, though it occurs only on the surface of the catalyst; therefore, the probability is much lower than when fresh catalyst is introduced into the regenerator, but this does not mean that such cracking will not occur here.

Furthermore, I believe that to characterize the hydrothermal stability of a catalyst, it is more important to assess its stability under high temperatures and in the presence of water vapor. Sometimes a catalyst does not crack, but it becomes inactive due to physical or chemical changes that result in alterations in its intercrystalline structure, such as changes in specific surface area. All these factors indicate whether the catalyst has good hydrothermal stability; therefore, the hydrothermal stability of a catalyst cannot be used to determine the likelihood of thermal degradation occurring.

Catalyst thermal collapse is mainly caused by intergranular water in the catalyst at high temperatures; since the oil and gas in the lift pipe already fill the pores of the catalyst, the likelihood of thermal collapse is low. However, it is not impossible for a small amount of water to enter the intergranular spaces and cause thermal collapse.

It should. Water will cause the catalyst to fail thermally. Last edited by chengkang on 2009-3-21 12:57.]

It should be possible, but the impact is minimal. Acidic water enters the nozzle along with the atomized steam and then comes into brief contact with a high-temperature catalyst, primarily to lower the temperature and terminate the reaction. It has a good atomization effect and will not cause any significant impact.

The possibility of thermal failure is extremely low. The hydrothermal temperature resistance of catalytic cracking catalysts can reach 730°C. When a terminator is injected in the middle to upper part of the riser, the catalyst temperature does not exceed 600°C, and thermal degradation basically does not occur.