Explain what it means that the vapor pressure of oil and gas in the lift pipe increases while the reaction depth decreases ?

Catalytic reactions are very complex; according to the normal carbocation reaction mechanism, a series of catalytic cracking reactions such as cleavage, isomerization, hydrogen transfer, and condensation occur, and reversible reactions are also present within these processes. Therefore, as the partial pressure of oil and gas increases, the reaction depth decreases to a certain extent.

Reply to 2# yiransunny: It doesn’t seem to relate much to the answer I’m looking for. Everyone, please help out! There’s a reward available

Take a look at the Q&A on catalytic cracking technology; it contains information on the catalytic reaction process. Once you understand that, you should be able to make the corresponding connections. It’s a bit difficult to explain this clearly. Study it; catalysis is still very complex. My hands got numb from taking the exam today

It can be simply understood in this way: after a catalytic cracking reaction, the molecular weight increases. If the partial pressure of hydrocarbons is high, it certainly hinders the progress of the reaction in the desired direction

Chemical reactions all proceed in a specific direction; factors such as temperature and pressure can have an impact. An increase in the partial pressure of oil and gas can lead to a slowdown in the reaction or even prevent it from occurring

If it’s difficult to understand, use magnification or the limit method. With the same amount of catalyst, as well as the same reaction temperature and pressure, which will yield a better reaction result: ten tons of oil and gas or 100 tons of oil and gas? This should be easier to understand

An increase in partial pressure can be understood as an increase in pressure. For a chemical reaction, if the reaction results in an increase in volume, then a lower pressure is more favorable for the reaction to proceed; conversely, a higher pressure is less favorable for it. The catalytic reaction is primarily a decomposition reaction, resulting in an increase in volume; therefore, as the partial pressure increases, the degree of reaction decreases. A high catalytic operating pressure is favorable for regeneration but unfavorable for the reaction; an increase in reaction pressure promotes the condensation reaction.

Reaction pressure is an independent operating variable, but it generally cannot be changed arbitrarily; it must be determined by taking into account the pressure of the apparatus, the equipment, and the conditions of various components. An increase in reaction pressure raises the concentration of reactants and the reaction time, which helps to increase the reaction rate and conversion rate. On the other hand, the char formation rate increases as a result, which leads to coking and deactivation of the catalyst, offsetting the aforementioned positive effects. Therefore, in actual production, the reaction pressure has little effect on conversion and selectivity. It should be noted, however, that in catalytic cracking a large amount of steam is used in the reaction (accounting for 15–25% of the feedstock volume). Although the reaction pressure is increased, the vapor pressure of the oil and gas products remains low; this helps to reduce coking rates and increase gasoline yield. It also facilitates an increase in the amount of olefins in the gasoline gases, thereby raising the octane rating of the gasoline. At the same time, it has no significant effect on the dry gas and liquefied gas yields. Increasing the reaction pressure requires a corresponding increase in the regeneration pressure as well. An increase in oxygen partial pressure is beneficial for regeneration. It is also beneficial for recycled flue gas and energy recovery. The key issue is that if the partial pressure of oil and gas is high, the reaction depth should increase! ! ! ! ! ! ! How could it decrease?

Reply to 9# Desert Off-road Flight: The parameters of catalytic cracking are interrelated, and each condition is conditional; otherwise, taking things out of context can lead to misunderstandings. My understanding is as follows: Assuming that the reaction temperature and pressure remain constant, an increase in the vapor pressure of the feedstock leads to a decrease in the steam pressure. This necessarily results in an increase in the feed rate, while the amount of steam used decreases (in terms of moles). With the reaction temperature fixed (and ignoring the effect of reduced steam volume on atomization), an increase in the feed rate means that the reaction time per unit mole of feed decreases (which is equivalent to an increase in space velocity). So, does this mean that the degree of reaction decreases?

Reply to 10# 328104062: Yes, if the total pressure remains unchanged while only the vapor pressure is high, then indeed, as you said, the reaction depth decreases