What are the reasons for the failure of the doctor test for desulfurized alcohol gasoline? How to solve it?

　　In the alkali-free fixed-bed process for desulfurization of alcohols, the typical dosage of the activator is 15–20 ppm, while the air-to-oil ratio is generally 1:30–50. Of course, appropriate adjustments should be made based on the quality of the oil. 　　The doctoral experiment failed; possible reasons include: 1. High thiol content in the oil ； 　　2. Failure of the fixed bed or reduced efficiency ； 　　3. Unstable incoming materials or significant fluctuations ； 　　4. Improper addition of additives ； 　　5. Unstable pressure in the fixed-bed reactor. 　

The mechanism behind gasoline corrosion failing to meet standards is quite complex, and currently, desulfurization units do not have an effective solution for this issue. However, controlling the air injection rate and maintaining the activity of the bed layer does have some effect; the main solution is to add corrosion inhibitors after desulfurization. The air supply volume should be twice the theoretical air volume.

First, it is necessary to determine whether it is the regular gasoline that does not meet the standards, or the desulfurized and denatured gasoline. If it is the latter, the analysis is as follows: Based on our experience, in such cases the issue could be either a design problem or a problem with the desulfurization catalyst. The design challenges include a small reactor, a high space velocity, and a short residence time for gasoline within the bed; generally, the space velocity is required to be no more than 2.0. Some users produce desulfurization alcohol catalysts of poor quality; they claim these to be second-generation catalysts, but in reality they are simply activated carbon to which titanium-sulfonated cobalt phthalocyanine has been added. Such catalysts are not as effective as those made by using high-performance coconut shell activated carbon and then adding titanium-sulfonated cobalt phthalocyanine to it. In your case: after running it for two months, the situation improved by increasing the activation dose; it’s basically a catalyst issue. This type of catalyst (usually coal-based) has a particularly strong adsorption capacity for impurities present in gasoline; these adsorbed impurities block the pores of the catalyst, preventing its active centers from functioning, which results in unsatisfactory desulfurization results. By increasing the amount of activator, the cleaning effect is enhanced and the activity can be improved; the activity can be restored through alkaline solution circulation cleaning or by adding sulfonated titanium cobalt complexes. However, due to the poor performance of the catalyst itself, this approach can only extend its usage time – the best solution is to replace it with a high-quality desulfurization catalyst. Apart from the above two factors, there may be the following influencing factors: 1) The air supply volume is low; the air-to-oil ratio is generally 1:30 to 1:40, and sometimes it needs to be higher. 2). The activator was not added continuously, or the properties of the activator itself deteriorated ； It is generally around 20 ppm. 3). Changes in the properties of the feedstock for the front catalytic unit, with an increase in sulfur content, result in a high level of thiols in gasoline; however, levels below 200 ppm are generally considered acceptable. 　4). Gasoline contains H2S (be sure to pay close attention to this if a fixed-bed H2S removal unit is used at the front end). 5). The gasoline flow rate fluctuates greatly, resulting in severe changes in the space velocity. 　　

What kind of base is the activator you are referring to? Could you explain it in detail?

Our unit also failed to meet the standards for long periods of time in the past; we tried almost all of the aforementioned adjustment methods, but with no satisfactory results. In the end, we stopped using the deodorization system and improved the S-ZORB unit directly to stabilize the gasoline

It would be helpful for me to analyze it if you could tell me the total sulfur content! ! ! !