Weekly Topic for Ammonia Production: Catalysts

The catalyst is severely pulverized, which is detrimental to production; replacing the catalyst poses hazards to the environment and workers……

I’d like to share my observations regarding the catalysts used in our facility. Our synthesis towers utilize Cassali technology, but the catalysts used are domestic-made. During handling, proper care is not taken, and as a result the catalysts get damaged through dropping or collisions, which causes them to become heavily powdered

Compared to domestic catalysts, imported catalysts generally have higher prices, which makes them a matter of concern for some users. It is mainly reflected in aspects such as charging, displacement, heating and reduction, process control, and protection after shutdown; the problem still lies in mindset. It is also due to these differences that domestic catalysts may not be able to realize their full potential.

I’ve never seen catalysts from abroad; maybe it’s supposed to look like this. Generally, imported products are of higher quality than domestic ones, but they shouldn’t be more expensive. It is reasonable to use imported products in cases where the manufacturing conditions are good and the operational life is long, such as at least one year or more. However, when the operating conditions are not optimal and the gas composition isn’t highly refined, it’s better to opt for domestic products as they are cheaper.

This post was last edited by 3968668 on 2011-7-4 21:23. Reply to 1# TH373637: In most cases, the differences in the composition of flue gases have a negligible impact on the catalytic chemical reactions (exceptions include, for example, the content of V). The influence of flue gas composition on catalyst design is primarily considered in terms of the rate of catalyst activity degradation. The most direct impact of ash on catalyst design is the selection of different pitches and an appropriate flue gas velocity. Secondly, considering the wear of the catalyst caused by ash and the changes in the rate of decline in catalyst activity due to ash coverage, appropriate considerations are given to the design margin in some cases, without making changes to the catalyst formula. The two most important factors to consider when selecting a formula are: flue gas temperature (for optimizing the optimal activity range and the temperature tolerance of the catalyst), and the SO2 oxidation rate. These two factors have a significant impact on catalyst performance, and they can be determined in a relatively clear and accurate manner within the design parameters. When there are high levels of toxic elements, it is appropriate to choose formulations with higher contents of molybdenum or tungsten. For toxic elements, it is difficult to achieve precision and accuracy in quantification; not only are the actual operating conditions and design parameters often quite different from each other, but research on the interactions between these toxic elements is also insufficient (exception: the mitigating effect of CaO on As poisoning). There are also preliminary studies on the accelerating effect of trace elements on the deactivation of PRB coal–CaO; these are largely explanatory theories rather than design-oriented theories. Regarding catalyst poisoning, there are limited options in terms of formulation; one mostly has to accept it passively by increasing the amount of catalyst used or by adopting a shorter design life for the catalyst. Therefore, research on the formulation and performance of catalysts should first focus on studies under conditions of pure flue gas; as for the influence of various other factors on the catalyst, this information is primarily obtained through operational databases rather than laboratory experiments. As mentioned earlier, the results of tests on toxic elements hardly lead to the development of new formulations; they often merely explain why the catalyst deactivates more rapidly.

Domestic catalysts are relatively cheaper, but their quality is lower; they are prone to damage and pulverization, and have a short service life. Catalysts abroad are more expensive, but they have a relatively longer service life. The specific selection method depends on the actual conditions of our factory. Currently, there are several domestic manufacturers whose catalysts are also quite good. As production technology continues to improve, it is believed that domestic catalysts will see significant development as well.

Reply to 7# shouzhang: Is it really just the catalyst that matters? The environment in which the catalyst is used is also very important. When catalysts from abroad are introduced, it’s usually as part of an entire process package, which allows for better purification of the process gases. Moreover, it’s usually established companies with sufficient resources that introduce such catalysts; they operate in accordance with chemical engineering principles, which helps to avoid many cases of human-induced damage. There are also many practical operating regulations. Many small factories, however, prioritize short-term gains at the expense of the catalyst’s lifespan

Domestically produced catalysts are no worse than those imported; for example, the A110 series of catalysts produced by Sinochem BASF is excellent.

Reply: 8# TH373637 is right – in our methanol synthesis unit, we often operate at 20-30% load. With such a low load, it’s impossible to raise the temperature of the material entering the tower; the steam injectors are used to full capacity, and the circulation rate can no longer be reduced any further. The manager won’t allow the load to be increased nor will they permit the machine to stop. With the inlet temperature remaining at 180+°C for an extended period, the formation of large amounts of paraffin can be clearly observed in the wastewater from the bottom of the atmospheric pressure tower. To increase the temperature entering the tower, it is necessary to raise the pressure in the steam drum, which is equivalent to forcing the catalyst to enter its middle stage of use earlier. The leader said: Protect the process, not the equipment. Hehe, you said that a bed of catalysts is supposed to last eight years, but it’s likely that it won’t even last five years in the end.

Read, it makes sense! . . . .