What the hell is colorful polymer denitration agent?

Recently, in the field of flue gas treatment, the so-called "polymer denitration" concept is quite popular, and many manufacturers have appeared in black powder, and have introduced their own polymer denitration equipment and polymer denitration agents.

A friend asked me why there are so many kinds of polymer denitration agents. Colorful: black, white, gray, red, blue and yellow, with large particles, small particles and powder. Is there no uniform production standard or index? Everyone says that their patented products have the best effect, which really makes people want to know which one to choose.

? In fact, the appearance and color are all gimmicks. The main component of polymer denitration agent is dry urea. In order not to let people know this ingredient and secret, some additives are mixed with different colors of agricultural urea to achieve the purpose of product differentiation and making it difficult for others to imitate.

Some people will ask, "Isn't urea white? Are there any other colors? " Hehe, I'm ignorant, as the picture shows: