Dear professors and researchers, I have a question that has troubled me for a long time, and I hope to get your answer.

In wet impregnation, the catalyst support and the precursor solution have an excess amount of water. I have read about three methods in the literature: 1. Dry at 80°C while stirring until completely dried, then place in a drying oven. 2. Dry at 80°C while stirring until a slurry state is reached, then place in a drying oven. 3. After impregnation and stirring, use a rotary evaporator until the solvent is removed and it is dry. Scrape off the substance adhering to the inside of the flask, then place it in a drying oven. I used the third method, and I am not sure if this approach results in uniform distribution of the metal. Additionally, I am concerned that the third method may cause the precursor salts to adhere to the inner walls without being loaded onto the carrier, and thus might be scraped off together with it. Although I personally believe that the first two methods also result in uneven distribution and also have metal salts that are not loaded onto the carrier.Thanks.