I tried out a synthesis method for a Mo2Al LDH, which has not been done before. Unfortunately it did not work out, however, I found the process very interesting and wanted to share it here. I was using MoCl5 which is highly reactive with water, it has to be stored under an inert gas as it will react with the moisture in the air (even here in dry Arizona). When it was mixed with water for the reaction, in the fume hood, it fizzed and released HCl gas which is a corrosive white gas. It was left to stir with aluminum chloride hexahydrate and a small amount of sodium chloride for one hour, the same procedure as used to synthesize the other Layered Double Hydroxides. After an hour, no precipitate had formed, and the solution was taken off and set aside.
After stirring for an hour
After talking to my PI, she suggested that some of the HCl evolved from the reaction may have dissolved in the solution, causing the pH to be too low for the Layered Double Hydroxide to form. Using pH strips, the pH of the solution was tested and found to be somewhere in the vicinity of < 1, based on this 19 M sodium hydroxide was added dropwise, until the pH strips showed a pH of around 9. A precipitate did form and it was left to stir for an hour again, before being centrifuged and washed three times to separate out the precipitate.
After the NaOH had been added
Unfortunately, neither the XRD nor the FT-IR resemble what would be expected of an LDH sample and it was decided that this experiment was not successful.
The precipitate from the reaction
Thank you for sharing! We learn a lot from experiments that do not work the way we want, and yet we never really talk about them, so thank you!