"a certain sort of" is correct and usable in written English.
You can use it when you want to refer to a specific kind of something. For example, "This plant needs a certain sort of soil to grow properly."
You know, there is a certain sort of sincerity that is opposed to a certain sort of fun.
This outward lie makes a certain sort of truth possible.
Every presidential candidate tells a certain sort of story.
If you attend a certain sort of conference, hang out at a certain sort of coffee shop or visit a certain sort of university, you've probably run into some of these wonderful young people who are doing good.
So maybe one can't reach that far without having a certain sort of insanity.
For a certain sort of Tory traditionalist, this was an egregious betrayal.
Evolutionary biology certainly renders a certain sort of Biblical literalism untenable.
There's a bunch of words a certain sort of woman likes that are like LUXE.
It's just a way of bringing in a certain sort of client".
Ahmet said, "There is a certain sort of excess that is interesting, don't you think?
It celebrated a certain sort of personality: the risk-taking entrepreneur.
