My phone interview with them was for their mech eng position so can’t really help with the type of questions you will get with chem eng. What I can say though was that the technical questions they asked me were really basic mech eng stuff. They did cover a range of theory but it was all pretty standard. The hard bit for me was taking down all the info when they were reading the question as I’m used to reading it myself on paper, but you can just ask them to repeat the question.
If you haven’t already, try googling chemical engineering technical interview questions for some sample questions. Doing that for mech eng helped me a lot.
As for the competency, like you said, very simple and standard competency questions.