One thing I wish I understood as an undergraduate is that learning how to frame a problem is critical to solving a problem.
As a student it is critical to learn to analyze a situation, pull out what is known and what is missing, what are the real constraints and what are only beliefs, and then to apply rigorous thinking to develop hypotheses on what is wrong and how to test for validity of the hypotheses. This requires understanding and not just memorizing the information that is contained in the formulas, graphs, etc., that are the basis of chemical engineering.
The second thing is that technical excellence means little if your communication skills are poor. The ability to write and speak with clarity and brevity is critical to a successful career in business. This requires learning about the drivers of the business and framing work in light of these drivers.