For the USA, it is recommended to score above 6.5 in each band in order to get into a respected college. Though most colleges allow students to give either the IELTS or the TOEFL exam. Some of these universities to study an MS in Chemical engineering are Georgia State University, California Institute of Technology, Florida Institute of Technology, Eastern Michigan University, etc. For more elaborate information and guidance on the graduate admission process, you can reach out to me or even visit https://ischoolconnect.com/.