"By faith Enoch was taken up so that he did not see death, and he was not to be found because God took him up. For before his removal he had been commended as having pleased God" (Heb. 11:5 NET).
Jesus stated categorically: "No one has ascended into heaven except the one who descended from heaven– the Son of Man" (John 3:13 NET).
According to a dictionary definition Gr. "taken up" means "removal to another place" or "of the taking up" or "taking away." The same dictionary gives two options for "death": 1) Natural death. 2) Death as a penalty (BDAG). That means he did not die a natural death or he was taken somewhere and kept in limbo. The latter would appeal to a Catholic. I would go for the first option according to the following: "And Enoch walked with God, and he was not; for God took him" (Gen. 5:24 JPS).