About Reciting Quran.

If one is memorizing the Quran and he needs to keep revising his lessons frequently, can he recite suraa?s while he is not ?clean/pure? and his shoes are on? Please note that he does not hold the Quran in his hands nor he has the Book in front of him. He only recalls everything from his mind. This includes his intention to utilize his time for a better purpose - reciting the Quran instead of humming songs while he is walking, driving or sitting free in his office. And also that due to shortage of time, he cannot memorize suraa?s otherwise.