So, lets see what Ketu can do in 9th house without any conjunction or aspect from any other planet. 1st lets see what these 2 things represent -

Just like Rahu, Ketu also represents illusion as both are illusionary planets but the difference is that Ketu is also the one who removes the illusion and brings enlightenment. Besides this, Ketu represents isolation, separation, spirituality,mystical world, other dimension means things related to alien world, also represents Son, Dog, Intuition, research ability, curious nature, things which we have already achieved in past life and not much concerned to perform in this life.

9th house represents Higher Education, Philosophy, Religion, Law, Faith, Fortune, Gurus, Teachings of Father (as father is 1st Guru we get) etc.

Aspect-wise, in Vedic Astrology, Ketu has 5th and 9th house aspect. He is unable to impact 7th house from its place as Rahu is sitting there, which is the other axis of Ketu and represents all those things which are non-Ketu. Although Ketu represents isolation and separation, but interestingly its aspects never isolate and separate a person from the things represented by house it is aspecting. Ketu only makes a person curious and research oriented and motivates a person to research about it.

So, Ketu (planet of spirituality) is now in 9th house (house of religion) and that is where we understand the difference between religion and spirituality. This is where we understand that religion is a set of man made rules and spirituality is something much beyond the set rules of religion. Difference between religion and spirituality can be easily understood if we can understand the difference between a Religious Guru and Gautama Buddha. Spirituality is far beyond the set rules of religion. So, that's what happens here in the 9th house with Ketu. This person feels isolated from the set rules and regulations of a religion. They initially like to get along with religious teaching but when they realize that it is not serving their purpose of spirituality, they start feeling separated from religion. They have constant arguments with their teachers over religion and spirituality. They reject their teaching. Relationship with their father remains distant. Although, religious learnings may suffer but philosophical/spiritual learnings are enriched. They actually do quite well in studies but it is just the tug of war between religion and spirituality continues in their mind. 

From 9th house, Ketu aspects the 1st house of life path and personality and 5th house of education and children etc. So again, it is all about dedicating self in pursuit of knowledge through research and higher education which can help in creating awareness of self.