What you hope to gain during your studies and any specific issues you wish to address.

Statement of purpose

An introduction about yourself, your interests and your motivations.
The reasons for applying to your chosen graduate program: PhD in Chemical Engineering
What you hope to gain during your studies and any specific issues you wish to address.
Your professional aspirations and how you think this qualification will help you achieve them.
How your previous studies and work experience, where applicable, relate to the program you have chosen.
Other matters you consider important and relevant to your application.