val = ''
idx = [val] + df.index.drop(val).tolist()
print (idx)
['', 'noun', 'verb', 'Adj', '']

print (df.reindex(idx))

       col1  col2  col3
index                  
       9     6     5
noun      1     1     1
verb      4     6     1
Adj       5     1     3
     0     0     0