There would be no point in converting the Hex to Bin!
The Keil toolset generates the Hex from the Bin in the first place!

Jesper is right: you should do a little routine to sort the Hex file.
The Intel Hex file spec does not guarantee (nor even require) that the addresses will be in any particular order - therefore your utility should be able to accept arbitrarily-ordered data (or just stick with the tools that give you the ordered Hex file).
It is not wise to rely upon the peculiarities of a particular version of a particular tool.

BTW: The Keil compiler doesn't generate a .Hex file; it's actually converted from the Linker's Absolute binary output file.