I'm sorry, I can't really give you good information about cat litter or even bentonite. We recommend utilizing hard-silicon rock dust. Please download the RTE primer.
Orlando at RTE
Most of the gardeners I know are partial towards the microfine grit, it is just more readily available to your plants. The brix blend that you described will just take a little longer to become available to the plant. It might be a great amendment for a clay soil since it is more sandy consistency.