It is sometimes necessary or desirable to hold customer money in a separate account because it is their property. For lawyers, this kind of account is highly regulated. For most other kinds of businesses, this kind if account is not highly regulated.
If you were required to have an account of this time, you could not borrow against it or pledge it as collateral. The whole point of having a separate account is to hold the property in trust for the benefit of the customers separate from your own funds and not subject to your creditors.
Sometimes a separate account of this type is set up to fund an employee retirement fund that does not qualify for the tax treatment of a 401(k) or IRA or similar account. An account set up for this purpose is called a "Rabbi Trust" (political correctness was not a big thing when this kind of trust was given its name, and the name has unfortunately stuck). But, in those circumstances the exposure to the firm's creditors is intended from the outset for tax purposes and to give the beneficiaries an incentive not to screw up the company, rather than being problematic.