You are asking for a lot of trouble by doing this. The electronic ticket serial number does appear on the boarding pass. An audit by your employer will reveal that you are asking for expense reimbursement on a ticket that you did not use to fly on. And the discrepancy is printed there, just waiting for anyone to see.

In my experience the credit card charge does reach the bank even if the ticket is refunded instantly, although this isn't a big issue as the eventual credit will cancel the charge, although if you're very unlucky, the credit might miss the close of your billing cycle by a day. If you are that unlucky, then you'll have a worse problem, however -- your employer will note that you tried to expense a ticket that you instead refunded, and fire you for fraud.

Although I can see why people would like to expedite taking the credit out of personal e-certs, it's not really your employer's job to help expedite your personal finances.