Depending on your credit score, you may not qualify for a high enough credit limit to meet your business expense needs. Credit cards made for business usually come with higher credit limits because the bank understands that businesses generally have larger transactions and more volume.
By keeping your personal and business expenses separate, you can control spending limits easier on both accounts. Plus, if you need to make a large business purchase, you don't have to worry that you won't have enough credit to pay for a smaller personal expense. Being responsible with your business credit card can help you build business credit, which can boost your spending power down the road.