Finally, we created a new role with the following privilege for the approver and it works:
Maintain sensitive birth information for vendor
Maintain sensitive vendor profile fields
Maintain vendor bank accounts
Maintain Vendor bank accounts entity
Maintain vendor cash discounts
Maintain vendor contacts
Maintain vendor method of payment bank accounts
Maintain vendor methods of payment
Maintain vendor payment days
Maintain vendor reason codes
Maintain vendor terms of payment
Maintain vendors
View sensitive birth information for vendor
View sensitive vendor bank account information
View sensitive vendor profile fields
View the print settings for vendor invoices