It is generally done to repair damages caused by false allegations, bad publicity etc. and can also be termed as public relations activity. It helps the company "brand" to be developed and not just the branding of their products.
Benefit in product sales can be a side effect of corporate advertising but is never the primary goal.
The primary goal is to clear a positive image for the company in consumer’s mind.
Example – Here Honda desh ki dhadkan campaign/ad is an example of corporate advertising where the company Hero Honda was promoted and not any bikes in particular.