When coffee was beginning to catch on in Europe in the seventeenth century, was it used as a “working drink” (as today) or just a recreational one? Would a Dutch merchant have done his paperwork with a cup of coffee on his desk?

I cant speak for all of Europe but Prussia in the 18th Century under Frederick II it was banned. From All About Coffee By William Harrison Ukers. The ban wasn't ultimately effective but it lead to a great quote in the same vein as the "kids these days" type rants only from an 18th century King.

"It is disgusting to notice the increase in the quantity of coffee used by my subjects, and the amount of money that goes out of the country in consequence. Everybody is using coffee. If possible, this must be prevented. My people must drink beer. His Majesty was brought up on beer, and so were his ancestors, and his officers. Many battles have been fought and won by soldiers nourished on beer; and the King does not believe that coffee-drinking soldiers can be depended upon to endure hardship or to beat his enemies in case of the occurrence of another war."

So with that information it certainly seems like it was not seen as a working drink. There's another article that mentions this in the context of alcohol in history, but I cant find it presently. Arguably it was popular, but its imported status helped drive some of the movement against it. I don't want to get so speculative this response gets deleted. So what I'd say is that from how that article outlines coffee in 18th century Prussia, it seems likely that a wealthy merchant might drink it, but since it was a status symbol and drank in coffee houses they probably wouldn't have drank it on the job, as it was expensive to brew with how the laws were structured to keep it "upper class".

Edit: I realize that while trying to properly source my claims about 18th century Prussia... there’s another chapter about coffee in Holland that would help give you some insight from that book.