Russia, yes, did proclaim itself an Empire. However, Portugal and the Dutch never formalised their status as an Empire - they had an Empire, but they weren't in and of themselves an empire. Whilst you had the Russian Emperor, the French Emperor, the Austrian Emperor, you didn't have a Portuguese Emperor, or a Dutch Empire.
Having said that, I'm going to go and edit my post to remove Spain, because it doesn't fit that criteria.
Brazil was a de jure imperial title, and the King of Portugal was also Emperor of Brazil 1808-1821 (barely in our time frame, but in it)
Also, Haiti was a de jure empire in our period (Emperor Jacques I of Haiti, 1804-1806), and Mexico was one 1821-1823, so there were plenty of Empires around.