Facebook recently has banned all cryptocurrency ads.
Source: https://www.theguardian.com/technology/2018/jan/31/facebook-bans-ads-cryptocurrencies-scams
Also, as everything may find its way through, the ads are being create one way or the other.
Source: https://www.bloomberg.com/news/articles/2018-02-09/cryptocurrency-ads-find-ways-around-facebook-s-ban

Note: Stay safe, research before you participate in any crypto activities.