A Schengen visa must be applied for if you are a holder of the below travel document :
If you hold a blue travel document (Conventions of Geneva 1951) issued by the United Kingdom, you do require a Schengen visa (type C) to travel to Belgium. However if you are only transiting via the airport (not leaving the international zone at Brussels Airport), you do not require an airport visa (type A).
If you hold a red travel document (Conventions of New York 1954) issued by the United Kingdom, you do need a Schengen visa to travel to Belgium.
If you hold a black travel document (Certificate of Identity) issued by the United Kingdom, please note that the travel document is not recognised by the Benelux authorities.
A visa application can still be submitted, however we will need to get an special authorisation from the Immigration Office in Belgium which can take up to 85 days.
You can find all the information on the procedure, requirements and appointments on the TLScontact visa application centre website Belgium Visa Application Centre | TLScontact