I had the same need and greatly disliked the idea of manually typing (and updating) all of the Request Type categories into an Excel spreadsheet for usage as my organization's service catalog.
In order to facilitate this so that it wouldn't require manual work and manual updates when Request Types changed, we ran an ODBC connection into Excel:
Paired with Slicers and any other type of filtering, you get a tidy, automatically-updated workbook which you can use to distribute your respective Service Catalogs.
I hope this helps! Please let me know if you need any assistance in the deployment of this type of solution.