If all you want to alter is the terminology of how the customer sees it (insteadd of seeing "model" you want them to see "catalog") then you can do this by looking at the language files.
In your case it would be specifically the following file:
/includes/languages/english/product_info.php
Find the following line and alter as needed
define('TEXT_PRODUCT_MODEL', 'Model: ');
(Yours would look like this:)
define('TEXT_PRODUCT_MODEL', 'Catalog: ');




