public enum CatalogSecondaryPortalContentType : System.Enum, System.IComparable, System.IConvertible, System.IFormattable, System.ISpanFormattable  

  //Gets the Catalog pane
  var catalogWindow = Project.GetCatalogPane() as ICatalogWindow;
  var catContentType = catalogWindow.GetCurrentContentType();
  //Is Portal the content type?
  if (catContentType == CatalogContentType.Portal)
  {
      //check what is the portal content type being shown...
      var secondaryContentType = 
catalogWindow.GetCurrentSecondaryPortalContentType();
      //TODO use secondary portal content type...
  }

//Gets the Catalog pane
var catalogWindow = Project.GetCatalogPane() as ICatalogWindow;
if (!catalogWindow.IsActiveWindow)
    return; //catalog dockpane must be the active window

var catContentType = catalogWindow.GetCurrentContentType();
//Is portal content being shown?
if (catContentType == CatalogContentType.Portal)
{
    //check what is the portal content type being shown...
    var portalContentType = (int)catalogWindow.GetCurrentSecondaryPortalContentType();
    //advance to the next tab
    portalContentType++;
    if (portalContentType > (int)CatalogSecondaryPortalContentType.LivingAtlas)
        portalContentType = (int)CatalogSecondaryPortalContentType.UserContent;

    //set the secondary portal content type
    //Must be on the UI - no QueuedTask!
    catalogWindow.SetSecondaryPortalContentTypeAsync(
        (CatalogSecondaryPortalContentType)portalContentType);
}