Here is the code snippet for saving Excel to pDF
Dim wb as Object = GetWorkbook(Handle,Workbookname)
Dim excel as Object = wb.Application
wb.ExportAsFixedFormat (Type:=0, Filename:=PDFPath, Quality:=0, IncludeDocProperties:=True, IgnorePrintAreas:=False, OpenAfterPublish:=False)
wb = Nothing