Hi,
For exporting a template from the catalog the following should work:
ovftool --X:logToConsole "vcloud://guest:guest1@myIP/?org=vcenter-1-org&catalog=cat1&vappTemplate=t" t/t.ovf
I believe it's also possible to export a vApp:
ovftool --X:logToConsole "vcloud://guest:guest1@10.27.68.47/?org=vcenter-1-org&catalog=cat1&vapp=a" a/a.ovf
For more details you can check the User Guide at OVF Tool Documentation
Best Regards,
Andrii