It looks like you are using late binding to Word in which case you need to use the numeric equivalents of all the Word specific commands e.g.
Code:
Private Sub CommandButton1_Click()
Dim MSWord As Object
Dim Datei As String
Dim pdfName As String
Set MSWord = CreateObject("Word.Application")
MSWord.Visible = True
Datei = "D:\WordTest.doc"
pdfName = "D:\WordTest.pdf"
MSWord.Documents.Add
With MSWord.Selection
.Font.Name = "Helvetica"
.Font.Size = 20
.Font.Color = 255
.Font.Bold = True
.Font.Italic = True
.TypeText Text:="Text"
.TypeParagraph
End With
MSWord.ActiveDocument.SaveAs Datei
MSWord.ActiveDocument.ExportAsFixedFormat _
OutputFileName:=pdfName, _
ExportFormat:=17, _
OpenAfterExport:=False, _
OptimizeFor:=0, _
Range:=0, _
Item:=0, _
IncludeDocProps:=False, _
KeepIRM:=True, _
CreateBookmarks:=0, _
DocStructureTags:=True, _
BitmapMissingFonts:=True, _
UseISO19005_1:=False
MSWord.ActiveDocument.Close
MSWord.Quit
Set MSWord = Nothing
End Sub