Here I highly recommend you to use KDEtools PST Merge tool which is a one-stop solution to combine multiple PST files into one PST without installing MS Outlook. The tool designed in such a way that it has a simple GUI making it easier for all and use it effortlessly.

Advanced Features of PST Merger:

- Add multiple PST into single PST including all data and attachments.
- Removes dupliactes PST files while merging the batch PST files.
- Performs Quick and safe conversion.
- Merge contacts and Calendars of PST files into new or existing PST file.
- Joins ANSI and UNICODE PST Files.
- Supports all the editions of Outlook and Windows.

Download For Free and Install: http://www.merge-pst.com/