This combines the text of all PDF's in a folder
function combinePDFs() {
var folder=DriveApp.getFolderById('1Zd_ty0O1WljjADzGQGrtUM57hvE5berT');
var destFolder=DriveApp.getFolderById('1mHRFCwzqccJn83N7THnvZ8_Z-DCLeGOV');
var files=folder.getFilesByType(MimeType.PDF);
var text='';
while(files.hasNext()) {
var file=files.next();
var blob=file.getBlob();
var resource={title:blob.getName(),mimeType:blob.getContentType()}
var f=Drive.Files.insert(resource, blob, {ocr: true,ocrLanguage: "en"});
var doc=DocumentApp.openById(f.id);
text+=doc.getBody().getText() + '\n------------------------------------------------------------\n';
DriveApp.getFileById(f.id).setTrashed(true);//trash intermediate files
}
var tf=DocumentApp.create('combined.doc');
tf.getBody().setText(text);
tf.saveAndClose();//combined text file
var docblob=DocumentApp.openById(tf.getId()).getAs('application/pdf');
docblob.setName('combined.pdf');//
destFolder.createFile(docblob);//combined PDF
DriveApp.getFileById(tf.getId()).setTrashed(true);//trashed combined text file
}
Reference from Amit Agarwal
Drive.Files.insert
Setup a Time Based Trigger
Upload files with Google Apps Script