ZRH > PVG > FRA

Yes, you are definitely eligible for 144 hour visa free transit valid for the entire Shanghai transit area and you do not need any kind of visa. You should just ensure that your flights to and from Shanghai do not have any additional landings that could compromise your eligibility for this visa free transit scheme. The basic rule of 144 hour visa free transit clearly states that the immediate points before and after a mainland Chinese destination have to be in two different countries or eligible territories (eligible territories: Hong Kong, Taiwan and Macau), so your flights have to be of nonstop nature.