A method of controlling tractive force of a vehicle comprising determining a tractive force request of a driver of the vehicle, determining an actual tractive force of the vehicle, and modifying the actual tractive force of the vehicle to be equal to the tractive force request. The system has a first piston that includes a first rod and is disposed in a first chamber. The process may be used in a xylene production facility to minimize or avoid the necessity of feedstock pretreatment such as hydrotreating, hydrogenation, or treating with clay andor molecular sieves.