Systems, reactors, and processes for regenerating ionic liquid using catalyst. A plurality of tubular reactors are provided having a first end and a second end and catalyst particles disposed in the tubular reactor between the first end and the second end. A line supplies separated ionic liquid catalyst to the first end of the tubular reactor. Hydrogen is also supplied. Regenerated ionic liquid catalyst is recovered from the second end of the tubular reactor. The inner surface of the tubular reactor is preferably non-corrosive or non-reactive. A fluoropolymer lining may be used. The tubular reactors are modular, and may be changed out with the catalyst inside when the catalyst are to be replaced.