We provide a segmented reactor for regenerating a spent acidic ionic liquid via hydrogenation and hydrocracking, comprising: no solid hydrogenation catalyst; a gas inlet for feeding a gas feed comprising a hydrogen; a liquid inlet for feeding a spent acidic ionic liquid; partitions along an axis of the reactor that create segments, wherein each segment functions as a bubble column reactor; and an outlet from which a regenerated acidic ionic liquid flow out of the segmented reactor. We also provide a process for regenerating a spent acidic ionic liquid, comprising contacting the spent acidic ionic liquid with hydrogen and without an addition of a solid hydrogenation catalyst in the segmented reactor.