This invention called PISTON ROTARY PUMP OF VARIABLE FLOW. Further, the present invention also provides hydrogenation catalysts prepared thereof. The streams may each contain a content item that is encoded at a different bit rate for each stream. At least one second flow way is formed between the flow guide plates. An outer diameter of the guiding wall decreases along a direction from the air inlet to the air outlet. Forming a gate structure where an inter-layer dielectric layer and a gate electrode layer are alternately stacked over the substrate of the cell region and the peripheral circuit region.