The present set-up consists of 2 Nos. upward flow packed bed reactors. The set-up is designed so that the reactors can be operated either parallel or in series. A buffer tank is provided in between the reactors to permit the discharge of excess flow from the first reactor when the second rector is operated in series but at a low flow rate. Individual Peristaltic pumps are provided for each packed bed reactor to set and control the flow rate of liquid. Two heaters surround the reactor to heat the liquid passing through the reactor and temperature of the liquid in reactor can be controlled by means of Digital Temperature Controllers provided individually for each reactor. The gas collecting vessels (2 Nos.) are provided and gas can be collected using volumetrically calibrated collecting vessel, which collects the gas based on water displacement method. A constant head, liquid seal device ensures that the gas pressure in the reactor is maintained at a constant level throughout the run. The vessel can be refilled with water during the run without breaking the liquid seal. Sampling of liquid and gas can be done with the help of provided sampling port at appropriate positions. Non-return valves and siphon break are provided to ensure that each reactor is running at constant volume. Further this arrangement also prevents the danger of accidental symphonic action.