Microwave (MW) heating has gained popularity because it can provide rapid and more uniform heating than conventional methods. As the pyrolysis mechanisms and products strongly depend on temperature, aside from uniformity of temperature also control of its level will strongly affect experimental results. A temperature control system was developed for use in an experimental MW cavity in which a metallic propeller driven at 50 rpm is used to scatter the MW radiation. The results show good performance of the developed feedback control system. It was experimentally tested with water at temperature setpoint 80 ℃; and with a pyrolysis substance (oil palm shell biomass or OPS, mixed with activated carbon or AC) at set-points 400, 500, and 600 ℃. The largest bio-oil yield was obtained at the experimental conditions: ratio 70:30 at 500℃; and the dominant chemical components found were phenol and acetic acid, as analyzed by GC-MS.
