COMPARATIVE STUDY OF CARBON FORMATION ON SUPPORTED NI CATALYSTS DURING CH4 REFORMING USING TEOM, TPO-IR, TPD-IR AND TGA TECHNIQUES

for the flow resistance 3 . Recently, a new technique for measuring the weight changes of the sample during the process of coking or gasification has been employed, i.e. the so-called TEOM (tapered element oscillating microbalance), in which the changes in sample weight (ATM, average total weight signal) are determined from changes in the vibration frequency of the cell containing the catalyst 4-5 . It appears that this method is free from disadvantages inherent in the conventional TGA method, since TEOM determines changes in the weight of the catalyst sample that is in contact with the full reaction mixture stream 6 . The TEOM reactor can be operated up to a pressure of 6 MPa and 700˚C. More recently, another sensitive method for measuring of carbon formation on used catalysts has been studied, i.e. the so-called TPO-IR, which combines the temperature-programmed oxidation of carbon with the infrared detection of CO2 (highly sensitive to existence of CO2) 7-8 . However, there has been less study on the comparison of these two new techniques (TPO-IR and TEOM) with the conventional TGA methods. Commercial Ni/Al2O3 reforming catalysts with or without CaO promoters were chosen in this study for the steam reforming and CO2 reforming of methane at different temperatures. The abovementioned three techniques were used for the detection of carbon deposition, with emphasis on the reliability and accuracy of each method. Experimental