Abstract:

The catalytic activities of Ni-5 and Ni-5-RM catalysts for reducing CO2 with CH4 or natural gas to produce synthesis gas have been studied by using a fixed-bed flow apparatus. It is found that the Ni-5RM catalyst not only has higher activity and selectivity due to higher dispersion of nickel, but also has better resistance to carbon deposition. It has been shown that a Ni-5-RM catalyst was not deactivated at all during 240h on a stream with CO2/CH4 ratio of 2.4:1 at 750℃ or 1.4:1 at 850℃. For the reduction of CO2 with natural gas, an important question is how to prevent the reaction system from carbon deposition. The experimental results indicate that addition of carboneliminator A into the raw material gases not only prevent carbon deposition, but also has no influence on the activity and selectivity. By adding carboneliminator A to a mixture of natural gas (containing 87% CH4) and CO2 a Ni-5-RM catalyst was not deactivated at all during 300h on a stream with CO2/natural gas ratio of 2.4:1 at 750℃ or 1.4:1 at 850℃. At conditions of 850℃ and CO2/natural gas =1.4:1, the contents of (CO+H2) have been reached to 96% (molar fraction). These results indicate that Ni-5-RM catalyst has a high activity, selectivity and stability for reducing CO2 with natural gas. Experiments magnified 500 times were carried out under the same conditions. The contents of synthesis gas obtained have been kept at 94~96%. These results first established the possibility of industrial utilization of the reduction of CO2 with natural gas to produce synthesis gas rich in carbon monoxide.

Key words: Chemical utilization CO₂, Preparation of synthesis gas, Catalytic reaction