EFFECTS OF CARBON DEPOSITS ON THE SPECIFIC ACTIVITY OF NICKEL AND NICKEL BIMETALLIC CATALYSTS

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Abstract
The effects of carbon formation on methanation activity of nickel and nickel bimetallic catalysts were investigated. Carbon was deposited on these catalysts at 675-700 K, 1 atm, H2/CO = 2 and space velocities of 80,000 to 200,000 h−1 over a period of 6-24 hours. Specific methanation activities were measured before and after carbon depositing treatments at 500-575 K, 1 atm H2/CO = 4 and space velocities of 100,000 h−1. The results show that Ni/Al2O3 loses 20-60% of its initial activity within 10-15 hours of treatment. Platinum and cobalt promoted nickel are significantly more resistant to deactivation by carbon. However, Ni-MoO2 is highly susceptible to deactivation, losing essentially all of its activity within a few hours. Data showing the effects of reaction conditions, metal concentration and catalyst composition on the extent of deactivation and the effects of deactivation on catalyst strength are presented and discussed