Precious Metal CPO Catalysts

It should be clear from the discussion of nickel catalysts that the use of inexpensive nickel comes with a price because of problems with deactivation from carbon formation. One way to solve this problem is to avoid the use of nickel and replace it with elements in which carbon does not dissolve.40 This is the main reason that research has focused on precious metal catalysts for CPO. The added cost of metal is to be justified by better performance in terms of stability and yields. It is also clear that the high space velocities obtainable in CPO will help reduce the total amount of catalyst and thus alleviate one of the inherent problems with the cost of the precious metals. 

Some of the earliest work on precious metal catalysts for CPO of methane was carried out by Ashcroft et al.41 In their work, Pr2Ru207 was evaluated for CPO performance. A methane conversion of 90% and selectivity of 94%-99% were achieved. Pure Ru metal was detected on the catalyst surface and believed to be the active component during the reaction. 

Another aspect that needs more research efforts is sulfur tolerant CPO catalyst design and understanding of sulfur deactivation mechanism to predict catalyst lifetime, which is critical for industrial application of the CPO technology. 

---