(624a) Effect of Transition Metal Doping into Cu-SSZ-13 on Direct Oxidation of Methane to Methanol.

Methane to methanol conversion is an important reaction to help upscale methane to a more versatile industrial chemical, methanol. Copper exchanged zeolites have been heavily investigated as potential catalysts for this reaction. To boost the methanol production level of Cu-SSZ-13, we theorized that we could modify the reactivity of the zeolite via the addition of a second d-block cation. In this talk we will report on our findings of Ni, Fe, and Zn co-exchanged Cu-SSZ-13. When a low copper Cu-SSZ-13 (Cu/Al » 0.1) was used as a parent material, Cu,Zn-SSZ-13 showed the highest increase in methanol production over Cu,Fe-SSZ-13, Cu,Ni-SSZ-13, and Cu-SSZ-13 (Figure 1). Further testing with different Cu,Zn-SSZ-13s showed that there is a relationship between the Zn/Cu ratio and the increase/decrease in methanol production observed when using the Cu,Zn-SSZ-13 samples compared to Cu-SSZ-13 samples. The optimal Zn/Cu ratio was found to be between 0.25-0.3 at which methanol production is increased for the Cu,Zn-SSZ-13 catalyst. Zn/Cu loading below 0.25 showed little to no increase in methanol production while Zn/Cu loading above 0.3 showed decrease in methanol production(Figure 2). The ion exchange protocol seems also to have a key role to play in the catalysis as Cu,Zn-SSZ-13 catalyst is order dependent, where the Cu must be exchanged in first into the parent SSZ-13 as any other order will lead to catalyst deactivation. Finally, the zinc seems to increase the methanol production by pushing more copper atoms into active sites due to its resistance to reduction and chemical similarity to copper. The Cu,Zn-SSZ-13 with the highest methanol production was found to be Cu,Zn-SSZ-13 (Cu/Al = 0.208 Zn/Al = 0.058) with its Specific Activity of 11.455 ± 0.263 𝝁mol/g*h and Site-Time-Yield of 26.36 ± 0.605 mmol/mol-Cu*h, about 67% increase in Specific Activity and Site-Time-Yield when compared to Cu-SSZ-13 (Cu/Al = 0.213).