Structure and performance of zeolite supported Pd for complete methane oxidation

• The influence of zeolite support materials and their impact on CH oxidation activity was studied utilizing Pd supported on H-beta and H-SSZ-13. A correlation between CH oxidation activity, Si/Al ratio (SAR), the type of zeolite framework, reduction-oxidation behaviour, and Pd species present was found by combining catalytic activity measurements with a variety of characterization methods (operando XAS, NH -TPD, SAXS, STEM and NaCl titration). Operando XAS analysis indicated that catalysts with high CH oxidation activity experienced rapid transitions between metallic- and oxidized-Pd states when switching between rich and lean conditions. This behaviour was exhibited by catalysts with dispersed Pd particles. By contrast, the formation of ion-exchanged Pd and large Pd particles appeared to have a detrimental effect on the oxidation-reduction behaviour and the conversion of CH . The formation of ion-exchanged Pd and large Pd particles was limited by using a highly siliceous beta zeolite support with a low capacity for cation exchange. The same effect was also found using a small-pore SSZ-13 zeolite due to the lower mobility of Pd species. It was found that the zeolite support material should be carefully selected so that the well-dispersed Pd particles remain, and the formation of ion-exchanged Pd is minimized. 4 4 3 4 4 2+ 2+ 2+

Ämnesord

NATURVETENSKAP  -- Kemi -- Oorganisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Inorganic Chemistry (hsv//eng)

NATURVETENSKAP  -- Kemi -- Materialkemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Materials Chemistry (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Kemiteknik -- Annan kemiteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Chemical Engineering -- Other Chemical Engineering (hsv//eng)

Nyckelord

Pd/SSZ-13

Pd/beta

Methane oxidation

Si/Al ratio

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