Selective hydrogenation of 1,3-butadiene on PdNi bimetallic catalyst: From model surfaces to supported catalysts

• PdNiPd(1 1 1) surface is more active for 1,3-butadiene hydrogenation than Pd(1 1 1).
• EXAFS confirms the formation of bimetallic bonds in supported catalyst.
• PdNi/γ-Al2O3 has higher hydrogenation activity than its monometallic counterparts.
• PdNi/γ-Al2O3 gives ∼20% higher 1-butene selectivity than Pd/γ-Al2O3.
• PdNi/γ-Al2O3 is a better catalyst for 1,3-butadiene removal.

The selective hydrogenation of 1,3-butadiene serves as a means to purify the butene stream generated from cracking naphtha or gas oil. To identify selective hydrogenation catalysts, 1,3-butadiene was studied on single crystal Ni/Pd(1 1 1) bimetallic surfaces, utilizing density functional theory (DFT) calculations and temperature-programmed desorption (TPD). DFT calculations predicted that the Pd-terminated bimetallic surface should be more active and selective to produce 1-butene, which were verified experimentally using TPD. The promising results on model surfaces were extended to γ-Al2O3-supported catalysts using both batch and flow reactors. Extended X-ray absorption fine structure (EXAFS) and transmission electron microscopy (TEM) confirmed the formation of bimetallic nanoparticles. The PdNi bimetallic catalyst showed higher hydrogenation activity and 1-butene selectivity than the monometallic catalysts. The excellent correlation between model surfaces and supported catalysts demonstrates the feasibility of designing effective bimetallic catalysts for selective hydrogenation reactions.

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