Accelerated development of ethanol-to-butadiene conversion catalysts by high-throughput experimentation

Ethanol-to-1,3-butadiene (ETB) conversion proceeds through a cascade of elementary steps, including ethanol dehydrogenation, dehydration, C-C coupling, and hydrogen transfer. Because these steps require a coordinated balance of redox and acid-base functions, and because their density, strength, and spatial proximity depend strongly on synthesis and post-treatment, ETB catalyst optimization is sensitive to both composition and preparation history. Here, a parallelized preparation platform is developed that integrates wet impregnation under agitation with gas-flow drying and calcination as a program-controlled sequence in a single furnace-based workflow. Coupled with high-throughput fixed-bed evaluation, this workflow was used to screen Zn-Hf catalysts supported on mesoporous silica and to map how pore structure and preparation history govern butadiene (BD) formation between 400 and 450 °C. Support type dominated product distributions, with Q-10 preferentially yielding BD, Q-30 favoring acetaldehyde (AcH), and Q-3 exhibiting ethylene-rich behavior. X-ray photoelectron spectroscopy revealed pronounced surface enrichment of Zn and Hf on Q-3, consistent with a stronger contribution from dehydration-promoting surface-expressed species. Follow-up tests at fixed nominal composition showed that preparation history can further tune product distributions, and sequential impregnation combined with a dilute HCl washing step after Hf impregnation increased BD yield to 58% on Q-10 while maintaining low ethylene yield. These results provide practical guidance for designing Zn-Hf ETB catalysts and demonstrate how workflow integration enables scalable, quantitatively comparable screening across preparation-dependent parameter spaces.