Single-Step Ethanol Conversion into 1,3‑Butadiene over Bimetallic Silica‑Supported Catalysts: Optimization of the Reaction Pathway

This study investigates the development of bimetallic silica‑supported catalysts for the single‑step conversion of ethanol to 1,3‑butadiene, a key monomer for synthetic rubbers. Catalysts were prepared via wet‑kneading on Grace DaviCat silica with formulations containing 1.5 wt% of a primary metal (Cr, Cu, Co, Ni, or Zn) and 0.5 wt% of a secondary metal, followed by calcination at 500 ºC. Catalytic tests were performed in a PID Eng & Tech microactivity unit under atmospheric pressure at 450 °C, with an ethanol flow rate of 0.001 mL min^-1 and argon as carrier gas (5 mL min^-1). Reaction products were analyzed by mass spectrometry, and the combined selectivity toward 1,3‑butadiene and acetaldehyde was calculated directly from relative peak areas. Among the systems evaluated, the Cu–Zn combination exhibited the best performance, with near‑complete ethanol conversion and a combined selectivity of approximately 65% toward the target products, while minimizing by‑products such as carbon oxides, light hydrocarbons, and oxygenated compounds. Catalyst characterization by BET, XRD, and SEM/EDS confirmed active site formation and adequate metal dispersion. To assess industrial viability, an Aspen HYSYS® V10 simulation was developed, integrating experimental kinetic data with calibrated response factors and literature‑based parameters; this simulation projected a molar yield of 97.45% for 1,3‑butadiene under optimized reaction and separation conditions. The integration of systematic experimental catalyst screening, detailed characterization, and process simulation represents the main novelty of this work, providing a scalable framework for a green and economically competitive route to 1,3‑butadiene from bio‑ethanol.