The Synergistic Effect to Promote the Direct Conversion of Bioethanol into Isobutene over Ternary Multifunctional Cr x Zn y Zr z O n Catalysts

A significant beneficial effect of introducing chromium over mesoporous Cr 1 Zn 1 Zr 8 O n oxide composite catalysts was observed in the upgrading and direct conversion of bioethanol into isobutene (ETIB), and a 38 % enhancement in the selectivity (yield) to isobutene was observed relative to that observed with its binary Zn 1 Zr 8 O n counterpart. Two critical factors were related to the surface properties of this catalyst: a proper surface acid/base balance and favorable redox properties dictated the selectivity to isobutene. Through combined experimental and theoretical efforts, synergistic effects of redox‐active Cr δ + in promoting the dehydrogenation of ethanol were elucidated and therefore the production of isobutene. This work provides a guide for the rational design of efficient catalysts for a highly active and selective cascade ETIB reaction, for which the relative strengths of the redox/acid and base/acid sites of the catalyst serve as catalytic descriptors.