Electronic Metal−Support Interaction Strengthened Pt/CoAl‐LDHs Catalyst for Selective Cinnamaldehyde Hydrogenation

Cinnamaldehyde (CAL) is a typical sustainable biomass molecule which is classified as alpha, beta-unsaturated aldehydes. Selective hydrogenation of CAL to produce high-value and fine chemical cinnamylalcohol (COL) is an attractive catalytic transformation process. However, the hydrogenation of C=O bond in CAL is more unfavorable than C=C bond in thermodynamics and kinetics, leading to great challenge on achieving high yield of unsaturated alcohol. In this work, a Pt/CoAl-LDHs catalyst was prepared for hydrogenation of CAL to COL, showing outstanding intrinsic activity (TOF as high as 4.93 s(-1)) and finally achieving 93.6 % selectivity at 95.4 % conversion. In contrast, the yields of COL over Pt/Co(OH)(2) and Pt/Al(OH)(3) were only 73 % and 34 % respectively. Characterizations including Raman, O-XAFS, XPS revealed that the Co2+-O2--Al3+ structure in CoAl-LDHs contributed to strengthened metal-support interactions, and resulted in electron-rich and geometric decoration Pt delta- sites. The electron-rich Pt delta- provided preferable H-2 activation capability, and also exposed abundant unsaturated sites which optimized the adsorption mode of cinnamaldehyde favorable for C=O hydrogenation. However, in Pt/Co(OH)(2) and Pt/Al(OH)(3) catalysts, the Pt-0 without electron-rich and unsaturated property cannot improve the H-2 activation capability as well as electronic repellency to C=C bond. In addition, a possible catalytic mechanism was proposed to illustrate the role of Pt delta--Co2+-O2--Al3+ interfacial structure on enhancing activity and selectivity.