Yifan Liu,Jiangang Wang,Yuhan Liu,Yuan Zhang,Hongzi Tan,Hongyou Cui
Herein, a series of Sn-based catalysts supported on SBA-15 with temperature responsive ability to in situ construct acidic and basic sites are reported for efficient conversion of biomass-derived sugars into ethyl lactate (EL). Based on the investigation on the effects of the molar ratio of Cl/OH in Sn(OH) x Cl 2-x and the support types, it is found that Sn(OH) 0.5 Cl 1.5 @SBA-15 is an excellent catalyst in catalytic conversion of various sugars to EL, achieving a maximum EL yield of 68.1 % from sucrose. The in situ generated basic SnO sites play important roles in accelerating the retro-aldol condensation reaction, while the concomitantly released acidic sites (Sn 2 + , SnCl + and H + ) could catalyze the reactions of hydrolysis, isomerization, intermolecular rearrangement and esterification to EL. Benefiting from the temperature responsive effect, not only can the reaction pathways be regulated toward high EL selectivity, but also the catalyst can be recycled easily. This research paves an avenue for exploring efficient catalysts for biomass valorization.
The catalytic activities of metal–based catalysts are largely dependent on the properties of their supports. The support (MgO, Al 2 O 3 , MgAl 2 O 4 , SiO 2, and CeO 2 ) effect of the Sn (1.2 wt%) based catalyst for the ethylbenzene dehydrogenation reaction was firstly investigated. The supported Sn-based catalysts were characterized by NH 3 -TPD, BET, XRD, and H 2 -TPR. Among the tested catalysts, the 1.2 Sn/CeO 2 catalyst presented the most effective catalytic activity, achieving a high ethylbenzene conversion of 56.2 wt% at 600 °C. The obvious support effect should originate from the electronic interaction between Sn and supports, instead of the geometric effect resulting from different dispersion of Sn species on carriers. The high activity of the 1.2 Sn/CeO 2 catalyst was attributed to the generation of oxygen vacancies on the CeO 2 surface. A typical strong metal-support interaction (SMSI) could be found in the 1.2 Sn/CeO 2 catalyst according to the comparison of H 2 -TPR, XPS, and Raman spectra result with pure CeO 2 support. The addition of Sn further promoted the generation of more oxygen vacancies by changing the redox properties of CeO 2 , and inhibited the agglomeration of CeO 2 nanoparticles, thereby enhancing greatly the catalyst's ethylbenzene dehydrogenation activity. Graphical Abstract
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