Friday, March 18, at 2 p.m. in Wegner G70
Professor Ye Wang, State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, College of Chemistry and Chemical Engineering, Xiamen University, China
Bifunctional Catalysts for Selective Conversions of Syngas and Cellulose into Fuels and Building-Block Chemicals
The conversion of syngas (H2/CO) to hydrocarbon fuels or chemicals, also known as Fischer-Tropsch (FT) synthesis, has received much interest in recent years. The control of C-C coupling on heterogeneous catalysts is a key to developing next-generation FT catalysts with controlled product selectivity. On the other hand, the selective cleavage of C-O or C-C bonds is crucial for the catalytic conversion of cellulose, the main component of lignocellulosic biomass, into chemicals or fuels. Here, I will present our work on the development of bifunctional catalysts for the conversions of syngas and cellulose into liquid fuels and chemicals.
The products over the conventional FT catalysts, i.e., supported Fe, Co or Ru, generally follow the Anderson-Schulz-Flory (ASF) distributions. We performed systematic work to develop bifunctional catalysts to break the ASF limitation by reaction coupling. The coupling of hydrogenation of CO based on Ru or Co nanoparticles and hydrocracking of primary heavier hydrocarbons based on mesoporous ZSM-5 or mesoporous beta can provide C5-C11 (gasoline) selectivity of 70-80%, breaking the ASF distribution (~45%) [1]. The use of mesoporous zeolite Y enhanced the formation of C10-C20 (diesel) hydrocarbons and the C10-C20 selectivity reached 65% over the Co/Na-meso-Y catalyst [2]. We demonstrated that the hydrogenolysis of heavier hydrocarbons occurred over supported Co and Ru catalysts, and the effective control of the hydrogenolysis could enhance the diesel fuel selectivity. I will also present our very recent work to develop bifunctional catalysts for the direct conversion of syngas to lower olefins with outstanding selectivity by coupling methanol synthesis and methanol to olefins [3].
The direct transformation of cellulose into high-value oxygenates without using expensive H2 is an attractive route for the utilization of cellulose. We have been focusing on the conversion of cellulose to organic acid under aerobic or anaerobic conditions. I will mainly present our work on the catalytic conversion of cellulose or the related carbohydrates into lactic acid, which involves selective C-C bond cleavage. We discovered that simple metal cations such as PbII could catalyze the selective conversion of cellulose into lactic acid under anaerobic conditions [4]. The computational work clarified that PbII in water could catalyze both the isomerization of glucose and the retro-aldol fragmentation of fructose, thus providing high yields of lactic acid. We further designed an efficient dual-cation bifunctional catalytic system composed of AlIII and SnII cations, which were responsible for the isomerization and retrol-aldol fragmentation, respectively.
References
1. J. C. Kang, K. Cheng, L. Zhang, Q. Zhang, J. S. Ding, W. Hua, Y. Lou, Q. Zhai, Y. Wang, Angew. Chem. Int. Ed. 2011, 50, 5200.
2. X. B. Peng, K. Cheng, J. Kang, B. Gu, X. Yu, Q. Zhang, Y. Wang, Angew. Chem. Int. Ed. 2015, 54, 4553.
3. K. Cheng, B. Gu, X. Liu, J. Kang, Q. Zhang, Y. Wang, Angew. Chem. Int. Ed. 2016, 55, DOI: 10.1002/anie.201601208.
4. Y. Wang, W. Deng, B. Wang, Q. Zhang, X. Wan, Z. Tang, Y. Wang, C. Zhu, Z. Cao, G. Wang, H. Wan, Nature Commun. 2013, 4, 2141.
