(416e) Production of Dimethylfuran From Hydroxymethylfurfural Through Catalytic Transfer Hydrogenation With Ruthenium Supported On Carbon

Vlachos, D. G., University of Delaware
Jae, J., University of Delaware
Zheng, W., University of Delaware
Lobo, R. F., University of Delaware

The hydrogenation of biomass-derived 5-(hydroxymethyl) furfural (HMF) to 2,5-dimethylfuran (DMF) is a key reaction in upgrading biomass derived furanic compounds into platform molecules toward the production of chemicals and liquid transportation fuels. For instances, DMF itself can be used as a gasoline additive or further upgraded into p-xylene through Diels-Alder reaction with ethylene. The hydrogenation of HMF to DMF has been studied over various metal catalysts (Cu, Pd, Ni, and Ru) using molecular hydrogen [1-4]. Copper-based catalysts, carbon supported copper-ruthenium and copper chromite, have been identified as the best metal for selective production of DMF (71% yield) [1]. However, hydrogenation utilizing petroleum-derived H2 is neither entirely green nor economic because it requires high-pressure H2 increasing process costs. In this study we introduce an alternative route for the conversion of HMF to DMF through catalytic transfer hydrogenation (CTH) where a hydrogen donor is used as a hydrogen source, instead of molecular H2.

            We have investigated the CTH of HMF using secondary alcohols and show that DMF is selectively produced with up to 80% yield over a carbon-supported Ru catalyst. Initial reaction kinetic studies were performed using 2-propanol (Isopropyl alcohol(IPA)) as a hydrogen donor in a batch reactor. It was found that the CTH reaction occurs at reaction temperatures lower than 373 K and the selectivity of the DMF increases with increasing reaction temperature. At low temperatures, the primary product is 2,5-bis(hydroxymethyl)furan (BHMF) and upon increasing the reaction temperature to 463 K, BHMF is completely converted with a selectivity to DMF of up to 81%. The main by-products detected are those formed through etherification of BHMF or 5-methyl furfuryl alcohol (MFA) with IPA. However, these ethers are slowly converted into DMF, especially at higher temperatures (e.g. 463 K). During the CTH reaction, H2 needed for hydrogenation of HMF is supplied from dehydrogenation of IPA. We have found that dehydrogenation of IPA to acetone and H2 is a faster reaction than hydrogenation of HMF. The acetone yield reaches chemical equilibrium with the carbon yield of 11.5% at 463 K after 1 hour while the corresponding H2 partial pressure is 0.95 MPa in the closed reactor. Importantly, the hydrogen transfer hydrogenation of HMF to DMF can be carried out with other hydrogen donors, including 1-propanol, 1-butanol, and 2-butanol. XRD and TEM analyses of the fresh and spent catalysts showed the presence of Ru metal particles. The active site of the catalyst has been identified with a series of experiments. Overall, our work suggests that the catalytic transfer hydrogenation can be a vial route to upgrade other biomass-derived molecules in an efficient and sustainable way without utilizing petroleum-derived H2.

[1] Y. Roman-Leshkov, C.J. Barrett, Z.Y. Liu, J.A. Dumesic, Nature, 447 (2007) 982-U985.

[2] S. Sitthisa, T. Sooknoi, Y.G. Ma, P.B. Balbuena, D.E. Resasco, J. Catal., 277 (2011) 1-13.

[3] S. Sitthisa, D.E. Resasco, Catal. Lett., 141 (2011) 784-791.

[4] J.P. Lange, E. van der Heide, J. van Buijtenen, R. Price, ChemSusChem, 5 (2012) 150-166.