“…In recent years, the ubiquitous solvent properties and potential abilities to donate hydrogen of SCW have aroused great interest in the scientific community (Yan et al, 2009). Some researchers believe that SCW could not only serve as the solvent but also provide the activehydrogen for capping of reactive fragments to form more light components and less coke in upgrading heavy oil (Cheng et al, 2009;Kozhevnikov et al, 2010;Morimoto et al, 2010;Sato et al, 2003;Watanabe et al, 2010;Zhao et al, 2006). It is also reported that C-O bonds in ethers and esters, C-S bonds in aliphatic chain and metal elements incorporated in asphaltene are easily broken in SCW (Mandal et al, 2011(Mandal et al, , 2012bSavage, 1999).…”