“…The study of reaction mechanisms must rely on analytical chemical methods, such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), gel permeation chromatography (GPC), high-performance liquid chromatography (HPLC), nuclear magnetic resonance (NMR) or gas/liquid chromatography-mass spectrometry (GC/LC-MS). To clarify liquefaction reactions and the chemical composition of products, many investigators have studied the crystallinity, functional groups and micromorphology of the residue from lignocellulosic liquefaction using XRD (Pan et al, 2007;Ahmadzadeh and Zakaria, 2009), FTIR (Vázquez et al, 1997;Schwanninger et al, 2004;Zou et al, 2009) and SEM (Pan et al, 2007;Ahmadzadeh and Zakaria, 2009;Nasar et al, 2010). As well, the molecular weight and distribution, molecular structures and the amount of free phenol of liquefied products in the presence of phenols or polyhydric alcohols by acid catalysts, were studied using GPC (Deng et al, 2008), GC/LC-MS (Basaran et al, 2003;Zhang et al, 2007;Soria et al, 2008), NMR (Lee and Ohkita, 2004;Lin et al, 2004) and HPLC (Lin et al, 2001a, b;Inoue et al, 2004;Zhang et al, 2005;Zhang et al, 2007).…”