Characterization of bio-oils and bio-chars obtained from the catalytic pyrolysis of alkali lignin with metal chlorides

The pyrolysis experiments were carried out in a fixed bed reactor at a reaction temperature of 873 K and gas residence time of 1.0 s. The physicochemical properties of bio-oils and bio-chars obtained from alkali lignin pyrolysis with and without KCl, CaCl2, and FeCl3 additives were studied. The compositions of bio-oils were examined using gas chromatography-mass spectrometry (GC-MS). Characterizations of bio-chars were performed using X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area and scanning electron microscopy (SEM) techniques. Adding KCl caused a sharp decrease in bio-oil yield while an increase in bio-char yield was found as a result. The addition of CaCl2 and FeCl3 significantly increased the yield of bio-oil and phenol content while inhibited the formation of char residues. The bio-char generated after FeCl3 addition has a much high BET surface area. This result indicates that the addition of FeCl3 in alkali lignin significantly improves the quality of both bio-oil and bio-char, which is beneficial to the usage of bio-oil for chemical materials and bio-char for activated carbon species.