Effects of NaOH on the catalytic pyrolysis of lignin/HZSM-5 to prepare aromatic hydrocarbons

Abstract

The pyrolysis of alkali lignin in black liquor to prepare bio-chemical is attracting increasing attention. In addition to alkali lignin, black liquor also contains a large amount of sodium salts (e.g., NaOH and Na2CO3). In the present study, the fast pyrolysis of lignin was carried out in a fixed bed reactor. The effect of NaOH on the preparation of aromatic hydrocarbons by catalytic pyrolysis of lignin/HZSM-5 was investigated; the effect of pyrolysis temperature and the NaOH to lignin ratio on the yield and relative content of aromatic hydrocarbons was also investigated, and the mechanism underlying the promotion of aromatic hydrocarbon formation due to NaOH was studied by using guaiacol as a model compound. The results indicated that the addition of NaOH improved the in situ hydrogen supply and promoted the removal of methoxyl groups, thus, the relative content of monocyclic aromatic hydrocarbons increased from 54.95 % to 66.92 %.