Catalytic pyrolysis-GC/MS of lignin from several sources

Authors: Mullen, Charles; Boateng, Akwasi

Submitted to: Fuel Processing Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/28/2010
Publication Date: 9/3/2010
Citation: Mullen, C.A., Boateng, A.A. 2010. Catalytic pyrolysis-GC/MS of lignin from several sources. Fuel Processing Technology, 91:1446-1458.

Interpretive Summary: With the need to find new and economical sources of renewable fuels increasing, interest in conversion of waste streams from various industries to fuels and other useful products is increasing. Lignin, the part of plants that gives it rigidity, is isolated as a co-product from the pulp, paper and cellulosic ethanol industries. Conversion of lignin into a high-density liquid called bio-oil is possible through a process called fast pyrolysis. This is done by rapidly heating the biomass in the absence of air and then quickly cooling the vapors. Bio-oil can be sent on to be upgraded into liquid transportation fuels or used as a starting material for synthetic chemicals. The composition and properties of bio-oil can be altered by use of a catalyst during the pyrolysis process. We used a small scale pyrolysis reactor, a “pyroprobe” coupled with a gas chromatograph (GC) to study the fast pyrolysis of lignin, with and without catalysts. The chemical compounds identified using GC are those that make up bio-oil. Our results showed that without a catalyst, lignin pyrolysis resulted in production of large amounts of oxygen containing compounds. However, with addition of a catalyst, HZSM-5, more non-oxygen containing compounds, called aromatic hydrocarbons were produced. These non-oxygenated compounds are found in gasoline. This information will be important to those in the paper, pulp and cellulosic ethanol industries looking for ways to utilize lignin co-products. It will also be useful for bio-oil producers and to those refining bio-oil into fuels and chemicals.

Technical Abstract: Lignin from four different sources extracted by various methods were pyrolyzed at 650 degree C using analytical pyrolysis methods, py-GC/MS. Pyrolysis was carried out in the absence and presence of two heterogeneous catalysts , an acidic zeolite (HZSM-5) catalyst and a mixed metal oxide catalyst (CoO/MoO3). The non-catalytic py-GC/MS was used to identify the lignin as characterized by their H-, G- or S-lignin makeup and also served as the control basis to evaluate the effect of the said catalysts on the production of aromatic hydrocarbon from these lignin sources. It was found that the selectivity to particular aromatic hydrocarbons vary with the composition of the lignin for both catalysts.