Conversion Of Lignin Model Compound Guaiacol To Chemicals And Fuels

With the depletion of non-renewable fossil fuels, it is urgent to find sustainable resources for substitute. Biomass is an ideal substitute due to several advantages, for example, it is available all over the world, and it is degradable, energy efficient, renewable, non-toxic and environmental benign. Biomass in this paper mainly focuses on lignocellulosic biomass, which consists of cellulose, hemicellulose and lignin. Cellulose and hemicellulose is made of monosaccharide, and lignin is an irregular polymer made of three kind of benzyl propane. Lignin depolymerization produces extremely complicated products and char as well, resulting in low utilization of lignin industry. So far, a primary application of lignin is combustion to produce heat. However to make full use of lignin’s special structure character, the best way to make use of lignin is to produce aromatics as productsSince the process of lignin depolymerization is extremely complicated, lignin model compound guaiacol is chosen to be studied to help understand the mechanism of lignin reactions. Guaiacol owns functional groups, such as methoxy group and phenolic hydroxyl group, which are very common in lignin. The best way to utilize lignin is to produce aromatics, so in this paper we primarily studied the hydrolysis of C-O cleavage in guaiacol. There are three parts in this paper. The first part focused on guaiacol hydrolysis in HCl solution. The second part studied guaiacol hydrolysis in water using water tolerant Lewis acid as catalyst. The transetherification of guaiacol in ethanol using Al2O3 as catalyst is studied in the third part. In the first part, water was selected as solvent for its low price and eco-friendly, and we used HCl as catalyst to produce catechol as a product. Several mechanisms were proposed in the study. In the second part, water still served as solvent, however, water tolerant Lewis acid was applied as catalyst to produce catechol. There are several advantage to use water tolerant Lewis acid instead HCl, such as low corrosity, easy to recycle and environmental benign. Besides guaiacol, other model compound such as benzyl phenyl ether and biphenyl ether was also studied using water tolerant Lewis acid. Kinetic constant of all the three compounds was calculated in the study. In the third part, bio-based ethanol was used as solvent for transetherification of guaiacol with the presence of Al2O3. The significance of the study is to highlight an insight to produce long chain compound from short chain compound.