Author : Tarit Nimmanwudipong
Publisher :
ISBN 13 : 9781267759382
Total Pages : pages
Book Rating : 4.7/5 (593 download)
Book Synopsis Catalytic Conversion of Lignin-derived Compounds to Fuels and Chemicals by : Tarit Nimmanwudipong
Download or read book Catalytic Conversion of Lignin-derived Compounds to Fuels and Chemicals written by Tarit Nimmanwudipong and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The environmental problems caused by the production and usage of non-renewable fossil fuels has encouraged scientists to conduct research on alternative fuels. Lignocellolusic biomass is considered one of the most promising resources of alternative liquid fuels as well as renewable chemicals. Among several potential routes for biomass conversion, fast pyrolysis and subsequent catalytic upgrading has gained interest widely. Although the combination involves minimum numbers of steps, the cost of resultant fuels and chemicals is not yet low. Therefore, research is needed for better understanding of the process. This study considered the potential use of "bio-oils", product from fast pyrolysis of lignin, the under-utilized part of lignocellulose, as possible aromatic chemical and fuel feedstock source with the key challenge being the removal of excessive oxygen. The literature of catalytic upgrading of lignin-derived bio-oils is still lacking fundamental chemistry. Detailed and quantitative information about the products, the important reaction pathways, and kinetics is limited, but vital as basis for predicting catalyst choices and designing processes. Thus, our goal was to provide such information and to begin unraveling the chemistry of conversion of oxygenate molecules characteristic of lignin-derived bio-oils--and specifically to understand crucial catalytic oxygen-removal reactions. We investigated the conversion of prototypical compounds that represent important components in lignin-derived bio-oils. The reactions were catalyzed by a solid acid (HY zeolite) and supported metals (Pt/[gamma]-Al2O3), which are typical in petroleum and petrochemical industries. This dissertation addresses catalytic reactions of guaiacol, cyclohexanone, and eugenol. For the first time in this field, our data determine quantitative conversion, selectivity of the products, and approximate kinetics of the primary products in the reactions with Pt/[gamma]-Al2O3. The results show that four major reaction classes including transalkylation, hydrogenation, hydrogenolysis, and hydrodeoxygenation were dominant. Without H2 as a reactant and a metal function in the catalyst, transalkylation was the only important reaction class as observed in the conversion catalyzed by acidic HY zeolite. Higher H2 partial pressure led to higher selectivity of oxygen removal products in the conversion catalyzed by Pt/[gamma]-Al2O3. The data identify the role of catalyst functions and imply that a supported-metal catalyst and high pressure H2 will be necessary for oxygen removal of compounds found in lignin-derived bio-oils. Catalyst deactivation was usually observed in the conversion with HY zeolite and Pt/[gamma]-Al2O3. The earlier results indicate that acid sites of the catalysts were associated with the formation of carbonaceous materials on those catalysts. Therefore, the conversion of guaiacol catalyzed by basic supported platinum (Pt/MgO) was investigated. The data show that Pt/MgO deactivated less rapidly compared to other catalysts. The corresponding selectivity to oxygen removal products was nearly doubled the value observed from the reactions catalyzed by Pt/[gamma]-Al2O3, demonstrating potential value of basic support for selective HDO process. In summary, results obtained from this research lead to better understanding of catalytic conversion of lignin-derived compounds. Extrapolation of these understanding will help predicting catalyst performance in the upgrading of bio-oils and ultimately designing suitable catalysts and optimizing operating conditions for the conversion of lignin to fuels and chemicals.