A formal kinetic model describing the main reaction pathways yielding demethoxylated monomeric phenols from wheat straw lignin in a hydrogen-enriched solvolysis reaction system using ethanol as cosolvent has been developed. The simplified lump model combines both a detailed focus on the deoxygenation reactions at molecular level as well as the reactions of global bulk lumps. The results show that depolymerization of lignin structures is quickly achieved and that deoxygenation reactions largely follow a main route pathway via intermediate methoxyphenols and catechols to give stable phenols in the liquid phase. Observed ethyl group substituents of phenolics are seen to originate from either alkylation reactions of the intermediates, or directly from the depolymerizing structures. A high correlation between primary 4-ethylphenol products and para-coumaryl units in the examined lignin suggests that main reaction pathways are strongly dependent on the type of plant lignin used.

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This thesis, submitted for the degree of Philosophiae Doctor at the University of Bergen, consists of two parts. The first includes an introduction, a summary of the work and main results from the papers in the second part, an overall conclusion and future work suggestions. The second part consists of six research papers and manuscripts, and one conference proceedings paper. The main part of the work has been performed at the Department of Chemistry, University of Bergen in the period 2010-2012, including several guest research stays

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Multivariate statistical methods, such as Principal Component Analysis (PCA), have been used extensively over the past decades as tools for extracting significant information from complex data sets. As such they are very powerful and in combination with an understanding of underlying chemical principles, they have enabled researchers to develop useful models. A drawback with the methods is that they do not have the ability to incorporate any physical / chemical model of the system being studied during the statistical analysis. In this paper we present a method that can be used as a complement to traditional chemometric tools in finding patterns in mass spectrometry data. The method uses a pre-defined set of equally spaced sequences that are assumed to be present in the data. Allowing for some uncertainty in the peak locations due to the uncertainties for the measurement instrumentation, the measured spectra are then projected onto this set. It is shown that the resulting scores can be used to identify homologous series in measured mass spectra that differ significantly between different measured samples. As opposed to PCA, the loading vectors, in this case the pre-defined homologous series, are readily interpretable.

In order to exploit the theoretical potential of small manure anaerobic digestion (AD) plants for flexible power generation, the technical retrofitting and the prospective additional revenue generated by direct marketing is assessed for two different manure AD plants by means of a profitability analysis. Due to the variation in the economic profitability by the individual direct marketing models, the economy of three plants was simulated in four different scenarios: basic feed-in tariff, direct marketing, electricity balancing market, and flexible operation. Economical operations were calculated and the additional revenue for small manure AD plants taking part in the direct marketing system was calculated.