Influence of Ionic Additives on the Pyrolysis Behavior of Paper

In the course of this study the influence of ionic additives (sodium, potassium, lithium, magnesium, and manganese as cations; acetate, lactate, malate, malonate, succinate, and citrate as anions) on the pattern of volatile pyrolysis products of finished paper is investigated. The pyrolysis of paper causes a cascade of reaction products. As expected, the most abundant pyrolysis product is levoglucosan, however, along with other volatile products, such as hydroxyl and carbonyl compounds, furan and pyran derivatives, phenols, and other anhydrosugars, respectively. These compounds can easily be separated and characterized online using analytical pyrolysis in combination with gas chromatography (GC) and mass spectrometry (MS) detection. Both the composition and total amount of volatile pyrolysis products are significantly altered when the paper samples contain metal salt ions and salts of organic acids, respectively. Principal Component Analysis (PCA) was employed for the multivariate analysis of the obtained pyrolysis products. This allows for a qualitative interpretation on how the various ionic additives affect the formation of specific pyrolysis products. When organic acids are added onto the paper, the pyrolysis pattern mainly depends on the protic properties of the organic acids (mono/di/triprotic) and to a lesser extent on the type within a protic class (monoprotic acetate or lactate vs.diprotic malate or malonate or succinate vs. triprotic citrate). The pyrolysis pattern of the paper samples is more markedly influenced by the type of metal ions rather than by the type of organic acid. These effects significantly depend on both the valence and the concentration of the specific metal salt.