关键词: 松脂, 催化歧化, 反应过程, 跟踪分析

Abstract: On-line tracking analysis for the changes of major chemical components during catalytic disproportionation of gum oleoresin over Pd/C catalyst was studied by the gas chromatography (GC) and gas chromatography-mass spectrometry-detection system (GC-MS-DS), and the reaction mechanism of catalytic disproportionation from gum oleoresin has been discussed. The results showed that the disproportionated rosin and high content of p-cymene could be obtained using the novel process from oleoresin. At reaction temperature 250℃ and reaction time 90 min, and the quantity of catalyst 0.05% (based on oleoresin weight), the contents of dehydroabietic acid and abietic acid were 79.15% and 0 of the acid fractions, respectively, and p-cymene was 62.52% of the neutral oil. The reaction rate of the resin acids was faster than that of turpentine, and dehydrogenations of resin acids and turpentine were main reactions during intermolecular hydrogen transfer reaction of oleoresin. Meanwhile, the tracking analysis indicated that the disproportionation rate of resin acids from oleoresin was faster than that of resin acids from rosin, and the conversion rate of abietic-type resin acids was 89.32% and the content of dehydroabietic acid was 63.20% when reaction time was 15 min. During one-step catalytic disproportionation of oleoresin, the viscosity of reaction system was reduced and liquid-solid mass transfer was improved by the solvent effect of turpentine, so the aromatization of abietic acid was intensified, and the double ring monoterpene in the turpentine was transformed into monocyclic ring monoterpene by ring-opening isomerization reaction, then converted into p-cymene by catalytic dehydrogenation under the resin acids. The present work may provide a reference for research of relevant reaction kinetics and optimization of process.

Key words: oleoresin, catalytic disproportionation, reaction process, tracking analysis