Research On Regulation Technology For Pyrolysis And Smoke Components Of Paper-making Reconstituted Tobacco

In order to overcomethe quality defects of paper-making reconstituted tobacco (PRT) on the high level of CO and some sensory attributes like irritation and off-tastein mainstream smoke, the thermal degradation behaviors of PRT and paper-base (the principalconstituent of PRT) were first studied deeply on the basement of systematical analysis on its physicochemical properties. Then the thermal degradation process of PRT was regulated via the change of the chemical components of paper-base and the addition of phosphorus-and nitrogen-bearing compounds, respectively, thus adjusting the smoke components of PRT and finally improving smoke quality of cigarette. This dissertation consists of the following parts:(1) In order to get an complete insight into the quality attributes of PRT, its physicochemical performances connected with the thermal decomposition behavior such as chemical components, inorganic ions and fiber morphologies were systematically investigated, and the difference of PRT, expanded cut tobacco (ECT) and expanded cut stem (ECS) in some key parameters, including tar, CO and static burning rate was compared too. It was found that CO delivery of PRT was much higher than that of ECT and ECS, especially CO level per puff, in spite of its higher static burning rate and lower tar delivery than that of ECT and ECS. To figure out the reason of higher CO delivery of PRT, the difference of PRT and paper-base in their respective mainstream components was further compared and the preliminary conclusion obtained is that base-paper is one of the principal reasons causing the higher CO delivery of PRT.(2) To deeply understand the thermal degradation behavior of PRT and paper-base, their respective thermal decomposition process, heat release properties and gas products evolution in the changing heat rates were systematically analyzed by TG/DSC-FTIR. It was shown that paper-base has a much higher CO delivery than PRT although they both present a similar two-stage CO delivery. Furthermore, the CO delivery of both significantly increases with elevating heat rate. These resultsfurther prove that paper-base is one of one of the principal reasons causing the higher CO delivery of PRT.(3) To reduce the bad effect of pectin and protein on the sensory quality of cigarette, pectinase and proteinase were selected to selectively degrade pectin and protein in the paper-base, respectively. The study of thermal degradation behavior of enzyme-treating paper-base displayed that the decrease of pectin and protein in paper-base can obviously change its thermal degradation process and the delivery of gas products like CO, CO2, NH3, carbonyl compounds and so on, implying the presence of regulation of pectin and protein on the formation of volatilized products during the pyrolysis of paper-base. In order to reveal the mechanism of thermal degradation of pectin more clearly, its thermal decomposition was first studied with tunable synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS).The results demonstrated a two-step pyrolysis process: intramolecular pyrolysis of galacturonic acid subunit at the chain ends of polymers in the lowtemperature range and the rupture of α-(â†'4) glycosidic bond between galacturonic acid subunit in the high temperature range. The deduced mechanism of reaction pathways in pectin pyrolysis should provide insight into the pyrolysis behavior of pectin, laying the foundation for the control of degraded products of prectin.(4) The influence of phosphorus-and nitrogen-containing additives (PNA) like diammonium phosphate (DAP), urea phosphate (UP) and ammonium polyphosphate (APP) on the thermal degradation behavior of PRT was investigated. It was exhibited that PNA can enhance the thermal-oxidative stability of the char residue of PRT and reduce its total amount of volatized species remarkably. And the decrease of CO delivery in the mainstream smoke of cigarette can be achieved by APP and UP. To clarify the mechanism of the reduction of CO delivery caused by APP and UP, a comparative analysis of CO evolution patterns in the flash and slow pyrolysis was carried out and the results showed that UP and APP mainly influenced the CO formation at the stage of thermal-oxidative decomposition of the char residue.