Jingli Wu

TG/FTIR analysis on co-pyrolysis behavior of PE, PVC and PS.

The pyrolysis and co-pyrolysis behaviors of polyethylene (PE), polystyrene (PS) and polyvinyl chloride (PVC) under N2 atmosphere were analyzed by Thermal gravimetric/Fourier transform infrared (TG/FTIR). The volatile products were analyzed to investigate the interaction of the plastic blends during the thermal decomposition process. The TGA results showed that the thermal stability increased followed by PVC, PS and PE. The pyrolysis process of PE was enhanced when mixed with PS. However, PS was postponed when mixed with PVC. As for PE and PVC, mutual block was happened when mixed together. The FTIR results showed that the free radical of the decomposition could combine into a stable compound. When PE mixed with PVC or PS, large amount of unsaturated hydrocarbon groups existed in products while the content of alkynes was decreased. The methyl (-CH3) and methylene (-CH2-) bonds were disappeared while PVC mixed with PE.

Multi-Gaussian-DAEM-reaction model for thermal decompositions of cellulose, hemicellulose and lignin: comparison of N2 and CO2 atmosphere.

Thermal decompositions of three components of biomass (cellulose, hemicellulose and lignin) were studied using nonisothermal thermogravimetric analysis (TGA) under both oxidative and inert atmospheres at a heating rate of 10 K min(-1). The multi-Gaussian-distributed activation energy model (DAEM)-reaction model was first developed to describe thermal decomposition behaviors of three components. Results showed that the presence of CO₂ enhanced the thermal decompositions of three components in high temperature range, but made little difference in low temperature range. Decomposition behaviors under CO₂ were analyzed by the two-stage reaction mechanism corresponding to the pyrolysis process of original materials and the gasification process of char. During gasification stage, CO₂ was reduced to CO, which provided a possibility of a reduction in greenhouse gas emissions. In addition, more CO was produced, and therefore the thermal value of gas was improved. The findings imply that CO₂ gasification technology of biomass has great research significance.

Gasification kinetic analysis of the three pseudocomponents of biomass-cellulose, semicellulose and lignin

The gasification kinetic analysis of the three pseudocomponents (hemicellulose, cellulose and lignin) of biomass decomposition in the agent of CO2 were investigated. The Multi-peaks method was used to fit the Gaussian distribution model of DTG curves. The Friedman method was used to estimate the effective Eα, and the master plot method was used for the determination of the kinetic model. The results showed that there were two reaction stages for semi-cellulose and lignin. The DTG curves of semicellulose and lignin cannot be fitted by Gaussian distribution model. The Eα were ranged from 80 to 220kJmol(-1) for the three pseudocomponents. The Fn model could describe the kinetic process of stage I of semi-cellulose decomposition. Both cellulose and stage II of semicellulose decomposition could be described by An model and the two reaction stages of the lignin were fitted the Rn model very well.

Corn stalks char from fast pyrolysis as precursor material for preparation of activated carbon in fluidized bed reactor

Corn stalks char from fast pyrolysis was activated by physical and chemical activation process in a fluidized bed reactor. The structure and morphology of the carbons were characterized by N2 adsorption and SEM. Effects of activation time and activation agents on the structure of activation carbon were investigated. The physically activated carbons with CO2 have BET specific surface area up to 880 m(2)/g, and exhibit microporous structure. The chemically activated carbons with H3PO4 have BET specific surface area up to 600 m(2)/g, and exhibit mesoporous structure. The surface morphology shows that physically activated carbons exhibit fibrous like structure in nature with long ridges, resembling parallel lines. Whereas chemically activated carbons have cross-interconnected smooth open pores without the fibrous like structure.

TG-MS analysis and kinetic study for thermal decomposition of six representative components of municipal solid waste under steam atmosphere

Thermal decomposition of six representative components of municipal solid waste (MSW, including lignin, printing paper, cotton, rubber, polyvinyl chloride (PVC) and cabbage) was investigated by thermogravimetric-mass spectroscopy (TG-MS) under steam atmosphere. Compared with TG and derivative thermogravimetric (DTG) curves under N2 atmosphere, thermal decomposition of MSW components under steam atmosphere was divided into pyrolysis and gasification stages. In the pyrolysis stage, the shapes of TG and DTG curves under steam atmosphere were almost the same with those under N2 atmosphere. In the gasification stage, the presence of steam led to a greater mass loss because of the steam partial oxidation of char residue. The evolution profiles of H2, CH4, CO and CO2 were well consistent with DTG curves in terms of appearance of peaks and relevant stages in the whole temperature range, and the steam partial oxidation of char residue promoted the generation of more gas products in high temperature range. The multi-Gaussian distributed activation energy model (DAEM) was proved plausible to describe thermal decomposition behaviours of MSW components under steam atmosphere.

Characteristics of a CaSO4 oxygen carrier for chemical-looping combustion: reaction with polyvinylchloride pyrolysis gases in a two-stage reactor

Chemical-looping combustion (CLC), which is a promising technique that includes an inherent separation of CO2 may reduce the generation of dioxins in municipal solid waste (MSW) disposal because in a CLC system, no free oxygen is available for incineration process. Polyvinylchloride (PVC) and kitchen garbage are the main chlorine substances in MSW. The reaction between PVC pyrolysis gas and a calcium (Ca)-based oxygen carrier was investigated in a two-stage reactor in this study. The thermal decomposition and reduction/oxidation cycle behaviors of the oxygen carrier were investigated by analyzing methane (CH4) using a thermogravimetric analyzer (TGA). The characteristics of CaSO4/Fe2O3 oxygen carrier were determined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that the addition of Fe2O3 into CaSO4 can enhance the reaction rate, and also that the CaSO4/Fe2O3 oxygen carrier showed a good heat stability at the temperature of 900 degrees C. The reduction/oxidation cycles confirmed that the decomposition of the CaSO4/Fe2O3 oxygen carrier is usually accompanied by some side reactions. These side reactions could cause the loss of their regeneration ability. The CaSO4/Fe2O3 oxygen carrier successfully reacted with PVC pyrolysis gas in a two-stage reactor and the complete reaction ratio of m(PVC) to m(oxygen carrier) is 8. The research documented herein provides a useful reference for the utilization of MSWs.

Nucleation and Growth Mechanism of Si Amorphous Film Deposited by PIAD

The nanoscale Si films with the thickness of 2 nm, 5 nm, 10 nm, and 20 nm were deposited by plasma ion assisted deposition (PIAD) on glass substrate, in order to investigate the initial stage and the nucleation and growth mechanism of the Si film. The atomic force microscopy (AFM) was used to investigate the surface topography of the as-deposited Si film. The initial nucleation and growth process of the film was described. The continuous film had been already formed when the film thickness was 10 nm. The growth of the deposited Si film accorded with the Volmer-Weber growth mode.