Study On The Mechanism Of Pyrolysis And Gasification Of Waste Textile Under Carbon Dioxide Atmosphere

Waste textiles,as one kind of the solid wastes,are gradually drawn much attention to due to the large amount of emissions,significant energies it contains and easy to be classified.Pyrolyzing and gasifying waste textile under CO2 atmosphere is thought to be one of the best ways that doesn’t only take full advantage of waste textile but also effectively completes the conversion of CO2,devoting to reduce the green-house gas emission in the atmosphere.In this paper,the characteristics and mechanism of pyrolysis and gasification of waste textile under CO2 atmosphere and the catalytic effect of catalyst on the catalytic pyrolysis and gasification processes were studied in order to improve the pyrolysis-gasification kinetic of textiles.The details are shown below:Firstly,in order to obtain the waste textiles’ pyrolysis and the corresponding char’gasification performance and mechanism under CO2 atmosphere,the pyrolysis and gasification characteristics of different kinds of waste textiles(Polyester Fiber(PF),Cotton and Woolen)were conducted in Thermo-gravimetric analyses-Fourier Transform Infrared Spectrometer(TG-FTIR)at atmospheric pressure.Scanning electron microscopy(SEM)and Raman spectrometer were used to characterize the char structure.The kinetic parameters of the pyrolysis and gasification processes were calculated by using the shrinking core model.The pyrolysis gas and liquid products were analyzed by GC and GC-MS.Results indicated that the pyrolysis and gasification properties(including product types and contents)of the three kinds of textile were different,such as the highest relative products of PF,Cotton and Woolen were benzoic acid(C7H6O2),acetic acid(C2H4O2)and ethyl cyanide(C3H5N),respectively.And the reaction kinetics and thermaldynamic of the two processes were different.The apparent pyrolysis activation energies for PF,Cotton and Woolen were 162.4kJ/mol,103.1kJ/mol and 110.0kJ/mol,respectively,while the gasification activation energies were 178.2kJ/mol,144.5kJ/mol and 79.4kJ/mol 178.1kJ/mol,respectively.Further,in order to enhance the pyrolysis and gasification kinetics of waste textiles under carbon dioxide atmosphere,the effects of various catalysts on the pyrolysis and gasification of waste textiles(polyester,cotton and wool)were studied by thermogravimetric analyzer,x-ray diffractometer and scanning electron microscope.Several parameters including catalysts’types,loadings and reaction temperatures were also conducted.Results showed that the pyrolysis reaction of the three textiles was best enhanced by 5 wt%ZnO while the gasification reaction was best enhanced by 5 wt%Fe2O3.The apparent pyrolysis activation energies for un-catalytic textile and 5 wt%ZnO loaded textile were 100.7kJ/mol and 65.1kJ/mol,while the gasification activation energies for un-catalytic char and 5 wt%Fe2O3 loaded char were 153.0kJ/mol and 89.0kJ/mol.Finally,a Zn-Fe composite catalyst was prepared by co-precipitation to develop a catalyst,which is both effective in reaction of pyrolysis and gasification.The results showed that the activation energy of the pyrolysis and gasification reaction was 57.1 kJ/mol and 83.3 kJ/mol,respectively,which was superior to the catalytic effect of the single catalyst when the composite catalyst is included in the pyrolysis and gasification reactions.The findings reported in the manuscript are beneficial to the development of energy utilization of waste textile under carbon dioxide atmosphere.