Authors:Hou-Yin Zhao, Yan Cao, Quentin Lineberry, and Wei-Ping Pan
The CO2 adsorption capacity of the low-cost solid sorbents of waste tire char (TC) and chicken waste char (CW) was compared with commercial active carbon (AC) and 5 Å zeolite (ZA) using thermogravimetric analysis (TG), pressurized TG, and differential scanning calorimetry (DSC). The sorbents were degassed in a TG up to 150 °C to release all gases on the surface of the sample, then cooled down to the designed temperature for adsorption. TG results indicated that the CO2 adsorption capacity of TC was higher than that of CW, but lower than those of AC and ZA. The maximum adsorption rate of TC at 50 °C was 0.61% min−1, lower than that of AC, but higher than that of CW, 0.44% min−1. The maximum adsorption rate of ZA at 50 °C was 3.1% min−1. When the pressure was over 4 bar, the adsorption rate of ZA was lower than that of TC and AC. At 30 bar, the total CO2 uptake of TC was 20 wt%, higher than that of CW and ZA but lower than that of AC. The temperature, nitrogen concentration, and water content also influenced the CO2 adsorption capacity of sorbents to some extent. DSC results showed that adsorption was an exothermic process. The heat of CO2 adsorption per mole of CO2 of TC at 50 °C was 24 kJ mol−1 while the ZA had the largest heat of adsorption at 38 kJ mol−1. Comparing the characteristics of TC and CW, TC may be a promising sorbent for removal of CO2.
Authors:Hou-yin Zhao, Yan Cao, Song P. Sit, Quentin Lineberry, and Wei-ping Pan
The pyrolysis behavior of bitumen was investigated using a thermogravimetric analyzer–mass spectrometer system (TG–MS) and a differential scanning calorimeter (DSC) as well as a pyrolysis-gas chromatograph/mass spectrometer system (Py-GC/MS). TG results showed that there were three stages of weight loss during pyrolysis—less than 110, 110–380, and 380–600 °C. Using distributed activation energy model, the average activation energy of the thermal decomposition of bitumen was calculated at 79 kJ mol−1. The evolved gas from the pyrolysis showed that organic species, such as alkane and alkene fragments had a peak maximum temperature of 130 and 480 °C, respectively. Benzene, toluene, and styrene released at 100 and 420 °C. Most of the inorganic compounds, such as H2, H2S, COS, and SO2, released at about 380 °C while the CO2 had the maximum temperature peaks at 400 and 540 °C, respectively. FTIR spectra were taken of the residues of the different stages, and the results showed that the C–H bond intensity decreased dramatically at 380 °C. Py-GC/MS confirmed the composition of the evolved gas. The DSC revealed the endothermic nature of the bitumen pyrolysis.