Kinetic and thermodynamic investigations of CO2 gasification of coal chars prepared via conventional and microwave pyrolysis

This study examined an isothermal CO2 gasification of four chars prepared via two different methods,i.e.,conventional and microwave-assisted pyrolysis,by the approach of thermogravimetric analysis.Physical,chemical,and structural behaviours of chars were examined using ultimate analysis,X-ray diffraction,and scanning electronic microscopy.Kinetic parameters were calculated by applying the shrinking unreacted core(SCM)and random pore(RPM)models.Moreover,char-CO2 gasification was further simulated by using Aspen Plus to investigate thermodynamic performances in terms of syngas composition and cold gas efficiency(CGE).The microwave-induced char has the largest C/H mass ratio and most ordered carbon structure,but the smallest gasification reactivity.Kinetic analysis indicates that the RPM is better for describing both gasification conversion and reaction rates of the studied chars,and the activation energies and pre-exponential factors varied in the range of 78.45–194.72 kJ/mol and 3.15–102,231.99 s−1,respectively.In addition,a compensation effect was noted during gasification.Finally,the microwave-derived char exhibits better thermodynamic performances than the conventional chars,with the highest CGE and CO molar concentration of 1.30%and 86.18%,respectively.Increasing the pyrolysis temperature,gasification temperature,and CO2-to-carbon molar ratio improved the CGE.

Thermal and Mechanical Properties of Epoxy Resin Modified with N-(4-hydroxyphenyl)terahydrophthalic Anhydrideimide

A novel epoxy-imide resin based on diglycidyl ether of bisphenol-A and N-（4-hydroxyphenyl）terahydrophthalic anhydrideimide（HTAM） was synthesized. The structural characterization of the epoxy-imide resin was conducted by FT-IR spectra. 4,4＇-diaminodiphneylmethane（DDM） was used as a curing agent for the epoxy-imide resin. The thermal properties of the cured resin were evaluated with dynamic mechanical analyses（DMA） and thermogravimetric analysis（TGA）. The results showed that the cured resin exhibited a high glass transition temperature（Tg） of 186 ℃ when the molar amount of HTAM was 0.04 mol in the resin. The yields of the cured resin at 800 ℃ raised from 16.45% to 19.41%. The flexural properties were also measured, the flexural strength raised from 79.4 to 95.7 MPa, and the flexural modulus exhibited from 2.6 to 3.0 GPa.

Cross-interaction of volatiles from co-pyrolysis of lignin with pig manure and their effects on properties of the resulting biochar

Biomass and pig manure have distinct compositions and the co-pyrolysis of them has gained much attention.However,the influence of volatiles interaction on the properties of the char was still unclear.In this study,lignin was selected as the model component of biomass with pig manure for co-pyrolysis at 600°C.The results indicate that volatiles from co-pyrolysis promoted re-condensation reaction,resulting in the higher char yield(48.0%in co-pyrolysis versus 31.0%in pyrolysis of single manure)and the formation of more aromatics in bio-oil.The co-pyrolysis also facilitated the dehydrogenation and dehydration reactions,which accounted for the elimination of oxygen and nitrogen contents and thus a higher carbon content(64.7%in the co-pyrolysis versus the averaged value of 46.4%from the pyrolysis of single feedstock),higher crystallinity and thermal stability of the char.The in-situ diffuse reflection infrared Fourier transform spectroscopy(DRIFTS)characterization results demonstrated that the functionalities abundances of char with temperature was influenced by volatiles interaction via accelerating the carbonization reaction.In addition,the high heating value(HHV)of char was obviously improved by cross-interaction of volatiles during co-pyrolysis(24.4 MJ/Kg in co-pyrolysis versus averaged value of 15.1 MJ/Kg from single pyrolysis),implying that the co-pyrolysis enhanced the energy density of the resulting char.