Thermogravimetric Analyzer Coupled With Fourier Transform Infrared Spectrometer Research Articles

Methane formation mechanism during pressurized pyrolysis of coal core in the context of deep underground coal gasification

Deep underground coal gasification (UCG) is characterized by high reaction pressure (dependent on hydrostatic pressure of coal seam) and high CH4 content. The formation mechanism of CH4 in product gases has always been an interesting topic. In this paper, pressurized pyrolysis characteristics of coal core were studied through a pressurized pyrolysis device. The formation mechanism of CH4 and structural evolution of semi-coke during the pressurized pyrolysis process were identified by X-ray diffractometer (XRD), pressurized thermogravimetric analyzer coupled with Fourier transform infrared spectrometer (TG-FTIR) and carbon-13 nuclear magnetic resonance (13C NMR). The results indicate that the yield of pyrolysis gas and carbon emission rate rise with an increase of pyrolysis pressure, while the yield of tar decreases. Compared with atmospheric pressure, the pyrolysis gas yield increases from 148.6 L/kg to 172.6 L/kg at 3.0 MPa, the CH4 yield increases from 32.6 L/kg to 77.3 L/kg. The CH4 begins to be released at around 400 °C at different pyrolysis pressures, and the generation rate reaches its maximum at around 500 °C. The analysis of 13C NMR shows that the relative content of the oxy-quaternary carbon in the aliphatic group decreases significantly from 9.2% to 1.8% with an increasing pyrolysis pressure. Therefore, pressure promotes the reaction of aliphatic carbon with hydrogen radicals to form CH4, which is one of the main reactions for the generation of CH4 by pressurized pyrolysis.

Investigation on combustion, gaseous pollutants emission and ash characteristics during co-combustion of semicoke and coal slime

Co-combustion of semicoke and coal slime is promising for their co-disposal. In this study, the co-combustion behaviors, interaction and gaseous pollutants emission of semicoke and coal slime were studied by thermogravimetric analyzer coupled with Fourier transform infrared spectrometer (TG-FTIR). The ash characteristics after co-combustion were also investigated. Results showed adding coal slime could improve the ignition and burnout performance of blends but lead to the declining comprehensive combustion index. Inhibitory effects were prominent at the early stage of co-combustion due to the heat competition while promoting effects existed in fixed carbon combustion. The ash accumulation suppressed co-combustion again at the burnout stage. Semicoke could reduce NO, NO2 and SO2 emission of blends but also cause serious slagging because of the high Ca content. Adding coal slime could prevent the generation of eutectics and thus decrease the ash slagging propensity of blends. The sulfur-retention reaction was more intense at coal slime blend ratio of 40%. Semicoke ash had higher Mn, Ni and Cu concentrations while coal slime ash has more Zn and Pb contents. With the increase of coal slime blend ratios, Mn, Ni and Cu in ash gradually decreased while Zn and Pb increased.

Interactions of lignin and LDPE during catalytic co-pyrolysis: Thermal behavior and kinetics study by TG-FTIR

Thermal behavior and interaction of Low-density polyethylene (LDPE) and lignin with HZSM-5 as catalyst during catalytic co-pyrolysis were analyzed by thermogravimetric analyzer coupled with Fourier transform infrared spectrometer (TG-FTIR). The synergistic effect of lignin and hydrogen-rich LDPE decreased the starting temperature of pyrolysis and accelerated the pyrolysis rate. Kinetic analysis based on the Coats-Redfern method showed that HZSM-5 catalysis significantly decreased the reaction’s activation energy. FTIR results also indicated that the composition of pyrolysis products shifted to more alkane and aromatics by co-feeding the lignin with LDPE and catalyst HZSM-5.

TG-FTIR study on co-combustion of bituminous coal semicoke and lignite

The combustion behaviors and pollutants emission characteristics during co-combustion of bituminous coal semicoke and lignite were investigated by thermogravimetric analyzer coupled with Fourier transform infrared spectrometer (TG-FTIR). Results showed the addition of lignite could lower the ignition and burnout temperature and also enhance the comprehensive combustion performance of blends. High heating rate could improve the combustion intensity and corresponding combustion characteristic indexes. The activation energy analysis by distributed activation energy model (DAEM) and Ozawa–Flynn–Wall (OFW) methods at lignite blend ratio of 40% indicated its distribution was consistent with the combustion process of blends. An obvious activation energy jump occurred at conversion rate range of 0.4–0.55 due to the poor ignition performance of semicoke. The average activation energy obtained by DAEM and OFW methods was 101.69 kJ mol−1 and 109.12 kJ mol−1, respectively. With the increase of lignite blend ratios, CO and CO2 emission gradually decreased. Meanwhile, NO emission increased, while NO2 and SO2 emission ascended after an initial decline. Semicoke had certain suppression effect on NOx and SO2 emission. The minimum NO2 and SO2 emission was obtained at lignite blend ratio of 20%.

Experimental study on co-combustion of low rank coal semicoke and oil sludge by TG-FTIR

Co-combustion was proposed as an effective and complementary means for the co-treatment of low rank coal semicoke (LRCS) and oil sludge. The combustion, kinetics and gaseous pollutants emission characteristics during co-combustion of LRCS and oil sludge were investigated by thermogravimetric analyzer coupled with Fourier transform infrared spectrometer (TG-FTIR). Results showed oil sludge had more complex weight loss characteristics than LRCS. Proper addition of oil sludge could effectively improve the ignition, burnout and comprehensive combustion performance of blends and 60% was a recommended oil sludge blend ratio. High heating rates could also enhance the combustion performance of blends. The activation energy determined by Coats-Redfern method gradually decreased with the increase of oil sludge blend ratio. DAEM kinetic analysis results showed the maximum activation energy of 113.4 kJ/mol was obtained when conversion rate was 0.4 due to the poor ignition performance of LRCS. All of the CO, CO2, NOx and SO2 emission gradually decreased with the increasing oil sludge blend ratio. LRCS had suppression effect on NOx emission during co-combustion while oil sludge was just the opposite. The low sulfur release rate of oil sludge resulted in the decreasing SO2 emission of blends although oil sludge had promotion effect on SO2 emission.

Preparation of activated carbon monolith from waste corrugated cardboard box via catalytic pyrolysis and gasification under CO2 atmosphere for adsorption and solar steam generation

Activated carbon monolith (ACM) was prepared from waste corrugated cardboard box (WCCB) via slurrying in seawater (SW) followed by dewatering, molding and heating under CO2 atmosphere. The thermal process was analyzed by thermogravimetric analyzer coupled with Fourier transform infrared spectrometer (TG-FTIR). ACM was characterized by N2-adsorption/desorption, FTIR, Raman spectroscopy and ultraviolet–visible-near infrared (UV–Vis-NIR) spectroscopy. The adsorption behavior of ACM for methylene blue (MB) and its solar steam generation performance were investigated. Results showed alkali and alkaline earth metals (AAEMs) in SW promoted the occurrence of pyrolysis of cellulose in WCCB at lower temperatures but inhibited the formation of organic volatiles, and the activation energy was reduced by 24.53 kJ mol−1. AAEMs catalyzed the formation of more CO during CO2 gasification of WCCB char between 755 and 860 °C, and the activation reaction with higher degree led to the formation of more micro- and mesopores in ACM at 785 °C. The adsorption behavior of ACM for MB fitted Langmuir model with a monolayer adsorption capacity of 174 mg g−1, and ACM in floating state was also effective in adsorption of MB from water. ACM exhibited high optical absorption above 90% within a broadband wavelength, and 66.7% higher water evaporation can be achieved with the assistance of ACM during solar steam generation under the same condition.

Quantification of low‐temperature oxidation of light oil and its SAR fractions with TG‐DSC and TG‐FTIR analysis

AbstractThe oxidation reaction is the key to determining the success of air flooding. In this paper, experimental and theoretical techniques have been developed to identify the low‐temperature oxidation (LTO) mechanisms for light oil during air flooding by comprehensively analyzing thermal stability and oxidation process of the crude oil and its SAR (ie, saturates, aromatics, and resins) fractions. Experimentally, both a thermogravimetric analyzer coupled with differential scanning calorimetry (TG‐DSC) and a thermogravimetric analyzer coupled with Fourier transform infrared spectrometer (TG‐FTIR) are employed to quantify the LTO process of crude oil and each SAR fraction as well as the corresponding oxidation properties. Theoretically, reaction models have been developed to reproduce the experimentally identified reactions. The results show that the oxygen addition reaction and the bond scission reaction occur simultaneously. The former can be initiated when temperature is higher than 50°C, and it is gradually shifted to the latter with the continuous increase in reservoir temperature. The LTO products of light oil include H2O, CO2, carboxylic acids, alcohols, phenols, and ethers. Saturates, aromatics, and resins are all the sources of H2O, CO2, alcohols, and carboxylic acids, whereas ethers are mainly derived from aromatics and resins. At the beginning of an air flooding process, heat is mainly generated from the oxidation of aromatics and resins. Subsequently, oxidizing saturates gradually dominates the air flooding process with an increase in the reservoir temperature.

Catalytic Effect of Cobalt Additive on the Low Temperature Oxidation Characteristics of Changqing Tight Oil and Its SARA Fractions

Air flooding is a potential enhanced oil recovery (EOR) method to economically and efficiently develop a tight oil reservoir due to its sufficient gas source and low operational costs, during which low temperature oxidation (LTO) is the key to ensuring the success of air flooding. In addition to inefficiency of conventional LTO, air flooding has seen its limited applications due to the prolonged reaction time and safety constraints. In this paper, a novel air injection technique based on the catalyst-activated low temperature oxidation (CLTO) is developed to improve the operational safety together with its oil recovery in tight oil reservoirs. Experimentally, static oxidation experiments are conducted to examine the influence of the catalyst on the LTO reaction kinetics of Changqing tight oil and its fractions. The catalytic oxidation characteristics are identified by applying a thermogravimetric analyzer coupled with Fourier transform infrared spectrometer (TG-FTIR) with respect to tight oil and its SARA (i.e., saturates, aromatics, resins, and asphaltenes) fractions. Accordingly, the catalyst can obviously decrease the LTO reaction activation energy of the Changqing tight oil and its SARA fraction. Cobalt additive can change the LTO reaction pathways of the SARA fractions, i.e., promoting the formation of hydroxyl-containing oxides and CO2 from the oxidation of saturates, aromatics and resins, while inhibiting the formation of ethers from the oxidation of aromatics and resins. The LTO of each SARA fraction contains both oxygen addition reaction and bond scission reaction that can be effectively promoted with the cobalt additive. The catalytic effect on the bond scission reaction is continuously enhanced and becomes gradually stronger than that on the oxygen addition reaction as the reaction proceeds.

Understanding the CO2 sorption mechanisms of the MgO‐doped Na‐based sorbent at low temperatures

AbstractUsing a solid Na‐based sorbent is one potential option to decrease CO2 emission in coal‐fired power plants, and the CO2 sorption reactivity of Na2CO3/γ‐Al2O3 sorbent was improved by mechanically doping MgO into Na2CO3/γ‐Al2O3 in our previous study while the mechanism was not clear. In this paper, the CO2 sorption/desorption mechanisms of the promising MgO‐doped Na‐based sorbent prepared by the two‐step incipient wetness impregnation method were studied using a fixed‐bed reactor, together with characterizations of X‐ray fluorescence, nitrogen adsorption apparatus, field emission scanning electron microscopy, X‐ray diffraction, and thermogravimetric analyzer coupled with Fourier transform infrared spectrometer (TG‐FTIR). Also, the sorption behaviors were well described with Avrami's fractional‐order kinetic model. Results demonstrated that MgO not only dispersed on γ‐Al2O3 but entered γ‐Al2O3’s lattice, leading to the formation of Mg‐Al mixed oxides for CO2 sorption. In addition, a new phase Mg6Al2CO3(OH)16·4H2O was produced during the CO2 sorption process, which plays a crucial role in facilitating the conversion of Na2CO3 to NaHCO3. The CO2 sorption capacity of MgO‐doped Na‐based sorbents is presumably determined by the trade‐off between microstructure and active component dispersion. The knowledge gained about the promotion mechanism of MgO provides fundamental direction for the synthesis of Mg–Al mixed oxides, supported with the developed microstructure for CO2 sorption enhancement of Na‐based sorbents. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd.

Pyrolysis and combustion characteristics of corncob hydrolysis residue

Corncob hydrolysis residue (CHR) is a by-product of the furfural industry. In this paper, the thermal behavior of CHR was determined with the aim to promote its application as fuels or chemicals. Firstly, the pyrolysis and combustion of CHR in nitrogen and air, were respectively investigated by thermogravimetric analyzer coupled with Fourier transform infrared spectrometer (TG-FTIR). The TG and DTG (differential thermos-gravimetric) curves revealed that both the pyrolysis and combustion of CHR included three distinct stages. The main evolving gaseous products during pyrolysis were H2O, CH4, CO, CO2 and oxygenated compounds, while combustion yielded considerable amounts of CO2 in the temperature range of 345–500 °C. The presence of oxygen can increase the volatilization rate of organic matter in CHR and accelerate thermal decomposition of CHR. A total weight loss of 57.29 wt% and 77.53 wt% was observed for pyrolysis and combustion, respectively. The non-isothermal kinetic was used to analyze the activation energy (E) of combustion and pyrolysis processes. The E of CHR pyrolysis reaction is 135.45 kJ mol−1 in temperature of 200–500 °C, while under the combustion process the value of E is 121.57 kJ mol−1 and 135.45 kJ mol−1 in 200–345 °C and 345–500 °C temperature ranges, respectively. In addition to it, the types of products and their proportions in pyrolysis process of CHR were studied by Py-GC/MS and the results indicated that the oxygenated compound produced from CHR pyrolysis mainly included acids, aldehyde, phenolics and anhydrides.

Comparison study on the pyrolysis of two kinds of ancient plant seeds of the 1st century BCE

Ancient hemp seeds (AHS) and melon seeds (AMS) excavated from the tomb of Marquis Haihun of the Western Han Dynasty (1st century, BCE) had been studied in this research. Elemental analyzer, X-ray fluorescence (XRF) and thermogravimetric analyzer coupled with Fourier transform infrared spectrometer (TG-FTIR) was applied in analyzing the samples together with single TG and FT-IR, and contents of different components in the samples had been measured by the Van Soest Method. Analytical results of TG-FTIR analysis showed that evolved gas in the pyrolysis process was mainly consisted of CO2, CO, alkanes, alcohols and phenols, and CO2 occupied a leading role in the gaseous products. Besides, acid detergent lignin of the samples were analyzed by FT-IR, and the analytical results suggested that lignin structures of AHS and AMS were different.

TG-FTIR study on pyrolysis of Enteromorpha prolifera

Pyrolysis of Enteromorpha prolifera was investigated for the first time by using thermogravimetric analyzer coupled with Fourier transform infrared spectrometer (TG-FTIR). The activation energies of pyrolysis reactions were obtained via the Flynn-Wall-Ozawa and Kissinger-Akahira-Sunose method, respectively. The experimental results showed that the main weight loss of EP occurred between 200 and 350 °C, and almost all the volatiles were evolved in this stage. CO2 was the most prominent non-condensable product, while aldehydes, organic acids, ketones, and ethers were the dominating condensable products. The minor weight loss of EP above 720 °C was possibly caused by the decomposition of calcium carbonate, and it resulted in the formation of CO2, which was further reduced to CO by EP char above 750 °C. In addition, the evolution curves of CH4 and aliphatic C-H exhibited two peaks located between 200 and 600 °C, due to the rupture of methoxy, ethoxy, and methylene. The activation energy of the pyrolysis of EP increased with the increase of conversion rate, and its average value was calculated as 299.84 kJ mol−1 for FWO method and 306.81 kJ mol−1 for KAS method. All of the findings would help further understanding of pyrolysis behavior of EP and its thermo-chemical utilization for fuels and chemicals.

Interactions of municipal solid waste components during pyrolysis: A TG-FTIR study

The interactions of three municipal solid waste (MSW) components (rice, poplar wood and PVC) during pyrolysis were investigated using the thermogravimetric analyzer coupled with Fourier transform infrared spectrometer (TG-FTIR). The results showed that the interaction of rice and poplar wood slightly suppressed the emission of CO2, with the TG curve overlap ratio of 0.9846. On the contrary, the interaction of rice/PVC or poplar wood/PVC was notable. The addition of PVC promoted the generation of CO2 and CO to occur earlier and tend to be a slower process. Between 350 and 500°C, HCl derived from PVC participated in the pyrolysis of rice and organic chlorides may be generated. Besides, the presence of chlorinated polymers in municipal solid waste may tend to increase char yields during pyrolysis.

GC-MS and TG-FTIR Study of Petroleum Ether Extract and Residue from Low Temperature Coal Tar

The heavy tar (H-tar) of low temperature coal tar was collected from a low temperature carbonization plant in Shanbei. H-tar was extracted with petroleum ether (PE) under ultrasonic irradiation and separated into PE soluble and insoluble fractions. Then, the PE insoluble fraction was extracted in a Soxhlet extractor with PE and methanol (MeOH), respectively. PE extract, PE residue, MeOH extract, and MeOH residue were obtained. PESE (PE soluble fraction and PE extract) and MeOH extract were examined by gas chromatography−mass spectrometry (GC-MS). GC-MS analysis of PESE shows considerable alkanes and extensive series of phenols, naphthalenes, fluorenes, benz[a]anthracene, chrysene, etc. Particularly, the content of methyl phenol is about 9.0%. No GC-MS detectable species are found in MeOH extract. So, additional research will focus on PE residue. The pyrolysis behavior of PE residue was investigated by using a thermogravimetric analyzer coupled with Fourier transform infrared spectrometer (TG-FTIR). The results indicate that the release of volatiles takes place mainly between 110 and 425 °C and the maximum mass loss rate occurs at 315 °C. The main products in the whole process are CO2, phenols, H2O, saturated hydrocarbons, aromatic compounds, anhydride compounds, oxygen heterocycles, pyridines, etc. But there is no significant peak of CO. The compounds of alkanes, phenols, heterocyclic compounds, and oxygen-containing heterocyclic compounds in PE residue can be also detected. PE residue semicoke (the products of PE residue after TG) and PE residue were estimated by FTIR. PE residue is mainly composed of phenols, aliphatics, and aromatics. The analyses indicate the high degree and polycyclic aromatic structure of PE residue semicoke.

Properties of Bio-oil from Fast Pyrolysis of Rice Husk

Physicochemical properties of bio-oil obtained from fast pyrolysis of rice husk were studied in the present work. Molecular distillation was used to separate the crude bio-oil into three fractions viz. light fraction, middle fraction and heavy fraction. Their chemical composition was analyzed by gas chromatograph and mass spectrometer (GC-MS). The thermal behavior, including evaporation and decomposition, was investigated using thermogravimetric analyzer coupled with Fourier transform infrared spectrometer (TG-FTIR). The product distribution was significantly affected by contents of cellulose, hemicellulose and lignin. The bio-oil yield was 46.36% (by mass) and the yield of gaseous products was 27% (by mass). The chemicals in the bio-oil included acids, aldehydes, ketones, alcohols, phenols, sugars, etc. The light fraction was mainly composed of acids and compounds with lower boiling point temperature, the middle and heavy fractions were consisted of phenols and levoglucosan. The thermal stability of the bio-oil was determined by the interactions and intersolubility of compounds. It was found that the thermal stability of bio-oil was better than the light fraction, but worse than the middle and heavy fractions.

Interactions of biomass components during pyrolysis: A TG-FTIR study

The pyrolysis of synthetic biomass samples as three-component (viz. hemicellulose, cellulose and lignin) mixtures was investigated by using the technology of thermogravimetric analyzer coupled with Fourier transform infrared spectrometer (TG-FTIR). The results reveal the occurrence of interactions among biomass components during pyrolysis, especially the influence of lignin to hemicellulose below 327°C and that of hemicellulose to cellulose above 327°C. By analyzing the FTIR spectra carefully, it was found that the presence of lignin decreased the yield of 2-furaldehyde and CO containing compounds. The existence of hemicellulose intensively decreased the yield of levoglucosan, and largely promoted the formation of hydroxyacetaldehyde.