Pyrolysis of Untreated and Various Torrefied Stem Wood, Stump, and Bark of Norway Spruce

The effect of torrefaction severity (temperature and residence time) was studied on the thermal decomposition of different parts of Norway spruce (stem wood, stump, and bark). The volatile content of the torrefied samples was characterized by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The tendencies of the intensities of the most characteristic pyrolysis products of the untreated and torrefied samples have been compared. The Py-GC/MS results are interpreted in terms of the chemical composition changes (cellulose and hemicellulose). It was found that the alkali ions do not catalyze the thermal decomposition of hemicellulose contrary to cellulose. The results of the Py-GC/MS analysis demonstrated that the yields of acetic acid and other compounds of low molecular mass were reduced in the pyrolyzates of each torrefied sample, including the treatment at 225 °C. Principal component analysis has been used to reveal correlations between the torrefaction temperature, residence time, and product distribution of the samples. The torrefied stem wood and stump behaved similarly during torrefaction; therefore, they can be used together in thermochemical conversion applications. However, the torrefaction of bark requires about a 25 °C lower torrefaction temperature than stem wood and stump. © 2019 American Chemical Society

Thermal decomposition of black locust and wheat straw under torrefaction

In this work the torrefaction of two typical Hungarian biomass materials, wheat straw and black locust wood was studied. Three different torrefaction temperatures were applied: 225, 250 and 300°C with one hour isothermal period. The untreated and torrefied biomass materials were characterized by thermogravimetric analysis (TGA) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) techniques. The alkali ion contents of the samples were determined by ICP-OES technique. It was found that the thermal treatment at 225°C for 1 hour modifies the thermal decomposition mechanism of the cellulose content of the sample, indicating chemical changes in the cellulose structure. At 250°C the hemicellulose content of the analyzed biomass materials partially decomposes. Furthermore, the most labile lignin groups (terminal CH2OH) also start to decompose. At 300°C torrefaction temperature the major part of hemicellulose and cellulose decomposes. The degree of the cellulose decomposition highly correlates with the alkali ion content of the samples

Catalytic pyrolysis of mixtures modeling municipal waste

In this work the temperatures of the thermal decomposition of model waste mixtures were determined with and without catalysts under slow heating conditions applying thermogravimetry-mass spectrometry (TG/MS) technique. The catalytic effect of HZSM-5 and Ni-Mo catalysts were tested on the thermal stability of model waste mixtures. Significantly decreased thermal decomposition temperature (by about 200°C) was observed in case of plastic mixture in the presence of 10 % HZSM-5 catalyst. The catalytic effect of HZSM-5 catalyst was hindered when the domestic waste model mixtures contained biomass components as well. The effect of cellulose and lignin on the catalytic activity of HZSM-5 catalyst was tested and significant poisoning effect was observed in both cases. The presence of 50% cellulose or 10% lignin in the waste mixture completely deactivates the HZSM-5 catalyst

Thermal characterization of new, artificially and naturally aged leather and parchment samples

Handwritten books, codices and letters stored or displayed in historic buildings are vulnerable to changes in the outdoor environment due to the limited climate control. Understanding the degradation mechanisms and changes in the structure of leather and parchment could help to find a proper way to protect these pieces from the aging and the environmental effects. In order to identify the aging mechanisms different analytical methods, among them thermoanalytical methods were used. In this work natural aging mechanisms were modeled by acid and alkaline pretreatments. Structural changes of the samples during the aging were explored using thermoanalytical methods, in order to understand the response of parchment and leather to the environmental effects

Thermal and catalytic decomposition studies of microalgal residue using pyrolysis-GC/MS and TG/MS

The marine algal biomass is one of the most promising candidates for the raw material of sustainable biofuel production. Biofuels of different phases can be converted by bio- or thermochemical methods. In this study thermogravimetry/mass spectrometry (TG/MS) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) were used to analyze the main decomposition products of the deoiled algal cake (DAC). Two mesoporous silica catalysts (SBA-15 and FSM-16) were applied to modify the composition of the evolving gas phase products. The yield of the evolving volatile gas products was enhanced by the use of the SBA-15. This catalyst promoted the decomposition of the inorganic carbonates into carbon dioxide. The formation of hydrocarbons during the fast pyrolysis simple alcohol molecules were formed from the deoiled algal residue. The yields of the anhydro-sugar derivatives were strongly affected by the presence of both catalysts. The intensity of the aromatic and aliphatic decomposition products were influenced by the catalytic decomposition procedure

Thermal degradation study of vegetable tannins and vegetable tanned leathers

In this study, hydrolyzable tannins (commercial chestnut, valonea and tara extracts), condensed tannins (commercial quebracho and mimosa extracts) as well as calf leathers produced using these vegetable tanning agents were characterized by thermal decomposition methods using slow and high heating rates. Calf gelatin obtained by heating calf pelt in water at 70 ˚C was chosen as a reference material. Thermogravimetry/mass spectrometry (TG/MS) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) experiments were performed on the tannin and leather samples. The evolution profiles of the decomposition products as well as the thermal stability of tannins and leathers were studied by TG/MS. A net difference was observed in the thermal behavior of hydrolyzable and condensed tannins. The condensed tannins produced the highest char yield, while the hydrolyzable tara extract released the most volatile products. The tannins of higher reactivity produced more stable leathers as it results from their higher decomposition temperature. The composition of both vegetable tanned leathers and vegetable tanning agents was characterized by the pyrolysis product distribution measured by Py GC/MS method. Resorcinol and its methylated derivative (orcinol) were found to be characteristic decomposition products for both condensed tannins, i.e. mimosa and quebracho. It was identified among the pyrolysis products of the mimosa and quebracho tanned leathers, as well. Characteristic decomposition product, a bisphenol derivative was identified among the pyrolyzates of hydrolyzable tannins and the leathers tanned with the hydrolyzable tannin agents

Thermal decomposition kinetics of wood and bark and their torrefied products

The pyrolysis kinetics of Norway spruce, its bark, and their torrefied products was studied. Thermogravimetry (TGA) was employed with linear and stepwise heating programs. Altogether 36 TGA experiments were evaluated simultaneously by the method of least-squares. Part of the kinetic parameters could be assumed common for the studied samples without a considerable worsening of the fit quality. This process results in better defined parameters and emphasizes the similarities between the studied materials. Three pseudocomponents were assumed. Two of them were described by distributed activation energy models (DAEM), while a simpler kinetics was assumed for the pyrolysis of the cellulose content of the samples. The pyrolysis kinetics of the wood and the torrefied wood showed remarkable similarities to the bark and torrefied bark, though essential differences were also observed

Thermal characterization of new, artificially aged and historical leather and parchment

The aging mechanism of leather and parchment was studied by thermoanalytical methods to understand the effect of the environment on the historical manuscripts and the heritage of libraries and archives. Alkaline and acidic treatments followed by thermal dehydration were applied to achieve chemical changes in the structure of new leather and parchment similar to the slow natural aging of historical samples. Chemical and structural changes during both natural and artificial aging processes were characterized by thermoanalytical techniques. The thermal stability and the evolution profile of the decomposition products under slow heating were studied by thermogravimetry/mass spectrometry (TG/MS). The distribution of the decomposition products of these collagen-based materials under fast pyrolysis was characterized by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). It was found that the maximal rate of the thermal decomposition (DTGmax) significantly decreases by aging in case of both leather and parchment samples indicating the degree of deterioration. Py-GC/MS has been found to be a suitable technique to sensitively monitor the degradation of the polyphenolic components of the vegetable tannins under natural or artificial aging. It was established that the tannin content of leather is more significantly affected by natural aging and alkaline treatment than the main structure of the polypeptide chains. Principal component analysis (PCA) has been used to find statistical correlations between the experimental data for leather samples. The results of the PCA confirmed that the alkaline treatment and the natural aging processes similarly modify the tannin content of the vegetable tanned leather

Comparative study on the thermal behavior of untreated and various torrefied bark, stem wood, and stump of Norway spruce

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