Composition Of Volatile Products Research Articles

An Analysis of the Influence of Low Density Polyethylene, Novolac, and Coal Tar Pitch Additives on the Decrease in Content of Impurities Emitted from Densified Pea Husks during the Process of Their Pyrolysis

The course of pyrolysis of pea husks was studied. It was stated that the compaction of a sample during its pyrolysis causes an almost two-fold increase in the content of hydrocarbons in the composition of volatile products in the temperature range of 350–470 °C. Low density polyethylene (LDPE), novolac, and coal tar pitch (CTP) wastes were added to feedstocks in the amount of 2 wt% in order to decrease the contribution of saturated and unsaturated hydrocarbons along with oxygen-containing compounds in volatile products. The analysis of the obtained products of pyrolysis was conducted using the techniques of thermogravimetry/Fourier transform infrared spectroscopy (TG/FT-IR), attenuated total reflectance (ATR) and ultraviolet (UV)-spectroscopies, gas chromatography-mass spectrometry (GCMS), X-ray diffractions (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray analysis (EDX). It was determined that pitch took the first place in a series of effectiveness in decreasing the content of harmful compounds in pyrolysis products; novolac was the second. A temperature of 370 °C (CTP) lowers the contribution of compounds with carbonyl groups (by approx. 2.7 times) and the contribution of alcohols, phenols, and esters (by approx. 4.4 times). At a temperature of 465 °C, this additive reduces the contribution of saturated and unsaturated hydrocarbons in the composition of volatiles (by approx. 5.8 times) and at a temperature of 520 °C, a more substantial decrease is observed (by approx. 14.3 times). During the pyrolysis in the temperature range of 420–520 °C, LDPE actively emits its own products of decomposition in the form of aliphatic hydrocarbons that negatively affect the environment. The composition of condensed pyrolysis products changes under the influence of additives. In water condensates, the concentration of determined phenols and anhydrosugars increases slightly under the influence of additives. The SEM and XRD investigations proved that inorganics interact with volatile pyrolysis products from the blends of pea husks with additives and change their composition. After the transformation of chemical composition, inorganics catalyse secondary reactions that take place in the pyrolysis products of blends.

Organic Based Additives Impact on Thermal Behavior of Ammonium Perchlorate: Superior 4, 4′‐Bipyridine Versus Inferior Biphenyl

AbstractFor the first time, the thermal decomposition behavior of heterogeneous mixtures of ammonium perchlorate (AP) with two organic additives – 4, 4’‐Bipyridine, and biphenyl – were investigated. The heterogeneous mixtures of the additives and ammonium perchlorate were prepared by dissolving 1, 2, 3, 4, and 5 mg of the organic additives and 100 mg ammonium perchlorate in 2 ml of methanol as solvent. After that, the thermal decomposition behavior of prepared solid heterogeneous mixtures was monitored by thermogravimetry analysis, differential scanning calorimetry, and mass spectrometry analysis. The effect of the 4, 4’‐Bipyridine on thermal decomposition of AP enhanced the released heat from 479 to 1842 J g−1 and produced a decrease of decomposition temperature from 433 °C to 308 °C while the thermal decomposition of AP in the presence of biphenyl did not change as dramatically as it did with 4, 4’‐Bipyridine. With biphenyl, the decomposition temperature was found to be similar to that of pure AP and the evolved heat was about 718 J g−1. The gaseous products of decomposition of 4, 4’‐Bipyridine /ammonium perchlorate were monitored by mass spectrometric analysis. The main evolved decomposition gases of pure AP are N2O, O2, Cl2, ClO, ClO2, ClO3, HClO4, and HCl, while the major gaseous products of the 5:100 (w/w) mixture of 4, 4’‐Bipyridine with AP were detected as N2, NO, N2O, O2, Cl2, ClO, ClO2, ClO3, HClO4, HCl and 4, 4’‐Bipyridine. The change in the composition of volatile products indicates a change in the mechanism of AP decomposition from proton transfer to electron transfer in the presence of 4, 4’‐Bipyridine.

The Influence of Freezing on the Course of Carbonization and Pyrolysis of a Bituminous High-Volatile Coal

The course of thermal behavior of a fresh bituminous high-volatile coal during carbonization and pyrolysis was compared to that of this coal thawed after storage. The research was carried out using the following techniques: X-raying, thermogravimetry/Fourier transform-infrared spectroscopy (TG/FT-IR), extraction, Diffuse Reflectance Infrared Fourier Transform Spectroscopes (DRIFT), Attenuated Total Reflectance (ATR), and SEM. The increase in range of the viscous-liquid state and a decrease in temperature of its appearance were stated along with the formation of a more compact residue at the re-solidification stagtablee for the thawed coal during its carbonization. There is a fourfold reduction in the charge volume. The leakage of bitumen that contains 87 At % of C atoms from swollen grains and a fourfold increase in the yield of the material extracted from these grains are the proof of a greater plasticization of thawed coal. During the pyrolysis of thawed coal, the yield in volatile products of pyrolysis increases, and the composition of these products changes. The contribution ratio of saturated and unsaturated hydrocarbons, CO2, alcohols, and phenols decreases in the composition of volatile products of thawed coal. It is suggested that the use of freezing during the storage of a freshly mined coal that has a poorer caking ability can improve its plasticization during carbonization.

Insight into the catalytic thermal decomposition mechanism of ammonium perchlorate

Copper oxide (CuO) is an attractive burn rate modifier for composite solid propellant based on ammonium perchlorate (AP). However, the mechanism of catalytic decomposition of AP in the presence of CuO is still uncertain. Amount of gaseous products at various decomposition temperatures of AP in the presence and absence of CuO is lacking. Herein, a systematic study using thermogravimetry-mass spectroscopy (TG-MS) was carried out to evaluate the effect of CuO on AP decomposition mechanism. A novel hydrothermal method was reported for the preparation of nanosized copper oxide. The conversion of precursor Cu(NO3)2·3H2O to intermediate Cu2(NO3)(OH)3 was accomplished by in situ carbonization of small quantity of cotton fiber in the hydrothermal reaction chamber. pH of the reaction medium was controlled by utilizing the nitric acid in the reaction medium by in situ carbonization of cotton. This synthetic method aimed to minimize the shape-controlling agents and strong alkali for controlling the pH of the reaction medium for the preparation of catalyst grade CuO. Evolved gas analysis of AP decomposition products by TG-MS showed increased oxygen, chlorine and nitrogen evolution and decreased ammonia evolution in the presence of CuO, compared with that of AP without catalyst. This confirmed the enhanced interaction of ammonia and perchloric acid; the initial decomposition products of AP; and their further reaction in the presence of CuO. The change in composition of volatile products indicates change in mechanism of AP decomposition from proton transfer to electron transfer in the presence of CuO.

Torrefaction of Fast-Growing Colombian Wood Species

The aim of this paper is to report fuel properties and torrefaction behavior of woody biomass from the Colombian highlands. Four wood species (Eucalyptus grandis, Pinus Maximinoi, Pinus patula, and Gmelina arborea) were selected due to their potential for expansion as bioenergy crops. Torrefaction of these feedstocks for the production of pellets for both domestic and international markets is a promising way to take advantage of these resources. Herein we report the impact of torrefaction temperature (between 200 and 300 °C) on the proximate and ultimate composition, heating value, thermal stability, and volatile products of the resulting solids. Although, all samples studied have similar volatile contents (70 wt%), heating value (~ 18.7 MJ/kg), and ash content (< 1 wt%), their thermal behavior during torrefaction is different. Our results confirm that the fuel properties of the materials studied have been improved by torrefaction. Py/GC-MS studies of torrefied materials suggest that the torrefaction conditions studied do not affect the structure of cellulose and lignin fractions; thus, the yield and composition of volatile products was not dramatically affected by the torrefaction conditions. The resulting materials could be good feedstocks for centralized pyrolysis based bio-refineries.

Potential influence of compounds released in degradation of phytates on the course of alcoholic fermentation of high gravity mashes – simulation with analogs of these compounds

Abstract Aim of the study was to evaluate the effect of supplementation of high gravity media with mineral compounds and myo-inositol, at concentration which would be obtained as a result of degradation of phytates present in raw material during alcoholic fermentation. The process of alcoholic fermentation was conducted under laboratory conditions in a 72 h system at 37°C with the use of S. cerevisiae D-2 strain. Calcium chloride proved to be the most effective of all supplements tested. Final ethanol concentration increased by 1.2% v v−1 and the yield of process increased by ca. 7 dm−3 ethanol 100 kg−1 of starch in comparison with control. Selective supplementation with KH2PO4, ZnSO4 and MgSO4 also increased the ethanol concentration, but the effect was accompanied by a deterioration in composition of volatile products. The hydrolysis of phytate complexes with microbial phytases can be an alternative solution to supplementation of HG mashes presented in this work.

Volatile production from pyrolysis of cellulose, hemicellulose and lignin

To better understand pyrolysis mechanism and further develop selective pyrolysis technology, characteristics of volatile products in the pyrolysis of three main components (cellulose, hemicellulose and lignin) were investigated and compared by amplifying experiments in a tube furnace at 300–700 °C. Distribution of volatile products (including bio-oil and bio-gas), the influence of temperature and contributions of each single component were discussed in depth. It was found that, for each sample pyrolysis, pyrolysis temperature and their own chemical structures played an important role in the yields, composition of bio-oil and bio-gas. The optimal temperatures for production of bio-oil from cellulose, hemicellulose and lignin focused at 500 °C, 450 °C and 600 °C, respectively, and cellulose made greater contribution to bio-oil formation, and hemiellulose was the major contributor for bio-gas. Moreover, the more bio-gases from the three components generated at the higher temperature, but compositions of volatile products were different depending on their unique chemical structures. In the three components, cellulose produced the highest CO, hemicellulose owned the highest CO2, and lignin generated the highest CH4 characterized by the largest HHV. As for bio-oil, cellulose bio-oil displayed unique saccharides and higher furans, hemicellulose bio-oil contained higher acids and ketones, while phenols were the dominant composition of lignin bio-oil.

Non-isothermal liquefaction of liptobiolith coal in supercritical water flow and effect of zinc additives

The liquefaction of liptobiolith coal in water vapor and supercritical water (SCW) flow at uniform increase in temperature from 300 up to 470°C and in SCW flow at 400°C (30MPa) with addition of zinc shavings to coal has been investigated. Temperature dependences of the yield of liquid and volatile products and kinetic parameters of the process have been obtained. The yields of oil, resin, asphaltene and volatile products in relation to the coal organic matter (COM) are 23.2, 16.1, 5.1 and 14.1%, respectively. CO2, CO, H2S and C1–C4 alkanes prevail in the composition of volatile products. The generation of oil, resin and asphaltene are found to have occurred in terms of the simultaneous chemical reactions of cleavage of the COM aliphatic CC bonds, while the volatile products result from the consecutive transformations of the COM components in the bulk and SCW solution. Participation of H2O molecules in thermochemical transformations of COM leads to increase in the oxygen amount in the conversion products and residue by 13.2%. Hydrogen and heat evolution during zinc oxidation by SCW provides for the hydrogenation of COM in situ. Addition of zinc to coal results in increase in the volatile products yield up to 48.6% and decrease in the conversion residue yield up to 20.8%. Under these conditions the yield of resin does not change, while the yields of oil and asphaltene decrease up to 21.2 and 2.5%, respectively. Based on the sulfur balance it is revealed that ≈40% of sulfur atoms pass into ZnS owing to the reactions of H2S with Zn and ZnO resulting in the removal of H2S from the volatile conversion products.

Extraction of boron and silicon in hydrodifluoride processing of a datolite concentrate

The composition of volatile products upon heating of a datolite concentrate that was fluorinated with ammonium hydrodifluoride were studied; the temperature parameters of the transition of the boron and silicon compounds to the gaseous phase were determined and it was established that the difference of the volatilities of the boron and silicon fluoroammoium salts allows selective extraction of these products. A closed technical scheme for processing datolite concentrate by ammonium hydrodifluoride to produce commercial products, viz., ammonium fluoborate, boric acid, amorphous silica, and fluorite, was proposed.

Influence of Conditions of Zinc Selenide Oxidation with Atmospheric Oxygen on the Composition of Volatile Products

The qualitative and quantitative composition of volatile products of zinc selenide oxidation with atmospheric oxygen was determined. The influence of the process conditions on quantitative composition of the volatile products was studied.

Pyrolysis of Polymers

The nature of their pyrolysis products, monomer, oligomers and carbonaceous residues enables one to group polymers into three classes, those that decompose by net main chain scission; by stripping of the main chain, for example the thermal dehydrochlorination of polyvinyl chloride; and by crosslinking of the main chain followed by some production of volatiles. Highly unsaturated or aromatic chains tend to follow the latter course. At the present time a theoretical framework exists which permits, provided adequate experiments are performed, the elucidation of the decompositions of the first type. For most of the well-known polymers in this class, this framework of knowledge gives very acceptable mechanistic explanations or interpretations of the decomposition process based on observations of rate of weight loss, of molecular weight changes and composition of volatile products. Knowledge of the decomposition of the second class of polymers is at an intermediate state development. However, an important practical research objective would be the acquisition of methods for converting the mechanisms of decomposition of class one substances to that for class two type. For the third class of materials, knowledge of their pyrolysis mechanisms is nonexistent. This is largely due to the fact that methods for quantitatively following solid-phase processes of decomposition are relatively difficult and unsatisfactory.