Amounts Of Aliphatic Compounds Research Articles

Insight into the desorption behavior and mechanism of tight oil with in-situ low-temperature thermal

A major challenge faced in using enhanced oil recovery techniques in tight sandstone reservoir is the unknown desorption mechanism of adsorbed oil in the reservoirs. In-situ low-temperature thermal desorption (LTTD) was used in this study to detect the desorption behavior and mechanism of tight oil found in tight sandstones. The study provides an insight into the micro-occurrence states, carbon number-based fractions, and functional group changes of adsorbed tight oil. The micro-occurrence states of adsorbed tight oil can be in the form of oil aggregate and oil film. The desorption capacity of tight oil present in tight sandstones at 120 °C, 160 °C, 200 °C, 240 °C and 280 °C were 0.028, 0.171, 0.886, 0.945 and 0.954 mg/g, respectively. The desorption behavior of tight oil reverses at approximately 200 °C. At temperatures below 200 °C, desorption of tight oil is dominated by the oil aggregate in the 20–200 nm reservoir space, while the desorption process itself is controlled by the original physical properties, skeleton minerals and original oil saturation level of the tight sandstone reservoir. However, at temperatures above 200 °C, clay minerals control the desorption of tight oil present in form of an oil film adsorbed on the 2–7 nm sized pores of the mineral surface. During the process of in-situ conversion of tight oil, the amount of aliphatic compounds in it decreases, the amount of aromatic compounds in it increases, and the branching chain degree increases. As the temperature increases, the oxygen-containing functional groups continue to increase in number.

Molecular-level insights into the transformation mechanism for refractory organics in landfill leachate when using a combined semi-aerobic aged refuse biofilter and chemical oxidation process

Landfill leachate contains high concentrations of complex organic matter (OM) that can severely impact the ecological environment. If landfill leachate is to be treated using a combined “biological + advanced treatment” process, the molecular information of OM must be investigated to optimize the operation parameters of the combined process and maximize the removal of organic pollutants. This study applied ultra-high resolution mass spectroscopy to investigate the degradation and transformation characteristics of refractory OM in mature landfill leachate at the molecular level (m/z = 150–800) during biological treatment (i.e., semi-aerobic aged refuse biofilter, SAARB) and subsequent chemical oxidation (i.e., the Fenton process and ozonation). After SAARB treatment, the polycyclic aromatics (aromatic index, AI > 0.66) and polyphenol (0.66 ≥ AI > 0.50) contents increased, and the highly unsaturated phenolic compounds (AI ≤ 0.50 and H/C < 1.5), which have a high bioavailability, were mostly removed. Compared with raw leachate, SAARB effluent (i.e., SAARB leachate) contained fewer organics with short carbon chains, more organics with long carbon chains, an elevated condensation degree for organics and, thus, a considerably reduced biodegradability. Although both the Fenton and ozonation processes could remove many of the polycyclic aromatics and polyphenols, ozone produced considerable amounts of aliphatic compounds with high bioavailability. Compared to ozonation, the Fenton process utilized the hydroxyl radical to non-selectively react with OM and produced better mineralization results.

Impact of CO2 on Pyrolysis Products of Bituminous Coal and Platanus Sawdust.

Abundant studies have been completed about factors on the pyrolysis of coal and biomass. However, few articles laid emphasis on using CO2 as a carrier gas to explore the compositional changes of pyrolysis products in coal and biomass pyrolysis for industrial application and commercial value. The experiments on coal and biomass pyrolysis in N2 and CO2 using a horizontal tube furnace were conducted at 500 °C. The impact of introducing CO2 on the pyrolysis process of bituminous coal and Platanus sawdust was investigated. The nuclear magnetic resonance (NMR) spectra of tar and the characterizations of char including Brunner-Emmet-Teller (BET) measurements, scanning electron microscope (SEM), Fourier transform infrared (FT-IR) spectroscopy, and element analysis were studied. The findings in light of the experimental results show that introducing CO2 enhances the coal and biomass pyrolysis in a solid product by promoting the fracture of hydroxyl groups. It also promotes tar decomposition and the release of volatiles, which contribute to the occurrence of char with high porosity, pore volume, and specific surface. Furthermore, higher specific surface enhances the adsorption performance of char as active carbon. Simultaneously, CO2 promotes the increase of oxygen-containing aromatics especially the methoxy-containing aromatics, and the decrease of deoxygenated aromatic hydrocarbons in pyrolysis oils. In addition, the introduction of CO2 changes the amount of aliphatic compounds in various ways for the pyrolysis of coal and biomass. From a perspective of business, the changes in the composition of pyrolysis oil brought by CO2 may create new value for fuel utilization and industrial products.

Investigation into the Catalytic Activity of Microporous and Mesoporous Catalysts in the Pyrolysis of Waste Polyethylene and Polypropylene Mixture

Catalytic pyrolysis behavior of synthesized microporous catalysts (conventional Zeolite Socony Mobil–5 (C-ZSM-5), highly uniform nanocrystalline ZSM-5 (HUN-ZSM-5) and β-zeolite), Mesoporous catalysts (highly hydrothermally stable Al-MCM-41 with accessible void defects (Al-MCM-41(hhs)), Kanemite-derived folded silica (KFS-16B) and well-ordered Al-SBA-15 (Al-SBA-15(wo)) were studied with waste polyethylene (PE) and polypropylene (PP) mixture which are the main constituents in municipal solid waste. All the catalysts were characterized by Brunauer-Emmett-Teller (BET), X-ray powder diffraction (XRD), and NH3-temperature programmed desorption (TPD). The results demonstrated that microporous catalysts exhibited high yields of gas products and high selectivity for aromatics and alkene, whereas the mesoporous catalysts showed high yields of liquid products with considerable amounts of aliphatic compounds. The differences between the microporous and mesoporous catalysts could be attributed to their characteristic acidic and textural properties. A significant amount of C2–C4 gases were produced from both types of catalysts. The composition of the liquid and gas products from catalytic pyrolysis is similar to petroleum-derived fuels. In other words, products of catalytic pyrolysis of plastic waste can be potential alternatives to the petroleum-derived fuels.

DRIFT spectroscopy combined with sodium hypochlorite oxidation reveals different organic matter characteristics in density-size fractions of organically managed soils

The objective of this study was to characterize the organic matter (OM) in density-size fractions of soil samples from a commercial organic farm using diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. The soil samples were separated by density fractionation with a sodium iodide (Nal) solution (1.6 g cm–3) into free particulate OM (fPOM), occluded particulate OM (oPOM), heavy particulate OM (hPOM), and mineral-associated OM (MAOM) fractions. The OM characterization by DRIFT spectroscopy was the difference in spectra obtained before and after sodium hypochlorite (NaClO) oxidation. However, the infrared absorption bands derived from the soil mineral matrix interfered with the detection of the absorption bands of polysaccharides. An increase in the amount of organic C under organic management was observed for all the density-size fractions, but the functional group composition of the NaClO-oxidizable OM differed among the fractions. The NaClO-oxidizable OM in the fPOM fraction was characterized by a high lignin content, whereas the oPOM fraction had high amounts of aliphatic compounds and lignin. The hPOM fraction contained less lignin and more proteinous materials, and the MAOM fraction was rich in proteinous materials. This study demonstrates that DRIFT spectroscopy combined with NaClO oxidation is a powerful tool for characterizing the relatively unstable OM in soils.

UTILIZATION OF PRODUCTS OBTAINED FROM COPYROLYSIS OF OIL SHALE AND PLASTIC

The main objective of the present study was to investigate pyrolysis of oil shale with polyethylene, in terms of yields and properties of the products obtained. A detailed characterization of gas, oil and char from copyrolysis is presented. Although no synergetic effect on the product yield was observed during the copyrolysis, the addition of polyethylene (PE) to oil shale improved fuel properties of shale oil leading to a decrease in the oxygen content of shale oil. As the ratio of polyethylene increased in the blends, the amount of aliphatic compounds in tars increased while that of polar compounds decreased. In addition, the presence of PE in the blend improved the composition of pyrolysis gas leading to an increase in combustible gases. The production of activated carbon from char obtained from oil shale/polyethylene (1/1) was also carried out. Although the surface area of activated carbon was smaller than that of obtained from lignocellulosic materials, it had a notable adsorption capacity for Cr(VI) (55.25 mg/g).

Potentiality of seaweed as a resource: analysis of the pyrolysis products of Fucus serratus

As a prelude to the investigation of the potentiality of seaweeds as a future source of organic chemicals or fuel, the products of pyrolysis under nitrogen of Fucus serratus(serrated wrack) have been analysed. The pyrolysis produces large amounts of charcoal, water and carbon dioxide with smaller amounts of an oil, pitch, hydrocarbon gases, carbon monoxide, ammonia and carboxylic acids. The oil proved to be a complex mixture of heterocyclic bases, phenols, aromatic hydrocarbons, nitrogen and oxygen heterocyclic compounds and small amounts of aliphatic compounds. A variety of analytical techniques have been employed to analyse the pyrolysis products, with gas chromatography and mass spectrometry being the most widely applicable.