Phenol preparation from catalytic pyrolysis of palm kernel shell at low temperatures

In the present study, the characteristics of phenol preparation from palm kernel shell (PKS) pyrolysis at the temperature range of 265-320 degrees C were investigated using TG-FTIR-MS analyses, based on the analysis about the decomposition characteristics of PKS comparing to other biomass samples. The GC-MS analysis was subsequently employed to qualitatively and quantitatively characterize the phenol in bio-oils from PKS catalytic pyrolysis at 265-320 degrees C. Two significant weight loss peaks with the closer values were observed in DTG curve of PKS that differentiated with other samples, which was mainly attributed to the content and especially the structural characteristics of lignin in the PKS. Phenol was mainly in bio-oils from decomposition of the "first weight loss peak" during PKS pyrolysis at 265-320 degrees C. The relative content in bio-oil, selectivity in phenolic compounds, and mass yield of phenol from PKS catalytic pyrolysis with CaO could reach to 83.21 area%, 100%, and 0.0075 g/(g biomass), respectively

Gasification Reactivity and Pore Structure Development: Effect of Intermittent Addition of Steam on Increasing Reactivity of PKS Biochar with CO2

Intermittent addition of steam was employed to increase the gasification reactivity of palm kernel shell biochar with CO2. The reactivity and variations in pore structures were initially assessed during CO2 and H2O-assisted gasification of biochars in a tube furnace, followed by characterization using thermogravimetric and surface area analysis. A quadratic orthogonal rotation regression combination design was used to investigate the effects of intermittent H2O addition on the total reaction time (t(100%)) of CO2 gasification. The achieving results showed that the formation of micropores with sizes of 0.3 to 1.5 nm was favored by CO, gasification, while the reactivity of biochar was highly correlated with the surface area of micropores of 0.93 to 1.47 nm. A pore expansion effect was the primary phenomenon observed during H2O gasification, while the reactivity of biochar with H2O was closely related to the surface area of pores with specific sizes. CO2 and H2O react with the biochar on separate active sites, and micropores of 0.93-1.54 nm are produced in the early stage of H2O gasification, which enhances CO, gasification. The intermittent addition of H2O increases the reactivity of biochar with CO2, such that the t100% value during CO2/intermittent H2O gasification is 31.89 and 15.80% lower than the values associated with using only CO2 or a simple mixture of CO2 and H2O

<p>Evaluation on the enhanced solid biofuel from co-hydrothermal carbonization of pharmaceutical biowastes with lignite</p>

Pharmaceutical biowastes are typical wet low-grade industrial biowastes, exhibiting a dual characteristic of hazardous waste and renewable resource. Their efficient and clean energy utilization is important and indispensable from the viewpoint of environmental protection and resource savings. However, low energy density and high nitrogen content are two typical defective characteristics to be resolved. In this study, targeting at solid biofuel product, co-hydrothermal carbonization of two pharmaceutical biowastes (Chinese herb residue and antibiotic fermentation residue) with a low-rank coal (ShenMu lignite coal, SLC) were performed at a fixed prevailing temperature (240 ?) and different mixing mass ratios. The compositional features, the structural properties, and the thermo-chemical behaviors of co-hydrochar products were evaluated to determine their fuel properties. The results indicated that co-hydrothermal carbonization of pharmaceutical biowastes with 25-50% SLC could achieve favorable energy recoveries and nitrogen removal for the reaction system. Under the circumstances, notable synergistic enhancements on both upgradation and denitrogenation capabilities were revealed, producing compatible co-hydrochar with high energy density (HHV up to 24-25 MJ/kg) and stable nitrogen structures (nitrogen content as low as 1.4-2.0 wt%). Furthermore, compared to feedstock or monohydrochar, co-hydrochar product exhibited better pyrolysis behavior with less N-containing and incombustible gaseous components, and longer combustion process with more stable flame. Thus, co-hydrothermal carbonization with lignite coal would be a potential strategy to transform pharmaceutical biowastes into clean and high-grade solid biofuel

Effect of pressure and H-2 on the pyrolysis characteristics of lignite: Thermal behavior and coal char structural properties

The aim of the present work was to investigate the effect of pressure and H-2 on the pyrolysis characteristics of lignite. Thermogravimetric behavior during lignite pyrolysis was studied under different Ar or H-2 pressures using a pressurized thermogravimetric analyzer (P-TGA). Structural properties of coal chars obtained from P-TGA were investigated by the application of elemental analyzer, Fourier transform infrared spectroscopy, X-ray diffraction analyzer, and gas sorption surface area and pore size analyzer. CO2 gasification reactivity of coal chars was also evaluated by TGA tests. The results demonstrated that the weight loss for lignite pyrolysis increased in the presence of H-2 and it became more remarkable with rising pressure. Meanwhile, conversion of C and H during pressurized hydropyrolysis was promoted to a higher level considerably. Aromaticity as well as graphitization degree for coal chars were both intensified with addition of H-2, especially under elevated pressures. As to the mesopore structure, BET specific surface area of coal chars from hydropyrolysis increased obviously in comparison with that of coal chars obtained in Ar atmosphere, especially under pressurized conditions. Moreover, coal chars from hydropyrolysis exhibited higher CO2 gasification reactivity

Emissions of nitrogenous pollutants in chemical looping gasification of high nitrogen wood waste using a K-modified copper slag oxygen carrier

This study uses K-modified copper slag as an oxygen carrier (OC) candidate to examine the characteristics of Chemical Looping Gasification (CLG) of high nitrogen wood waste (HNWW) and investigated the emissions of nitrogenous pollutants (NH3/HCN). K modification significantly improves the reactivity of original copper slag because some new species were generated. The calcined copper slag loaded with 10 mass% K (10 K-CS) has relatively higher performance, thus, it was selected as an OC in the CLG of HNWW. The presence of 10 K-CS significantly promotes the conversion of HNWW, especially the char conversion. A suitable HNWW to 10 K-CS mass ratio was determined as 3:7. The OC not only promotes the release of nitrogen (N) in HNWW and oxidizes the reducing nitrogenous-pollutants, thus, the generated NH3 and HCN content decrease significantly. Compared with HNWW pyrolysis, the NH3 and HCN content decrease by 78.86% and 46.20%, respectively, at the mass ratio of HNWW to 10 K-CS of 1:10. High temperature promotes the non-gas-phase nitrogen in char/tar to be converted into the nitrogenous pollutants. A long residence time facilitates the oxidization of nitrogenous pollutants. The introduction of steam promotes the release of nitrogenous pollutants, especially NH3

The lignin pyrolysis composition and pyrolysis products of palm kernel shell, wheat straw, and pine sawdust

The lignin monomer composition of palm kernel shell (PKS) was characterized using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), and the characteristics and distributions of products obtained from PKS pyrolysis were investigated using Py-GC/MS, GC, and a specially designed pyrolysis apparatus. The gasification reactivity of PKS biochar was also characterized using thermogravimetry (TG) and Raman spectroscopy. All the results were compared with those obtained from wheat straw (WS) and pine sawdust (PS). The results showed that PKS lignin is primarily composed of p-hydroxyphenyl structural units, while WS and PS lignins are mainly made up of guaiacyl units. Both the mass and energy yields of non-condensable gases from PKS pyrolysis were lower than those obtained from WS and PS pyrolysis at 650-850 degrees C, owing to the lower volatile content (75.21%) and lack of methoxy groups in PKS. Compared with WS and PS, higher bio-oil productivity was observed during PKS pyrolysis. Phenols were the main component of PKS bio-oil from pyrolysis at 500 degrees C, and the phenol content of PKS bio-oil (13.49%) was higher than in WS bio-oil (1.62%) and PS bio-oil (0.55%). A higher yield of biochar (on an ash-free basis) was also obtained from PKS pyrolysis. Because of its greater relative degree of ordered carbon, PKS biochar exhibited lower in situ reactivity during CO2 or H2O gasification than WS and PS biochars. A longer residence time and addition of steam were found to be beneficial during PKS biochar gasification. (C) 2016 Elsevier Ltd. All rights reserved

Evolution of Char Structure During In-Situ Biomass Tar Reforming: Importance of the Coupling Effect Among the Physical-Chemical Structure of Char-Based Catalysts

In order to illustrate the importance of a coupling effect in the physical-chemical structure of char-based catalysts on in-situ biomass tar reforming, three typical char-based catalysts (graphite, Zhundong coal char, and sawdust biochar) were studied in the fixed-bed/fluidized-bed reactor. The physical-chemical properties of carbon-based catalysts associated with their catalytic abilities were characterized by inductively coupled plasma-atomic emission spectroscopy (ICP-AES), Raman, X-ray photoelectron spectroscopy (XPS), scanning electron microscope&ndash;energy dispersive spectrometer (SEM-EDS) and N2 adsorption. The relationship between the specific reactivity and tar reforming ability of carbon-based catalysts was discussed through a micro fluidized bed reaction analyzer (MFBRA&ndash;MR). The results indicate that the char-based catalyst has a certain removal ability for in-situ biomass tar of corn straw in an inert atmosphere, which is as follows: sawdust biochar &gt; Zhundong (ZD) coal char &gt; graphite. During the in-situ tar reforming, the alkali and alkaline earth metal species (AAEMs) act as adsorption/reaction sites, affecting the evolution of the aromatic ring structure and oxygen-containing functional groups of the char-based catalyst, and also its pore structure. AAEM species on the surface of char-based catalysts are the active sites for tar reforming, which promotes the increase of active intermediates (C-O bond and C-O-AAEMs), and enhances the interactions between char-based catalysts and biomass tar. The abundant AAEMs may lead to the conversion of O=C&ndash;O and C=O to C&ndash;O. For tar reforming, the internal pore structure of char-based catalysts is little changed, mainly with the carbon deposit forming on the surface pore structure. The carbon deposit from the reformation of straw tar on the char surface has better reactivity than the inherent carbon structure of ZD coal char and sawdust biochar. There is a positive relationship between the MFBRA&ndash;MR specific reactivity and tar catalytic reforming ability of char-based catalysts (decided by the coupling effect in their physical-chemical structure), which can be used to determine the catalytic ability of char-based catalysts on tar reforming directly