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Torrefaction of biomass is one of the most promising pretreatment methods for deriving biofuels from biomass via thermochemical conversion processes. In this work, the changes in physicochemical properties and morphology features of the torrefied corn stalk, the changes in physicochemical properties and morphology features of the torrefied corn stalk were investigated. The results of this study showed that the elemental content and proximate analysis of the torrefied corn stalk significantly changed compared with those of the raw corn stalk. In particular, at 300 °C, the volatile content decreased to 41.79%, while the fixed carbon content and higher heating value increased to 42.22% and 21.31 MJ/kg, respectively. The H/C and O/C molar ratios of torrefied corn stalk at the 300 °C were drastically reduced to 0.99 and 0.27, respectively, which are similar to those of conventional coals in China. Numerous cracks and pores were observed in the sample surface of torrefied corn stalk at the torrefaction temperature range of 275 °C–300 °C, which could facilitate the potential application of the sample in the adsorption process and promote the release of gas products in pyrolysis. In the pyrolysis phase, the liquid products of the torrefied corn stalk decreased, but the H2/CO ratio and the lower heating value of the torrefied corn stalk increased compared with those of the raw corn stalk. This work paves a new strategy for the investigation of the effect of torrefaction on the physiochemical characteristics and pyrolysis of the corn stalk, highlighting the application potential in the conversion of biomass. [ABSTRACT FROM AUTHOR]

The pyrolysis of corn stalk (CS) was carried out to investigate the effect of wet torrefaction (WT) pre-treatment and Zn/Ni-HZSM-5 on the production of bio-oil characteristics. The synergy between WT and the loaded metal catalyst was also analyzed. The oxygen content of the CS was reduced from 50.5% to 40.8% with WT, and hemicellulose was almost removed. WT pretreatment also significantly reduced the oxygenated compounds of bio-oil and increased the selectivity of phenols, aromatics, and anhydro-sugars. The addition of catalyst improved the deoxygenation, oligomerization, and aromatization during pyrolysis. The loading of Zn and Ni could optimize the pyrolysis reaction path and increased the relative content of monocyclic aromatics (MAHs) from 3.58% to 9.67% and 6.44% during the pyrolysis of CS-WT, respectively, and bimetallic catalyst further enhanced the relative content of MAHs to 11.1%. The relative content of aromatics below C9 was higher than other groups (14.8%). Thus, the WT pretreatment of raw materials and synergistic effect of catalysts can jointly optimize the biomass pyrolysis reaction. [ABSTRACT FROM AUTHOR]

Environmental-friendly biochar (BC) with low cost was obtained by simple pyrolysis of corn stalk core, which was employed as an adsorbent for efficiently removing organic pollutants in water. The physicochemical properties of BCs were characterized by various techniques, including X–ray diffractometer (XRD), Fourier transforms infrared (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X–ray photoelectron spectrometer (XPS), Raman, Thermogravimetric (TGA), N2 adsorption–desorption and zeta potential tests. The influence of pyrolysis temperature on the structure and adsorption efficiency of the adsorbent was emphasized. The graphitization degree and sp2 carbon content of BCs were enhanced by increasing the pyrolysis temperature, which was favorable for the enhancement of the adsorption efficiency. The adsorption results showed that corn stalk core calcined at 900 °C (BC-900) displayed exceptional adsorption efficiency toward bisphenol A (BPA) in wide pH (1–13) and temperature (0–90 °C) ranges. Moreover, adsorbent BC-900 could adsorb various pollutants from water, including antibiotics, organic dyes, and phenol (50 mg·L–1). The adsorption process of BPA over BC-900 matched well with the Langmuir isotherm and pseudo-second-order kinetic model. Mechanism investigation suggested that large specific surface area and pore filling acted the foremost role in the adsorption process. Adsorbent BC-900 has the potential application in wastewater treatment due to its simple preparation, low cost, and excellent adsorption efficiency. [ABSTRACT FROM AUTHOR]

Carbon sequestration is the primary function of biochar. Hence, it is necessary to design biochar with high carbon (C) retention and low C loss. In this study, three P compounds, including KH2PO4, Ca(H2PO4)2, and NH4H2PO4, were premixed with corn stalk (1:4, w/w), aiming to produce biochars (CSB+K, CSB+Ca, and CSB+N) with high C sequestration and slow release of P at three temperatures (300, 500, and 700 °C). The addition of all P sources obviously increased C retention, with the order of NH4H2PO4 (65.6–83.5%) > Ca(H2PO4)2 (60.4–78.2%) > KH2PO4 (50.1–76.1%), compared with the pristine biochar (47.8–73.6%). The addition of Ca(H2PO4)2 and KH2PO4 led to an increase in aromaticity and graphitization, as evidenced by H/C, FTIR, Raman and XPS analysis, whereas an opposite result occurred on CSB+N. Furthermore, all three phosphates reduced C loss of biochars with H2O2 oxidation, and CSB+Ca showed the best effect. Ca(H2PO4)2 and KH2PO4 pretreated biochars had higher resistance to K2Cr2O7 oxidation and thermal treatment. In contrast, the C loss of NH4H2PO4-added biochar at 500 and 700 °C with K2Cr2O7 oxidation was increased by 54% and 36%, respectively. During the pyrolysis process, Ca(H2PO4)2 was transformed into insoluble Ca2P2O7, leading to the lowest P release rate of CSB+Ca. This study indicates that co-pyrolysis of corn stalk and Ca(H2PO4)2 is optimal for increasing C retention, enhancing C stability and improving slow-release performance of P regardless of pyrolysis temperature. [ABSTRACT FROM AUTHOR]

This paper investigates separate pyrolysis of corn stalk(CS)and polypropylene(PP)and co-pyrolysis of CS and PP over Zn-Al co-modified MCM-41 to produce aromatics, and the product distribution of catalytic co-pyrolysis of CS and PP was studied based on a rotating bed reactor. The results showed that the product contents and composition were significantly influenced in the presence of catalysts. Zn and Al showed a certain synergistic effect, under the catalysis of MCM-41 co-modified by Zn with mass fraction of 1% and Al with mass fraction of 3%, and the maximum proportions of aromatics(24.31%)and the minimum production of oxygenated compounds(12.37%)were obtained. In the experiment of catalytic co-pyrolysis of CS and PP in rotating bed, with the increase of pyrolysis temperature(500—800 ℃), the yield of bio-oil decreased gradually. The decrease of olefins and oxygenates in bio-oil significantly increased the content of aromatic hydrocarbons. With the increase of catalyst dosage(1:0—1:10), the yield of bio-oil reduced gradually. The contents of aromatic hydrocarbons in bio-oil increased obviously, while the contents of olefins and oxygenates decreased. With the increase of rotating speed(0—20 r/min), the yield of bio-oil first decreased and then increased. The extreme values of aromatics, olefins, and oxygenates in bio-oil were all obtained at 15 r/min. [ABSTRACT FROM AUTHOR]

The production of methane-enriched gas via thermo-chemical process is an important approach for biomass valorization. However, current pyrolysis processes generally give low yield of value-added gas product. Herein, a series of Ni-based materials with hydroxyapatite (HAP) and titanium silicate (TS) as supports were prepared and investigated as catalysts to boost CH 4 production from pyrolysis-steam reforming of corn stalk. The surface element composition, chemical state and crystal structure of materials were characterized by transmission electron microscope (TEM), N 2 adsorption-desorption, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis. The expected loading of Ni, La and Ce were successfully loaded onto HAP via simple impregnation method, while the loading of active metals on TS is finite. Ni-5La 2 O 3 /HAP exhibited the best catalytic activity for pyrolysis-steam reforming of corn stalk, attaining CH 4 yield (19.41 mmol/g) that is 89.9 % and 46.2 % higher than control experiment and Ni-5CeO 2 /MCM-41, indicating that loading high-density Ni and La species onto HAP supports can greatly boost the CH 4 formation. However, the catalysts lost activity obviously during recycling experiment probably due to carbon accumulation. [Display omitted] • High loading of Ni, La and Ce were successfully loaded onto HAP to construct composite catalyst. • Both supports and promoter affect the performance of pyrolysis-steam reforming of corn stalk. • Ni-5La 2 O 3 /HAP gave CH 4 yield (19.41 mmol/g) 89.9 % and 46.2 % higher than control experiment and Ni-5CeO 2 /MCM-41. [ABSTRACT FROM AUTHOR]

To increase the added value of corn stalk and improve the performance of corn stalk biochar, magnesium chloride (MgCl2) was used to modify biochar, and the effects of temperature on the structure and properties of modified biochar were considered. With the increase of temperature, the yield of biochar decreased. There was a marked increase in the number of mesopores and micropores, but the mesopore pore diameter changed to a smaller pore diameter, and the specific surface area remarkably increased. As the temperature increased, the content of C increased, while the range of H and O decreased. In addition, the number of oxygencontaining functional groups and methyl groups decreased, indicating that the structure of biochar became more aromatized. An obvious Mg(OH)2 crystal peak appeared in the X-ray diffraction pattern, which meant that Mg ions were loaded on the surface of biochar. Moreover, the highest removal rate of methylene blue dye by biochar was 83.6%. The authors conclude that temperature and magnesium chloride modification can improve and enhance the performance of corn stalk biochar. These findings will help deepen people's understanding of biochar modification and serve as a reference for future related research. [ABSTRACT FROM AUTHOR]

Pyrolysis (Pyr) and hydrothermal carbonization (HTC) of corn stalk (CS) catalyzed with sewage sludge salts were investigated as a comparison of two biomass refining processes to produce char. The influence of the following salt-catalysts (SC)- NH4H2PO4, KH2PO4, Na2HPO4, and CaCl2- on the higher heating value (HHV), char yield (CY), energy yield (EY), and energy densification (ED) as well as an elemental analysis (C, H, N, S, O) of the produced chars were determined. Besides, ATR–FTIR spectra were made from the resulting biochar (BC) and hydrochar (HC). For each processing method, two temperatures were set: HTC 180/210 °C and Pyr 400/500 °C. CS had an HHV of 19 MJ/kg, and the catalyst-free HC and BC came out with 22 MJ/kg. The NH4H2PO4-catalyst demonstrated the maximal efficiency in advancing the HHV for the HTC with 27 MJ/kg (23 MJ/kg for the Pyr), as the Mixed catalysts for the Pyr with 24 MJ/kg, the Pyr-BC increased 2–5 MJ/kg, and the HTC-HC 5–7 MJ/kg. The HC ended up with higher results compared with the BC: HHV 2–3 MJ/kg, CY and EY 5–10%, and ED 0.1–0.2. On the opposite BC marked a higher level of coalification than the HC, the BC came close to that of coal while the HC ranged in the area of peat. Both processing methods were improved by most SC and the Mixed catalysts. Especially the chars of the Mixed SC reached the same carbonization level at lower processing temperature. [ABSTRACT FROM AUTHOR]

Pyrolytic biochar and hydrothermal biochar of corn stalk were prepared at different temperatures, and their abilities to remove iodate were compared. The characterization results show that the preparation temperature determines the degree of carbonization and the specific surface area of biochar. Pyrolytic biochar has a larger specific surface area than hydrothermal biochar, but retains fewer oxygen-containing functional groups. The adsorption capacity of hydrothermal biochar (16.87 mg g−1) is better than that of pyrolytic biochar (10.31 mg g−1). Corn stalk hydrothermal biochar is fully recyclable for multiple adsorption/desorption trials, which makes it extremely attractive for iodate contaminant separation. [ABSTRACT FROM AUTHOR]

In a multi-station fast pyrolysis reactor, the influence of oil shale ash on the potassium retention characteristics of corn stalk under different pyrolysis conditions was investigated in the study. The influence of oil shale ash on the potassium migration process during the pyrolysis of corn stalk was elucidated by analyzing changes in the composition and concentration of potassium and other minerals in the pyrolysis semi-coke of corn stalk. This analysis was conducted using inductively coupled plasma emission spectroscopy (ICP-AES), X-ray diffraction (XRD), and complemented by thermodynamic simulation. The findings demonstrate that oil shale ash could fix potassium in corn stalk, and the potassium retention rate peaked when the oil shale ash additive amount reached to 10 %. This is because the silica-aluminum compounds in the oil shale ash reacts with potassium salts in a semi-molten state to produce KAl 2 Si 3 AlO 10 (OH) 2 , KAlSi 3 O 8 , and KAlSi 2 O 6.When the amount of oil shale ash added is increased to 15 %, KAlSi 3 O 8 and KAlSi 2 O 6 in the semi-coke would continue to react with Al 2 O 3 and SiO 2 , converting to KAl 2 Si 3 AlO 10 (OH) 2. Thermodynamic simulation results indicate that the alkali metal potassium in corn stalk semi-coke mainly existed in potassium metasilicate, potassium feldspar, and leucogranite. In order to enhance potassium fixation in corn stalk, the addition of oil shale ash would promote the transformation of potassium-solidifying minerals from potassium metasilicate to potassium feldspar and leucite in the semi-coke. • Oil shale ash show a remarkable capacity to fixing potassium during biomass pyrolysis. • Potassium retention ratio is the highest when 10 % oil shale ash is added. • The main solid potassium mineral, KAlSi 3 O 8 , is converted to KAl 2 Si 3 AlO 10 (OH) 2. [ABSTRACT FROM AUTHOR]

Pyrolysis technology is one of the main ways to treat the biomass wastes. A typical agricultural and forestry waste, corn straw contains alkali metals and other catalytic components, showing the excellent pyrolysis behavior with high volatile matter while low ash content. Another typical municipal solid waste, the sludge contains a large amount of thermally degradable organic matter, pathogenic microorganisms, toxic and harmful organic matter. There is relatively high moisture and ash content in the sludge, compared with the corn straw. The co-pyrolysis of the sludge and the corn straw can be an effective way to improve the energy efficiency, thereby to enhance the performance of the products. As such, it can fully realize the complementary advantages of two wastes. In this study, a ThermoGravimetric Analysis (TGA) test was performed on the mixed samples with the corn stalk and municipal sludge in the mass ratio of 9:1, 3:7, 5:5, 7:3, and 1:9 at different heating rates (10, 20, and 30 ℃/min), in order to explore the pyrolysis characteristics and the Degree of Synergy (DS) in the single and mixed samples. A Coats Redfern method was used to clarify the kinetic of weight loss curves. The results indicated that there were great differences in pyrolysis characteristics between corn stalks and municipal sludge, where the residual rate differed by 18.57 percentage points, the comprehensive pyrolysis index differed by 35.73×10-5, and the activation energy differed by 35.31 -46.88 kJ/mol. Specifically, the activation energy of sludge pyrolysis was lower than that of corn straw. Furthermore, the activation energy increased with the increase of heating rate, with the maximum of 30 ℃/min. The initial temperature of pyrolysis decreased from 360.3 ℃ to 440.3 ℃, with the content of municipal sludge varied from 10% to 90%, while the main pyrolysis interval of mixed samples became longer from 277.7-360.3 ℃, shifting to the high temperature zone. The residual rate increased from 33.69% to 45.83%, whereas, the maximum weight loss rate decreased from 7.88 to 3.11%/min. There was a similar behavior in the comprehensive pyrolysis index, indicating a decrease from 8.5×10-5 to 1.7×10-5. The starting temperature of pyrolysis in the mixed samples was significantly improved by the municipal sludge, but some negative effects also occurred, including the longer interval time of pyrolysis, the higher residual rate, the slower weight loss rate, and the lower comprehensive pyrolysis index. The comprehensive pyrolysis index of mixed samples was lower than that of theoretical value, indicating an inhibitory effect in the co-pyrolysis of mixed samples. The activation energy required for the individual pyrolysis of corn stalks was greater than that of municipal sludge. The increase of activation energy varied at low and high temperature in the mixed samples of corn stalks and municipal sludge, as the heating rate increased. The activation energy of pyrolysis in the mixed samples decreased from 66.01-46.16 kJ/mol to 44.47-17.04 kJ/mol, as the content of municipal sludge increased from 10% to 90%. The findings can provide insightful data support to the co-pyrolysis of corn straw and municipal sludge, and the further application of products in low-carbon agriculture. [ABSTRACT FROM AUTHOR]

Catalytic coal gasification technology shows prominent advantages in enhancing coal gasification reactivity and is restrained by the cost of catalyst. Two typical biomass ash additions, corn stalk ash (CSA, high K–Na and low Si) and poplar sawdust ash (PSA, high K–Ca and high Si), were employed to study the influence of biomass ash on pyrolysis process and char gasification reactivity of the typical anthracite. Microstructure characteristics of the char samples were examined by X-ray diffraction (XRD). Based on isothermal char-CO2 gasification experiments, the influence of biomass ash on reactivity of anthracite char was determined using thermogravimetric analyzer. Furthermore, structural parameters were correlated with different reactivity parameters to illustrate the crucial factor on the gasification reactivity varied with char reaction stages. The results indicate that both CSA and PSA additives hinder the growth of adjacent basic structural units in a vertical direction of the carbon structure, and then slow down the graphitization process of the anthracite during pyrolysis. The inhibition effect is more prominent with the increasing of biomass ash. In addition, the gasification reactivity of anthracite char is significantly promoted, which could be mainly attributed to the abundant active AAEM (especially K and Na) contents of biomass ash and a lower graphitization degree of mixed chars. Higher K and Na contents illustrate that the CSA has more remarkable promotion effect on char gasification reactivity than PSA, in accordance with the inhibition effect on the order degree of anthracite char. The stacking layer number could reasonably act as a rough indicator for evaluating the gasification reactivity of the char samples. [ABSTRACT FROM AUTHOR]

• Hybrid thermochemical conversion of agricultural wastes is an effective strategy. • Furfural, levoglucosan, nutrient solution and boiler fuels are the main products. • The maximum furfural yield of 4.2% was achieved from peanut shell hydrolysis. • Peanut shell hydrochar pyrolysis could get the highest levoglucosan yield of 7.3% • Total revenue from hybrid thermochemical process could reach up to $0.362. The liquid product from biomass direct pyrolysis is usually complex and difficult to effectively utilize. By combining hydrothermal conversion and low-temperature pyrolysis, the hemicellulose and cellulose of biomass can be transformed into value-added furfural and levoglucosan (LG), respectively. The effects of temperature during hydrothermal treatment (160–240 °C) and subsequent pyrolysis (340–400 °C) on the production of furfural and LG were investigated by using three typical agricultural wastes, namely corn stalk, peanut shells, and rice stalk. The maximum furfural yield of 4.2% was achieved upon hydrolysis of peanut shells at 200 °C. The hydrochar produced from peanut shells presented the highest LG yield of 7.3% (based on original biomass weight) for a pyrolysis temperature of 360 °C. Under this optimal condition, the total revenue from various products of the hybrid thermochemical process was estimated at $0.362 per kilogram of peanut shells, whereas furfural and LG account for 90% of the revenue. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pyrolysis temperature regulated the toxicities of biochar (BC) and Cu2+ doped BC. • BC pyrolyzed at 550 °C showed the strongest inhibition to M. aeruginosa. • Cu2+-doping of BC substantially enhanced the Chl-a inactivation efficiencies. • PFRs and Cu2+ was identified as the major contribution to algae inactivation. In this study, biochars (BCs) derived from corn stalk treated at various pyrolysis temperatures (350–950 °C) were prepared and then loaded with Cu2+ to form highly efficient algaecide, i.e. Cu2+-doped BC composites (Cu-BCs). The results showed BCs pyrolyzed at higher temperatures suppressed the growth of Microcystis aeruginosa in the order of BC550 ≫ BC750 > BC950, while BC350 accelerated cell growth due to the release of inorganic nutrients. The difference could be attributed to the physicochemical characteristics, including specific surface area, adsorption capacity of nutrients and the presence of particularly persistent free radicals. Furthermore, Cu-BCs exhibited the improved inactivation performance, but the 72 h growth inhibition rates and reaction activities of Cu-BCs were still influenced by the Cu2+ loading ratio and pyrolysis temperature. These results, reported for the first time, demonstrated the algae inactivation efficiency of pristine BCs, and Cu-BCs were principally manipulated by the biochar pyrolysis temperature. [ABSTRACT FROM AUTHOR]

Biomass pyrolysis technology is a thermochemical conversion technique. Through the pyrolysis technology, straw recycling can be realized, and high value-added energy products such as biochar and pyrolysis gas can be obtained. However, the tar produced in the pyrolysis process contains heavy poisonous components, and the low temperature viscosity is high, which easily causes pipeline blockage. In order to study the effect of biochar as catalyst for reducing tar and improving pyrolysis gas quality, taking corn stalk as raw material, the tar conversion rate, pyrolysis gas yield and pyrolysis gas heat value were selected as index. The effects of reforming temperature (550, 600, 650, 700, 750, 800 °C), residence time (0.2, 0.6, 1.0, 1.4, 1.8 s) and biochar characteristics (corn straw charcoal, rice husk, wood charcoal) on pyrolysis gas quality were studied. The changes of specific surface area of biochar catalysts before and after reforming were analyzed. The results showed that at high temperature cracking, the pyrolysis gas yield was 33.8%, and the pyrolysis gas heat value was 18.0 MJ/m3, biochar had better catalytic properties than quartz sand (high temperature cracking), and its catalytic properties were: rice husk charcoal > wood charcoal > corn straw charcoal, indicating that the catalytic properties of rice hull carbon were better. The pyrolysis gas yields of rice husk charcoal, wood charcoal and corn straw charcoal were 39.7%, 38.6%, and 37.9%, respectively, and the tar conversion rates were 79.8%, 78.6% and 72.6%, the calorific values were 17.7, 17.8 and 17.6 MJ/m3, respectively. When the reforming temperature was increased from 550 to 800 °C, the pyrolysis gas yield increased from 21.0% to 37.9%, the tar conversion rate increased from 23.8% to 72.6%, and the pyrolysis gas calorific value increased from 13.0 to 17.6 MJ/m3, which was due to the increase of temperature to promote the cracking reaction of tar. The tar heavy components were partially converted into light components and non-condensable gases. As the residence time increased from 0.2 to 1.8 s, the pyrolysis gas yield increased from 37.9% to 54.3%, and the tar conversion rate increased from 76.2% to 79.8%. The pyrolysis gas heat value was reduced from 17.6 to 16.8 MJ/m3. It was due to the increase in residence time, which promoted the catalytic conversion of the tar component on the active site of the mineral component on the surface of the biochar, resulting in an increase in the yield of the pyrolysis gas. At 800 , the specific surface area of biochar after °C catalytic cracking was 79.81 m2/g, which was higher than the specific surface area of pyrolysis biochar of 37.96 m2/g. In summary, as the reforming temperature and residence time increased, the pyrolysis gas yield and tar conversion rate increased, and the pyrolysis gas heat value increased only as the reforming temperature increased. Although biochar can increase pyrolysis gas yield and tar conversion rate, the calorific value was low. Biochar can not only improve the quality of pyrolysis gas, but also increase the specific surface area of biochar at 800 °C, indicating that the interaction between biochar and pyrolysis gas can not only improve the quality of pyrolysis gas, but also increase the specific surface area of biochar. [ABSTRACT FROM AUTHOR]

The bifunctional Ga/HZSM-5 catalyst has been proven having the capability to increase the selectivity of aromatics production during catalytic pyrolysis of furan and woody biomass. However, the reaction chemistry and kinetics of pyrolysis of herbaceous biomass promoted by Ga/HZSM-5 is rarely reported. Pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS) analysis and non-isothermal thermogravimetric analysis at four heating rates were carried out to investigate the decomposition behavior and pyrolysis kinetics of corn stalk without and with Ga/HZSM-5. The effective activation energies for corn stalk pyrolysis were calculated by using the Friedman isoconversional method. The Py–GC/MS analysis results indicated that the Ga/HZSM-5 catalyst had a high selectivity toward producing the aromatic chemicals of xylene, toluene and benzene, whereas the major products from non-catalytic pyrolysis of corn stalk were oxygenated compounds. The presence of Ga/HZSM-5 could significantly reduce the effective activation energies of corn stalk pyrolysis from 159.9–352.4 kJ mol−1 to 41.6–99.8 kJ mol−1 in the conversion range of 0.10–0.85. [ABSTRACT FROM AUTHOR]

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Highlights • With increasing the volatiles residence time, bio-oil quality is improved at 600 °C and deteriorated at 440 °C. • Volatiles reaction yields THF-insoluble compounds, more on the reactor downstream wall (coke -wall) and less in bio-oil. • The amount of coke -wall increases with increasing volatiles temperature and residence time. • The average size of coke -wall may be mainly 1–2 rings at 440–600 °C. Abstract Reaction of nascent volatiles is unavoidable during biomass pyrolysis and significantly influences the product yield, bio-oil quality and coking on the reactor wall. However, experimental studies in this aspect are still very limited. This work aims to advance the knowledge in this aspect using a two-stage reactor. Volatiles were generated in-situ from pyrolysis of corn stalk at 540 °C and swept off to the second-stage reactor preheated at 440–650 °C with a residence time of 1.5–4.7 s. The bio-oil quality was evaluated using simulated distillation gas chromatography. Results show that with increasing the volatiles temperature, the bio-oil yield decreases but the quality is improved: the contents of phenols, aldehydes and monocyclic aromatics increase significantly, those of esters and alcohols increase slightly and the contents of ketones, acids and furans decreases. Effect of volatiles residence time on the bio-oil quality depends on the volatiles temperature: becoming worse at 440 °C and better at 600 °C with increasing the residence time. The volatiles reaction also generates a few tetrahydrofuran-insoluble compounds, depositing on the downstream wall of the second-stage reactor (termed coke -wall) or suspending in bio-oil (termed soot -oil). The coke -wall yield increases with increasing volatiles temperature and residence time and is generally higher than the soot -oil yield. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Corn stalk was washed with three solutions and then torrefied at three temperatures. • All combined pretreatments would remove AAEMs and improve fuel properties. • Pyrolysis oil yields from WCS290, LCS290 and CCS290 increased by 134%, 128% and 130%. • Sugar relative contents (rich in levoglucosan) increased to 36.63%, 45.89% and 52.34%. • CO, H 2 and CH 4 increased while CO 2 decreased in pyrolysis after combined pretreatment. Abstract Untreated corn stalk (CS), deionized water washed CS (WCS), aqueous phase bio-oil washed CS (LCS), and 5% acetic acid washed CS (CCS) were torrefied at 230, 260, and 290 °C. The influences of washing, torrefaction, and combined washing-torrefaction pretreatments on corn stalk pyrolysis were investigated. The combined pretreatments, especially aqueous phase bio-oil washing-torrefaction improved fuel properties of pretreated samples largely by increasing their volatile and hydrogen contents. Absorption peaks of O–H and C O groups in combined pretreatment samples increased when torrefaction temperature increased. In addition, CO, H 2, and CH 4 contents of pyrolysis gas increased, while CO 2 decreased after combined pretreatments. The bio-oil yields from WCS290, LCS290, and CCS290 increased by 134.04%, 127.66%, and 129.79% respectively, compared with that from CS290. Similarly, their relative sugar contents (rich in levoglucosan) increased to 36.63%, 45.89%, and 52.34%, respectively. Aqueous phase oil washing-torrefaction is a promising pretreatment and acetic acid plays the most important role. [ABSTRACT FROM AUTHOR]

Highlights • Analytical pyrolysis was applied on mechanism investigation of biomass liquefaction. • Liquefaction temperature influenced the product distribution in pyrolysis process. • Liquefaction improved the thermal stabilities of solid residues. Abstract Few investigations have been made to apply thermal analysis methods on solid residue analysis to understand biomass liquefaction mechanistic information. To investigate the mechanism of cornstalk liquefaction in water/ethanol mixtures, the solid residues remaining after the liquefaction process were characterized by thermogravimetric analysis (TGA) and analytical pyrolysis (Py-GC/MS). Pyrolysis temperature and liquefaction temperature have synergetic effects on the distributions and yields of various chemical groups during the pyrolysis process. The thermal stabilities of the solid residues remaining after the cornstalk liquefaction process increased with the increase of liquefaction temperature. Compared with raw cornstalk pyrolysis, the proportions of total phenol compounds from solid residue pyrolysis at 400 °C, 500 °C and 600 °C were reduced. The volatilized compounds identified by Py-GC/MS analysis of solid residues and cornstalks displayed significant variability in the peak area and composition distribution. These changes reflect different mechanistic information during the biomass liquefaction process. These results indicate that analytical pyrolysis of the solid residues remaining after biomass liquefaction in water/ethanol mixtures could provide new information about the mechanism of the liquefaction process. [ABSTRACT FROM AUTHOR]

Abstract The work reports a comparative study on the pyrolysis of five agricultural crop residues (peanut straw, cotton straw, sorghum stalk, corn stalk and reed) using a gas-sweeping fixed bed reactor. The study aims at clarifying the role played by the neutral extractives and inherent active minerals in the pyrolysis characteristics, product distributions and bio-oil compositions. Among five crop residues, reed showed the highest bio-oil yield but with the highest oxygen content and the lowest HHV (higher heat value), in relation to the least alkali and alkaline earth metals (AAEMs) in it. Peanut straw had a content of neutral extractives as high as 47.4%, which contributed to the formations of a significantly higher proportion of long chain aliphatic hydrocarbons and liquid nitrogenous compounds, distinct from four other crop residues. Peanut straw was also highly enriched with AAEMs, which was responsible for a strong catalytic activity for the selective deoxygenation of bio-oil. Neutral extractives in sorghum stalk and corn stalk formed some long chain fatty oxygenates and less nitrogenous compounds. The bio-oils derived from these two biomasses contained oxygenates as dominant compounds, however, they had a lower fraction of heavy constituents, lower oxygen contents, and higher HHVs than those of reed and cotton straw. This result was attributed to the catalyzed bio-oil deoxygenation by the relatively abundant AAEMs in sorghum stalk and corn stalk. Highlights • Pyrolysis of five crop residues were studied with a focus on bio-oil production. • Neutral extractives are an important contributor to bio-oil formations. • Inherent potassium showed a catalytic effect on deoxygenation of bio-oil. • Peanut straw showed a distinctly selective bio-oil deoxygenation. [ABSTRACT FROM AUTHOR]

Highlights • Microwave assissted wet torrefaction with aqueous ammonia was employed on corn stalk. • A significant physicochemical modification was achieved with combined pretreatment. • Pyrolysis of pretreated corn stalk gave more ketones and aldehydes, and less acids. • This study provides a promising way for enhancing bio-oil quality. Abstract The physicochemical characteristics and pyrolysis performance of corn stalk (CS) torrefied in water and aqueous ammonia by microwave heating were investigated. Physicochemical characterization revealed that both microwave water torrefied CS (MCS) and microwave ammonia torrefied CS (MACS) showed low hemicellulose content, disrupted macrostructure, improved porous properties, and low ash content. MACS exhibited a significantly lower crystallinity degree of 44.34% than CS (79.55%) and MCS (89.50%). MACS also showed increased methyl/methylene groups intensity, and complete acetyl groups disrupture. Pyrolysis coupled with gas chromatography/mass spectrometry (Py-GC/MS) revealed that compared with CS and MCS, MACS exhibited higher peak areas for ketones, aldehydes, furans and esters, and significantly lower peak areas for acids and phenols. A possible mechanism was proposed for the effects of wet torrefaction with aqueous ammonia on changes in physicochemical structure and pyrolysis behavior of corn stalk. [ABSTRACT FROM AUTHOR]

Appropriate pretreatment plays a pivotal role in biomass pyrolysis as it facilitates high-value utilization of pyrolysis products. In this study, hydrogen peroxide pretreatment with cleanliness, economy, and efficiency was applied for fast pyrolysis of corn stalks. The effects of pyrolysis temperature, hydrogen peroxide pretreatment, and different pHs on the structure of corn stalks and the properties of resultant pyrolysis products were investigated. The results revealed that the pretreatment could effectively promote lignin depolymerization and significantly reduce the reaction activation energy (E). Meanwhile, the pretreatment increased the cellulose content and removed the majority of alkali and alkaline earth metals from the biomass. The removal of lignin and ash by the pretreatment was affected by the pH of the hydrogen peroxide solution. Moreover, the composition of bio-oil changed significantly. Among them, the relative content of levoglucosan in the bio-oil from untreated raw material was only 1.38 %. After pretreatment, the relative content of levoglucosan was up to 14.5 %. The present findings offer valuable guidance for the further exploration and exploitation on hydrogen peroxide pretreatment for depolymerization of woody fibrous biomass as well as for the preparation of high-value chemical products. [Display omitted] • Pyrolysis characteristics of corn straw pretreated with H 2 O 2 were investigated. • H 2 O 2 pretreatment increased the relative content of cellulose. • Significant increase in the relative content of levoglucosan up to 14.50 %. • Acids in bio-oil are greatly reduced, as low as 5.33 %. • Degradation mechanism of corn stalk pretreated with H 2 O 2 was elucidated. [ABSTRACT FROM AUTHOR]

Graphical abstract The mechanism of tween combined with HTC. Highlights • Fuel properties, pyrolysis and combustion behavior of hydrochar was investigated. • O/C ratio and HHV of CS + H 2 SO 4 + tween hydrochar are 0.3 and 28.89 MJ/kg. • Lignin was separated with cellulose and hemicellulose via HTC combined with surfactant. • Tween inhibited formation and adsorption of pseudo-lignin and promoted hydrolysis of CS. • E decreased from 271.16 to 21.68 kJ mol−1 via combining surfactant with HTC. Abstract The surfactant/ultrasonic combined with hydrothermal carbonization (HTC) were performed to investigate the effect on fuel properties, pyrolysis and combustion behavior of hydrochar under different condition. The results showed that the C/H and O/C ratio of corn stalk (CS) + H 2 SO 4 + tween was 1.1 and 0.29, which were close to coal, and the heat value reached 28.89 MJ/kg. HTC combined with ultrasonic/surfactant realized the complete separation of lignin with cellulose and hemicellulose in CS. Ultrasonic restricted the hydrolysis of lignin under alkaline condition and pseudo-lignin formation under acidic condition. Tween inhibited the formation and deposition of "pseudo-lignin". The thermogravimetric (TG) experiments displayed the tween combined with HTC improved the pyrolysis temperature and decreased activation energy as well as the combustion ignition temperature which showed better pyrolysis and combustion characteristics. The nth-order kinetic mode was fit with the TG datas. The mechanism of tween combined with HTC was also analyzed. [ABSTRACT FROM AUTHOR]

Char in-situ (charis) obtained from corn stalk pyrolysis was evaluated as a catalyst to upgrade corn stalk pyrolysis vapors. A catalyst evaluation device was introduced to conduct the experiments. The effects of reaction temperature and charis dose on catalytic performances in biomass pyrolysis were evaluated. The results showed that the char in-situ had a remarkable effect on the pyrolysis products. Under the action of charis, the primary compounds of pyrolysis vapors were catalytically converted into phenolic products, such as phenol and 4-ethyl-phenol, while the acetic acid content was evidently reduced. The product selectivity was not dependent on the polar functional groups on the charis's surface according to the Fourier transform infrared (FTIR) results, but might have been dependent on the mesoporous structure and the basicity sites of the charis as well as the metallic species in the charis. A possible reaction mechanism for phenols production and acetic acid inhibition was proposed. [ABSTRACT FROM AUTHOR]

To study the release and transformation of fuel K during rapid pyrolysis of biomass, wheat straw, corn stalk and rice hull are pyrolyzed in a fixed-bed reactor system during 400–1000 °C, and weight measurement, elemental composition analysis, and chemical fractionation analysis are performed. The effects of fuel type, pyrolysis temperature, co-pyrolysis of different fuels, and water washing pretreatment are discussed. The results show that for all biomass fuels, the released K is far less than the water-soluble K and a sudden increase occurs in the fraction of ion-exchangeable K at 400 °C, whereas a significant increase happens in the fraction of insoluble K above 800 °C. Wheat straw releases less than 5% of K at 400 and 500 °C. As temperature rises, the K release increases abruptly and around 40% of K enters the gas phase at 1000 °C. Rice hull has a slow and linear K release with increasing pyrolysis temperature. Corn stalk has the lowest K release during 400–800 °C. Co-pyrolysis of wheat straw and rice hull reduce the K release at 1000 °C, and the biggest decrement is 0.76 mg g −1 . Water washing removes all the water-soluble K of corn stalk and part of ion-exchangeable K enters the gas phase during pyrolysis of the washed sample. Water washing decreases the K release from 2.77 to 0.18 mg g −1 at 1000 °C. [ABSTRACT FROM AUTHOR]

Two waste biomass materials, pine needle (PN) and corn stalk (CS), were pyrolyzed at different temperatures (200-900 °C). The organic functional groups and carbonaceous structure of the biomass chars were characterized by Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy, respectively. The combustion characteristics and kinetics of biomass chars were investigated by thermogravimetric analysis (TGA). The content of carbon-, hydrogen-, and oxygen-containing functional groups in the biomass samples decreases with an increase in preparation temperature, leading to more aromatic macromolecular structure at elevated pyrolysis temperatures. With increasing pyrolysis temperature, the comprehensive combustibility index (S) of both chars related to combustion reactivity generally decreases especially for CS char because of the loss of active groups. However, the Raman spectra show that the degree of order decreases with increasing pyrolysis temperature from 400 to 700 °C because of the generation of isolated sp2 carbon. [ABSTRACT FROM AUTHOR]

Wet torrefaction (WT) possesses some advantages over dry torrefaction (DT). In this study, a comparative analysis of torrefied corn stalk from WT and DT was conducted along with an investigation of their pyrolysis properties under optimal conditions for biomass pyrolysis polygeneration. Compared with DT, WT removed 98% of the ash and retained twice the amount of hydrogen. The impacts of DT and WT on the biomass macromolecular structure was also found to be different using two-dimensional perturbation correlation infrared spectroscopy (2D-PCIS). WT preserved the active hydroxyl groups and rearranged the macromolecule structure to allow cellulose to be more ordered, while DT removed these active hydroxyl groups and formed inter-crosslinking structures in macromolecules. Correspondingly, the bio-char yield after WT was lower than DT but the bio-char quality was upgraded due to high ash removal. Furthermore, higher bio-oil yield, higher sugar content, and higher H 2 generation, were obtained after WT. [ABSTRACT FROM AUTHOR]

Although the study of co-pyrolysis of coal and biomass have dominated the primary chemicals production in the field of renewable energy utilization, it is still challenging for tar to become lighter. Here we design a set of experimental programs, including the individual pyrolysis, staged catalytic pyrolysis and the co-pyrolysis of physical mixture to investigate the effects of feedstock arrangement on pyrolysis product characteristics. We demonstrated that the experimental results of co-pyrolysis of physical mixture indicate some synergetic effects on pyrolysis products rather than the superposition of individual pyrolysis process of lignite and straw, thus the subsequent tar composition and char structure were characterized. Based on the existing catalytic cracking mechanism, we obtained the staged catalytic pyrolysis have a more pronounced catalytic cracking effect on heavy components compared with the co-pyrolysis of physical mixture, which enables the formation of light oil, naphthalene oil, tar with the lower oxygen content and higher benzene. The Raman spectra of char in catalytic bed exhibits the total peak area of char and the amount of large aromatic ring formed by polymerization increased with the increase of pyrolysis temperature. Simultaneously, the role of catalytic cracking of straw char was stronger than that of lignite char remarkably has been confirmed from the point of view of the chemical structure of char. [ABSTRACT FROM AUTHOR]

To investigate synergetic effects on pyrolysis of municipal solid waste and corn stalk, pyrolysis characteristics and product distributions of their mixtures were examined by thermal gravimetric and fixed-bed. Results indicated that co-pyrolysis process can be divided into four steps: losing water, main pyrolysis, carbonization and catalytic gasification of char. Under different blending ratio conditions, char and liquid yields were lower than the theoretical values calculated on pyrolysis of each individual sample, and consequently, gas yields were higher. Linear relationship can be applied to char and liquid products, however, hardly applied to gas yields. [ABSTRACT FROM AUTHOR]

Modeling of lignocellulosic biomass pyrolysis processes can be used to determine their key operating and design parameters. This requires significant amount of information about pyrolysis kinetic parameters, in particular the activation energy. Thermogravimetric analysis (TGA) is the most commonly used tool to obtain experimental kinetic data, and isoconversional kinetic analysis is the most effective way for processing TGA data to calculate effective activation energies for lignocellulosic biomass pyrolysis. This paper reviews the overall procedure of processing TGA data for isoconversional kinetic analysis of lignocellulosic biomass pyrolysis by using the Friedman isoconversional method. This includes the removal of “error” data points and dehydration stage from original TGA data, transformation of TGA data to conversion data, differentiation of conversion data and smoothing of derivative conversion data, interpolation of conversion and derivative conversion data, isoconversional calculations, and reconstruction of kinetic process. The detailed isoconversional kinetic analysis of TGA data obtained from the pyrolysis of corn stalk at five heating rates were presented. The results have shown that the effective activation energies of corn stalk pyrolysis vary from 148 to 473 kJ mol −1 when the conversion ranges from 0.05 to 0.85. [ABSTRACT FROM AUTHOR]

The performance, combustion and emission characteristics of diesel engine fuelled with corn stalk pyrolysis bio-oil/diesel emulsions (CBDEs) with Ce 0.7 Zr 0.3 O 2 nanoadditive were studied. The density and viscosity of CBDEs increased by 10.7% and 159.3% with increasing bio-oil concentration up to 25%, respectively. Meanwhile, the calorific value was correspondingly reduced by 18.5%. Compared to diesel, a lower specific fuel consumption was achieved with the CBDE fuels at medium and high powers. This was attributed to micro-explosion, which resulted in more thorough splitting of fuel droplets caused by the instantaneous and intense vaporization of water, thereby significantly improving fuel vaporization and combustion process. In addition, the addition of Ce 0.7 Zr 0.3 O 2 nanoparticles led to reduced ignition delay and rapid oxidation, thus resulting in more complete combustion. The specific fuel consumption of CBDEs first decreased and then increased in correlation to the increased bio-oil content, in which CBDEs with bio-oil proportion of 20% showed the lowest and had the highest fuel saving rate close to 8.4%. By comparison of diesel, the CBDEs with lower bio-oil proportion than 20% reduced CO, HC and smoke emission, which were decreased by reducing bio-oil content. Increasing bio-oil proportion led to the effective reduction of NO x emission. [ABSTRACT FROM AUTHOR]

In this paper, corn stalk was alkalized by gradient concentrations of sodium hydroxide and briquetted with anthracite coal. The bonding mechanism was explored by a combined analysis of physicochemical, microstructure and mechanical properties. Alkaline treatment had a large effect on decomposing most of lignin and dissolving the carbohydrates in corn stalk even at a low concentration of 1%. With the increase in alkaline concentration (for 1%–2%), the degree of decomposition of hemicellulose and amorphous cellulose increased gradually. When the concentration of alkaline reagent was higher than 3%, more than 40% of hemicellulose was degraded. A complete surface structure of a spatial network was achieved when corn stalk was treated by 2% alkaline, which mainly contributed to the bonding performance of compound briquette. Under this condition, the ratio of cellulose to hemicellulose to lignin was approximately 7.0:2.5:0.5, and it also exhibited a good pyrolysis performance for energy conversion. [ABSTRACT FROM AUTHOR]

The cornstalk and chlorella were selected as the representative of lignocelulosic and algal biomass, and the pyrolysis experiments of them were carried out using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The physicochemical properties of samples and the pyrolytic product distribution were presented. And then the compositional differences between the two kinds of pyrolytic products were studied, the relevant pyrolysis mechanisms were analyzed systematically. Pyrolytic vapor from lignocellulosic biomass contained more phenolic and carbonyl compounds while that from algal biomass contained more long-chain fatty acids, nitrogen-containing compounds and fewer carbonyl compounds. Maillard reaction is conducive to the conversion of carbonyl compounds to nitrogenous heterocyclic compounds with better thermal stability. [ABSTRACT FROM AUTHOR]

Water-soluble organic compounds (WSOCs) were extracted from corn stalk biochar produced at increasing pyrolysis temperatures (350-650 °C) and from the corresponding vapors, collected as bio-oil. WSOCs were characterized by gas chromatography (semivolatile fraction), negative electron spray ionization high resolution mass spectrometry (hydrophilic fraction) and fluorescence spectroscopy. The pattern of semivolatile WSOCs in bio-oil was dominated by aromatic products from lignocellulose, while in biochar was featured by saturated carboxylic acids from hemi/cellulose and lipids with concentrations decreasing with decreasing H/C ratios. Hydrophilic species in poorly carbonized biochar resembled those in bio-oil, but the increasing charring intensity caused a marked reduction in the molecular complexity and degree of aromaticity. Differences in the fluorescence spectra were attributed to the predominance of fulvic acid-like structures in biochar and lignin-like moieties in bio-oil. The divergence between pyrolysis vapors and biochar in the distribution of WSOCs with increasing carbonization was explained by the hydrophobic carbonaceous matrix acting like a filter favoring the release into water of carboxylic and fulvic acid-like components. The formation of these structures was confirmed in biochar produced by pilot plant pyrolysis units. Biochar affected differently shoot and root length of cress seedlings in germination tests highlighting its complex role on plant growth. [ABSTRACT FROM AUTHOR]

Pyrolysis of corn stalk biomass briquettes was carried out in a developed microwave (MW) reactor supplied with 2.45 GHz frequency using 3 kW power generator. MW power and biomass loading were the key parameters investigated in this study. Highest bio-oil, biochar, and gas yield of 19.6%, 41.1%, and 54.0% was achieved at different process condition. In terms of quality, biochar exhibited good heating value (32 MJ/kg) than bio-oil (2.47 MJ/kg). Bio-oil was also characterised chemically using FTIR and GC–MS method. This work may open new dimension towards development of large-scale MW pyrolysis technology. [ABSTRACT FROM AUTHOR]

• Two-stage electromagnetic induction reactor is proposed for cornstalk pyrolysis. • Temperatures in each stage reach to higher than 1000 °C in less than 1 min. • 94.8 % oil in volatiles converts to coke and gas in 0.5 s with a gas yield of 69.6 %. • Gas composions are 45.7 % H 2 and 43.8 % CO in volume. To utilize the promising green electricity from regenerable energies and promote the production of chemicals from biomass generated syngas, this work studies rapid high-temperature cornstalk (CS) pyrolysis in a two-stage reactor heated by electromagnetic induction under 398 kHz. The induction medium in the first stage is an iron rod immersed in CS particles while that for the second stage is a set of 304 stainless steel nets for the conversion of CS generated volatiles. The pyrolysis experiments were carried out at different heating rates, power in puts, volatile reaction times and overall pyrolysis times. The yields of char, oil, H 2 O, gas and coke, as well as the gas composition were discussed. It is found that the temperatures of rod and nets reach to higher than 1000 °C in 49 and 9 s, respectively, and the CS pyrolysis and the volatiles reaction can be accomplished in 5 min. The second stage effectively converts 94.8 % oil to gas and coke, with the participation of H 2 O. The final products in 5 min include 69.6 wt% gas, 15.6 wt% char, 7.8 wt% coke, 2.2 wt% oil and 4.8 wt% H 2 O, while the gas mainly contained 45.7 % H 2 and 43.8 % CO in volume, respectively. [ABSTRACT FROM AUTHOR]

Bio-oil as an important renewable energy product has been successfully made from corn stalks and lignin via a fast pyrolysis process. This study investigated the effects of alkali and alkaline earth metallic species (AAEMs) on phenolic products in corn stalk and lignin pyrolysis oil. Corn stalks were demineralized with 0.5 M HCl, and lignin was doped with 0.2wt%, 2wt%, and 20wt% KCl and CaCl2, respectively. The pyrolysis experiments were conducted in a fixed bed tubular furnace ranging from 450 °C to 600 °C. It was found that AAEMs exert positive effects on the formation of char and gas and inhibit the production of bio-oil. The effect of KCl on the product distribution from lignin is somewhat stronger than CaCl2. Moreover, the content of P, HP, GP, and SP decreases after removal of AAEMs. KCl can promote the polymerization of light molecular aromatic hydrocarbons to increase the SP yield at 600 °C, whereas the effect on increase in P and HP content is relatively weaker than CaCl2. KCl and CaCl2 play notable roles in demethxylation and demethoxylation in increasing phenol content and removing the R group from the ring. [ABSTRACT FROM AUTHOR]

Two novel magnetic biochar composites (FeC-H and FeC-P) were synthesized using corn stalks and ferrous sulfate through hydrothermal method and traditional pyrolysis, respectively. The samples were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), vibrating sample magnetometer, and particle size analyzer. Batch experiments were conducted to investigate the ability of those samples to absorb aqueous phosphate. FeC-H had lower surface area than FeC-P, but more hydrophilic functional groups were detected on the rough surface of FeC-H. The impregnated iron was present as Fe3O4 in the prepared magnetic biochar composites. The introduced Fe3O4 resulted in high performance of magnetic separation and also played the role as adsorption sites for phosphate. FeC-H and FeC-P demonstrated higher sorption capacity than bare Fe3O4 due to the highly dispersed and smaller crystalline sizes of Fe3O4 particles loaded in corn stalk derivedbiochar support. FeC-H had the best performance, with Langmuir adsorption capacity as high as 5.04 mg/g for phosphate. These results indicate that the magnetic biochar composites prepared from corn stalks by hydrothermal method (FeC-H) have potential as a high-efficiency and cost-effective adsorbent for phosphorus removal from wastewater. [ABSTRACT FROM AUTHOR]

Pyrolysis characteristics of the corn stalk were investigated at different temperatures and pressures, with focus mainly on the releasing profiles and forming behaviors of gas. The results show that a higher pressure was conducive to the yield of H 2 and CH 4 , and was not conducive to the generation of CO. Combustible gas components increase with the increase temperature. H 2 concentration was affected significantly by temperature, was mainly released at higher temperatures (>500 °C). At 700 °C, the combustible gas components are up to 90% and H 2 concentration is up to 51.78%. The gas components of corn stalk pyrolysis char steam gasification mainly consisted of CO and H 2 , 25.7% and 50.7% respectively. The calorific value of gasification gas is up to 9508.9 kJ/M 3 . A kinetic study of the pyrolysis process of the corn stalk was investigated using a thermogravimetric analyzer. As the heating rate increased, the activity energy reduced. By using the Popescu method to determine that shrinking core model can reflect the pyrolysis process of corn stalk truly at low temperature pyrolysis, and chemical reaction model can reflect the pyrolysis process of corn stalk truly at high temperature pyrolysis. Experimental results showed that values of kinetic parameters can be successfully used to understand the degradation mechanism of solid-state reaction. [ABSTRACT FROM AUTHOR]

Organic aerosol (OA) can absorb solar radiation in the low-visible and ultra-violet wavelengths thereby modifying radiative forcing. Agricultural waste burning emits a large quantity of organic carbon in many developing countries. In this work, we improved the extraction and analysis method developed by Chen and Bond, and extended the spectral range of OC absorption. We examined light absorbing properties of primary OA from pyrolysis of corn stalk, which is a major type of agricultural wastes. Light absorption of bulk liquid extracts of OA was measured using a UV–vis recording spectrophotometer. OA can be extracted by methanol at 95%, close to full extent, and shows polar character. Light absorption of organic aerosol has strong spectral dependence (Absorption Ångström exponent = 7.7) and is not negligible at ultra-violet and low-visible regions. Higher pyrolysis temperature produced OA with higher absorption. Imaginary refractive index of organic aerosol ( k OA ) is 0.041 at 400 nm wavelength and 0.005 at 550 nm wavelength, respectively. [ABSTRACT FROM AUTHOR]

The purpose of this work is to investigate adsorption characteristic of corn stalk (CS) biochar for removal of cadmium ions (Cd2+) from aqueous solution. Batch adsorption experiments were carried out to evaluate the effects of pH value of solution, adsorbent particle size, adsorbent dosage, and ionic strength of solution on the adsorption of Cd2+ onto biochar that was pyrolytically produced from CS at 300 WC. The results showed that the initial pH value of solution played an important role in adsorption. The adsorptive amount of Cd2+ onto the biochar decreased with increasing the adsorbent dosage, adsorbent particle size, and ionic strength, while it increased with increasing the initial pH value of solution and temperature. Cd2+ was removed efficiently and quickly from aqueous solutions by the biochar with a maximum capacity of 33.94 mg/g. The adsorption process was well described by the pseudo-second-order kinetic model with the correlation coefficients greater than 0.986. The adsorption isotherm could be well fitted by the Langmuir model. The thermodynamic studies showed that the adsorption of Cd2+ onto the biochar was a spontaneous and exothermic process. The results indicate that CS biochar can be considered as an efficient adsorbent. [ABSTRACT FROM AUTHOR]

The yield and composition of pyrolysis products depend on the characteristics of feed stock and process operating parameters. Effect of particle size, reaction temperature and carrier gas flow rate on the yield of bio-oil from fast pyrolysis of Pakistani maize stalk was investigated. Pyrolysis experiments were performed at temperature range of 360-540°C, feed particle size of 1-2 mm and carrier gas fl ow rate of 7.0-13.0 m3/h (0.61.1 m/s superficial velocity). Bio-oil yield increased with the increase of temperature followed by a decreasing trend. The maximum yield of bio-oil obtained was 42 wt% at a temperature of 490°C with the particle size of around 1.0 mm and carrier gas flow rate of 11.0 m3/h (0.9 m/s superficial velocity). High temperatures resulted in the higher ratios of char and non-condensable gas. [ABSTRACT FROM AUTHOR]

Red mud is a solid waste residue with alkaline nature (pH>12)-originating from the Bayer process in the production of alumina, which was probed in catalytic pyrolysis to determine its feasibility as a solid catalyst for bio-oil formulation. The red mud was characterized using X-ray fluorescence, XRD (X-ray diffraction), TG-DTG (thermogravimetry-derivative thermogravimetry), BET (surface area and pore size analyzer) measuring and testing techniques. Experiments of non-catalytic and catalytic pyrolysis of 40-60 mesh size corn stalk powder were channelled for bio-oil production in a fixed bed reactor. It was ascertained that adding different proportions of red mud had minute influence on bio-oil production rate and product distribution. The study signaled that liquid yield from the catalytic pyrolysis was lower than that from non-catalytic pyrolysis. Through a series of bio-oil characterization, it was encountered that the most obviously change in the bio-oil from catalytic pyrolysis was significant acidity reduction (pH>4). Meanwhile, the content of ketones and phenols was enhanced. Hence, the co-processing of agricultural waste and by-products alumina industry may offer an economical and environmentally friendly way of catalytic pyrolysis with abbreviating the red mud environmental effects. [ABSTRACT FROM AUTHOR]

To explore the changes of pyrolysis behaviors from xylophyta to herbage, pyrolysis properties of red pepper stalks (RPS) as a representative kind of biomass of high lignin content of agricultural residues were studied by using TGA and Py-GC/MS. The results indicated that contents of cellulose, 43.2 wt.%, and of lignin, 24.7 wt.% were higher than those of corn stalks, wheat stalks and cotton stalks, but closer to those of the poplar wood. The pyrolysis process mainly occurred in three stages, and with an increasing heating rate from 10 °C/min to 30 °C/min, the TGA curves shifted to a lower temperature. With an increase in pyrolysis temperature, the contents of sugars, phenols and furans decreased from 3.96%, 13.54% and 10.13% to 1.09%, 7.13% and 1.65%, respectively. The contents of hydroxyacetaldehyde and acetone reached a maximum 13.71% and 20.05% at 500 °C. At 300 °C levoglucose, pentanal and methyl furan content reached maxima of 3.63%, 13.09% and 7.49%, respectively. Different chemical components could account for the changes of pyrolytic behaviors from xylophyta to herbage. [ABSTRACT FROM AUTHOR]

Co-pyrolysis of municipal solid waste with cassava stalk or corn stalk was investigated in this work. Profiles of the product yields versus different agricultural stalk adding ratios during pyrolysis at 600°C reveal that the char yields reduced, and the liquid and gas yields increased at start-up stage but afterwards decreased with adding ratios of agricultural stalk increasing. The differences between experimental and theoretical yields of char ranged from 18.26 to 10.35% as cassava stalk ratios from 10 to 50%, and from 8.13 to 11.09% as corn stalk ratios from 10 to 50%. The statistical analysis of theoretical and experimental data implied the synergistic effect between municipal solid waste and agricultural stalk during co-pyrolysis process. The energy balance showed that pyrolysis of municipal solid waste alone could not produce enough pyrolysis liquid to compensate the energy consumption of pyrolysis system, and the co-pyrolysis system could dispose of municipal solid waste without extra energy input. The calculated results also showed that the feed stock comprised of 49.21% of cassava stalk or 40.12% of corn stalk could guarantee the energy balance of the co-pyrolysis system. © 2015 American Institute of Chemical Engineers Environ Prog, 35: 547-552, 2016 [ABSTRACT FROM AUTHOR]

In this work, an integrated process of anaerobic digestion (AD) and pyrolysis (PY) was developed to eliminate the obstacles of single AD or PY application, such as long period, low efficiency and poor quality of products. The influence mechanism of different AD times on the energy recovery of integrated process was explored, and alkali pretreatment was performed to optimize energy recovery. Results showed that the fluctuation of indicators mainly concentrated in the initial stage of AD due to the limited biodegradability of substrate. The PY characteristics was altered due to the decrease of volatiles with AD time. The energy recovery decreased first and then increased, and tended to be stable on day 25–30 (About 11–12 MJ/kg). Cumulative methane production was the crucial factor for coupling time node with a correlation coefficient of 0.9299–0.9278. This study provides theoretical guidance and insights for efficient energy recovery from integrated AD and PY. [Display omitted] [ABSTRACT FROM AUTHOR]

In order to minimize coke yield during biomass catalytic fast pyrolysis (CFP) process, ethylene diamine tetraacetie acid (EDTA) chemical modification method is carried out to selectively remove the external framework aluminum of HZSM-5 catalyst. X-ray diffraction (XRD), nitrogen (N 2 )-adsorption and ammonia-temperature programmed desorption (NH 3 -TPD) techniques are employed to investigate the porosity and acidity characteristics of original and modified HZSM-5 samples. Py-GC/MS and thermo-gravimetric analyzer (TGA) experiments are further conducted to explore the catalytic effect of modified HZSM-5 samples on biomass CFP and to verify the positive effect on coke reduction. Results show that EDTA treatment does not damage the crystal structure of HZSM-5 zeolites, but leads to a slight increase of pore volume and pore size. Meanwhile, the elimination of the strong acid peak indicates the dealumination of outer surface of HZSM-5 zeolites. Treatment time of 2 h (labeled EDTA-2H) is optimal for acid removal and hydrocarbon formation. Among all modified catalysts, EDTA-2H performs the best for deacidification and can obviously increase the yields of positive chemical compositions in pyrolysis products. Besides, EDTA modification can improve the anti-coking properties of HZSM-5 zeolites, and EDTA-2H gives rise to the lowest coke yield. [ABSTRACT FROM AUTHOR]

A series of experiments on co-pyrolysis of subbituminous coal/corn stalk blends with solid heat carrier (boiler ash) were carried out in a bench-scale moving bed pyrolyzer with different biomass blending ratios at different temperatures. Deviation of gaseous, liquid and char products yields between experimental values and calculated ones was discussed. Some characteristics of char and char-ash after co-pyrolysis were investigated, such as elemental analysis, heat value, ash melting point and ash composition. Results indicated that with increasing blending ratio of corn stalk and temperature, both gas and tar yields increased. Gas heat value decreased with increasing corn stalk blending ratio while increased with rising temperature. Compared with coal pyrolysis alone, more light-oil and water were found during the co-pyrolysis process. The char-ash showed little impact on boiler combustion ash at the blending ratio of biomass less than 30%. Application of co-pyrolysis in a poly-generation system was evaluated environmentally and economically. [ABSTRACT FROM AUTHOR]

Pyrolysis of corn stalk with a solid heat carrier was studied under temperatures ranging from 430 to 620 °C. The solid heat carrier used was high-temperature ash from a CFB boiler. The yields of three products and their characteristics were investigated. Moreover, the distributions of sulfur and nitrogen in the products were determined. The results indicate that with increasing temperature, the char yield decreased, gas yield increased, and calorific value of the gas increased from 10.13 to 16.65 MJ/m³. The yield of bio-oil reached a maximum, 14.24 wt.%, at 510 °C. Light-oil in the bio-oil accounted for more than 69.12 wt.%. The elemental composition of the char and char ash were analyzed. The distribution of sulfur and nitrogen in the char decreased to 60.44 and 46.52 wt.%, respectively, depending on the raw materials used. These results provide basic data for the possible industrial application of corn stalk. [ABSTRACT FROM AUTHOR]