A compound additive consisting of methanol, N,N-dimethylformamide (DMF), and acetone was obtained with the A-Optimal mixture design of Design-Expert. How the solvent effected the stability of bio-oil was analyzed on the basis of viscosity, moisture content, and pH. Bio-oil with the optimal compound additive (1 wt % methanol, 5.064 wt % DMF, and 1.940 wt % acetone) had a low viscosity and moisture content and high pH after aging (80 °C for 24 h). The corresponding property values were 4.36 mm2/s, 24.03%, and 4.49, respectively, and the result was better than bio-oil with a single solvent. Gas chromatography–mass spectrometry (GC–MS) analysis revealed that the phenol contents in all of the compounds in bio-oil were high. After aging, the contents of sugars and esters increased and several chemical compounds, such as 2-ethoxy-5-(1-propen-1-yl) and 5-hydroxy-2-methylbenzaldehyde, disappeared in bio-oil with the compound additive. Elemental analysis showed that the contents of O and N increased after the addition of the optimal compound additive. The compound additive exerted a positive effect on the bio-oil during storage.

•Two-step pyrolysis of soybean stalk (SS) was studied by Py-GC/MS.•The effects of the first step temperatures on the two-step pyrolysis were studied.•Two-step pyrolysis mechanism was analyzed by using TG-FTIR of SS and FTIR of chars.•High selectivities toward high value chemicals were achieved in the first step.•High quality bio-oil was obtained in the second step.Two-step pyrolysis (TSP) of soybean stalk (SS) was investigated by Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and Thermogravimetric analyzer coupled with FTIR spectrophotometer (TG-FTIR) to obtain high value chemicals and high quality bio-oil. The hemicellulose and cellulose in SS were almost decomposed from 200 °C to 400 °C in TG process, while little lignin was decomposed in this stage. Then the first step temperature (T1) was set from 250 °C to 450 °C, and the second step temperature was set as 650 °C to compare with the one-step pyrolysis at 650 °C (OSP). The yields of volatiles of TSP were lower than that of OSP, but the yields of solid products were similar to each other approximately. T1 of 250 °C and 300 °C torrified the SS, but had little influence on the product distribution of the second step. T1 of 350 °C enhanced polycondensation reaction of SS and reached minimum volatile yield. For optimum conditions at T1 of 400 °C and 450 °C, higher contents of oxygenous products (acids, furans, alcohols, ketones and phenols with methoxyl) and nitrogen compounds were achieved in the first step to increase the selectivities toward high value chemicals, and high quality bio-oil with high contents of hydrocarbons could be obtained in the second step.

•Blending bituminous coal could improve the behaviors of pyrolysis of distillation residue.•The synergistic interaction was observed during co-pyrolysis of the blends.•The synergistic effects were prone to occur at lower temperatures.•The gas products were quantitatively analyzed by infrared peak area.•Coats-Redfern and Flynn-Wall-Ozawa method were applied to obtain kinetics parameters.Co-pyrolysis characteristics of bio-oil distillation residue and bituminous coal were investigated through thermogravimetric analysis coupled with Fourier transform infrared spectrophotometer (TGA-FTIR). The addition of bituminous coal changed the behaviors and kinetics of pyrolysis reaction. With temperature increasing, synergistic effects rapidly increased at relatively low temperatures, and then kept a decreasing tendency with different rates until a relatively steady state. The results of the quantitative analysis of chemical functional group by the peak area of infrared spectroscopy indicated that the addition of bituminous coal had a positive effect on the production of CO2 and CO, and a negative effect on the functional groups containing CH, CC and CO bond. The co-pyrolysis mechanism and kinetics parameters were calculated by the Coats-Redfern and Flynn-Wall-Ozawa method, suggesting that the activation energy and the reaction order of co-pyrolysis increased with mixing ratio increasing in main step. The lowest activation energy (73.17 kJ/mol by Coast-Redfern method and 71.46 kJ/mol by Flynn-Wall-Ozawa method) was obtained by blending 20 wt% bituminous coal.

•W2C/MCM-41(Si/W = 50) has high activity toward catalytic fast pyrolysis of lignin.•The yield of arenes increases from 3% to 20% after upgrading.•The selectively of monocyclic arenes is about 80% after upgrading.•The possible mechanisms to form monocyclic arenes were proposed.W2C/MCM-41-catalyzed upgrading of vapors from fast pyrolysis of lignin was investigated with the aim of arene production. The experiments were conducted in a micro pyrolyzer-gas chromatography/mass spectrometer (P-GC/MS). A series of W2C/MCM-41 catalysts with different catalyst loading amount (Si/W) were prepared and the activity, selectivity, and stability of the catalysts were investigated. Associated with the analysis results of P-GC/MS for the pyrolysis vapors, the optimal condition for producing arenes was found. Besides, possible mechanisms for lignin conversion with the as-prepared catalysts were discussed. In the presence of W2C/MCM-41 (Si/W = 50), the arenes yield is about 20% of volatile product and the selectivity for monocyclic arenes is over 85% at 750°C. The yield of arenes increases significantly with the increase of catalyst-to-lignin mass ratio (C/L). According to the run tests, the conversion of arenes decreases slightly by 1% or 2% after each run, indicating that the catalyst features good stability under the experimental conditions. Thus, W2C/MCM-41 catalysts effectively catalyzed the formation of monocyclic arenes in the fast pyrolysis process.

•Mo2N/γ-Al2O3 was prepared to explore its effect on the production of aromatics.•The effects of the catalyst-to-lignin weight ratio and temperature were studied.•Mo2N/γ-Al2O3 exhibited a high selectivity for the monocyclic aromatics.•A reaction mechanism was proposed about the formation of aromatics.This study investigates the online catalytic cracking of lignin fast pyrolysis vapors using Mo2N/γ-Al2O3 prepared by nitriding an alumina-supported molybdenum oxide precursor with nitrogen hydrogen mixtures though temperature programming. The activity and selectivity of the catalyst toward aromatic hydrocarbons were determined in the pyrolysis-gas chromatography/mass spectrometry system. Results show that the catalyst has a significant function in the pyrolysis process. In the presence of the catalyst, the primary pyrolysis products from lignin are catalytically converted into aromatic products, benzene and toluene, as well as to an insignificant quantity of dimethylbenzene, ethylbenzene, trimethylbenzene, and naphthalene. The highest aromatic hydrocarbon yield of 17.5% is obtained using Mo2N/γ-Al2O3 (the catalyst-to-lignin weight ratio = 4) at 700 °C; by contrast, this yield is only 1.4% when no catalyst is used. Furthermore, the highest benzene yield of 70.1% is obtained using Mo2N/γ-Al2O3 (catalyst-to-lignin weight ratio = 4) at 850 °C. Under this condition, the monocyclic aromatic hydrocarbons together contribute >95% of the total aromatic hydrocarbon yield, whereas the selectivity toward naphthalene is only 2.2%.

Drying characteristics of cotton stalk were investigated at four temperatures (60, 80, 100 and 120 °C) using a simultaneous thermal analyzer (TG-DSC). Heat requirements of cotton stalk during drying were calculated ranging from 189 to 406 kJ/kg. Consequently, Midilli-Kucuk model showed the best fit to experimental drying data. The values of effective diffusivity ranged from 4.38 × 10−9 to 8.15 × 10−9 m2/s, and the activation energy was calculated to be 11.6 kJ/mol.

Porous silica with high specific surface areas is prepared from rice husk char within a short period by avoiding the commonly used hydrothermal treatment step and using polyethylene glycol (PEG, molecular weight = 20,000) as a template. The preparation process mainly involves sodium silicate production, precipitation with ortho-phosphoric acid, and calcination. The amount of used PEG significantly affects the silica textural properties like the specific surface area, total pore volume and mesopore volume. The reason should be attributed to the amount of PEG removed from the PEG-silica composites by calcination. By varying the PEG dosage from 100 to 176 mg, porous silica with specific surface areas ranging from 709 to 936 m2/g could be successfully prepared within 10 h.

Model liquid phase reactions of 1-octene with phenol in the presence of water, acetic acid, methanol, and 2-hydroxymethylfuran, respectively, were carried out over acid catalysts for bio-oil upgrading, including 30 wt % acidic salt Cs2.5H0.5PW12O40 supported on K-10 clay (30%Cs2.5/K-10), Nafion (NR50) and Amberlyst 15. Temperatures from 40 to 120 °C were examined. Both catalysts had a high activity and selectivity for O-alkylation of phenol with 1-octene but not with 2,4,4-trimethylpentene. The presence of water, acetic acid, and methanol lowered the yield of alkylated phenols by the competitive formation of octanols and dioctyl ethers, octyl acetates, and methyl ethers, respectively. Higher O-alkylation selectivity was obtained at the expense of lower phenol conversion in the presence of water, methanol, or acetic acid. 30%Cs2.5/K-10 is an excellent water-tolerant catalyst while Amberlyst 15 decomposed at higher temperatures and higher water concentrations. 2-Hydroxymethylfuran deactivated catalysts significantly, indicating furan derivatives in bio-oil may require modification before upgrading with olefins.

Palladium supported on SBA-15 catalysts were developed and employed for catalytic cracking of biomass fast pyrolysis vapors using analytical pyrolysis−gas chromatography/mass spectrometry (Py-GC/MS). The Pd/SBA-15 catalysts displayed prominent capabilities to crack the lignin-derived oligomers to monomeric phenolic compounds and further convert them to phenols without the carbonyl group and unsaturated C−C bond on the side chain. Moreover, the catalysts almost completely eliminated the anhydrosugar products and decarbonylated the furan compounds. They also significantly decreased the linear aldehydes and dehydroxylated the linear ketones. In addition, the catalysts slightly decreased the acids, while methanol and hydrocarbons were increased. The above catalytic capabilities of the Pd/SBA-15 catalyst were enhanced with the increase of Pd content from 0.79 wt % to 3.01 wt %.

Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) was employed to achieve fast pyrolysis of xylan and on-line analysis of pyrolysis vapors. Tests were conducted to investigate the effects of temperature on pyrolytic products, and to reveal the effect of HZSM-5 and M/HZSM-5 (M = Fe, Zn) zeolites on pyrolysis vapors. The results showed that the total yield of pyrolytic products first increased and then decreased with the increase of temperature from 350°C to 900°C. The pyrolytic products were complex, and the most abundant products included hydroxyacetaldehyde, acetic acid, 1-hydroxy-2-propanone, 1-hydroxy-2-butanone and furfural. Catalytic cracking of pyrolysis vapors with HZSM-5 and M/HZSM-5 (M = Fe, Zn) catalysts significantly altered the product distribution. Oxygen-containing compounds were reduced considerably, and meanwhile, a lot of hydrocarbons, mainly toluene and xylenes, were formed. M/HZSM-5 catalysts were more effective than HZSM-5 in reducing the oxygen-containing compounds, and therefore, they helped to produce higher contents of hydrocarbons than HZSM-5.

Pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS) was employed to achieve fast pyrolysis of sawdust and on-line analysis of the pyrolysis vapors. A mesoporous SBA-15 catalyst and four Al/SBA-15 catalysts with different Si/Al ratios were prepared, and tests were performed to determine their effects on cracking the pyrolysis vapors. After catalysis, levoglucosan was significantly reduced or even completely eliminated. The yields of heavy furans and heavy phenols decreased significantly, while light furans and light phenols increased. Moreover, the catalytic cracking reduced the yields of light aldehydes and ketones, while increased the formation of acetic acid. Catalytic cracking also resulted in the formation of hydrocarbons, but their yields were not high. In regard to the four Al/SBA-15 catalysts, their effects on cracking the pyrolysis vapors were enhanced with the reducing of Si/Al ratios.

Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) was employed to achieve fast pyrolysis of biomass and on-line analysis of the pyrolysis vapors. Four biomass materials (poplar wood, fir wood, cotton straw and rice husk) were pyrolyzed to reveal the difference among their products. Moreover, catalytic cracking of the pyrolysis vapors from cotton straw was performed by using five catalysts, including two microporous zeolites (HZSM-5 and HY) and three mesoporous catalysts (ZrO2&TiO2, SBA-15 and Al/SBA-15). The results showed that the distribution of the pyrolytic products from the four materials differed a little from each other, while catalytic cracking could significantly alter the pyrolytic products. Those important primary pyrolytic products such as levoglucosan, hydroxyacetaldehyde and 1-hydroxy-2-propanone were decreased greatly after catalysis. The two microporous zeolites were effective to generate high yields of hydrocarbons, while the three mesoporous materials favored the formation of furan, furfural and other furan compounds, as well as acetic acid.

In this paper, pyrolysis of pine wood sawdust was carried out by microwave heating at ca. 470 °C under dynamic nitrogen atmosphere. Eight inorganic additives (NaOH, Na2CO3, Na2SiO3, NaCl, TiO2, HZSM-5, H3PO4, Fe2(SO4)3) were investigated in terms of their catalytic effects on the pyrolysis. All of the eight additives have increased yields of solid products greatly and decreased yields of gaseous products more or less. Yields of liquid products have not subjected to dramatic change. The incondensable gases produced from pyrolysis consist mainly of H2, CH4, CO and CO2. All of the eight additives have made these gases evolve earlier, among which the four sodium additives have the most marked effect. All the additives have made the amount of CH4 and CO2 decrease, while all of them except NaCl, TiO2 and Fe2(SO4)3 have made that of H2 increase and all of them except Na2SiO3 and HZSM-5 have made that of CO decrease. Alkaline sodium compounds NaOH, Na2CO3 and Na2SiO3 favor H2 formation most. The most abundant organic component in the liquid products from pyrolysis of untreated sample and samples treated by all the additives except H3PO4 and Fe2(SO4)3 is acetol. All the four sodium compounds favor acetol formation reaction and the selection increasing effect follows the order of NaOH > Na2CO3 ≈ Na2SiO3 > NaCl. TiO2 goes against the formation of acetol, HZSM-5 has no marked effect on acetol formation. The two dominant organic components identified in the liquid products from pyrolysis of H3PO4 and Fe2(SO4)3 treated samples are both fufural and 4-methyl-2-methoxy-phenol. A possible pathway for acetol formation is tentatively proposed.

A new technology called double acid hydrolysis of lignocellulosic waste for bioethanol production has been proposed via combination of hydrochloric acid and sulfuric acid. Double acid hydrolysis is characterized with several advantages, i.e., low process energy consumption, high monosaccharide concentration and yield, inner recycle of wastewater, and no interference to ethanol distillation from crystal calcium sulfate evolving. On the basis of this hydrolysis technology, industrialization of bioethanol production is promising in terms of both economical and environmental aspects. The effects of reaction temperature and time, acid concentration, and the ratio of liquid to solid biomass (L/S) on monosaccharide concentration and yield were investigated and the optimum reaction conditions were determined as follows. The temperatures for the first stage hydrolysis and the second stage hydrolysis are 120 and 165 °C, respectively. The time for the first stage hydrolysis and the second stage hydrolysis is 25 and 15 min, respectively. Acid concentration is 1 wt %, and L/S is 8. Under these conditions, the concentration of xylose and glucose can attain values of 34.47 and 40.51 mg/mL, respectively, and the total fermentable monosaccharide concentration and yield can attain 74.98 mg/mL and 76.55%, respectively.

The decomposition and calcination characteristics at high temperatures of calcium-enriched bio-oil (CEB) were investigated from 900 to 1100 °C in the study. The CEB were produced by reacting bio-oil with calcium hydroxide, which combined the functions of desulfurization and providing heat during the decomposition and calcination processes. The decomposition of CEB consisted of four steps, partly similar to the case of pure calcium acetate (CA). The rate of the final step, i.e., the calcination rate to derive CaO, was higher in the case of CEB than in the case of CA. The alkali metal migrated from bio-oil might accelerate the calcination rate of CEB-derived CaCO 3 and sintering rate of CaO. The porosities of CEB-derived CaO particles were higher than that from CA, but the Brunauer−Emmett−Teller (BET) surface areas were lower. Dried CEB of pH 10.0 (CEB10) were typical amorphous solids, which should be the optimum bifunctional material with a medium heating value. The decomposition of CEB10 yielded porous CaO particles of moderate surface area and sintering rate for potential SO 2 capture.

Bio-oil is a new liquid fuel but very acidic. In this study, bio-oil pyrolyzed from rice husk and two bio-oil/diesel emulsions with bio-oil concentrations of 10 wt% and 30 wt% were prepared. Tests were carried out to determine their corrosion properties to four metals of aluminum, brass, mild steel and stainless steel at different temperatures. Weight loss of the metals immersed in the oil samples was recorded. The chemical states of the elements on metal surface were analyzed by X-ray photoelectron spectroscopy (XPS). The results indicated that mild steel was the least resistant to corrosion, followed by aluminum, while brass exhibited slight weight loss. The weight loss rates would be greatly enhanced at elevated temperatures. Stainless steel was not affected under any conditions. After corrosion, increased organic deposits were formed on aluminum and brass, but not on stainless steel. Mild steel was covered with many loosely attached corrosion materials which were easy to be removed by washing and wiping. Significant metal loss was detected on surface of aluminum and mild steel. Zinc was etched away from brass surface, while metallic copper was oxidized to Cu2O. Increased Cr2O3 and NiO were presented on surface of stainless steel to form a compact passive protection film. The two emulsions were less corrosive than the bio-oil. This was due to the protection effect of diesel. Diesel was the continuous phase in the emulsions and thus could limit the contact area between bio-oil and metals.

The Stoechiometric Ratio (SR) is a key parameter to determine the equivalence ratio (ER) for combustion of materials, and which will play an important effect in energy conversion processes such as combustion, gasification, pyrolysis and reforming of fossil and renewable fuels. In this paper, an equation is presented that correlates the equivalence ratio (ER) with the higher heating value (HHV). From this, the SR can be calculated. The error in the analysis is calculated for 28 fuels, showing remarkable accuracy of the new.

The process of bio-oil pyrolysis/gasification and gas evolution characteristic was studied using a thermogravimetric analyzer coupled with Fourier transform infrared spectroscopy (TG-FTIR). Pyrolysis/gasification of bio-oil and its fractions were also performed in a fixed bed. As a result, the process of bio-oil pyrolysis/gasification can be divided into two stages. The first is volatilization and pyrolysis of the light compounds at low temperature and the second is cracking and polymerization of the heavy compounds at high temperature. The values of activation energy are 35–38 kJ/mol in the first stage and 15–22 kJ/mol in the second stage, respectively. With temperature increasing, the conversion of pyrolysis/gasification grows higher and the yield of synthesis gas (syngas) increases. However, the calorific value of the gas has an inverse correlation with the temperature. In comparison, the light fraction (LF) makes more contribution to the overall H2 release; while CO and CH4 are mainly generated from the heavy fraction (HF).

•Fast pyrolysis of lignocellulosic and algal biomass were studied by using Py-GC/MS.•The compositional difference between the two kinds of pyrolytic vapor was presented.•The pyrolysis mechanism was analyzed systematically.•Maillard reaction can convert carbonyl compounds into nitrogenous compounds.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.

A thermogravimetric approach was applied to study the drying of powdered rice straw particles to determine the drying kinetics under isothermal and nonisothermal drying conditions. The isothermal drying experiments were performed at 50, 60, 70, and 80 °C, and the nonisothermal drying experiments were performed at a heating rate of 10 °C/min from 30 to 140 °C. The thermogravimetric approach was suitable for determining the effective moisture diffusivity and drying kinetics due to its online weight recording and minimal material requirements as well as its capacity for precise temperature control. The drying process under both conditions mainly occurred during the falling rate period. However, the trend of water loss in rice straw under nonisothermal conditions was different from that under isothermal conditions, especially in terms of the drying rate and the final moisture content. Four widely used models were chosen to describe the isothermal drying process, and their corresponding nonisothermal models were obtained for describing the observed nonisothermal drying behavior. The results of model fitting showed that the logarithmic model was the best model for describing isothermal drying, whereas the nonisothermal Henderson model had the best fit for results obtained under nonisothermal conditions. The effective moisture diffusivity varied from 4.35 × 10–8 to 5.13 × 10–8 m2/s, and the drying activation energy values were 5.3 and 6.5 kJ/mol under isothermal drying conditions and nonisothermal drying conditions, respectively.