Pyrolysis of safflower (Charthamus tinctorius L.) seed press cake: part 1. The effects of pyrolysis parameters on the product yields

Safflower (Charthamus tinctorius L.) seed press cake was pyrolysed in a fixed-bed reactor. The effects of pyrolysis temperature, heating rate and sweep gas flow rates on the yields of the products were investigated. Pyrolysis runs were performed using pyrolysis temperatures between 400 and 600 °C with heating rates of 10, 30 and 50 °C min⁻¹. The obtained bio-char, gas and bio-oil yields ranged between 25 and 34 wt%, 19 and 25 wt%, and 28 and 36 wt%, respectively, at different pyrolysis conditions. The highest liquid yield was obtained at 500 °C pyrolysis temperature with a heating rate of 50 °C min⁻¹ under the sweep gas of N₂ with a flow rate of 100 cm³ min⁻¹. Employing the higher heating rate of 50 °C min⁻¹ results in maximum bio-oil yield, probably due to the decrease in mass transfer limitations. According to the results obtained under the conditions of this study, the effects of pyrolysis temperature and sweep gas flow rate are more significant than the effect of heating rate on the yields.     

Pyrolysis of olive residue and sugar cane bagasse: non-isothermal thermogravimetric kinetic analysis

Thermal degradation and kinetics for olive residue and sugar cane bagasse have been evaluated under dynamic conditions in the presence of nitrogen atmosphere, using a non-isothermal thermogravimetric method (TGA). The effect of heating rate was evaluated in the range of 2-50 K min(-1) providing significant parameters for the fingerprinting of the biomass. The DTG plot for the olive residue and sugar cane bagasse clearly shows that the bagasse begins to degrade at 473 K and exhibits two major peaks. The initial mass-loss was associated with hemicellulose pyrolysis and responsible for the first peak (538-543 K) whereas cellulose pyrolysis was initiated at higher temperatures and responsible for the second peak (600-607 K). The two biomass mainly devolatilized around 473-673 K, with total volatile yield of about 70-75%. The char in final residue was about 19-26%. Mass loss and mass loss rates were strongly affected by heating rate. It was found that an increase in heating rate resulted in a shift of thermograms to higher temperatures. Ozawa-Flynn-Wall and Vyazovkin methods were applied to determine apparent activation energy to the olive residue and sugar cane bagasse. Two different steps were detected with apparent activation energies in the 10-40% conversion range have a value of 153-162 kJ mol(-1) and 168-180 kJ mol(-1) for the hemicellulose degradation of olive residue and sugar cane bagasse, respectively. In the 50-80% conversion range, this value is 204-215 kJ mol(-1) and 231-240 kJ mol(-1) for the cellulose degradation of olive residue and sugar cane bagasse, respectively.     

Pyrolysis of groundnut de-oiled cake and characterization of the liquid product

Renewable biomass is considered as an important energy resource all over the world and for an agriculture based economy like that of India, the future prospects of being able to convert widely available biomass materials into various forms of fuel is most attractive. In this study, pyrolysis of groundnut de-oiled cake was investigated with an aim of studying the physical and chemical characteristics of the bio-fuel produced and to determine its feasibility as a commercial fuel. Thermal pyrolysis of groundnut de-oiled cake was done in a semi-batch reactor at a temperature range of 200-500 °C and at a heating rate of 20 °C/min. The chemical analysis of the bio-fuel showed the presence of functional groups such as alkanes, alkenes, alkynes, aldehydes, ketones, carboxylic acids, esters, amines, nitriles, nitro compounds and aromatics rings. The physical properties of the bio-fuel obtained were close to that of diesel and petrol.     

The effect of fire retardants on combustion and pyrolysis of sugar-cane bagasse

Experiments were conducted by thermal gravimetric analysis (TGA) and cone calorimetry to measure the affect of three fire retardants (ammonium sulphate, boric acid and borax) on the mass-loss rate and combustion characteristics of sugar-cane bagasse. Compared with untreated bagasse, bagasse impregnated with aqueous solutions of 0.1-0.5 M fire retardants exhibited an increase in char mass production from 16% up to 41% when pyrolysed and up to a 41% reduction in total heat release (THR) during combustion. Char mass production was only a weak function of additive concentration over the range of concentrations (0.1-0.5 M) used. Combining the additives did not show any synergistic effects for char production or heat release rate (HRR). Treatment of bagasse by these chemicals could be useful to enhance biochar yields in pyrolysis processes or to reduce flammability risk in composites containing bagasse.     

Influence of pyrolysis condition on switchgrass bio-oil yield and physicochemical properties

The poor and inconsistent physicochemical properties of bio-oil are inhibiting its industrialized production. We investigated the variability in properties of switchgrass bio-oil produced at three pyrolysis temperatures (T = 450, 500, and 550 °C) and three feedstock moisture contents (MC = 5%, 10%, and 15%) in a 3 × 3 factorial experiment in order to exploit opportunities to improve bio-oil properties through optimization of pyrolysis parameters. Results showed that even with the single type of feedstock and pyrolysis system, the two main factors and their interaction caused large variations in bio-oil yield and most of the measured physicochemical properties. Following improvements of bio-oil properties could be individually achieved by selecting an optimal pyrolysis condition (shown in parenthesis) comparing with the worst case: increase of bio-oil yield by more than twofold (MC = 10%, T = 450 °C), increase of pH by 20.4% from 2.74 to 3.3 (MC = 10%, T = 550 °C), increase of higher heating value by 18.1% from 16.6 to 19.6 MJ/kg (MC = 10%, T = 450 °C), decrease of density by 5.9% from 1.18 to 1.11 g/cm³ (MC = 5%, T = 550 °C), decrease of water content by 36% from 31.4 to 20.1 wt.% (MC = 5%, T = 450 °C), decrease of viscosity by 40% from 28.2 to 17 centistokes (MC = 5%, T = 550 °C), decrease of solid content by 57% from 2.86 to 1.23 wt.% (MC = 15%, T = 550 °C), and decrease of ash content by 41.9% from 0.62 to 0.36 wt.% (MC = 15%, T = 550 °C). There is no single, clear-cut optimal condition that can satisfy the criteria for a bio-oil product with all the desired properties. Trade-offs should be balanced according to the usage of the end-products.     

The effect of biomass moisture content on bioethanol yields from steam pretreated switchgrass and sugarcane bagasse

This study aimed to determine the effect of moisture content of three different feedstocks on overall ethanol yield. Switchgrass and sugarcane bagasse from two sources were either soaked in water (∼80% moisture) or left dry (∼12% moisture), and half each of these were impregnated with 3% w/w SO₂ and all were steam pretreated. The twelve resulting substrates were compared based on overall sugar recovery after pretreatment, cellulose conversion following enzymatic hydrolysis, and ethanol yield following simultaneous saccharification and fermentation. The overall ethanol yield after simultaneous saccharification and fermentation of hexoses was 18-28% higher in samples that were soaked prior to SO₂ addition than in SO₂-catalyzed samples that were not soaked. In samples that were uncatalyzed, soaking made little difference, indicating that the positive effect of increased moisture content may be related to increased permeability of the biomass to SO₂.     

In-situ upgrading of biomass pyrolysis vapors: catalyst screening on a fixed bed reactor

In-situ catalytic upgrading of biomass fast pyrolysis vapors was performed in a fixed bed bench-scale reactor at 500 °C, for catalyst screening purposes. The catalytic materials tested include a commercial equilibrium FCC catalyst (E-cat), various commercial ZSM-5 formulations, magnesium oxide and alumina materials with varying specific surface areas, nickel monoxide, zirconia/titania, tetragonal zirconia, titania and silica alumina. The bio-oil was characterized measuring its water content, the carbon-hydrogen-oxygen (by difference) content and the chemical composition of its organic fraction. Each catalytic material displayed different catalytic effects. High surface area alumina catalysts displayed the highest selectivity towards hydrocarbons, yielding however low organic liquid products. Zirconia/titania exhibited good selectivity towards desired compounds, yielding higher organic liquid product than the alumina catalysts. The ZSM-5 formulation with the highest surface area displayed the most balanced performance having a moderate selectivity towards hydrocarbons, reducing undesirable compounds and producing organic liquid products at acceptable yields.     

Properties of oil and char derived from slow pyrolysis of Tetraselmis chui

Pyrolysis of biomass is a means to industrially manufacture renewable oil and gas, in addition to biochar for soil amendment and long-term carbon fixation. In this work, oil and char derived from the slow pyrolysis of the unicellular marine diatom Tetraselmis chui are analysed using a variety of techniques. The pyrolytic oil fraction exhibits a wide variety of fatty acids, alkanes, alkenes, amides, aldehydes, terpenes, pyrrolidinines, phytol and phenols, with a high heating value (HHV) of 28 MJ/kg. The biochar produced has a HHV of 14.5 MJ/kg and reveals a number of properties that are potentially valuable from an agronomic point of view, including high cation exchange capacity (CEC), large concentration of N, and a low C:N ratio. The quantity of C in T. chui biochar that can be expected to stabilise in soil amounts to approximately 9%/wt of the original feedstock, leading to a potential net reduction in atmospheric CO₂.     

Bio-oil and bio-char from low temperature pyrolysis of spent grains using activated alumina

The pyrolysis of wheat and barley spent grains resulting from bio-ethanol and beer production respectively was investigated at temperatures between 460 and 540 °C using an activated alumina bed. The results showed that the bio-oil yield and quality depend principally on the applied temperature where pyrolysis at 460 °C leaves a bio-oil with lower nitrogen content in comparison with the original spent grains and low oxygen content. The viscosity profile of the spent grains indicated that activated alumina could promote liquefaction and prevent charring of the structure between 400 and 460 °C. The biochar contains about 10-12% of original carbon and 13-20% of starting nitrogen resulting very attractive as a soil amendment and for carbon sequestration. Overall, value can be added to the spent grains opening a new market in bio-fuel production without the needs of external energy. The bio-oil from spent grains could meet about 9% of the renewable obligation in the UK.     

蔗渣制备低聚木糖的有机酸预处理条件研究

采用有机酸法水解制备蔗渣低聚木糖,通过单因素实验、正交试验研究了甲酸-乙酸比例、温度、水解时间、固液比等因素的影响,以水解率、总糖收率和聚糖收率为考察指标,得到有机酸法水解蔗渣制备低聚木糖的最优预处理条件为甲酸∶乙酸=9∶1、水解温度100℃、水解时间60min、固液比1∶7,在此条件下蔗渣水解率为47.78%,总糖收率20.57%,聚糖收率11.88%。HPLC检测结果显示:水解物中木二糖含量为17.69%,木三糖为11.23%,更高聚合度聚糖所占比例为29.42%,木糖为36.78%。半纤维素有机酸水解物可进一步通过木聚糖酶水解、分离制备低聚木糖。研究结果可为蔗渣制备低聚木糖新工艺提供科学依据。     

Pyrolysis of Mixed Date Stones and Pistachio Shells: Identification of Bio-Oil and Utilization of Bio-Char as Activated Carbon Precursor

Thermal pyrolysis of mixed date stones and pistachio shells in a semi-batch reactor was addressed in this study. The highest yield of liquids (51.20 %) was produced at 500 °C, 90 min, 20 °C/min heating rate, and 50 mesh particle size. Under these conditions, yield of liquid from date stones and pistachio shells separately was 49.12 % and 47.67 %, respectively. The FT-IR results confirmed the presence of multiple oxygen-containing compounds in the bio-oil. Results from GC–MS declared that it was predominately composed of acids (57.57 %), esters (21.35 %), phenols (4.63 5), and alcohols (3.49 5). The obtained biochar was transformed into activated carbon (AC) by the optimized ZnCl₂ activation method. The ideal AC was synthesized at 600 °C for 60 min using a 2 : 1 ZnCl₂: biochar impregnation ratio. FESEM and XRD measurements showed that the AC was amorphous. The prepared AC was effective in eliminating dibenzothiophene (DBT) from model fuel (200 ppm DBT/hexane) with a maximum performance 95.26 % at 40 °C for 1h using 0.35 g of the AC. The exhausted AC was regenerated and reutilized 4 times, and removal efficiency reached 88.23 % in the 4^th cycle under ideal working conditions.     

Fast pyrolysis of soybean cake: product yields and compositions

This study was an investigation of the role of important parameters influencing pyrolysis yields from soybean cake. Experiments were carried out at temperatures ranging from 400 to 700 degrees C, for various nitrogen flow rates, heating rates and particle sizes. The maximum liquid yield was 42.83% at a pyrolysis temperature of 550 degrees C with a sweeping gas rate of 200 cm3 min(-1) and heating rate of 700 degrees C min(-1) for a soybean cake sample having 0.425 < D(p) < 0.85 mm particle size. The various characteristics of liquid product were identified. Thus, the aliphatic sub-fraction of the bio-oil was analysed by GC-MS and further structural analyses of bio-oil and aromatic and polar sub-fractions were conducted using FT-IR and 1H-NMR. The H/C ratios and the structural analysis of the fractions obtained from the biocrudes showed that the fractions were quite similar to currently utilised transport fuels.     

Extraction and characterization of wax from sugarcane bagasse and the enzymatic hydrolysis of dewaxed sugarcane bagasse

Extraction of high-value products from agricultural wastes is an important component for sustainable bioeconomy development. In this study, wax extraction from sugarcane bagasse was performed and the beneficial effect of dewaxing pretreatment on the enzymatic hydrolysis was investigated. About 1.2% (w/w) of crude sugarcane wax was obtained from the sugarcane bagasse using the mixture of petroleum ether and ethanol (mass ratio of 1:1) as the extraction agent. Results of Fourier-transform infrared characterization and gas chromatography–mass spectrometry qualitative analysis showed that the crude sugarcane wax consisted of fatty fractions (fatty acids, fatty aldehydes, hydrocarbons, and esters) and small amount of lignin derivatives. In addition, the effect of dewaxing pretreatment on the enzymatic hydrolysis of sugarcane bagasse was also investigated. The digestibilities of cellulose and xylan in dewaxed sugarcane bagasse were 18.7 and 10.3%, respectively, compared with those of 13.1 and 8.9% obtained from native sugarcane bagasse. The dewaxed sugarcane bagasse became more accessible to enzyme due to the disruption of the outermost layer of the waxy materials.     

Fractional and physico-chemical characterization of hemicelluloses from ultrasonic irradiated sugarcane bagasse

The present study was undertaken to investigate the extractability of the hemicelluloses from bagasse obtained by ultrasound-assisted extraction methods. The results showed that the ultrasonic treatment and sequential extractions with alkali and alkaline peroxide under the conditions given led to a release of over 90% of the original hemicelluloses and lignin. This fact as well as the sugar composition and structural features of the isolated seven hemicellulosic fractions indicated that ultrasonication attacked the integrity of cell walls, cleaved the ether linkages between lignin and hemicelluloses, and increased accessibility and extractability of the hemicelluloses. Increasing alkali concentration from 0.5 to 2M and alkaline peroxide percentage from 0.5% to 3.0% resulted in degradation of hemicellulosic backbone as shown by a decrease in their molecular weights from 43,580 to 14,470 and 30,180 to 18,130gmol(-1), respectively. However, there were no significant differences in the structural features of the seven sequential alkali- or alkaline peroxide-soluble hemicellulosic fractions, which are composed mainly of L-arabino-(4-O-methyl-D-glucurono)-D-xylans. Ferulic and p-coumaric acids were found to be chemically linked with hemicelluloses.     

Modeling of the devolatilization kinetics during pyrolysis of grape residues

Thermo-gravimetric analysis (TGA) was performed on grape seeds, skins, stalks, marc, vine-branches, grape seed oil and grape seeds depleted of their oil. The TGA data was modeled through Gaussian, logistic and Miura-Maki distributed activation energy models (DAEMs) and a simpler two-parameter model. All DAEMs allowed an accurate prediction of the TGA data; however, the Miura-Maki model could not account for the complete range of conversion for some substrates, while the Gaussian and logistic DAEMs suffered from the interrelation between the pre-exponential factor k₀ and the mean activation energy E₀ - an obstacle that can be overcome by fixing the value of k₀a priori. The results confirmed the capabilities of DAEMs but also highlighted some drawbacks in their application to certain thermodegradation experimental data.     

Influence of manure types and pyrolysis conditions on the oxidation behavior of manure char

Livestock manure can be quickly converted into valuable products (H₂, syn-gas and char) by low temperature gasification. Manure char combustion offers energy for the gasification reactions. In the paper, the influence of manure type and pyrolysis conditions on manure char reactivity is addressed. The results show that the oxidation behaviors of manure char are dependent strongly on manure type and pyrolysis conditions employed. The large difference between the oxidation behaviors of pig and hen manure chars can be attributed to the difference in the organic materials and minerals of the samples. High final temperature, flash pyrolysis and water steam atmosphere used for char preparation promote the resultant char reactivity.     

Fast pyrolysis of palm kernel cake in a closed-tubular reactor: product compositions and kinetic model

In this study, fast pyrolysis of palm kernel cake (PKC) was carried out in a closed-tubular reactor over a temperature range of 550 to 750 °C with various retention times. The pyrolyzing gas products mainly included CO, CO₂, and light hydrocarbons; it is noted that no hydrogen was detected in the product. In order to investigate the reaction pathway, the kinetic lump model of Liden was applied to verify and calculate all rate constants. The results obtained at different temperatures indicated that the rate constant increased with pyrolysis temperature. Furthermore, the experimental results were in good agreement with the proposed mechanism.     

Effect of hot vapor filtration on the characterization of bio-oil from rice husks with fast pyrolysis in a fluidized-bed reactor

To produce high quality bio-oil from biomass using fast pyrolysis, rice husks were pyrolyzed in a 1-5 kg/h bench-scale fluidized-bed reactor. The effect of hot vapor filtration (HVF) was investigated to filter the solid particles and bio-char. The results showed that the total bio-oil yield decreased from 41.7% to 39.5% by weight and the bio-oil had a higher water content, higher pH, and lower alkali metal content when using HVF. One hundred and twelve different chemical compounds were detected by gas chromatography-mass spectrometry (GC-MS). The molecular weight of the chemical compounds from the condenser and the EP when the cyclone was coupled with HVF in the separation system decreased compared with those from the condenser and EP when only cyclone was used.     

Synthesis and properties of polyaniline–cellulose acetate blends: The use of sugarcane bagasse waste and the effect of the substitution degree

Membranes of blends of polyaniline (PANi) and cellulose acetate (CA) produced from sugarcane bagasse with different degrees of substitution were produced and characterized using various techniques. Results showed that incorporation of PANi into the CA matrices leads to significant alterations of the blend morphologies, with phase separation, and that these differences are less significant for PANi/cellulose triacetate blends. The blends also showed a significant increase in electrical conductivity, with that of PANi/cellulose diacetate demonstrating an almost 200-fold increase.