Phosphorus catalysis in the pyrolysis behaviour of biomass

Phosphorus is a key plant nutrient and as such, is incorporated into growing biomass in small amounts. This paper examines the influence of phosphorus, present in either acid (H₃PO₄) or salt ((NH₄)₃PO₄) form, on the pyrolysis behaviour of both Miscanthus × giganteus, and its cell wall components, cellulose, hemicellulose (xylan) and lignin (Organosolv). Pyrolysis–gas chromatography–mass spectrometry (PY–GC–MS) is used to examine the pyrolysis products during thermal degradation, and thermogravimetric analysis (TGA) is used to examine the distribution of char and volatiles. Phosphorus salts are seen to catalyse the pyrolysis and modify the yields of products, resulting in a large increase in char yield for all samples, but particularly for cellulose and Miscanthus. The thermal degradation processes of cellulose, xylan and Miscanthus samples occur in one step and the main pyrolysis step is shifted to lower temperature in the presence of phosphorus. A small impact of phosphorus was observed in the case of lignin char yields and the types of pyrolysis decomposition products produced. Levoglucosan is a major component produced in fast pyrolysis of cellulose. Furfural and levoglucosenone become more dominant products upon P-impregnation pointing to new rearrangement and dehydration routes. The P-catalysed xylan decomposition route leads to a much simpler mixture of products, which are dominated by furfural, 3-methyl-2-cyclopenten-1-one and one other unconfirmed product, possibly 3,4-dihydro-2-methoxy-2H-pyran or 4-hydroxy-5,6-dihydro-(2H)-pyran-2-one. Phosphorus-catalysed lignin decomposition also leads to a modified mixture of tar components and desaspidinol as well as other higher molecular weight component become more dominant relative to the methoxyphenyl phenols, dimethoxy phenols and triethoxy benzene. Comparison of the results for Miscanthus lead to the conclusion that the understanding of the fast pyrolysis of biomass can, for the most part, be gained through the study of the individual cell wall components, provided consideration is given to the presence of catalytic components such as phosphorus.     

Analytical pyrolysis studies of corn stalk and its three main components by TG-MS and Py-GC/MS

The pyrolysis behaviors of corn stalk and its three real components (i.e. hemicellulose, cellulose, and lignin) have been investigated with the techniques of TG-MS and Py-GC/MS. The thermal behavior and the evolution profiles of major volatile fragments from each sample pyrolysis have been discussed in depth, while paying close attention to the impact and contributions of each component on the raw material pyrolysis. It was found that pyrolysis of the corn stalk was a comprehensive reflection of its three main components both on thermogravimetric characteristics and on products distribution and their formation profiles. Hemicellulose definitely made the greatest contribution to the formation of acids and ketones at around 300 °C. Cellulose was more dedicated to the products of furans and small molecule aldehydes in a short temperature range 320–410 °C. While lignin mainly contributed to produce phenols and heterocyclic compounds over a wider temperature range 240–550 °C. The experimental results obtained in the present work are of interest for further studies on selective fast pyrolysis of biomass into energy and chemicals.     

Pyrolysis of textile wastes: I. Kinetics and yields

Thermal behavior of textile waste was studied by thermogravimetry at different heating rates and also by semi-batch pyrolysis. It was shown that the onset temperature of mass loss is within 104–156 °C and the final reaction temperature is within 423–500 °C. The average mass loss is 89.5%. There are three DTG peaks located at the temperature ranges of 135–309, 276–394 and 374–500 °C, respectively. The first two might be associated with either with decomposition of the hemicellulose and cellulose or with different processes of cellulose decomposition. The third peak is possibly associated to a synthetic polymer. At a temperature of 460 °C, the expected amount of volatiles of this waste is within 85–89%. The kinetic parameters of the individual degradation processes were determined by using a parallel model. Their dependence on the heating rate was also established. The pyrolysis rate is considered as the sum of the three reaction rates. The pyrolysis in a batch reactor at 700 °C and nitrogen flow of 60 ml/min produces 72 wt.% of oil, 13.5 wt.% of gas and 12.5 wt.% of char. The kinetic parameters of the first peak do not vary with heating rate, while those of the second and the third peak increase and decrease, respectively, with an increasing heating rate, proving the existence of complex reaction mechanisms for both cases.     

Pyrolysis of biocollagenic wastes of vegetable tanning. Optimization and kinetic study

Three solid wastes generated from the vegetable tanning of bovine skin in the Leather Industry (shavings, trimmings and buffing dust) were mixed together in the same proportions in which they were produced and the mixture was then used as a pyrolysis precursor for this research study. The optimal pyrolysis conditions for obtaining energy from the generated fractions (char, tar and gas fraction), and the preparation of activated carbons from the carbonaceous material (char), were established. The final conditions were chosen from two different points of view, the thermogravimetric results (TG/DTG) obtained at different heating rates (2–20 °C/min) and an optimization of the pyrolysis parameters by means of experiments carried out in a conventional furnace. The pyrolysis conditions finally selected were: heating rate (5 °C/min), final temperature (750 °C), and time at final temperature (60 min) and inert gas flow (N₂ 150 ml/min). The carbonaceous material (char) obtained exhibits good properties as a solid fuel due to its high calorific value and relatively low ash content. It also shows suitable characteristics as a precursor for the preparation of activated carbons. The condensable fraction has a predominantly phenolic nature and contains significant amounts of nitrogen compounds (nitriles, diketopiperazines, etc.), alkanes, alkenes, acids and esters, derived from the decomposition of tannins and collagen, with possible industrial applications in the preparation of chemical products. The gaseous phase is rich in carbon monoxide and carbon dioxide, and also contains a certain amount of methane and hydrogen. The syngas content increases with the pyrolysis temperature. A kinetic study of the pyrolysis was carried out using a model of independent reactions. The variation in the heating rate produced a slight shift to higher temperatures of the decomposition peaks, although this did not significantly affect either the kinetic parameters of the degradation processes or the percentage weight losses.     

Characterization of the water-insoluble pyrolytic cellulose from cellulose pyrolysis oil

Water-insoluble pyrolytic cellulose with similar appearance to pyrolytic lignin was found in cellulose fast pyrolysis oil. The influence of pyrolysis temperature on pyrolytic cellulose was studied in a temperature range of 300–600 °C. The yield of the pyrolytic cellulose increased with temperature rising. The pyrolytic cellulose was characterized by various methods. The molecular weight distribution of pyrolytic cellulose was analyzed by gel permeation chromatography (GPC). Four molecular weight ranges were observed, and the M_w of the pyrolytic cellulose varied from 3.4 × 10³ to 1.93 × 10⁵ g/mol. According to the elemental analysis (EA), the pyrolytic cellulose possessed higher carbon content and lower oxygen content than cellulose. Thermogravimetric analysis (TGA) indicated that the pyrolytic cellulose underwent thermo-degradation at 127–800 °C and three mass loss peaks were observed. Detected by the pyrolysis gas chromatography–mass spectrometry (Py-GC/MS), the main pyrolysis products of the pyrolytic cellulose included saccharides, ketones, acids, furans and others. Fourier transforms infrared spectroscopy (FTIR) also demonstrated that the pyrolytic cellulose had peaks assigned to CO stretching and glycosidic bond, which agreed well with the Py-GC/MS results. The pyrolytic cellulose could be a mixture of saccharides, ketones, and their derivatives.     

Selective pyrolysis of Organosolv lignin over zeolites with product analysis by TG-FTIR

Organosolv lignin has been selected to investigate the thermal behavior of lignin over zeolites by using a thermogravimetric analyzer coupled with a Fourier-transform infrared spectrometer (TG-FTIR). The chemical structure of this lignin has been determined by ¹H NMR to obtain the distribution of main functional groups such as methoxyl groups and free aliphatic and phenolic hydroxyl groups. All three zeolite catalysts tested, HZSM-5, H-β, and USY, exerted significant influences on the dehydration reaction in the initial stage, the deoxygenation reaction of oxygenated compounds such as methanol and phenols, and the char-forming process during lignin pyrolysis in the range 30–800 °C. The dehydration reaction was enhanced in the order USY > HZSM-5 > H-β, while char formation was suppressed in the reverse order. The presence of HZSM-5 and H-β catalyzed the conversion of both oxygenated compounds and chars into the low-molecular-weight gases CO, CO₂, and methane. The addition of USY clearly aided decomposition of the oxygenated compounds, but had little effect on the char degradation.     

The effect of storage duration on bio-oil properties

Bio-oil produced by fluidized fast pyrolysis of yellow poplar wood (Liriodendron tulipifera) was stored in sealed glass bottles at 23 °C for 2, 4, 6, 8, or 10 weeks to investigate the effect of storage time on bio-oil properties. Bio-oil viscosity increased with increasing storage duration, while pH, water content and heating value remained unchanged. Thirty-three components were identified in the bio-oils and were classified into five sub-groups: aldehydes and ketones from carbohydrates, aliphatic phenols, phenolic aldehydes, and phenolic ketones from lignin. The concentrations of the sub-groups, especially the carbohydrate-derived ketones and lignin-derived compounds, gradually decreased with prolonged storage. In contrast, the yield of pyrolytic lignin extracted from bio-oils increased with storage duration from 13.2 wt% (fresh bio-oil; control) to 24.3 wt% (10 weeks). The average molecular weight of pyrolytic lignin also increased from 872 (control) to 1161 g mol⁻¹ (10 weeks). The amounts of phenolic hydroxyl and methoxyl groups decreased from 11.2 wt% (control) to 8.0 wt% (10 weeks) and 11.9 wt% (control) to 8.6 wt% (10 weeks), respectively. The observations strongly indicate that the low molecular weight components could participate in the re-polymerization with pyrolytic lignin, and the plausible polymerization reactions could be predicted to esterification, oxidation, hemiacetal/acetal formation and olefinic condensation.     

Catalytic effects of copper(II) chloride and aluminum chloride on the pyrolytic behavior of cellulose

The cellulose without and with catalyst (CuCl₂, AlCl₃) was subjected to pyrolysis at temperatures from 350 to 500 °C with different heating rate (10 °C/min, 100 °C/s) to produce bio-oil and selected chemicals with high yield. The pyrolytic oil yield was in the range of 37–84 wt% depending on the temperature, the heating rate and the amount of metal chloride. The non-catalytic fast pyrolysis at 500 °C gives the highest yield of bio-oil. The mixing cellulose with both metal chlorides results with a significant decrease of the liquid product. The non-catalytic pyrolysis of cellulose gives the highest mass yield of levoglucosan (up to 11.69 wt%). The great influence of metal chloride amount on the distribution of bio-oil components was observed. The copper(II) chloride and aluminum chloride addition to cellulose clearly promotes the formation of levoglucosenone (up to 3.61 wt%), 1,4:3,6-dianhydro-α-d-glucopyranose (up to 3.37 wt%) and unidentified dianhydrosugar (MW = 144; up to 1.64 wt%). Additionally, several other compounds have been identified but in minor quantities. Based on the results of the GC–MS, the effect of pyrolysis process conditions on the productivity of selected chemicals was discussed. These results allowed to create a general model of reactions during the catalytic pyrolysis of cellulose in the presence of copper(II) chloride and aluminum chloride.     

Conventional and microwave induced pyrolysis of coffee hulls for the production of a hydrogen rich fuel gas

This paper describes the conventional and microwave-assisted pyrolysis of coffee hulls at 500, 800 and 1000 °C. The influence of the pyrolysis method and temperature on the product yields and on the characteristics of the pyrolysis products is discussed. It was found that the pyrolysis of this particular residue gives rise to a larger yield of the gas fraction compared to the other fractions, even at relatively low temperatures. A comparison of microwave-assisted pyrolysis and conventional pyrolysis showed that microwave treatment produces more gas and less oil than conventional pyrolysis. In addition, the gas from the microwave has much higher H₂ and syngas (H₂ + CO) contents (up to 40 and 72 vol.%, respectively) than those obtained by conventional pyrolysis (up to 30 and 53 vol.%, respectively), in an electric furnace, at similar temperatures. From the pyrolysis fraction yields and their higher heating values it was found that the energy distribution in the pyrolysis products decreases as follows: gas > solid > oil. Moreover, the energy accumulated in the gas increases with the pyrolysis temperature. By contrast, the energy accumulated in the char decreases with the temperature. This effect is enhanced when microwave pyrolysis is used.     

The effects of temperature on product yields and composition of bio-oils in hydropyrolysis of rice husk using nickel-loaded brown coal char catalyst

Hydropyrolysis of rice husk was performed using nickel-loaded Loy Yang brown coal char (Ni/LY) catalyst in a fluidized bed reactor at 500, 550, 600 and 650 °C with an aim to study the influence of catalyst and catalytic hydropyrolysis temperature on product yields and the composition of bio-oil. An inexpensive Ni/LY char was prepared by the ion-exchange method with nickel loading rate of 9 ± 1 wt.%. Nickel particles which dispersed well in Loy Yang brown coal char showed a large specific surface area of Ni/LY char of 350 m²/g. The effects of catalytic activity and hydropyrolysis temperature of rice husk using Ni/LY char were examined at the optimal condition for bio-oil yield (i.e., pyrolysis temperature 500 °C, static bed height 5 cm, and gas flow rate 2 L/min without catalyst). In the presence of catalyst, the oxygen content of bio-oil decreased by about 16% compared with that of non-catalyst. Raising the temperature from 500 to 650 °C reduced the oxygen content of bio-oil from 27.50% to 21.50%. Bio-oil yields decreased while gas yields and water content increased with increasing temperature due to more oxygen being converted into H₂O, CO₂, and CO. The decreasing of the oxygen content contributed to a remarkable increase in the heating value of bio-oil. The characteristics of bio-oil were analyzed by Karl Fischer, GC/MS, GPC, FT-IR, and CHN elemental analysis. The result indicated that the hydropyrolysis of rice husk using Ni/LY char at high temperature can be used to improved the quality of bio-oil to level suitable for a potential liquid fuel and chemical feedstock.     

Low temperature mechanism for the formation of polycyclic aromatic hydrocarbons from the pyrolysis of cellulose

The formation of polycyclic aromatic hydrocarbons (PAHs) from the pyrolysis of cellulose over the temperature range of 300–650 °C has been investigated. Detectable amounts (microgram per gram) of 2–4 ring PAHs were observed at and above 400 °C. Benzo[a]pyrene and benz[a]anthracene were observed at and above 500 °C. Changing the gas phase residence time from 2 to 18 s and the sample size from 200 to 500 mg did not significantly affect the yields of PAHs formed over this low temperature range. The addition of oxygen to the carrier gas stream significantly reduced the yields of PAHs. The pathway to PAH formation in the 300–650 °C temperature range is believed to proceed via the carbonization process where the solid residue undergoes a chemical transformation and rearrangement to give a more condensed polycyclic aromatic structure. The evolution profiles of PAHs from the solid residue suggests that smaller 2–3 ring PAHs evolve first and pass through a maximum at a slightly lower temperature than the larger 4–5 ring PAHs. The yields of PAHs obtained from the pyrolysis of d-glucose and sucrose are comparable to those obtained from cellulose.     

Syngas Production from Lignite Coal Using K2CO3 Catalytic Steam Gasification with Controlled Heating Rate in Pyrolysis Step

Gasification uses steam increases H2 content in the syngas. Kinetics of gasification process can be improved by using K₂CO₃ catalyst. Controlled heating rate in pyrolysis step determines the pore size of charcoal that affects yield gas and H₂ and CO content in the syngas. In previous research, pyrolisis step was performed without considering heating rate in pyrolysis step. This experiment was performed by catalytic steam gasification using lignite char from pyrolysis with controlled heating rate intended to produce maximum yield of syngas with mole ratio of H₂/CO ≈ 2. Slow heating rate (3 °C/min) until 850 °C in the pyrolysis step has resulted in largest surface area of char. This study was performed by feeding Indonesian lignite char particles and K₂CO₃ catalyst into a fixed bed reactor with variation of steam/char mole ratio (2.2; 2.9; 4.0) and gasification temperature (750 °C, 825 °C, and 900 °C). Highest ratio of H₂/CO (1.682) was obtained at 750 °C and steam/char ratio 2.2. Largest gas yield obtained from this study was 0.504 mol/g of char at 900 °C and steam/char ratio 2.9. Optimum condition for syngas production was at 750 °C and steam/char mole ratio 2.2 with gas yield 0.353 mol/g of char and H₂/CO ratio 1.682.     

Characterization of the different fractions obtained from the pyrolysis of rope industry waste

A study of the possibilities of pyrolysis for recovering wastes of the rope's industry has been carried out. The pyrolysis of this lignocellulosic residue started at 250 °C, with the main region of decomposition occurring at temperatures between 300 and 350 °C. As the reaction temperature increased, the yields of pyrolyzed gas and oil increased, yielding 22 wt.% of a carbonaceous residue, 50 wt.% tars and a gas fraction at 800 °C. The chemical composition and textural characterization of the chars obtained at various temperatures confirmed that even if most decomposition occurs at 400 °C, there are some pyrolytic reactions still going on above 550 °C. The different pyrolysis fractions were analyzed by GC–MS; the produced oil was rich in hydrocarbons and alcohols. On the other hand, the gas fraction is mainly composed of CO₂, CO and CH₄. Finally, the carbonaceous solid residue (char) displayed porous features, with a more developed porous structure as the pyrolysis temperature increased.     

Study of products yield of bagasse and sawdust via slow pyrolysis and iron-catalyze

In this paper, the via slow pyrolysis behavior of the bagasse and sawdust were studied at the different heating rates, the different iron-containing blend pyrolysis and the treatment temperature, the further understood for the pyrolysis of agricultural residues. The distribution of the products yield of the slow pyrolysis process, it is typically performed at temperature between 200 and 600 °C, the pyrolysis temperature increased, the bio-liquids and gas yields tended to increase, which at 400 °C was able to achieve maximum bio-liquids yields, the biochar yields tended to downward. For different heating rate, in the heating rate ranges for 80–100 W, the bio-liquids products yield curve increased from 44.5 wt% to 46.5 wt% for bagasse; the sawdust products yield increased from 41 wt% to 42.75 wt%. Iron-catalysts blend pyrolysis (0, 10, 25, 40 and 50 wt%), the bagasse bio-liquid yields respectively 56.25 wt% in the presence 50% iron-catalysts blend pyrolysis; the sawdust bio-liquid yields respectively 52.5 wt% in the presence 40% iron-catalysts blend. The pyrolysis process were calculated according to the kinetic mechanism were examined, the pyrolysis activation energy was between 6.55 and 7.49 kcal/mol for bagasse. Sawdust the pyrolysis activation energy was between 11.52 and 11.76 kcal/mol. Therefore, in this study a pyrolysis model of bagasse and sawdust thermal treatment may provide both agricultural and forestry transformation importance of resources.     

Chemical composition of bio-oil produced by co-pyrolysis of biopolymer/polypropylene mixtures with K2CO3 and ZnCl2 addition

The chemical composition of liquid products of cellulose and lignin co-pyrolysis with polypropylene at 450 °C with and without the potassium carbonate or zinc chloride as an catalyst was investigated. The yield of liquid products of pyrolysis was in the range of 26–45 wt% and their form was liquid or semi-solid highly depending on the composition of sample and pyrolysis conditions. The potassium carbonate and zinc chloride addition to blends has also influenced the range of samples decomposition as well as the chemical composition of resulted bio-oils. All bio-oils from biopolymer and polypropylene mixtures were three-phase (water, oil and solid). While zinc chloride acted as catalyst, all bio-oils obtained from biopolymer and polypropylene mixtures were yellow liquids with well-separated water and oil phases. All analyses proved that the structure and quality of bio-oil strongly depends on both the composition of the blend and the presence of the additive. The FT-IR and GC–MS analyses of oils showed that oxygen functionalities and hydrocarbons contents highly depend on the composition of biomass/polypropylene mixture. Results confirmed the significant removal and/or transformation of oxygen containing organic compounds, i.e. levoglucosan, 1,6-anhydro-β-d-glucofuranose and phenol derivatives due to the zinc chloride presence during pyrolysis process. All analyses showed that zinc chloride as catalyst was generally much more effective for removal of hydroxyl and methoxy groups than was potassium carbonate. It was demonstrated in this study that catalysts used in present work lead to the increased char yield and improved the fuel quality of bio-oil.     

Effect of conditions on fast pyrolysis of bamboo lignin

Products derived from bamboo EMAL pyrolysis were investigated by means of pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and the effects of temperature and catalyst (sodium chloride, permutite) on the yields of pyrolysis products were probed in detail. The results showed that thermal degradation of EMAL mainly occurred at the temperature range from 250 °C to 600 °C, and both the temperature and catalyst in EMAL pyrolysis were important factors in the formation or inhibition of products. The products that derived from p-hydroxyphenylpropanoid, guaiacylpropanoid, and syringylpropanoid of lignin units by pyrolytic reactions were classified as the heterocycle (2,3-dihydrobenzofuran), phenols, a small quantity of acetic acid and furans, etc. With an increase of pyrolysis temperature, the amount fraction of 2,3-dihydrobenzofuran (DHBF) decreased from 66.26% to 19.15%. Moreover, when the additive catalyst increased from 5% to 20%, permutite catalyst improved in the formation of DHBF from19.15% to 24.19%, whereas NaCl catalyst was effective to inhibit the production of DHBF from 19.15% to 13.08%. Permutite promoted the production of coke from EMAL pyrolysis, conversely, NaCl had an inhibiting effect on the generation of coke. And NaCl catalyst had a significant catalytic effect on raising or reducing of the product yields in bamboo lignin pyrolysis.     

Kinetic study of the pyrolysis and combustion of tomato plant

A kinetic study of the thermal decomposition of tomato plant has been carried out under different conditions by TG and TG–MS. A total of 24 experiments were performed in a nitrogen atmosphere (pyrolysis runs) and also in an oxidative atmosphere with two different oxygen concentrations (10% and 20% oxygen in nitrogen). Dynamic runs and dynamic + isothermal runs have been carried out to obtain many data of decomposition under different operating conditions.A scheme of five independent reactions for pseudocomponents has been proposed for the pyrolysis process, although only three fractions have probed to be significant, comparing the weight fractions of volatiles evolved with the hemicellulose, cellulose and lignin content of the plant. For the combustion runs, four new reactions have been added: two competitive oxidation reactions for the cellulose and lignin, and two combustion reactions of the carbonaceous residue obtained from pyrolysis. The kinetic parametres have been calculated by integration of the differential equations and minimizing the differences between the experimental and calculated values. It is important to emphasize that the same set of parameters has been proposed for the pyrolysis and combustion runs, and which do not depend on either the heating rate in dynamic runs or whether the run is carried out in a dynamic or isothermal mode. The influence of the oxygen pressure has been also discussed.     

Py-GC/MS characterization of a wild and a selected clone of Arundo donax,and of its residues after catalytic hydrothermal conversion to high added-value products

Two analytical procedures based on gas chromatography and mass spectrometry were used to study the compositions of a wild population and a selected clone (Torviscosa) of giant reed (Arundo donax L.), one of the most promising biomass both in terms of energy and fine chemicals production. Gas chromatography/mass spectrometry (GC/MS) was used to characterize and quantitatively determine the monosaccharide composition. Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), using hexamethyldisilazane (HMDS) as a derivatising agent, was used to characterize the lignocellulosic polymers. Analytical pyrolysis was also used to study the composition of residues left after the catalytic hydrolysis used to convert cellulose to levulinic acid and hemicellulose to furfural.GC/MS allowed us to determine the monosaccharide composition and polysaccharide content of the giant reed samples, highlighting that there was no significant difference between the wild population and the selected clone. GC/MS also highlighted that the giant reed leaves have a higher percentage (roughly 60%) of polysaccharide material than the stalks, which contain approximately 50%.Py-GC/MS, following the disappearance of the pyrolysis products of polysaccharides, showed that 150 °C and 190 °C are the best temperatures to obtain the complete catalytic conversion of hemicellulose and cellulose, respectively. Analytical pyrolysis also highlighted that in the course of catalytic hydrothermal conversion a partial depolymerisation of lignin was obtained. In particular, the formation of lignin units containing free phenol groups via the cleavage of the β-aryl ether bonds was demonstrated. The presence of these free phenols in the lignin network suggests the possible exploitation of lignin residues as antioxidant components or in high value biopolymer industries rather than the traditional use as low-value fuel for energy production.     

Biomass valorisation by staged degasification: A new pyrolysis-based thermochemical conversion option to produce value-added chemicals from lignocellulosic biomass

Pyrolysis of lignocellulosic biomass leads to an array of useful solid, liquid and gaseous products. Staged degasification is a pyrolysis-based conversion route to generate value-added chemicals from biomass. Because of different thermal stabilities of the main biomass constituents hemicellulose, cellulose and lignin, different temperatures may be applied for a step-wise degradation into valuable chemicals. Staged degasification experiments were conducted with deciduous (beech, poplar), coniferous (spruce) and herbaceous (straw) biomass. Thermogravimetry was used to estimate appropriate temperatures for a two-stage degradation process that was subsequently evaluated on bench-scale by moving bed and bubbling fluidised bed pyrolysis experiments. Degasification in two consecutive stages at 250–300 °C and 350–400 °C leads to mixtures of degradation products that originate from the whole biomass. The mixtures that were generated at 250–300 °C, predominantly contain hemicellulose degradation products, while the composition of the mixtures that were obtained at 350–400 °C, is more representative for cellulose. Lignin-derived fragments are found in both mixtures. Yields up to 5 wt% of the dry feedstock are obtained for chemicals like acetic acid, furfural, acetol and levoglucosan. Certain groups of thermal degradation products like C₂–C₄ oxygenates and phenols are formed in yields up to 3 wt%. Highest yields have been obtained for beech wood. Staged degasification is a promising pyrolysis-based route to valorise lignocellulosic biomass. Clear opportunities exist to increase product yields and selectivities by optimisation of reactor conditions, application of catalysts and specific biomass pretreatments like demineralisation and pre-hydrolysis.     

Pyrolysis of sweet orange (Citrus sinensis) dry peel

Three different products were obtained from the pyrolysis of dry peel sweet orange: bio-oil, char and non-condensable gases. The yield of each product was determined. The bio-oil was characterized by GC–MS to determine that can be used as a renewable source of valuable industrial chemicals or as a source of energy, high heating value was calculated by Channiwala and Parikh correlation based on Dulong's Formula.Thermogravimetric analysis at 1, 5, 10, 20, and 40 °C/min, shows three different overlapped steps resulting in an average mass loss of ∼80% within the temperature range of 114–569 °C. The bench scale pyrolysis experiments, produces average yields of 53.1, 21.1 and 25.8 wt.% for bio-oil, char and gases, respectively. Bio-oil characterization by GC–MS and FTIR identified limonene as its main component while other identified compounds included δ-limonene, alcohols, phenols, benzene, toluene, xylene and carboxylic acids.