熔盐热裂解生物质制生物油

为探讨热裂解条件对熔盐中生物质热裂解制生物油的影响,在自行设计的反应器中,以摩尔比为7∶6的ZnCl2-KCl混合熔盐作为热裂解的热载体、催化剂和分散剂,考察了500 ℃时添加的金属盐和生物质原料的影响,并采用气相色谱-质谱仪 (GC-MS) 对生物油的主要组成进行了分析。结果表明：添加的金属盐显著影响热裂解产物得率,稀土金属盐显著提高生物油得率,降低生物油的含水率,添加摩尔分数为5.0％ LaCl3时生物油得率为32.0％,含水率为61.5％;水稻秸秆热裂解的生物油和焦炭得率较高,稻壳热裂解的气体得率较高;金属添加盐对生物油组成有较强的选择性,LiCl和FeCl2对生物质向小分子裂解具有较强的催化作用,而CrCl3、CaCl2和LaCl3对生物油二次裂解具有抑制作用。研究结果为熔盐热裂解生物质制生物油提供了参考。     

The effects of different catalysts on the pyrolysis of industrial wastes (olive and hazelnut bagasse)

Pyrolysis of olive and hazelnut bagasse biomass samples with two selected catalysts, namely activated alumina and sodium feldspar, have been conducted in a fixed-bed reactor. Experiments were carried out under certain pyrolysis conditions in a fixed-bed Heinze reactor. The catalyst was mixed with feedstock in different percentages. The effects of catalysts and their ratio (10%, 20%, 30% and 40% w/w) on the pyrolysis product yields were investigated and the results were compared with the results of experiments performed without catalyst under the same conditions. The maximum bio-oil yields for the bio-oils obtained from pyrolysis of olive bagasse were found as 37.07% and 36.67% on using activated alumina and sodium feldspar as catalysts, respectively, while these values were 27.64% and 31.68%, respectively, for the bio-oils from hazelnut bagasse. The oxygen contents of the bio-oils were also markedly reduced while the yield of bio-oil was reduced by the use of catalysts. The pyrolysis oils were examined using some spectroscopic and chromatographic analysis techniques. The results were compared with the petroleum fractions and the possibility of being a potential source of bio-oils was investigated.     

Catalytic upgrading of oil fractions separated from food waste leachate

In this work, catalytic cracking of biomass waste oil fractions separated from food waste leachate was performed using microporous catalysts, such as HY, HZSM-5 and mesoporous Al-MCM-48. The experiments were carried out using pyrolysis gas chromatography/mass spectrometry (Py-GC/MS) to allow the direct analysis of the pyrolytic products. Most acidic components, especially oleic acid, contained in the food waste oil fractions were converted to valuable products, such as oxygenates, hydrocarbons and aromatics. High yields of hydrocarbons within the gasoline-range were obtained when microporous catalysts were used; whereas, the use of Al-MCM-48, which exhibits relatively weak acidity, resulted in high yields of oxygenated and diesel-range hydrocarbons. The HZSM-5 catalyst produced a higher amount of valuable mono aromatics due to its strong acidity and shape selectivity. Especially, the addition of gallium (Ga) to HZSM-5 significantly increased the aromatics content.     

Biomass fast pyrolysis in a fluidized bed reactor under N2, CO2, CO, CH4 and H2 atmospheres

Biomass fast pyrolysis is one of the most promising technologies for biomass utilization. In order to increase its economic potential, pyrolysis gas is usually recycled to serve as carrier gas. In this study, biomass fast pyrolysis was carried out in a fluidized bed reactor using various main pyrolysis gas components, namely N₂, CO₂, CO, CH₄ and H₂, as carrier gases. The atmosphere effects on product yields and oil fraction compositions were investigated. Results show that CO atmosphere gave the lowest liquid yield (49.6%) compared to highest 58.7% obtained with CH₄. CO and H₂ atmospheres converted more oxygen into CO₂ and H₂O, respectively. GC/MS analysis of the liquid products shows that CO and CO₂ atmospheres produced less methoxy-containing compounds and more monofunctional phenols. The higher heating value of the obtained bio-oil under N₂ atmosphere is only 17.8 MJ/kg, while that under CO and H₂ atmospheres increased to 23.7 and 24.4 MJ/kg, respectively.     

Thermal conversion of glucose to aromatic hydrocarbons via pressurized secondary pyrolysis

In this study, glucose, a primary building-block of biomass was subjected to secondary pyrolysis in a reactor that was retrofitted subsequent to a primary micro-pyrolysis reactor. It was observed that incorporation of a secondary reactor resulted in producing significant amounts of gasoline range hydrocarbons. The hydrocarbon yields improved further as a result of increasing pyrolysis reactor pressure and temperatures. The temperature of the secondary reactor was varied between 400 and 800 °C and pressure between 0 and 150 psi. This study indicates that secondary cracking of primary pyrolysis products of biomass oxygenates undergo gas-phase homogenous molecular restructuring. The result of this process is production of substantial amounts of thermodynamically stable gasoline-range hydrocarbons even in the absence of a catalyst.     

Impact of Harvest Time and Cultivar on Conversion of Switchgrass to Bio-oils Via Fast Pyrolysis

The study of the effects of harvest time on switchgrass (Panicum virgatum L.) biomass and bioenergy production reported herein encompasses a large study evaluating the harvest of six switchgrass cultivars grown at three northern US locations over 3 years, harvested at upland peak crop (anthesis), post-frost, and post-winter. Delaying harvest of switchgrass until after frost and until after winter has resulted in decreased yields of switchgrass and reduced amounts of minerals in the biomass. This report examines how changes in biomass composition as a result of varying harvest time and other factors affect the distribution of products formed via fast pyrolysis. A subset (50) of the population (n = 864) was analyzed for fast pyrolysis and catalytic pyrolysis (zeolite catalyst) product yields using a pyrolysis-GC/MS system. The subset was used to build calibrations that were successful in predicting the pyrolysis product yield using near-infrared reflectance spectroscopy (NIRS), and partial least squares predictive models were applied to the entire sample set. The pyrolysis product yield was significantly affected by the field trial location, year of harvest, cultivar, and harvest time. Delaying harvest time of the switchgrass crop led to greater production of deoxygenated aromatics improving the efficiency of the catalytic fast pyrolysis and bio-oil quality. The changes in the pyrolysis product yield were related to biomass compositional changes, and key relationships between cell wall polymers, potassium concentration in the biomass, and pyrolysis products were identified. The findings show that the loss of minerals in the biomass as harvest time is delayed combined with the greater proportion in cellulose and lignin in the biomass has significant positive influences on conversion through fast pyrolysis.     

A renewable energy source — hydrocarbon gases resulting from pyrolysis of the marine nanoplanktonic alga Emiliania huxleyi

The marine coccolithophore, Emiliania huxleyi, grown in the laboratory was subjected to vacuum pyrolysis at various temperatures from 100 to 500 °C. The highest yield of pyrolytic gases (183 mL g⁻¹ dry cells) was obtained at 400 °C. The amount of total hydrocarbon gas produced at 400 °C was 129 mL, about 10 times higher than at 300 °C. CH₄ was the major component at the high gas-production stage (400–500 °C). The great increase in hydrocarbon gases at 400 °C was accompanied by a marked decrease in liquid saturates and aromatics. The results indicate that the liquid hydrocarbons (oil) produced by pyrolysis at lower temperature is a direct source for the formation of the hydrocarbon gases. Due to its large potential for the production of biomass and hydrocarbons with low energy input, E. huxleyi is suggested as one of candidates for the production of renewable fuels. This revised version was published online in July 2006 with corrections to the Cover Date.     

Investigation of hydrocarbon fractions form waste plastic recycling by FTIR, GC, EDXRFS and SEC techniques

Waste high-density polyethylene was converted into different hydrocarbon fractions by thermal and thermo-catalytic batch cracking. For the catalytic degradation of waste plastics three different catalysts (equilibrium FCC, HZSM-5 and clinoptilolite) were used. Catalysts differ basically in their costs and activity due to the differences of micro- and macroporous surface areas and furthermore the Si/Al ratio and acidities are also different. Mild pyrolysis was used at 430 °C and the reaction time was 45 min in each case. The composition of products was defined by gas chromatography, Fourier transform infrared spectroscopy, size exclusion chromatography, energy-dispersive X-ray fluorescence spectroscopy and other standardized methods. The effects of catalysts on the properties of degradation products were investigated. Both FCC and clinoptilolite catalysts had considerably catalytic activity to produce light hydrocarbon liquids, while HZSM-5 catalyst produced the highest amount of gaseous products. In case of liquids, carbon numbers were distributed within the C₅–C₂₃ range depending on the cracking parameters. Decomposition of the carbon chain could be followed by GC and both by FTIR and SEC techniques in case of volatile fractions and residues. Catalysts increased yields of valuable volatile fractions and moreover catalysts caused both carbon chain isomerization and switching of the position of double bonds.     

Catalytic pyrolysis of tobacco rob: kinetic study and fuel gas produced

The pyrolysis kinetics of tobacco rob (TR) was investigated using thermogravimetric analysis (TGA) under inert atmosphere, adding chemicals (dolomite and NiO) as catalysts by catalytic-mixing method. The TGA results showed that mass loss and mass loss rates were affected by catalysts. The conversion rates increased while the activation energy decreased. Moreover, the thermal decomposition behaviors of TR were studied in the fixed-bed reactor using dolomite and NiO/γ-Al₂O₃ as catalysts by catalyst-bed method. A series of experiments had been performed to explore the effects of catalysts, and reaction temperature on the composition and yield of fuel gas. The experiments demonstrated that the catalysts had a high activity of cracking tar and hydrocarbons, as well as yielding a high fuel gas production. For both methods, dolomite and NiO revealed better catalytic performance as a view of enhancing conversion rates and increasing product gas yield.     

Advances in thermochemical conversion of woody biomass to energy,fuels and chemicals

Biomass has been recognised as a promising resource for future energy and fuels. The biomass, originated from plants, is renewable and application of its derived energy and fuels is close to carbon-neutral by considering that the growing plants absorb CO₂ for photosynthesis. However, the complex physical structure and chemical composition of the biomass significantly hinder its conversion to gaseous and liquid fuels.This paper reviews recent advances in biomass thermochemical conversion technologies for energy, liquid fuels and chemicals. Combustion process produces heat or heat and power from the biomass through oxidation reactions; however, this is a mature technology and has been successfully applied in industry. Therefore, this review will focus on the remaining three thermochemical processes, namely biomass pyrolysis, biomass thermal liquefaction and biomass gasification. For biomass pyrolysis, biomass pretreatment and application of catalysts can simplify the bio-oil composition and retain high yield. In biomass liquefaction, application of appropriate solvents and catalysts improves the liquid product quality and yield. Gaseous product from biomass gasification is relatively simple and can be further processed for useful products. Dual fluidised bed (DFB) gasification technology using steam as gasification agent provides an opportunity for achieving high hydrogen content and CO₂ capture with application of appropriate catalytic bed materials. In addition, multi-staged gasification technology, and integrated biomass pyrolysis and gasification as well as gasification for poly-generation have attracted increasing attention.     

Phenol and phenolics from lignocellulosic biomass by catalytic microwave pyrolysis

Catalytic microwave pyrolysis of biomass using activated carbon was investigated to determine the effects of pyrolytic conditions on the yields of phenol and phenolics. The high concentrations of phenol (38.9%) and phenolics (66.9%) were obtained at the temperature of 589 K, catalyst-to-biomass ratio of 3:1 and retention time of 8 min. The increase of phenol and its derivatives compared to pyrolysis without catalysts has a close relationship with the decomposition of lignin under the performance of activated carbon. The concentration of esters was also increased using activated carbon as a catalyst. The high content of phenols obtained in this study can be used either directly as fuel after upgrading or as feedstock of bio-based phenols for chemical industry.     

Microwave induced pyrolysis of oil palm biomass

The purpose of this paper was to carry out microwave induced pyrolysis of oil palm biomass (shell and fibers) with the help of char as microwave absorber (MA). Rapid heating and yield of microwave pyrolysis products such as bio-oil, char, and gas was found to depend on the ratio of biomass to microwave absorber. Temperature profiles revealed the heating characteristics of the biomass materials which can rapidly heat-up to high temperature within seconds in presence of MA. Some characterization of pyrolysis products was also presented. The advantage of this technique includes substantial reduction in consumption of energy, time and cost in order to produce bio-oil from biomass materials. Large biomass particle size can be used directly in microwave heating, thus saving grinding as well as moisture removal cost. A synergistic effect was found in using MA with oil palm biomass.     

Catalytic pyrolysis of Miscanthus x giganteus over activated alumina

The catalytic effects of activated alumina (Al(2)O(3)) on the pyrolysis of Miscanthusxgiganteus, a new energy crop, were investigated. Catalytic pyrolysis experiments carried out under static and nitrogen atmospheres were performed in a fixed-bed reactor. The final pyrolysis temperature was kept constant at 550 degrees C in all of the experiments. The effect of catalyst loading (by weight of feedstock as 10%, 20%, 40%, 60%, 80% and 100%), heating rate (10 degrees C and 50 degrees Cmin(-1)), nitrogen flow rate (50, 100, 150 and 200cm(3)min(-1)) on the pyrolysis conversion and product yields were investigated. The results were compared with those obtained in non-catalytic pyrolysis. Activated alumina catalyst has a strong influence on the Miscanthusxgiganteus pyrolysis product and conversion yield. Furthermore, the catalytic bio-oils obtained from catalytic pyrolysis under static and nitrogen atmospheres were examined using elemental analysis, column chromatography, Fourier transform infrared (FTIR) and nuclear magnetic resonance ((1)H NMR) spectroscopy methods.     

Catalytic Pyrolysis of Raw and Thermally Treated Cellulose Using Different Acidic Zeolites

Fast pyrolysis of biomass using zeolite catalyst has shown to be effective in improving aromatic production. This study focuses on aromatic production through catalytic pyrolysis of major biomass constituent i.e., cellulose. Furthermore, cellulose was torrefied to understand torrefaction’s effect on pyrolysis products. The influence of SiO₂/Al₂O₃ ratios of zeolite (ZSM-5) catalyst on aromatic production during pyrolysis of raw and torrefied cellulose was investigated. Results showed that the catalyst acidity played a pivotal role in eliminating anhydro sugars and other oxygenated compounds while producing more aromatics. The maximum aromatic yield (~25 wt%) was obtained when ZSM-5 with the highest acidity (SiO₂/Al₂O₃?=?30) was used, while the lowest yield (7.99 wt%) was obtained when the least acidic catalyst was used (SiO₂/Al₂O₃?=?280) for raw cellulose pyrolysis. Torrefaction process showed to have positive effect on the aromatic production from pyrolysis. There were no aromatics produced from pyrolysis of raw cellulose in the absence of catalyst, whereas significant amount of aromatic compounds were produced from both catalytic and noncatalytic pyrolyses of torrefied cellulose. The aromatic hydrocarbons produced from catalytic pyrolysis of torrefied cellulose were 5 % more than those produced from raw cellulose at the highest temperature and catalyst acidity (SiO₂/Al₂O₃?=?30).     

Formation and growth of heterotrophic aerobic biofilms on small suspended particles in airlift reactors

In this article, the conditions for aerobic biofilm formation on suspended particles, the dynamics of biofilm formation, and the biomass production during the start-up of a Biofilm Airlift Suspension reactor (BAS reactor) have been studied. The dynamics of biofilm formation during start up in the biofilm airlift suspension reactor follows three consecutive stages: bare carrier, microcolonies or patchy biofilms on the carrier, and biofilms completely covering the carrier. The effect of hydraulic retention time and of substrate loading rate on the formation of biofilms were investigated. To obtain in a BAS reactor a high biomass concentration and predominantly continuous biofilms, which completely surround the carrier, the hydraulic retention time must be shorter than the inverse of the maximum growth rate of the suspended bacteria. At longer hydraulic retention times, a low amount of attached biomass can be present on the carrier material as patchy biofilms. During the start-up at short hydraulic retention times the bare carrier concentration decreases, the amount of biomass per biofilm particle remains constant, and biomass increase in the reactor is due to increasing numbers of biofilm particles. The substrate surface loading rate has effect only on the amount of biomass on the biofilm particle. A higher surface load leads to a thicker biofilm.A strong nonlinear increase of the concentration of attached biomass in time was observed. This can be explained by a decreased abrasion of the biofilm particles due to the decreasing concentration of bare carriers. The detachment rate per biofilm area during the start-up is independent of the substrate loading rate, but depends strongly upon the bare carrier concentration.The Pirt-maintenance concept is applicable to BAS reactors. Surplus biomass production is diminished at high biomass concentrations. The average maximal yield of biomass on substrate during the experiments presented in this article was 0.44 +/- 0.08 C-mol/C-mol, the maintenance value 0.019 +/- 0.012 C-mol/(C-mol h). The lowest actual biomass yield measured in this study was 0.15 C-mol/C-mol. (c) 1994 John Wiley & Sons, Inc.     

Pyrolysis biochar systems,balance between bioenergy and carbon sequestration

This study aimed to investigate the extent to which it is possible to marry the two seemingly opposing concepts of heat and/or power production from biomass with carbon sequestration in the form of biochar. To do this, we investigated the effects of feedstock, highest heating temperature (HTT), residence time at HTT and carrier gas flow rate on the distribution of pyrolysis co‐products and their energy content, as well as the carbon sequestration potential of biochar. Biochar was produced from wood pellets (WP) and straw pellets (SP) at two temperatures (350 and 650 °C), with three residence times (10, 20 and 40 min) and three carrier gas flow rates (0, 0.33 and 0.66 l min^?1). The energy balance of the system was determined experimentally by quantifying the energy contained within pyrolysis co‐products. Biochar was also analysed for physicochemical and soil functional properties, namely environmentally stable‐C and labile‐C content. Residence time showed no considerable effect on any of the measured properties. Increased HTT resulted in higher concentrations of fixed C, total C and stable‐C in biochar, as well as higher heating value (HHV) due to the increased release of volatile compounds. Increased carrier gas flow rate resulted in decreased biochar yields and reduced biochar stable‐C and labile‐C content. Pyrolysis at 650 °C showed an increased stable‐C yield as well as a decreased proportion of energy stored in the biochar fraction but increased stored energy in the liquid and gas co‐products. Carrier gas flow rate was also seen to be influential in determining the proportion of energy stored in the gas phase. Understanding the influence of production conditions on long term biochar stability in addition to the energy content of the co‐products obtained from pyrolysis is critical for the development of specifically engineered biochar, be it for agricultural use, carbon storage, energy generation or combinations of the three.     

Extraction of chlorophylls and carotenoids from dry and wet biomass of isolated Chlorella Thermophila: Optimization of process parameters and modelling by artificial neural network

Chlorophylls and carotenoids can be extracted from microalgae using various solvents. However, there is lack of studies regarding the comparison of extraction yield of these pigments from wet and dry microalgal biomass using different combination of cell disruption methods. Therefore, in this work, we have investigated the comparison of the extraction yield of chlorophylls and carotenoids from the wet and heat-dried microalgal biomass (isolated Chlorella thermophila) using ethanol. Extraction parameters such as homogenisation time, homogenisation speed, solvent temperature, solid-solvent ratio, boiling time and microwave time have been optimised. Chlorophyll extraction yield was observed to be 2.7 fold higher from wet biomass than dry biomass while carotenoid yield was 6.7 fold higher. Highest chlorophyll yield (∼60 mg/g-dry biomass) was observed at 6 min of homogenisation time, 10,000 rpm, solid solvent ratio of 1 mg/mL and 58 °C of solvent temperature from wet biomass with extraction efficiency of ∼94 %. Highest carotenoid yield was noticed following the same conditions of chlorophyll extraction except 4 °C of solvent temperature. The modelling of the extraction process was performed using artificial neural network (ANN) which may be useful for the scale-up of the extraction process at the industrial level.     

Lignin Pyrolysis Components and Upgrading—Technology Review

Biomass pyrolysis oil has been reported as a potential renewable biofuel precursor. Although several review articles focusing on lignocellulose pyrolysis can be found, the one that particularly focus on lignin pyrolysis is still not available in literature. Lignin is the second most abundant biomass component and the primary renewable aromatic resource in nature. The pyrolysis chemistry and mechanism of lignin are significantly different from pyrolysis of cellulose or entire biomass. Therefore, different from other review articles in the field, this review particularly focuses on the recent developments in lignin pyrolysis chemistry, mechanism, catalysts, and the upgrading of the bio-oil from lignin pyrolysis. Although bio-oil production from pyrolysis of biomass has been proven on commercial scale and is a very promising option for production of renewable chemicals and fuels, there are still several drawbacks that have not been solved. The components of biomass pyrolysis oils are very complicated and related to the properties of bio-oil. In this review article, the details about pyrolysis oil components particularly those from lignin pyrolysis processes will be discussed first. Due to the poor physical and chemical property, the lignin pyrolysis oil has to be upgraded before usage. The most common method of upgrading bio-oil is hydrotreating. Catalysts have been widely used in petroleum industry for pyrolysis bio-oil upgrading. In this review paper, the mechanism of the hydrodeoxygenation reaction between the model compounds and catalysts will be discussed and the effects of the reaction condition will be summarized.     

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.     

ZSM-5(38)/Al-MCM-41复合分子筛对纤维素催化热解的影响

以纤维素为原料,以自制的不同硅铝比ZSM-5(38)/Al-MCM-41微-介孔复合分子筛为催化剂,在固定床反应器上进行了催化热解实验。采用XRD表征分子筛,采用GC-MS分析生物油成分,考查了催化剂的改变对生物质热解产物及生物油成分的影响。实验结果表明：添加催化剂后,生物油产率降低,且其含水率也有所增加。与未添加催化剂相比,生物油中D L-2,3-丁二醇有明显提高。其中,ZSM-5(38)/Al-MCM-41(20) 最有利于苯酚、愈创木酚 (2-甲氧基-苯酚) 的生成。此外,这几种催化剂均有利于小分子化合物的生成,其中,ZSM-5(38) 有利于C4~C5化合物的生成,微-介孔复合分子筛则有利于C6~C8化合物的生成。