生物质和废塑料混合热解协同特性研究

选取聚丙烯(PP)和竹屑作为废塑料与生物质的典型代表,在热重分析仪和固定床台架上研究了塑料掺混比例对混合热解失重特性、动力学机理、产物分布行为等特性的影响,并分析了混合热解时生物质和废塑料间的协同作用机制。结果表明,随着塑料掺混比例的增加,混合热解终止温度由501℃降低至471℃,主要热解温度区间缩短;混合热解所需活化能呈现先减小后增大的趋势,在塑料掺混比例为0.25时取得最小值。通过对比实验数据和理论数据发现,生物质与废塑料混合热解具有很强的协同作用:该协同作用降低了生物质反应所需能量,增加了废塑料反应所需能量,降低了混合热解过程的总活化能;此外,协同作用促进大分子挥发分转化为小分子气体,促进芳烃、烷烃等烃类生成,抑制CO₂、苯酚、羧酸、呋喃和酮类等含氧物质生成。     

Production of Low-carbon Light Olefins from Catalytic Cracking of Crude Bio-oil

Low-carbon light olefins are the basic feedstocks for the petrochemical industry. Catalytic cracking of crude bio-oil and its model compounds (including methanol, ethanol, acetic acid, acetone, and phenol) to light olefins were performed by using the La/HZSM-5 catalyst. The highest olefins yield from crude bio-oil reached 0.19 kg/(kg crude bio-oil). The reaction conditions including temperature, weight hourly space velocity, and addition of La into the HZSM-5 zeolite can be used to control both olefins yield and selectivity. Moderate adjusting the acidity with a suitable ratio between the strong acid and weak acid sites through adding La to the zeolite effectively enhanced the olefins selectivity and improved the catalyst stability. The production of light olefins from crude bio-oil is closely associated with the chemical composition and hydrogen to carbon effective ratios of feedstock. The comparison between the catalytic cracking and pyrolysis of bio-oil was studied. The mechanism of the bio-oil conversion to light olefins was also discussed.     

自由落下床中生物质与煤共热解的协同效应对焦油组成的影响

利用溶剂萃取-柱层析方法,将自由落下床中豆秸与大雁褐煤共热解以及单种原料热解的液体产品分为沥青烯、酚类、脂肪烃类、芳香烃类和极性物等组分。结果表明,共热解的沥青烯产率为11.4%,低于根据煤和生物质单独热解的质量加权平均计算值19.0%,且芳香性增大;与计算值相比,低分子量的酚类、甲基苯酚、二甲基苯酚及其衍生物的含量提高了5%;而且长侧链的脂肪烃含量减少。共热解焦油的芳香类组分中十氢萘的质量分数是43.37%,但其在单一原料热解焦油中并没有被检测到。热解油分析结果表明,自由落下床生物质与煤快速共热解过程中存在协同效应,其主要原因是,发生氢解和加氢反应。煤与生物质共热解有利于产生低分子量的化合物,改善油品的质量。     

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.     

Preparation of Bio-hydrogen and Bio-fuels from Lignocellulosic Biomass Pyrolysis-Oil

In recent years, production of engine fuels and energy from biomass has drawn much interest. In this work, we conducted a novel integrated process for the preparation of bio-hydrogen and bio-fuels using lignocellulosic biomass pyrolysis-oil (bio-oil). The process includes (i) the production of bio-hydrogen or bio-syngas by the catalytic cracking of bio-oil, (ii) the adjustment of bio-syngas, and (iii) the production of bio-fuels by ole nic polymerization (OP) together with Fischer-Tropsch synthesis (FTS). Under the optimal conditions, the yield of bio-hydrogen was 120.9 g H₂/(kg bio-oil). The yield of hydrocarbon bio-fuels reached 526.1 g/(kg bio-syngas) by the coupling of OP and FTS. The main reaction pathways (or chemical processes) were discussed based on the products observed and the catalyst property.     

Flash co-pyrolysis of biomass: The influence of biopolymers

A high water content is one of the major drawbacks for the utilisation of bio-oil. One technology which shows the potential to satisfy the demand for bio-oil with a reduced water content is the flash co-pyrolysis of biomass with biopolymers. The influence of biopolymers on the pyrolysis yield of a biomass waste stream is investigated with a semi-continuous home-built pyrolysis reactor. Polylactic acid (PLA), corn starch, polyhydroxybutyrate (PHB), Biopearls, Eastar, Solanyl and potato starch are the biopolymers under investigation. All biopolymers show their specific benefits during flash co-pyrolysis with willow (target biomass) at 723 K. Each (co-)pyrolysis of pure willow (reference) and all 1:1 (w/w) ratio willow/biopolymer blends is evaluated based on five predefined criteria. A multi-criteria decision aid (MCDA) method ‘PROMETHEE’ is used in order to obtain an objective ranking of the different biopolymer options.The flash co-pyrolysis of biomass and biopolymers results in improved pyrolysis characteristics. The flash co-pyrolysis of 1:1 willow/PHB is the most performant option, while 1:1 willow/PLA, 1:1 willow/Biopearls and 1:1 willow/potato starch show increased potential as well. The fact that biopolymers, despite their biodegradability, should be considered as waste, further increases the appealing features of the flash co-pyrolysis of biomass and biopolymers.     

Co-pyrolysis of macroalgae and lignocellulosic biomass

Synergistic effect of co-pyrolysis of macroalgae [Enteromorpha prolifera (EP)] and lignocellulosic biomass [rice husk (RH)] in a fixed bed reactor for maximum and enhanced biofuels yield has been investigated. The main and interaction effects of three effective co-pyrolysis parameters (pyrolysis temperature, feedstock blending ratio, and heating rate) were also modeled and simulated to determine the yield rates of bio-oil and bio-char, respectively. Optimization studies were, then, performed to predict the optimal conditions for maximum yields using the central composite circumscribed experimental design in Design Expert^® software 8.0.6. Analysis of variance was carried out to determine whether the fit of the multiple regressions is significant for the second-order model. Normal pyrolysis oils from EP, RH, and co-pyrolysis oils obtained from different feedstock blending ratios were examined using the gas chromatography-mass spectrometry to identify their compositions. Some vital properties of oils and bio-chars such as the heating value, water content, elemental compositions, and specific gravity were also determined, which unveiled that synergistic effect exists between EP and RH during co-pyrolysis, and this led to increase in products’ yields and improved co-pyrolysis products’ quality.

     

Microwave-assisted pyrolysis of oil palm shell biomass using an overhead stirrer

Oil palm shell biomass contains a high amount of lignin and thus has the potential to be converted into value-added products. If this biomass is not utilised efficiently, significant loss of valuable chemical products may occur, which otherwise can be recovered. In this paper, a new technique using an overhead stirrer to pyrolyse biomass under microwave (MW) irradiation was investigated. The ratio of biomass to activated carbon was varied to investigate its effect on the temperature profile, product yield and phenol content of the bio-oil. Interestingly, the microwave pyrolysis temperature could be controlled by varying the biomass to carbon ratio. The highest bio-oil yield and phenol content in bio-oil were obtained at a biomass to carbon ratio of 1:0.5. Chemical analyses of bio-oil were performed using FT-IR, GC–MS and ¹H NMR techniques. These results indicate that bio-oil consists mainly of aliphatic and aromatic compounds with high amounts of phenol in the bio-oil. Thus, MW pyrolysis with a stirrer successfully produced high-phenol bio-oil compared to other methods. This significant increase in bio-oil quality could either partially or wholly replace petroleum-derived phenol in many phenol-based applications.     

微拟球藻热解及其催化热解制备生物油研究

在氮气气氛下对微拟球藻直接热解及其在H-ZSM-5上的催化热解实验进行了研究。在573K～773K考察了热解温度对热解油产物分布的影响。与木质纤维素生物质的热解相比,微拟球藻的热解不仅温度更低,而且油的收率更高。催化剂H-ZSM-5在热解中起到了脱极性官能团和芳构化的作用,使得热解油中的芳香族化合物含量增多,极性化合物含量减少。与木质纤维素生物质相比,微拟球藻热解获得的油热值更高,适合进一步加工为燃油。     

Aromatics and phenols from catalytic pyrolysis of Douglas fir pellets in microwave with ZSM-5 as a catalyst

Microwave assisted catalytic pyrolysis was investigated to convert Douglas fir pellets to bio-oils by a ZSM-5 zeolite catalyst. A central composite experimental design (CCD) was used to optimize the catalytic pyrolysis process. The effects of reaction time, temperature and catalyst to biomass ratio on the bio-oil, syngas, and biochar yields were determined. GC/MS analysis results showed that the bio-oil contained a series of important and useful chemical compounds. Phenols, guaiacols, and aromatic hydrocarbons were the most abundant compounds which were about 50–82% in bio-oil depending on the pyrolysis conditions. Comparison between the bio-oils from microwave pyrolysis with and without catalyst showed that the catalyst increased the content of aromatic hydrocarbons and phenols. A reaction pathway was proposed for microwave assisted catalyst pyrolysis of Douglas fir pellets.     

Design of Multiple Metal Doped Ni Based Catalyst for Hydrogen Generation from Bio-oil Reforming at Mild-temperature

A new kind of multiple metal (Cu, Mg, Ce) doped Ni based mixed oxide catalyst, synthesized by the co-precipitation method, was used for efficient production of hydrogen from bio-oil reforming at 250-500 oC. Two reforming processes, the conventional steam reforming (CSR) and the electrochemical catalytic reforming (ECR), were performed for the bio-oil reforming. The catalyst with an atomic mole ratio of Ni:Cu:Mg:Ce:Al=5.6:1.1:1.9:1.0:9.9 exhibited very high reforming activity both in CSR and ECR processes, reaching 82.8% hydrogen yield at 500 oC in the CSR, yield of 91.1% at 400 oC and 3.1 A in the ECR, respectively. The influences of reforming temperature and the current through the catalyst in the ECR were investigated. It was observed that the reforming and decomposition of the bio-oil were significantly enhanced by the current. The promoting effects of current on the decomposition and reforming processes of bio-oil were further studied by using the model compounds of bio-oil (acetic acid and ethanol) under 101 kPa or low pressure (0.1 Pa) through the time of flight analysis. The catalyst also shows high water gas shift activity in the range of 300-600 oC. The catalyst features and alterations in the bio-oil reforming were characterized by the ICP, XRD, XPS and BET measurements. The mechanism of bio-oil reforming was discussed based on the study of the elemental reactions and catalyst characterizations. The research catalyst, potentially, may be a practical catalyst for high efficient production of hydrogen from reforming of bio-oil at mild-temperature.     

离子液体作用下微波辐照生物质快速热解制备生物质油(英文)

以离子液体1-丁基-3-甲基咪唑氯([Bmim]Cl)和1-丁基-3甲基咪唑四氟化硼([Bmim]BF4)为催化剂,在微波加热作用下,研究了稻草和锯屑的热解。微波加热20 min,稻草和锯屑的生物油产率分别为38%和34%。考察了微波加热时间、微波功率和离子液体用量对生物质油产率的影响。当以相同的离子液体为催化剂时,稻草微波热解得到的生物质油产率大于锯屑的。生物油成分主要有糠醛、醋酸和1-羟基-2-丁酮等,其含量主要取决于生物质原料和加入的离子液体的类型。     

HZSM-5上生物质催化裂解的近期研究进展

概述了近期的HZSM-5对生物质和生物油催化裂解的研究进展,重点介绍了催化剂的应用、生物油提质的方法和反应机理.     

Bio-oil from Jackfruit Peel Waste

Fossil fuels such as petroleum, charcoal, and natural gas sources are the main energy sources at present, but considering their natural limitation in availability and the fact that they are not renewable, there exists a growing need of developing bio-fuel production. Biomass has received considerable attention as a sustainable feedstock that can replace diminishing fossil fuels for the production of energy, especially for the transportation sector. JackfruitwasteisabundantinIndonesiamake itpotentiallyas one of thegreenrefineryfeedstockforthe manufacture ofbio-fuel.As intermediate of bio-fuel,jackfruitpeelsisprocessed intobio-oil. Pyrolysis, a thermochemical conversion process under oxygen-absent condition is an attractive way to convert biomass into bio- oil.In this study, the pyrolysis experiments were carried out ina fixed-bedreactor at a range of temperature of400-600 °C, heating rate range between 10-50 °C/min, and a range of nitrogen flow between 2-4litre/min. The aims of this work were to explore the effects of pyrolysis conditions and to identify the optimum condition for obtaining the highest bio-oil yield.The effect of nitrogen flow rate and heating rate on the yield of bio-oil were insignificant. The most important parameter in the bio-oil production was the temperature of the pyrolysis process.The yield of bio-oil initially increased with temperature (up to 550 °C) then further increase of temperature resulting in the decreased of bio-oil yield. Results showed that the highest bio-oil yield (52.6%)wasobtainedat 550 °C with nitrogen flow rate of 4L/min and heating rate of 50 °C/min. The thermal degradation of jackfruit peel was also studied using thermogravimetric analysis (TGA). Gas chromatography (GC-MS) was used to identify the organic fraction of bio-oil. The water content in the bio-oil product was determined by volumetric Karl-Fischer titration. The physicochemical properties of bio-oil produced from pyrolysis of jackfruit peels such as gross calorific value, pH, kinematic viscosity, density, sulfur content, ash content, pour point and flash point were determined and compared to ASTM standard of bio-oil (ASTM 7544).     

Catalysts developed from waste plastics: a versatile system for biomass conversion

The end-of-life treatment for post-consumer plastic waste constitutes one of modern society’s greatest problems, whereby highly unsustainable landfilling and incineration are the two main disposal routes. At present, the chemical upcycling of plastic waste is largely limited to its pyrolytic conversion into hydrocarbon fuels or nanomaterials. Herein, we demonstrate the upcycling of high-volume plastic waste by turning them into catalysts for biomass valorization. Many existing studies synthesize organocatalysts from a bottom-up approach using specialized monomers. Yet, transforming widely available waste polymers into functionalized materials for catalysis remains relatively unexplored. In this study, homogeneous and cross-linked heterogeneous catalysts derived from waste polystyrene food containers are shown to convert readily available saccharide precursors from biomass into 5-hydroxymethylfurfural (5-HMF), a key biorefinery platform chemical, under short reaction times and mild conditions. In addition, the heterogeneous catalyst can be reused multiple times with little loss of yield between repeated runs. Other than 5-HMF, doping the reaction with water or halide salts also allowed the formation of valuable products such as formic acid and diformylfuran. Our work expands on existing upcycling options for post-consumer plastic waste by giving them a new lease of life as value-added catalysts.     

Transformation of Bio-oil into BTX by Bio-oil Catalytic Cracking

Production of benzene, toluene and xylenes (BTX) from bio-oil can provide basic feedstocks for the petrochemical industry. Catalytic conversion of bio-oil into BTX was performed by using different pore characteristics zeolites (HZSM-5, HY-zeolite, and MCM-41). Based on the yield and selectivity of BTX, the production of aromatics decreases in the following order: HZSM-5>MCM-41>HY-zeolite. The highest BTX yield from bio-oil using HZSM-5 reached 33.1% with aromatics selectivity of 86.4%. The reaction conditions and catalystcharacterization were investigated in detail to make clear the optimal operating parameters and the relation between the catalyst structure and the production of BTX.     

C12A7-MgO催化剂上的生物油裂解制氢

Catalytic steam reforming of condensable vapors, i.e. bio-oil, derived from pyrolysis of biomass is an important process for hydrogen production, which is expected to form renewable and clean energy. The generation of hydrogen from bio-oil was investigated from 250 to 750 ℃ by a MgO mixed C12A7-O-(C12A7-MgO) catalyst in a fixed-bed micro-reactor. The hydrogen yield on C12A7-MgO was about 44% at 750 ℃. It is found that both the catalytic activity and catalysis life are improved by doping MgO. The XRD results show that the C12A7 structure of the positively charged lattice framework remains in the C12A7-MgO catalyst.     

Simulation of the fast pyrolysis of Tunisian biomass feedstocks for bio-fuel production

An optimized model is developed for the production of bio-fuels from biomass using a SuperPro Designer tool. Four types of Tunisian biomass feedstocks including date palm rachis, olive stones, vine stems and almond shells were selected for the fast pyrolysis process simulation. Simulation tests were performed at different temperatures ranging from 450 to 650 °C, and residence times ranging from 0.1 to 10 s and the products yield were determined. The obtained results indicate that a temperature of 575 °C and 0.25 s vapor residence time are the optimum parameters to maximize the bio-oil yield. Comparison between the different feedstocks indicates that a higher bio-oil fraction was obtained from the date palm rachis and vine stem. However, the difference between the samples is not significant and further investigations on the bio-oil properties are requested to select the suitable biomass for bio-oil production in Tunisia.     

Effects of Current on Microcosmic Properties of Catalyst and Reforming of Bio-oil

Highly effective production of hydrogen from bio-oil was achieved by using a low-temperature electrochemical catalytic reforming approach over the conventional Ni-based reforming catalyst （NiO-Al2O3）, where an AC electronic current passed through the catalyst bed. The promoting effects of current on the bio-oil reforming were studied. It was found that the performance of the bio-oil reforming was remarkably enhanced by the current which passed through the catalyst. The effects of currents on the microcosmic properties of the catalyst, including the Brunauer-Emmett-Teller （BET） surface area, pore diameter, pore volume, the size of the crystallites and the reduction level of NiO into Ni, were carefully characterized by BET, X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscope. The desorption of the thermal electrons from the electrified catalyst was directly observed by the TOF （time of flight） measurements. The mechanism of the electrochemical catalytic reforming of bio-oil is discussed based on the above investigation.     

Catalytic Transformation of Bio-oil to Olefins with Molecular Sieve Catalysts

Catalytic conversion of bio-oil into light olefins was performed by a series of molecular sieve catalysts, including HZSM_-5, MCM_-41, SAPO_-34 and Y_-zeolite. Based on the light olefins yield and its carbon selectivity, the production of light olefins decreased in the following order:HZSM_-5>SAPO_-34>MCM_-41>Y_-zeolite. The highest olefins yield from bio-oil using HZSM_-5 catalyst reached 0.22 kg/kg_bio-oil with carbon selectivity of 50.7% and a nearly complete bio-oil conversion. The reaction conditions and catalyst characterization were investigated in detail to reveal the relationship between the catalyst structure and the production of olefins. The comparison between the pyrolysis and catalytic pyrolysis of bio-oil was also performed.