生物质三组分热裂解行为的对比研究

在热天平上对比研究了生物质中的纤维素、半纤维素和木质素三种主要组分的热失重规律。结果表明，作为半纤维素模型化合物的木聚糖热稳定性差，在217℃～390℃发生明显分解；纤维素热裂解起始温度最高，且主要失重发生在较窄温度区域，固体残留物仅为6.5%；木质素表现出较宽的失重温度区域，最终固体残留物高达42%。在红外辐射机理试验台上对比研究了三组分热裂解产物随温度的变化规律。三组分热裂解生物油产量随温度变化先升后降。纤维素生物油产量在峰值上最高，但纤维素生物油热稳定性差，高温时挥发分的二次分解最明显；木聚糖和木质素生物油产量较低，表现出较好的热稳定性。三组分热裂解焦炭产量随温度升高而降低，最终纤维素热裂解焦炭产量为1.5%，而木聚糖和木质素分别为22%和26%。三组分热裂解气体产物随温度升高而增长，但在气体组成分布上因三组分的结构上的差异而不同。     

基于Fe负载的HZSM-5催化热解制备生物油实验研究

通过离子交换法制备含2%Fe(质量分数)的HZSM-5催化剂,采用X射线衍射仪(XRD)、激光粒度分析仪以及比表面积及孔径分析仪对催化剂进行表征,并在550℃下进行木屑的催化热解实验。对无催化剂和不同比例催化剂条件下得到的生物油进行GC-MS分析,结果表明,在Fe负载的HZSM-5作用下,生物油产率明显升高(最大增幅7%),轻质组分产率明显升高,重质组分产率略微升高。同时,轻质组分中的酮类、呋喃等含氧化合物含量降低,酚类、酸含量升高;重质组分中的酮类、呋喃类等含氧化合物含量明显降低,酚类、萘类含量明显增多。Fe负载的HZSM-5催化剂对木屑的热解反应有较好的催化效果,加强了对热解初始蒸汽的择形修饰,从而抑制了生物质三组分木质素初始热解产物中的醌类等容易一次或二次结焦物质的生成,孔道结构对蒸汽的二次反应被抑制,产物向较小分子的轻质产物上富集。     

Pyrolysis of waste tire on ZSM-5 zeolite with enhanced catalytic activities

Catalytic copyrolysis of waste tires over ZSM-5 zeolite with lubricant base oil (LBO) was undertaken at 430 °C under nitrogen atmosphere in a batch mode, and the pyrolysis oils were characterized using gas chromatography/mass spectroscopy (GC-MS). By combining with LBO, the ZSM-5 catalyzed pyrolysis system of tires has a sharply enhanced degradation rate. Compared to the pyrolysis without LBO, the liquid yield is increased from 33.6% to 48.0%, while the gas and the residue yields are decreased. In the pyrolysis oils, the content of heavy components is decreased and the content of light oils (n-C ≤ 12) is increased from 77.8%(without LBO) to 83.1%(with LBO); especially, the content of C₁₀ components has a sharp increase. Moreover, the liquid compositions are changed. Particularly, the percentage of limonene increased dramatically from 7.54% for thermal degradation to 13.58%. These results suggest that the enhanced catalytic effects on pyrolysis of tires in the catalytic systems are due to the improved interactions between tires and catalysts with the help of LBO. Therefore, it is possible to improve the process economics of scrap tires by catalytic copyrolysis with LBO, which can not only increase the pyrolysis rate remarkably but also produce high-value oil products.     

催化热解废轮胎制衍生油

催化热解废轮胎对于资源利用及环境保护具有重要意义,近年来引起人们关注.在废轮胎胶粉热解反应中加入催化剂,不仅会加速胶粉裂解速率,缩短反应时间,而且可以通过催化剂择形催化改变产物分布,从而提高目的产物衍生油的收率和性能.国内外对废轮胎催化热解已做了大量研究,以期提高衍生油中高附加值单环芳烃的含量,同时降低S, N和Cl含量,虽然已取得较大进展,但衍生油收率较低,大大降低了该技术的可行性.
　　本文采用带搅拌器的1000 mL不锈钢反应器,在常压条件下研究了反应温度和催化剂类型对废轮胎胶粉热解反应及产物衍生油性能的影响,通过元素分析、馏程模拟和色谱-质谱等表征手段检测了衍生油的理化性能.结果表明,在废轮胎胶粉热解反应过程中,随反应温度上升,出油速率先增加后降低.至500 oC时,热解衍生油收率最高达55.65 wt%,所得衍生油呈黑棕色,具有轻质油含量低、S和N含量高、粘度低和流动性好的特点,其轻质芳烃含量低,却含有大量可以转变为芳烃的脂肪烃类.因此,为了提高衍生油中轻质油和轻质芳烃收率,降低S和N含量,尽量维持较高的衍生油收率,在热解反应过程中引入少量ZSM-5, USY,β, SAPO-11和ZSM-22等常见催化剂,利用催化剂独特的孔道结构和酸分布,达到定向催化和转化的目的,提高轻质芳烃含量.同时,为了克服催化剂与胶粉难以接触进行反应的问题,在反应温度升至200 oC时,维持一定时间保证胶粉发生溶胀和液化反应形成液体烃类,使得催化剂不仅能够均匀分散于液体烃中与其接触进行反应,而且有效提高了反应物料与催化剂之间传质传热效率,使得裂解反应在均相中进行,降低因传热不均匀而造成的结焦和过度裂化反应.在催化热解过程中,1.0 wt%催化剂的加入可明显缩短反应时间,在保证衍生油收率基本不变的情况下,获得的衍生油呈黄棕色,轻质油收率较高为70–75 wt%, S和N含量分别降至0.3–0.58wt%和0.78–1.0 wt%.以具有较高酸性和孔径分布的ZSM-5, USY,β和SAPO-11为催化剂时,衍生油中总芳烃含量可达到50 wt%,其中单环芳烃含量高达45 wt%.     

Analytical strategies for chemical characterization of bio‐oil

Bio‐oils, produced by biomass pyrolysis, have become promising candidates for feedstocks of high value‐added chemicals and alternative sources for transportation fuels. Bio‐oil is such a complicated mixture that contains nonpolar hydrocarbons and polar components which cover almost all kinds of organic oxygenated compounds such as carboxylic acids, alcohols, aldehydes, ketones, esters, furfurals, phenolic compounds, sugar‐like material, and lignin‐derived compounds. Comprehensive characterization of bio‐oil and its subfractions could provide insight into the conversion process of biomass processing, as well as its further utilization as transportation fuels or chemical raw materials. This review focuses on advanced analytical strategies on in‐depth characterization of bio‐oil, which is concerned with gas chromatography, high‐resolution mass spectrometry, FTIR spectroscopy and NMR spectroscopy, offering complementary information for previous reviews.     

Ni/Zr-MOF催化剂的制备及其在生物质热解中的应用

通过均匀沉淀法制备了以锆-金属有机骨架化合物(Zr-metal organic framework,Zr-MOF)为载体的Ni/Zr-MOF催化剂,并用于湿污泥和秸秆混合催化热解实验。采用元素分析、X射线荧光光谱(XRF)、热重分析(TG)、X射线衍射(XRD)、扫描电镜(SEM)和N_2吸附-脱附等温(BET)对载体和催化剂进行表征分析,通过一系列实验来探讨热解温度、秸秆添加量和Ni负载量对于湿污泥和秸秆混合催化热解制备富氢合成气的影响。结果表明,Zr-MOF载体颗粒均匀呈八面体,比表面积高达805.93 m~2/g,平均孔径为20.14 nm,为介孔结构。Ni/Zr-M OF催化剂具有较高的热稳定性和催化活性。与不添加催化剂相比,使用Ni/Zr-MOF催化剂在500℃下热解,H_2的产量从0.39 mol/kg显著提高到12.65 mol/kg。随着热解温度的升高,催化剂出现团聚现象,同时在反复使用之后其表面产生了少量的积炭,导致催化剂催化活性逐渐降低。因此,Ni/Zr-MOF催化剂适用于生物质低温催化热解。     

生物油酸性组分分离精制研究

生物油因水分含量高和呈酸性未能作为高品位能源直接规模化应用。利用分子蒸馏技术将生物油水分与酸性组分作为整体对象进行分离,既得到生物油酸性组分富集馏分,又获得了水分含量低、酸性较弱与热值较高的精制生物油Ⅰ（蒸馏重质馏分）与精制生物油Ⅱ（常温冷凝馏分）。同时,具体考察了精制前后生物油的pH值、热值和水分等参数的变化规律。研究表明,生物油的水分与酸性组分得到有效分离,精制生物油Ⅰ和Ⅱ的低级羧酸含量从原始生物油的18.85%分别降低至0.96%和2.2%     

蟹壳基氮/氧共掺杂多孔炭的原位制备及其超级电容器性能

采用废弃蟹壳为碳源,KOH为活化剂原位制备了氮/氧共掺杂多孔炭,并研究其作为电极材料在超级电容器中的应用。 固定蟹壳与KOH的质量比为5:3,考察了煅烧温度对所得炭材料产率、孔结构和氮氧含量的影响。 结果表明,蟹壳基炭材料的孔结构和氮/氧含量可通过改变煅烧温度调变。 随着煅烧温度从500 ℃上升至700 ℃,多孔炭的比表面积和孔体积逐渐增大,而氮/氧含量随温度升高则降低。 采用循环伏安和恒流充放电对所得材料的电化学性能进行测试。 结果表明,所得多孔炭的电化学性能取决于其孔结构与氮/氧表面性质的协同作用,其中煅烧温度为600 ℃所得的多孔炭比表面积为612 m²/g,氮和氧含量分别为3.53%和32.8%,在50 mA/g的电流密度下比电容达到310 F/g,循环1000次比电容仍然保持95%以上,展现出良好的电化学性能。     

Will Zeolite‐Based Catalysis be as Relevant in Future Biorefineries as in Crude Oil Refineries?

Transition from petroleum‐ to biomass‐based fuel economy will require new conversion strategies. In a petroleum refinery, particular hydrocarbon fractions from crude oil are catalytically converted into high‐grade fuels. Certain zeolite catalysts are performing exceptionally well. Unlike petroleum fractions, biomass‐derived compounds have a high oxygen content requiring low‐temperature catalytic aqueous phase processes for selective conversion and stability of zeolite catalysts in hot liquid water. It will be shown that recent developments in zeolite synthesis and modification allow adapting zeolite properties to achieve selective conversion of biomass compounds/fractions as well.     

MCM-41/SBA-15中孔分子筛对生物质热解油的催化裂解研究

以中孔MCM 41/SBA 15分子筛作催化剂，对不同条件下快速热解得到的木屑热解蒸气进行催化裂解，采用元素分析、凝胶色谱(s.e.c.)和气质联用（GC MS）等手段表征。结果表明,同未加催化剂比较，分子筛MCM 41/SBA 15的存在可使热解液体中氧的质量分数降低，长链化合物所占比例明显减小，其中SBA 15作催化剂比MCM 41作催化剂对热解蒸气裂解更容易得到接近柴油和汽油分子量的热解油，但芳香类化合物的质量分数明显增加。热解油中Pentadecane、Hexadecane、Dimethyjbenzene、Naphthalene等质量分数增加，而含氧类物质Methyl Phenol、2 Methoxy 4 Methyl Phenol、2 Methoxy 4 Propyl Phenol 等质量分数减少。     

Light olefins and light oil production from catalytic pyrolysis of waste tire

This paper investigates the catalytic activity of MCM-41 synthesized via silatrane route and Ru/MCM-41 in waste tire pyrolysis. The experimental results showed that the presence of catalysts strongly influenced the yield and nature of products. Namely, the gas yield increased at the expense of liquid yield. In addition, a considerable high yield of light olefins, 4 times higher than non-catalytic pyrolysis, can be achieved for Ru/MCM-41 catalyst. Furthermore, the uses of catalysts produced much lighter oil and there was a drastic increase in the concentration of single ring aromatics in accordance to a reduction in polycyclic aromatic compounds in the derived oils. Ru/MCM-41 produced the lightest oil and the oil has the highest concentration of mono-aromatics. The high activity of catalysts, particularly Ru/MCM-41 was discussed in relation with the catalyst characterization results obtained from various techniques including TPD-NH₃, H₂-chemisorption, XRD, N₂-adsorption/desorption analysis, and TPO.     

生物质在超临界水中热解行为的初步研究

在间歇式高压反应釜中，考察了生物质（稻杆）在超临界水中的热解行为，研究了热解产物分布随反应温度、压力以及停留时间的变化规律。结果表明,气体收率随温度升高而增加，油收率则先增加后减少，380 ℃～410 ℃产油量较大，可达28.57%；气体收率和油收率随压力升高而增加，残渣收率则明显减小，但当压力高于31.5 MPa后，油收率基本不再随压力的升高而变化；气体收率随停留时间的延长而增加，油收率则先增加后减少。     

Nachhaltige Bausteine für die Kunststoff‐Herstellung

Plant oils are currently the principle resource for the production of bio‐based, high performance polymers, such as polyamides. This process is facilitated by giant strides in chemical catalysis and biotechnology, which allows conversion of vegetable oils in “drop‐in” chemical building blocks. These bio‐based polymer building blocks have equivalent chemical and physical properties as well as similar cost structures compared to conventional petrochemical synthesis feedstock. This allows integration of bio‐based resources into industrial production processes without significant adaptations in logistics or process configuration. However, only use of synergies between chemical and biotechnological unit operations will in future provide for sustainable and eco‐efficient process designs. To allow sustainable supply of bio‐oils to a growing chemical industry without a significant impact on food production demands development of alternative bio‐oil sourcing strategies. In this respect the development of processes for the production of microbial oils, which have equivalent chemical properties to their plant counterparts is imperative. One leading option is the biotechnological conversion of agricultural and food waste streams into microbial oils by combining enzymatic hydrolysis and fermentative production using oleaginous organisms, such as yeasts.     

Thermal stability studies of some cerrado plant oils

Thermogravimetry technique is useful to determine the thermal stability of vegetable oils. In this paper some vegetable oils obtained from brazilian Cerrado native plants were studied based on their high oleic acid content. Amburana, baru and pequi pulp oils presented higher yield of extraction compared to soybean oil. The thermal stability of oils in nitrogen was very close hence their fatty acid composition was very similar. Amburana and baru oils have major amount of unsaturated fatty acids, especially linoleic acid and pequi pulp oil has the highest short chain fatty acid content which can explain its lowest thermal stability in synthetic air.     

Catalytic Biorefining of Plant Biomass to Non‐Pyrolytic Lignin Bio‐Oil and Carbohydrates through Hydrogen Transfer Reactions

Through catalytic hydrogen transfer reactions, a new biorefining method results in the isolation of depolymerized lignin—a non‐pyrolytic lignin bio‐oil—in addition to pulps that are amenable to enzymatic hydrolysis. Compared with organosolv lignin, the lignin bio‐oil is highly susceptible to further hydrodeoxygenation under low‐severity conditions and therefore establishes a unique platform for lignin valorization by heterogeneous catalysis. Overall, the potential of a catalytic biorefining method designed from the perspective of lignin utilization is reported.     

Peat semicoking and hydrocracking

This work deals with thermochemical conversion of peat into solvent-soluble oil and volatile gaseous products by using pyrolysis and catalytical hydrocracking methods. Distribution of liquid compounds between solubilized in water, benzene, and in acetone was determined and as a result the oil yield as total solubles was calculated. Chromatographic and FTIR-spectroscopic methods were used to characterize the composition of conversion products. Investigation of peat pyrolysis regularities in comparison with those of oil shale by using Rock-Eval analysis demonstrated essential differences between peat and oil shale as pyrolysis feedstock. As a result of hydrocracking the total oil yield was increased more than twice compared with that of semicoking, 29.8 and 13%, respectively. Hydrocracking and semicoking led to significant deoxygenation of oil and solid residual conversion products via oxygen removal as carbon dioxide and water. Hydroxyl-, carboxyl-, carbonyl- and other oxygen functionalities in peat initial matter being hydrocracked and modified, the oil was characterized by elevated hydrocarbon content and decreased that of polar oxygen compounds. As the oxygen content of the product decreases, the energy content significantly increases and peat oil, particularly its hydrophobic fractions, can be used for synthetic liquid fuel.     

Influence of residence time and catalyst regeneration on the pyrolysis–zeolite catalysis of oil shale

Oil shale from the Kark region of Pakistan has been pyrolysed in a fixed bed batch reactor and the properties of the derived shale oil determined. The reactor system was then modified to incorporate a second reactor where the derived vapours from oil shale pyrolysis were passed directly to the second reactor containing zeolite ZSM-5 catalyst. The influence of the process parameters of vapour residence time (VRT) over the catalyst and the regeneration of the catalyst were examined. The yield and composition of the derived gases before and after catalysis were determined. In addition, the yield and composition of the derived oil in terms of total nitrogen and sulphur content and the content of aromatic hydrocarbons in the oils was investigated. The results showed that the yield of oil after catalysis was reduced with a consequent higher yield of gases and formation of coke on the catalyst. The main gases from the pyrolysis of oil shales were CO₂, CO, H₂, CH₄, C₂H₄, C₂H₆ and C₃H₆, C₃H₈ and minor concentrations of other hydrocarbon gases. The main role of catalysis was to convert the long chain alkanes and alkenes in the oil to lower molecular weight, short chain, alkyl substituted and iso species and high concentrations of aromatic hydrocarbons. Total nitrogen and sulphur contents in the oils were markedly reduced after catalysis. This reduction was reflected in the reduced concentration of nitrogen and sulphur containing aromatic hydrocarbons. The influence of longer VRTs was to increase the formation of aromatic hydrocarbons, reduce the nitrogen, and sulphur compounds in the oils. The influence of catalyst regeneration, involving five regenerations was not significant on the yield and composition of the derived catalytically upgraded oils.     

Catalysis Meets Nonthermal Separation for the Production of (Alkyl)phenols and Hydrocarbons from Pyrolysis Oil

A simple and efficient hydrodeoxygenation strategy is described to selectively generate and separate high‐value alkylphenols from pyrolysis bio‐oil, produced directly from lignocellulosic biomass. The overall process is efficient and only requires low pressures of hydrogen gas (5 bar). Initially, an investigation using model compounds indicates that MoC_x /C is a promising catalyst for targeted hydrodeoxygenation, enabling selective retention of the desired Ar−OH substituents. By applying this procedure to pyrolysis bio‐oil, the primary products (phenol/4‐alkylphenols and hydrocarbons) are easily separable from each other by short‐path column chromatography, serving as potential valuable feedstocks for industry. The strategy requires no prior fractionation of the lignocellulosic biomass, no further synthetic steps, and no input of additional (e.g., petrochemical) platform molecules.     

Covalent Grafting of Carbon Nanotubes with a Biomimetic Heme Model Compound To Enhance Oxygen Reduction Reactions

The oxygen reduction reaction (ORR) is one of the most important reactions in both life processes and energy conversion systems. The replacement of noble‐metal Pt‐based ORR electrocatalysts by nonprecious‐metal catalysts is crucial for the large‐scale commercialization of automotive fuel cells. Inspired by the mechanisms of dioxygen activation by metalloenzymes, herein we report a structurally well‐defined, bio‐inspired ORR catalyst that consists of a biomimetic model compound—an axial imidazole‐coordinated porphyrin—covalently attached to multiwalled carbon nanotubes. Without pyrolysis, this bio‐inspired electrocatalyst demonstrates superior ORR activity and stability compared to those of the state‐of‐the‐art Pt/C catalyst in both acidic and alkaline solutions, thus making it a promising alternative as an ORR electrocatalyst for application in fuel‐cell technology.     

Separation of phenol‐containing pyrolysis products using comprehensive two‐dimensional chromatography with columns based on pyridinium ionic liquids

We describe the application of columns with highly polar stationary liquid phases based on pyridinium ionic liquids for the two‐dimensional chromatography separation of bio‐oil and product of coal pyrolysis. By using inverse combination columns—a first ionic liquid column and a second nonpolar column—good separation results have been obtained. In the analysis of coal pyrolysis products, the suggested approach provides a much better resolution between components in comparison with a less polar first‐dimension column (based on polyethylene glycol). A good selectivity for the peaks of phenols is observed, and the group of phenols is well detached and separated from the group of diaromatics. A good separation picture was obtained also for bio‐oil, the groups of phenols and guaiacol derivatives are distinguished with good resolution of substances within each group.