木质素与高密度聚乙烯共热解特性研究

生物质与塑料共热解是一种非常有效的生物质利用方法之一,但由于生物质结构的复杂性,共热解过程的机理尚不明晰。木质素是生物质的主要组分之一,本文通过热重-质谱联用仪和裂解器-气相色谱质谱仪研究其与高密度聚乙烯共热解过程,获取共热解特性及热解产物分布特性,以揭示共热解过程机制。结果显示,木质素与高密度聚乙烯共热解过程存在协同效应,使得热解失重速率加快,热解固体残渣含量减少。共热解过程有利于CH₄、H₂O、CO和C₂H₄的生成,抑制CO₂的生成。同时,酚类、醇类和糖类等含氧化合物产量减少,烷烃和烯烃类化合物产量增加。结果表明,共热解过程会发生氢转移现象,氢与木质素衍生热解产物结合发生反应,从而抑制含氧化合物的生成,促进烷烃类和烯烃类化合物生成。     

Pyrolysis and co-pyrolysis of Laminaria japonica and polypropylene over mesoporous Al-SBA-15 catalyst

The catalytic co-pyrolysis of a seaweed biomass, Laminaria japonica, and a typical polymer material, polypropylene, was studied for the first time. A mesoporous material Al-SBA-15 was used as a catalyst. Pyrolysis experiments were conducted using a fixed-bed reactor and pyrolysis gas chromatography/mass spectrometry (Py-GC/MS). BET surface area, N₂ adsorption-desorption isotherms, and NH₃ temperature programmed desorption were measured to examine the catalyst characteristics. When only L. japonica was pyrolyzed, catalytic reforming slightly increased the gas yield and decreased the oil yield. The H₂O content in bio-oil was increased by catalytic reforming from 42.03 to 50.32 wt% due to the dehydration reaction occurring on the acid sites inside the large pores of Al-SBA-15. Acids, oxygenates, mono-aromatics, poly aromatic hydrocarbons, and phenolics were the main components of the bio-oil obtained from the pyrolysis of L. japonica. Upon catalytic reforming over Al-SBA-15, the main oxygenate species 1,4-anhydro-d-galactitol and 1,5-anhydro-d-manitol were completely removed. When L. japonica was co-pyrolyzed with polypropylene, the H₂O content in bio-oil was decreased dramatically (8.93 wt% in the case of catalytic co-pyrolysis), contributing to the improvement of the oil quality. A huge increase in the content of gasoline-range and diesel-range hydrocarbons in bio-oil was the most remarkable change that resulted from the co-pyrolysis with polypropylene, suggesting its potential as a transport fuel. The content of mono-aromatics with high economic value was also increased significantly by catalytic co-pyrolysis.     

生物质与催化裂化油浆共热解协同作用研究

基于生物质焦油氧含量高、品质差的缺陷,本文提出将生物质与重油共转化利用的方法。以催化裂化油浆（FCC）、稻壳（RH）、木屑（PS）为原料,通过低温固定床热解实验对其共热解产物分布进行了研究。结果表明,在FCC的供氢作用下,共热解有利于焦油中含氧化合物的脱除,随着生物质比例增加,反应过程中脱羧基、脱羰基反应减弱,脱羟基反应增强,产物中CO、CO₂产率较计算值增加幅度减小,水的产率较计算值逐渐增大。焦油中烃类物质增加,其中芳香烃以二元环和四元环增加为主,脂肪烃中以C₁₃~C₂₀增加为主。整体上,共热解过程促进了半焦产率的增加,焦油产率虽无明显改变但品质得到了显著提升。     

煤直接液化残渣与褐煤共热解动力学研究

为了解决煤炭液化残渣在热解过程中软化熔融并剧烈膨胀导致难以利用的问题,在温度范围为30 ～900℃,升温速率分别为10、20、30、40℃/min的情况下,借助热重分析仪对煤直接液化残渣与褐煤进行程序升温共热解试验,采用Doyle法分析共热解动力学,将动力学结果与共热解协同作用进行关联.结果表明:共热解过程可用3个串联的一级反应描述,温度区间分别为200 ～310、310～470、470～900℃,其中310 ～470℃对应共热解反应的活泼分解阶段,反应活化能(40 ～ 50 kJ/mol)远大于低、高温反应活化能(10 ～20 kJ/mol).液化残渣与褐煤共热解降低了活泼分解阶段的反应活化能,加快了反应速率,增大了热解失重率,使共热解反应在300 ～550℃表现出正协同作用.     

基于正交实验优化凤眼莲与低阶煤共热解条件

采用自行改装设计的干馏炉,基于L9 (34)正交实验对凤眼莲和低阶煤低温共热解进行条件优化,以提高热解油产率,正交实验得出因素主次关系为:终温＞配比＞粒径＞保温时间,并且当凤眼莲添加量为35％,终温为550℃,凤眼莲粒径为0.355 mm～0.500 mm,保温时间为25 min时,热解油产率达到最大值11.70％,比优化前提高了3.36％.并对热解油进行了GC-MS检测,优化后热解油中苯类物质得到了大量的富集,其质量分数达到了63.17％,比优化前提高了81.99％.元素分析和热值分析得出优化前后热解油n(H)∶n(C)和热值变化不大,在不影响热解油品质的情况下实现了提高热解油产率的目的.     

Insights into pyrolysis and catalytic co-pyrolysis upgrading of biomass and waste rubber seed oil to promote the formation of aromatics hydrocarbon

To solve the problem of low aromatic hydrocarbon yield and selectivity in biomass catalytic pyrolysis, we used added oxygen-containing hydrogen supplier of rubber seed oil (RSO) with a higher hydrogen-to-carbon ratio to investigate the thermal decomposition behaviors, kinetic and production distribution of biomass, cellulose and RSO with the weight ratio of 1:2 using thermogravimetric analyzer (TGA) for kinetic analysis and fixed bed reactor with the feed composition of 1.2 g: 0.4 mL/min (Biomass to RSO) for product distribution in non-catalytic and catalytic co-pyrolysis over a HZSM-5 catalyst. The results show that there was a positive synergistic interaction between biomass and RSO according to the difference in weight loss, which could decrease the formation of solid coke at the end of experiment. The addition of the HZSM-5 catalyst can markedly increase the reaction activity, accelerate the reaction rate, and the reaction Ea, leading to a substantial increase in the conversion rate; furthermore, the residual carbon content will decrease, and the activations of Cellulose + RSO + Catalyst and Biomass + RSO + Catalyst are only 50.80 kJ/mol and 62.36 kJ/mol, respectively. The kinetic analysis showed that adding a catalyst did not change the decomposition mechanism. Co-pyrolysis of biomass and RSO could effectively improve the yield and selectivity of aromatics, when the pyrolysis temperature and catalytic temperature were 550 °C and 500 °C, respectively, the mass space velocity of RSO was 0.4 mL/min, the reaction time was 30min, the yields of benzene, toluene, xylene and ethyl benzene (BTXE) were up to 78.77%, and the selectivity of benzene, toluene and xylene was much better. Finally, the coke yield was substantially lower.     

PET和关中麦秆共热解特性及其动力学研究

利用TG-FTIR技术研究陕西关中地区小麦秸秆（麦秆）、聚对苯二甲酸乙二醇酯（PET）及其两者混合物麦秆-PET（质量比1：1）在20 K/min的升温速率下的热解行为、主要热解产物、协同效应和动力学。研究结果表明：PET热解初始温度为375℃,最大热失重速率处的温度为454.9℃,失重率为62.87%,其热解残余质量为19.42%;麦秆-PET的热解DTG曲线表现为麦秆和PET主失重峰（339.9和444℃）的叠加,且混合试样在两个强峰处的失重率分别为22.9%和73.9%,最终热解残余质量为23.52%;PET和麦秆共热解过程中会出现两个协同效应（339.9和444℃）,这使得共热解产物中的CO、CH₄以及芳香族、酸类、酮类、醛类、醇类、烷烃、酚类和醚类等轻质焦油组分含量高于麦秆和PET单独热解,共热解提高了热解产物的热值,改善了热解产物组成,提升了热解产物的稳定性和燃料品质;采用Coats-Redfern积分法计算得到PET在主热解区的表观活化能为355.48 kJ/mol,远高于麦秆的表观活化能（86.5 kJ/mol）,麦秆-PET在低温区（258~363℃）的表观活化能为53.6 kJ/mol,在高温区（393~463℃）的表观活化能为81.6 kJ/mol。     

褐煤与大豆荚共热解的产物特性分析

利用自制的低温热解装置研究褐煤与大豆荚共热解的产物特性,考察大豆荚掺混比和催化剂Fe₂O₃对热解产物特性的影响。通过FT-IR、GC-MS、SEM-EDX和UV-vis分析共热解产物的性质,并将半焦用于亚甲基蓝吸附实验。研究结果表明：掺混比30%时,共热解焦油的产率达到最大值11.98%,比煤焦油产率增加44.86%,与计算值的正偏差最大（0.8%）,同时,大豆荚的添加有促进焦油生成的协同作用。大豆荚的添加有利于共热解焦油中含氧杂环的断裂,使共热解焦油中直链烷烃增多,芳香族化合物减少,使重质组分转化为轻质组分,从而提高焦油品质;同时,大豆荚的添加使共热解半焦的含氧基团增加,微观形貌变粗糙。而Fe₂O₃的加入使共热解焦油中酚、醇类物质增加;加Fe₂O₃共热解半焦的褶皱更加明显。共热解半焦对亚甲基蓝的吸附率为33.62%,比煤半焦的吸附率提高8.84%,加Fe₂O₃共热解半焦的吸附率为55.57%,比共热解半焦提高65.29%。     

生物质与废轮胎共热解及催化对热解油的影响

生物质稻壳与废轮胎以不同比例组成的均匀混合物在管式固定床内共热解，MCM-41和SBA-15作为催化剂，对产生的热解油性质进行了研究。结果表明，随着废轮胎在混合物中比例增加，热解油产率和热值在增加，而黏度和密度在降低。当稻壳占到60%（质量）时，热解液体产率为44.5%（质量），热解油热值为40 MJ·kg-1，热值与柴油接近;温度对热解油的产率和组分柠檬精油的生成影响较大。对组成一定的混合物，在热解温度500℃时二者均达到最大。通过对热解油主要组分柠檬精油和氧含量的分析说明，共热解过程中组分间可以产生一定的相互作用，并具有协同效果，体现在柠檬精油组分的含量低于加权后的浓度，氧含量大于加权后的数值;与没有催化剂存在情况相比，MCM-41和SBA-15的存在能显著降低热解液体的黏度和密度，其中，SBA-15的降低效果更为明显。     

生物质混合物与煤共热解的协同特性

该文选取了秸秆、稻壳、玉米芯、木屑、沙柳枝和叶、旱柳枝和叶、紫花苜蓿、芦苇、碱草等13种农业和林业废弃物、草木类及不同生长期的薪炭林等生物质，按等比例混合制备成粉状生物质混合物，在不同的工况下采用热重分析仪，分析研究生物质混合物与典型的褐煤、贫煤和烟煤煤粉的单独热解特性，以及分别与3种煤均匀掺混20%、33%与50%生物质混合物的共热解特性，合理定义了共热解中煤挥发分开始热解的温度。对热解试验数据与计算特性参数的分析表明：不同比例生物质混合物和不同煤化程度煤在共热解过程中，产物的产率基本等于单独热解生物质和煤的产物产率的加权平均值；与单独热解试验结果比较，生物质混合物与煤挥发分的各自析出开始和终止温度均随着生物质掺混比例不同与煤种不同有不同程度的变化，并对其规律进行了机理分析，认为生物质与煤共热解过程中存在协同作用。