氧含量对热解废轮胎产物影响研究

以含氧木屑为探针材料,同废轮胎以不同比例共热解以准确控制其氧含量,考察氧含量对热解废轮胎得到的气、液、固三相产物的影响及多环芳烃(PAHs)含量的影响。采用热重分析仪(TG)、元素分析仪(EA)以及气相色谱仪(GC)分别对它们热行为、热解油中氧含量及PAHs的变化规律进行了观察。TG分析表明,木屑中氧含量对废轮胎热解最大失重速率发生的温度产生了推后的影响。在木屑∶废轮胎质量为2∶1时,温度滞后3.7℃。EA分析表明,热解油中氧含量越高,氢含量较加权值越低,碳含量基本不变。GC分析表明,适量木屑所含的氧能够有效抑制PAHs的生成;对三相产物影响表明,氧含量越高,液体产率较加权值越小,气体产率较加权值越大,固体产率较加权值有所降低但与氧含量多少关联不明显。通过木屑和废轮胎共热解过程氧含量对热解产物影响的分析,为科学利用生物质、合理处置废轮胎提供科学帮助。     

生物质与废轮胎共热解对热解液体性质的影响

研究了影响生物质与废轮胎共热解得到的液体性质及组成的因素。结果表明生物质和废轮胎最大热分解温度均发生在330~360℃,共热解能够产生协同效应。随着加热速率的增大,最大热分解温度逐渐向高温处移动;生物质比例越低热解得到的液体越多;温度越高,得到的液体越少,在350℃下进行共热解得到的液体最多。混合后热解液体的氧含量比生物质单独热解得到液体的氧含量有所降低,芳香族化合物有所增加,并分析了热解液体的族组成。     

HZSM-5/MCM-41对小球藻催化热解的影响

以HZSM-5/MCM-41为催化剂,在管式炉内对小球藻进行了催化热解研究。考察了HZSM-5/MCM-41复合催化剂中MCM-41的添加比例对小球藻热解产物影响,并采用GC-MS和元素分析对所制取生物油进行了表征。结果表明:与HZSM-5催化剂相比,90%HZSM-5与10%MCM-41混合后生物油中3,7,11,15-四甲基-2-十六烯的选择性最好。羧酸类和含氮物质分别降低12.85%、43.97%,脂肪烃和芳烃的质量分数之和达到50.34%,且不存在硬脂酰胺和油酸腈等物质。根据元素分析可知,10%的MCM-41的引入使生物油含氧量降低23.52%,O/C原子比明显降低,H/C原子比得到提高,热值达到32.995 MJ·k-1,且油品组成与生物柴油接近。热重实验表明,分子筛催化剂失活主要是由于积炭的产生,HZSM-5/MCM-41具有良好的稳定性。随着催化剂用量的增加,生物油热值增加,同时含水量也增多,HZSM-5/MCM-41与小球藻质量比例为1:5时,生物油产率最高。     

ZSM-5/SBA-15复合催化剂制备及其对生物质热解制生物油

通过表面响应法，以Box-Behnken试验原理，对生物质（玉米秸秆）的非催化热解进行三因素试验，其中生物油产率为响应值，温度、升温速率、氮气流速为自变量，确定最大生物油产率的工艺参数进行催化热解。以硅酸四乙酯为硅源，通过水热合成法合成了复合催化剂ZSM-5/SBA-15，并进行玉米秸秆的微波催化热解产物分析。通过XRD、SEM、TEM、NH3-TPD进行催化剂表征，得到复合催化剂不仅具有介孔催化剂SBA-15的性质，且兼备微孔催化剂ZSM-5的性质。通过GC-MS分析，复合催化剂ZSM-5/SBA-15的加入，相比非催化热解烃类收率（6.42%）和酚类收率（39.65%）都有所增加。     

稻壳热解和生物油精制的研究

在一个间歇给料的流化床反应器中热解稻壳生产生物油,热解温度范围为450-650℃.在500℃,生物油的最大产量为53.8%.用色质联机研究了生物油的化学成分,确定了生物油的元素组成、密度、pH、黏度和热值.研究了生物油与柴油的乳化油的比例和理化特性,结果表明乳化方法是一种实用的生物油利用途径.     

活性炭催化热解纤维素协同制备酚类和合成气

苯酚和合成气均为工业生产中重要的基础化工原料。以自制的活性炭为催化剂,以纤维素为原料实现了催化热解液相产物中苯酚和气相产物中CO的同时富集。实验发现,生物质灰分中的钾、热解过程中催化剂/纤维素质量比和热解温度均对气液相产物的品质有着不同程度的影响。研究表明：钾的存在不利于热解产物品质的提高。钾虽然提高了生物油中苯酚的富集度,但降低了实际产率。而热解气中CO的浓度和产率均下降。对催化热解条件的研究表明热解温度450℃,催化剂比例为1∶1时可获得最佳的热解产物。此时,生物油中酚类物质占可检测有机物相对含量的62.31%,其中苯酚为45.37%,产率为1.78%（质量）。热解气中CO的浓度和产率分别为69.21%（体积）和 169.95 ml/g,热值为12.93 MJ/m³。     

碱土金属氧化物基催化剂催化热解生物质研究进展

快速热解是生物质高效转化利用的重要方法之一,然而其目标产物生物油因含氧量高、组分复杂等不足而难以直接利用。通过在热解体系中引入碱土金属氧化物基催化剂,可以将热解产物中的氧元素以CO₂和H₂O等方式脱除,从而实现生物油品质的提升。总结了典型碱土金属氧化物基催化剂对生物质催化热解过程中发生的酮基化、羟醛缩合、开环和侧链断裂反应及机理,讨论了催化剂类型（CaO、MgO、基于碱土金属氧化物的分子筛和活性炭等）、生物质原料、温度、催化剂用量、停留时间、催化方式、催化剂失活等因素对生物油产率与品质的影响,并对生物质催化热解制备高品质生物油及其应用进行了展望。     

废轮胎热解制油技术及油品应用前景

综述了国内外废轮胎热解制油技术的研究进展,对比了真空移动床热解、外热式批量进料固定床热解、内热式火焰固定床热解、回转窑热解和流化床快速热解等各种废轮胎热解技术的工艺及其特点;总结了热解产物中热解油的理化特性;并针对热解油高热值、高芳烃含量等特点,提出废轮胎热解油的可能应用前景,包括热解油整体作为燃料油燃烧或提取苯、甲苯、二甲苯及苧烯等具有较高经济价值的化工产品。     

条浒苔与稻壳共热解协同效应

为了进一步探究大型海藻与陆生生物质共热解的协同效应,选取条浒苔与稻壳生物质作为代表进行了单样以及不同混合比例的共热解台架试验。通过三相产物产率的计算,以及生物油产物的GC-MS、FT-IR、热值分析和对气相产物的GC分析,研究了条浒苔与稻壳共热解协同效应的影响。共热解的气相产物产率在各个混合比例下均高于理论值,说明共热解对气相产物的生成具有促进作用,同时共热解气相产物中甲烷、乙烷、乙烯、丙烷为主的小分子烃类物质产率高于理论值,生物油中以乙酸为代表的小分子产物明显增多,分析认为条浒苔灰分中Na、K等碱金属具有促进大分子产物进一步裂解的催化作用,进一步验证了条浒苔与稻壳共热解的协同效应。     

N2/CO2气氛下木屑生物质热解特性的实验研究

本研究利用固定床管式炉开展了不同N2/CO₂比例气氛下的木屑生物质热解实验,考察了CO₂浓度、载气流速和停留时间对热解油和焦炭产率的影响。结果表明：热解油和焦炭的产率随反应温度和停留时间的增加而降低,热解油产率随反应气氛中CO₂浓度的升高而增加。在N₂和CO₂气氛下,载气流速升高均使热解油产率下降,而焦炭产率则在15%左右保持不变。添加HZSM-5和ZIF-67两种催化剂,发现ZIF-67在CO₂气氛下的热解油产率可以达到72.3%,相比其在N₂气氛下的热解油产率提升了近1.5倍;而HZSM-5由于其微孔孔道对生物质大分子传质的限制,产生最多焦炭(24.1%)。     

Investigations into the characteristics of oils produced from co-pyrolysis of biomass and tire

Co-pyrolysis of wood biomass and waste tire with such catalysts as SBA-15, MCM-41 and HZSM-5 was carried out in a fixed-bed reactor. The influences of the mixture composition on liquid yield and characteristics of the oil were investigated. The properties of the oil were determined by gel permeation chromatograph (GPC), elemental analyzer (EA), thermal analyzer (TA), densimeter, ubbelohde viscosimeter and compared with that of diesel oil 0#. The contents of the polycyclic aromatic hydrocarbons (PAHs) in the oils were also determined by gas chromatograph (GC). The result shows that co-pyrolysis is in favor of inhibiting the formation of polycyclic aromatic hydrocarbons (PAHs) produced from tire. There exist a hydrogen transfer and a synthetic effect during co-pyrolysis of the biomass and tire. They improve the quality of the oil. SBA-15 as a catalyst is more significant than MCM-41 or HZSM-5 for reducing the density and viscosity of the oil and it can effectively decompose some large molecular compounds into small ones.     

Preparation of bio-fuels by catalytic cracking reaction of vegetable oil sludge

Biofuel production from vegetable oil is potentially a good alternative to conventional fossil derived fuels. Moreover, liquid biofuel offers many environmental benefits since it is free from nitrogen and sulfur compounds. Biofuel can be obtained from biomass (e.g. pyrolysis, gasification) and agricultural sources such as vegetable oil, vegetable oil sludge, rubber seed oil, and soybean oil. One of the most promising sources of biofuel is vegetable oil sludge. This waste is a major byproduct of vegetable oil factories. It consists of triglycerides (61%), free fatty acid (37%) and impurities (2%). The hydrocarbon chains of triglycerides and free fatty acid are mainly made up of C₁₆ (30%) and C₁₈ (36%) hydrocarbons. The others consist of C₁₂-C₁₇ hydrocarbon chains. Transesterification can help in converting vegetable oil sludge into biofuel. The disadvantage of this method is that a large amount of methanol is required. The alternative method for this conversion is catalytic cracking. The objective of this research is to evaluate and compare the pyrolysis process with cracking catalytic reaction of vegetable oil sludge by Micro-activity test MAT 5000 of Zeton-Canada.A ZSM-5/MCM-41 multiporous composite (MC-ZSM-5/MCM-41), was successfully synthesized using silica source extracted from rice husk. The material has the MCM-41 mesoporous structure, and its wall is constructed by ZSM-5 nanozeolite crystals. The porous system of the material includes pores of the following sizes: 5 Å (ZSM-5 zeolite), 40 Å (MCM-41 mesoporous material), and another porous system whose diameter is in the range of 100-500 Å (mesoporous system) formed by the burning of organic compounds that remain in the material during the calcination process. This pore system contributes to an increase in the catalytic performance of synthesized material.The results of vegetable oil sludge cracking reaction show that the product consists of fractions such as dry gas, liquefied petroleum gas (LPG), gasoline, light cycle oil (LCO), and (heavy cycle oil) HCO, which are similar to those of petroleum cracking process.MC-ZSM-5/MCM-41 catalyst is efficient in the catalytic cracking reaction of vegetable oil sludge as it has higher conversion and selectivity for LPG and gasoline products in comparison to the pyrolysis process. Product distribution (% of oil feed) of cracking reaction over MC-ZSM-5/MCM-41 is coke (3.4), total dry gas (7.0), LPG (31.1), gasoline (42.4), LCO (8.9), HCO (7.2); and that of pyrolysis are coke (19.0), total dry gas (9.3), LPG (16.9), gasoline (28.8), LCO (13.7), and HCO (12.3).These results have indicated a new way to use agricultural waste such as rice husk for the production of promising catalysts and the processing of vegetable oil sludge to obtain biofuel.     

The isolation of pyrolysis oil from castor seeds via a Low Temperature Conversion (LTC) process and its use in a pyrolysis oil-diesel blend

A Low Temperature Conversion (LTC) process carried out on a sample of castor seeds, Ricinus communis, generated fractions of pyrolysis oil, pyrolitic char, gas and aqueous extracts in the following relative amounts, respectively: 50%, 28%, 10% and 12% [w/w]. The pyrolysis oil was added at loadings of 2%, 5%, 10%, 20% and 30% [w/w] to commercial diesel. The density, viscosity, sulfur content, glow point, volatility and cetane index of these mixtures were determined. The results indicate that the addition of pyrolysis oil to commercial diesel results in fuel mixtures within the norms of ANP diesel directive no 15, made on 19. 7. 2006, with the exception of the 20% mixture (which has an unfavorable viscosity) and the 30% mixture (which has an unfavorable viscosity and volatility).     

Evaluation of pyrolytic oil from used tires and natural rubber (Hevea brasiliensis)

The pyrolysis of used tires, UT, and natural rubber (Hevea brasiliensis), NR obtained from Nigerian NIG800 clonal rubber tree, was performed and the effects of process conditions on product yield were investigated. An optimum yield was attained at operating temperature of 600°C, a heating rate of 15°C?min^?1, for a feed size of 6?mm. The UT and NR gave maximum pyrolytic oil yield of 34.40 and 75.93?wt%, respectively. The pyrolytic oil was characterized using Fourier transform infrared, nuclear magnetic resonance, and gas chromatography–mass spectrometry (GC–MS). Results obtained reveal the pyrolytic oil to be a complex mixture, mainly of aliphatic and aromatic compounds, which can serve as feedstock for industrial application. Nevertheless, a comparative evaluation of the physical and chemical properties of the UT and NR pyrolytic oil showed that NR had hydrocarbon composition of 80% aliphatics, 12% aromatics (with less than 2% polycyclic aromatic hydrocarbon concentration). However, the UT pyrolytic oil had 42% aliphatic and 34% aromatic compounds (with polycyclic aromatic hydrocarbons concentrations of 18%). Also, NR pyrolytic oil had better physical properties such as density, viscosity, flash point, pour point, and higher heating value than that produced from UT in this study, and comparable with that of commercial diesel. Moreover, sulfur content, which is a limiting factor in the direct combustion of UT pyrolytic liquid, was absent in NR pyrolytic oil. Hence, it is technologically feasible for NR from H. brasiliensis to be a suitable source of pyrolytic oil than UT.     

稻壳热解油的特性

利用自行搭建的固定床热反应器对稻壳进行热解实验制备热解油, 采用两种不同极性的石英毛细柱对收油后的二氯甲烷溶液进行GC-MS检测。实验结果表明:热解终温对热解油品的组分种类几乎无影响, 但热解油产率随热解终温增大呈先升高后降低趋势;热解油二氯甲烷溶液的水相部分化合物种类相对较少, 主要物质为甲酸、乙酸和1-羟基-2-丙酮, 油相部分有机物种类极为复杂, 主要物质为糠醛、糠醇以及酚类和酮类物质;可凝结的热解有机气体主要在500～600℃发生二次裂解;对稻壳600℃热解油油相检测时发现:在RTX-5MS柱检测条件下, 组分中前5种化合物是糠醛、2-丁酮、乙酸、苯酚和2-甲氧基苯酚, 而在RTX-WAX 柱检测条件下, 前5种化合物是苯酚、2-甲氧基苯酚、4-乙基苯酚、乙酸和3-甲基苯酚。     

Evaluation of two different scrap tires as hydrocarbon source by pyrolysis

The main objective of the present study is to investigate the effect of the polymer types in scrap tires on the pyrolysis products. Two different types of scrap tires (passenger car tire, PCT and truck tire, TT) have been pyrolyzed in a fixed bed reactor at the temperatures of 550, 650 and 800 °C under N₂ atmosphere. Pyrolysis products (gas, oil and carbon black) obtained from PCT and TT were investigated comparatively. The gaseous products were analyzed by GC–TCD. The psychical and chemical properties of pyrolytic oils were characterized by means of GC–FID, GC–MS, ¹H NMR. In addition, boiling point distributions of hydrocarbons in pyrolytic oils were determined by using simulated distillation curves in comparison with commercial diesel fuel. The production of activated carbon from pyrolytic carbon blacks (CBp) was also carried out. The composition of gaseous products from pyrolysis of PCT and TT were similar and they contained mainly hydrocarbons (C₁–C₄). Pyrolytic oils were found lighter than diesel but heavier than naphtha. The physical properties of pyrolytic oils from PCT and TT were similar at the same temperature. However, the composition of aromatic and sulphur content from pyrolysis of PCT was higher than that of TT. Furthermore, TT derived pyrolytic carbon black was found more suitable for the production of activated carbon due to its low ash content.     

Synthesis of hexagonal and cubic mesoporous silica using power plant bottom ash

An alkali fusion method was adopted to extract silicate species from coal bottom ash in a power plant and the supernatant solution was used for the synthesis of MCM-41, SBA-15, and SBA-16 mesoporous silica materials. The minor impurities present in the bottom ash were not found to be detrimental to the successful formation of mesoporous silica phases. Additional silica from sodium metasilicate was introduced to improve the textural properties for SBA-15 and SBA-16. According to SEM analyses, particle morphology of the samples gradually approaches those prepared using pure chemical as the amount of external silica source increases. XRD analyses confirmed well-ordered mesostructures in all of these silica materials. N₂ adsorption–desorption isotherms of MCM-41 prepared using bottom ash showed a type IV isotherm with a region of steep increase due to capillary condensation, whilst SBA-15 and SBA-16 showed type IV isotherm with H1 and H2 hysteresis loops, respectively. ²⁷Al MAS NMR analysis of MCM-41 synthesized from the supernatant solution reveals that the extracted Al species from bottom ash were tetrahedrally incorporated in the framework. TEM clearly showed the uniform pore structure of the materials prepared using the industrial waste.     

The influence of the waste ethylene vinyl acetate copolymer on the thermal degradation of the waste polypropylene

The pyrolysis of the waste polypropylene (PP), the waste ethylene vinyl acetate copolymer (EVA) and their blends has been carried out in a fixed bed reactor at 500 °C. The effect of different ratios of the waste EVA in the waste PP/EVA blends on the thermal degradation of the waste PP was investigated in terms of both product distributions and liquid fuel properties. The compositions of pyrolysis products were characterized in detail. The liquid products from the pyrolysis of the waste PP, the waste EVA and their blends were analyzed using different analytical techniques and fuel properties of pyrolytic liquids were investigated in comparison with commercial diesel. There were no synergistic effects between products from the waste PP and products from the waste EVA. While the ratio of the waste EVA increased in the waste PP/EVA blends, aromatic content of the pyrolytic liquids increased and subsequently paraffinic content of the pyrolytic liquids decreased. In addition, the boiling point distributions of pyrolytic liquids derived from the waste PP/EVA blends were found to be similar for all tested ratios of the waste PP/EVA blends.     

Room temperature blue-green photoluminescence of MCM-41, MCM-48 and SBA-15 mesoporous silicas in different conditions

The photoluminescence (PL) properties of siliceous MCM (MCM-41 and MCM-48) and SBA-15, no Na-containing MCM-41, and modified SBA-15 by silylation were comparatively investigated in dry and damp conditions, displaying the highest PL intensity of MCM-48. The PL intensity of MCM-41 is lower than that of SBA-15 in dry conditions, but reverse in damp conditions. In comparison with that of Na-containing MCM-41, the PL intensity of MCM-41 without Na⁺ is stronger. The PL intensity of modified SBA-15 by silylation is decreased in dry conditions, and however, against moisture and degradation in damp conditions. Twofold coordinated silicon centers in the tested samples are responsible for the blue-green bands at 440 nm. The shoulder peaks around 460–490 nm occurred in damp conditions are assigned to peroxy free radicals.     

Novel utilization of mesoporous molecular sieves as supports of cobalt catalysts in Fischer–Tropsch synthesis

Mesoporous molecular sieves (MCM-41 and SBA-15) with different pore diameters have been studied as supports of high loading of Co catalysts, and the performances in FT synthesis have been examined with a fixed bed stainless steel reactor at 2.0 MPa for the purpose of efficient production of C₁₀–C₂₀ fraction as the main component of diesel fuel. The method of exchanging template ions in uncalcined MCM-41 with Co²⁺ ions is effective for holding 10–20% Co within the mesopores while keeping the structure regularity of MCM-41 to some extent, compared with the conventional impregnation method using calcined MCM-41. At 523 K, CO conversion and selectivity to C₁₀–C₂₀ hydrocarbons are both higher at larger loading of 20% Co for the exchanged catalysts with pore diameters of 2.7–2.9 nm. When four kinds of 20% Co/SBA-15 with the diameters of 3.5–13 nm, prepared by the impregnation method using an ethanol solution of Co acetate, are used in FT synthesis at 523 K, the catalyst with the diameter of 8.3 nm shows the largest CO conversion, which is higher than those over MCM-41 supported Co catalysts. At a lower temperature of 503 K, however, the acetate-derived Co is almost inactive. In contrast, the use of Co nitrate alone or an equimolar mixture of the acetate and nitrate as Co precursor drastically enhances the reaction rate and consequently provides high space–time yield (260–270 g C/kg_cat h) of C₁₀–C₂₀ hydrocarbons. The X-ray diffraction and temperature-programmed reduction measurements show that the dependency of the catalytic performance of 20% Co/SBA-15 on its precursor originates probably from the differences in not only the reducibility of the calcined catalyst but also the dispersion of metallic Co. Catalyst characterization after FT synthesis strongly suggests the high stability of the most effective Co/SBA-15 in the dispersion and reducibility of the oxide species and in the mesoporous structure.