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。     

碱处理HZSM-5催化纤维素热裂解制备芳烃

使用不同浓度的NaOH溶液(0.2~1.0mol/L)对不同硅铝比的HZSM-5沸石进行碱处理制备多级孔HZSM-5,研究了NaOH浓度对碱处理制备多级孔HZSM-5的影响规律以及多级孔HZSM-5在纤维素催化热裂解中的催化性能。采用N2吸附-脱附、XRD、TEM和NH_3-TPD对催化剂进行表征:XRD结果显示HZSM-5碱处理后,多级孔HZSM-5依然有MFI结构特征峰;N_2吸附-脱附和TEM表征结果表明碱处理后的ZSM-5晶体内有明显的介孔孔道,形成多级孔结构;NH3-TPD结果表明随着NaOH浓度的增加,多级孔HZSM-5的强酸量呈现先增加后减少的趋势,在0.4mol/L处达到最高值。在微型裂解仪与气相色谱-质谱联用装置中研究多级孔HZSM-5对纤维素催化热裂解制备芳烃的催化性能,结果显示硅铝比为25、38、50的HZSM-5芳烃产率分别从碱处理前的33.5%、35.6%和32.2%,最高增加至37.1%、38.5%和34.0%(0.4mol/L NaOH碱处理);焦炭产率分别由碱处理前的33.1%、31.5%和33.8%降低至29.1%、25.8%和29.8%。结果表明,通过有效调控碱处理条件能够提高纤维素催化热裂解过程中的芳烃产率,同时降低焦炭产率。     

基于PDEC的生物油在线提质工艺优化与机理研究1

构建了等离子体前置放电增强催化的反应系统,依托该系统开展了HZSM-5在线提质生物油的研究,采用响应面法分析了反应温度、催化剂填装高度和放电功率等对精制生物油产率的影响规律;并在最佳工艺下引入Ti/HZSM-5进行生物油提质,探讨催化反应机理。结果表明,各因素对产率影响显著,且相互之间存在交互作用;当反应温度为400℃,催化剂填装高度为20 mm,放电功率为30 W时,精制生物油产率达到18.1%,与预测值18.5%较为接近。采用Ti/HZSM-5催化时裂解脱氧性能明显增强,产率下降至16.0%,但烃类含量和组成得到明显提高和改善,多环芳香烃降至6.33%,C_(14)及以上的大分子烃类仅为2.81%。前置放电为后续催化反应提供了物料基础,且活性物质的冲击既增强了催化剂活性,又改变了反应物的吸附行为,而Ti离子与活性物质的相互作用促进了碳正离子反应的进行,并在"烃池"机理的作用下,形成以单环芳香烃为主的产物。     

介孔分子筛催化裂解聚合物材料的研究进展

综述了近几年来国内外介孔分子筛催化聚合物材料裂解回收相应产品的研究现状,重点介绍的主要降解方法包括热裂解法和催化裂解法。主要催化剂包括MCM-41、ZSM-5、SBA-15、MAS-7、SiO_2/Al_2O_3和介孔SiO_2。其中催化裂解主要包括催化裂解聚乙烯(PE)、聚苯乙烯(PS)、聚丙烯(PP)等高聚物的方法,同时通过X射线粉末衍射、傅立叶变换红外光谱等表征手段和考察反应体系的工艺条件分析了热裂解法和催化裂解法的优缺点。最后对介孔分子筛催化解聚聚合物材料进行了探讨与展望。     

Fe-Zn共改性ZSM-5催化作用下生物质快速热解特性研究

选取木屑和花生壳作为原料进行生物质热解,研究有机产物分布,催化剂使用Fe、Zn两种金属元素进行改性。通过X射线衍射（XRD）、扫描电镜（SEM）、傅里叶红外（FT-IR）、比表面积测试（BET）对Fe-Zn改性的ZSM-5进行分析。使用闪速裂解-气质联用仪（PY-GC/MS）对原料进行热解,探究生物质催化热解的产物分布变化。催化剂的使用使得芳烃类产物产率获得较大提升,在木屑热解中,Fe负载的分子筛催化获得了酚类的最高产率,比ZSM-5催化热解产率提升18.30%。金属改性催化剂在花生壳热解中,大幅提升了芳烃类产物产率,其中Zn负载催化剂芳烃类产物产率最高,Zn负载催化热解比直接热解的酚类产率降低了18.92%。Zn负载催化获得了最低的酮类产率,与直接热解相比酮类产率降低19.74%,显示出较强的脱羟基效果。此外Zn负载催化和Fe-Zn双金属负载催化在花生壳热解中都大幅降低了酸类产物产率,与直接热解相比酸类产率分别降低了30.46%、36.71%。     

金属氧化物活化P/HZSM-5催化生物质热解气重整制备富烃生物油

为了探讨催化剂的酸性和孔道结构与热解产物之间的构-效关系,采用金属改性的M-P/HZSM-5 (M=Zn、Ce、Co、Cu、Ga和Mg)为催化剂,催化生物质热解气相重整制备富烃生物油,探究金属的种类对产品的产率以及选择性的影响,采用XRD、BET、NH₃-TPD、FTIR对催化剂进行表征,采用GC/MS、UV-荧光光谱和元素分析仪对重整生物油的产物组成、脱氧特性以及共轭结构进行分析,并用TGA、拉曼光谱和SEM对失活催化剂进行评价,探究其结构-性能关系以及催化失活机制。结果表明：金属的添加并未改变催化剂的骨架结构,但形成了新的金属位点,调整了催化剂酸性分布,使比表面积以及孔容下降,平均孔径增加。金属位和酸性位的协同作用明显地促进了生物油的脱氧和单环芳烃的转化,脱氧顺序为Zn>Mg>Co>Ce>HZSM-5>Ga>P>Cu,且芳烃产率与总酸含量呈正相关,较高的酸度和平均孔径以及适宜的比表面积有利于芳烃的生成。然而,较低的酸度和较小的孔径促进了烯烃化合物的转化。当采用Zn-P/HZ为催化剂时,碳氢和芳烃产率最高,为86.46%...     

封装型Ni基催化剂制备及其原位提质煤热解焦油的性能

为实现煤热解焦油原位轻质化,分别用原位封装法和浸渍法制备Ni基催化剂,并考察这两种催化剂对热解焦油原位催化提质的影响。与不加催化剂相比,Ni含量2%Ni/HZSM-5可使焦油中轻质组分产率由5.8%提至6.9%,而相同Ni含量的Ni@HZSM-5可使轻质焦油产率提至7.6%。进一步分析Ni/HZSM-5和Ni@HZSM-5催化剂对焦油各馏分产率的影响,结果表明,2种催化剂均使焦油中重质组分明显降低,沥青质产率分别由5.4%降至1.3%和2.0%,但相较Ni/HZSM-5,Ni@HZSM-5使焦油中轻油和酚油产率分别上升38.5%和25.5%,萘油产率也有所上升,说明封装法制备的Ni基催化剂可使焦油中轻质组分最大程度保留。因为在Ni/HZSM-5中焦油裂解和热解气中富氢组分活化均发生在Ni表面,在促进富氢气体活化的同时也造成焦油过度裂解。而Ni@HZSM-5中Ni主要分布于分子筛孔道内,其良好择形催化性可使富氢气体分子进入HZSM-5分子筛内部与Ni接触产生·H和·CH_x等富氢自由基,而焦油中大分子无法进入HZSM-5孔道,其裂解仅发生在分子筛外表面酸性位点上,避免...     

生物质快速催化热解制氢的研究

在自制的固定床反应器上以水葫芦为原料进行快速催化热解制氢研究,考察了反应温度及4种催化剂（NaCl、Na2CO3、KOH和分子筛HZSM-5）在不同反应温度下对热解气产率、气体成分及Hz产率的影响。结果表明：无催化剂条件下,随着反应温度的升高．热解气产率、H2的体积分数及产率上升;催化剂的添加能够改变热解气中各成分的含量。除Na2CO3外,在其它3种催化剂作用下．H2的体积分数显著提高．CO2的体积分数显著下降．CO的体积分数有所下降。CH4的体积分数有所提高;另一方面,升高反应温度有助于提高催化剂的催化效果,不同催化剂的催化热解效果并不相同,其中NaCl、分子筛HZSM-5和KOH均能提高H2产率．达到催化热解制氢的目的,而Na2CO3的催化效果并不明显。     

轻汽油催化裂解生产丙烯催化剂的研究

采用HZSM-5和改性的HZSM-5催化剂,以抚顺石油二厂初馏点~75℃的催化裂化轻汽油馏分为原料,在实验室连续固定床反应装置上进行了催化裂化轻汽油的催化裂解反应,考察了反应条件对催化裂化轻汽油裂解及芳构化反应的影响和A l2O3作为催化剂的载体对HZSM-5催化剂上催化裂解产品分部的影响,并且考察了载镧HZSM-5催化剂上主要产品分布的影响。研究结果表明,在载镧量5%左右的催化剂上,丙烯产率比改性前下降5%、芳烃产率下降15%;当催化剂中载体组分为30%时,丙烯产率最高为38.26%,芳烃产率为26.26%,同不使用载体相比,芳烃产率下降了5.1%。     

不同类型分子筛催化热解陈腐垃圾性能研究

选用3种不同类型的分子筛催化剂HZSM-5、HY和HBeta,以垃圾填埋场陈腐垃圾为原料,进行绝氧热解和催化热解对比研究。结果表明,分子筛催化剂的加入不仅对陈腐垃圾热解产物产率有明显影响,而且对热解气和热解油的品质有明显的提高。对比3种催化剂发现,HZSM-5更有利于热解气的产生,而且所得热解气的热值最高,为67.45 MJ·m^-3,所得热解油中汽油组分最多,为质量分数65.4%,而重馏分油组分仅为6.9%。HY和HBeta则得到相对更高的热解油产量,尤其是轻质柴油,质量分数分别为38.1%和41.4%。3种催化剂截然不同的催化热解产物产率和产品性质与其孔道结构、织构性质和酸性质均密切相关。     

纤维素快速热解反应气体的在线催化裂解

通过浸渍法制备MHZSM-5(M Fe,Zr,Co)催化剂,采用激光粒度分析仪、比表面积及孔径分析仪和X射线衍射仪(XRD)对催化剂的性质进行表征,并在立式两段加热炉上进行纤维素快速热解蒸汽的在线催化实验。对不同催化剂条件下的产物分布特性及生物油组成特性进行分析,结果表明,随着催化剂的引入,液相产率从52.06%最大下降至23.63%,气相产率从42.39%最大提高至70.84%,CoHZSM-5对于热解蒸汽的催化气化效果最为明显;纤维素快速热解生物油中以1,6-脱水-β-D-吡喃葡萄糖(左旋葡聚糖)为主,引入催化剂对纤维素热解蒸汽进行在线催化重整后,产物中芳烃类物质显著增加,以FeHZSM-5和ZrHZSM-5效果最佳;HZSM-5催化下生物油中左旋葡聚糖的含量提高至63.78%;催化后热解油中乙酸及丙酸含量均减少,但降低幅度有限。综合催化剂对产率及组分的影响效果来看,FeHZSM-5和ZrHZSM-5对纤维素快速热解蒸汽的催化调控作用较为显著。     

Short Vapour Residence Time Catalytic Pyrolysis of Spruce Sawdust in a Bubbling Fluidized-Bed Reactor with HZSM-5 Catalysts

Catalytic pyrolysis of spruce sawdust was carried out in a bubbling fluidized-bed reactor using HZSM-5 catalysts. The effects of space velocity, catalyst deactivation, catalyst acidity and catalyst regeneration were studied. The use of catalysts decreased the yield of organic liquids compared to non-catalytic yields while the yields of pyrolytic water and gases increased. Decreasing the space velocity enhanced these effects. The rate of catalyst deactivation depended on the acidity of the catalyst, with more acidic catalysts deactivating more rapidly. Using a catalyst with a Si/Al ratio of 140 resulted in the largest changes in bio-oil properties. Periodic regeneration of the catalyst in the fluidized-bed reactor was also demonstrated using varying regeneration times and temperatures. It was shown that compared to BFB reactors, CFB reactor types would offer better operating characteristics for commercial scale catalytic pyrolysis processes in regard to vapour residence times, and catalyst activity and regeneration.     

Catalytic Pyrolysis of Pine Wood Sawdust to Produce Bio-oil: Effect of Temperature and Catalyst Additives

In this work, non-catalytic pyrolysis of Turkish pine (Pinus brutia Ten.) wood sawdust was performed in a fixed-bed reactor at various temperatures to obtain the optimum conditions to achieve a maximum bio-oil yield. The highest yield of bio-oil was obtained about 46 wt% at 550°C for non-catalytic pyrolysis. At the optimum conditions, the effects of different catalyst types (KOH, ZnCl₂, and ZnO) and amount of catalyst (5, 10, 15, and 20 wt%) on the pyrolysis product yields and bio-oil properties were investigated. The presence of catalysts changed the product distribution considerably. Increasing the amount of catalyst led to a decrease in the yield of liquid product, while the gas and char yields increased compared to non-catalytic pyrolysis. The chemical compositions of bio-oil were determined with GC-MS analyses. It was determined that bio-oils contain a large variety of organic compounds, such as furans, aldehydes, ketones, phenols, acids, benzenes, alcohols, alkanes, and polycyclic aromatic hydrocarbons (PAHs). The catalysis by KOH significantly increased the levels of phenols, while it reduced the formation of acids and aldehydes. ZnCl₂ produced bio-oil with high percentages of aldehydes. Moreover, ZnO reduced the proportion of PAH in the bio-oil. These results demonstrated that bio-oils could improve with a catalyst. Therefore, catalyst selection for high bio-oil quality is crucial in industrial applications.     

Converting Alkali Lignin to Biofuels over NiO/HZSM‐5 Catalysts Using a Two‐Stage Reactor

A series of NiO/HZSM‐5 catalysts were used to convert alkali lignin to hydrocarbon biofuels in a two‐stage catalytic pyrolysis system. The results indicated that all NiO/HZSM‐5 catalysts reduced the content of undesirable phenols, furans, and alcohols of the biofuel compared to non‐catalytic treatment. The NiO/HZSM‐5 catalyst with the lowest amount of NiO generated the highest biofuel yield in all catalytic treatments, and it also produced biofuel with the highest content of hydrocarbons. The emission of carbon oxides (CO and CO₂) increased in the treatments with higher‐NiO loading HZSM‐5 due to the redox reaction between NiO and the oxygenated compounds in the bio‐oil. Ni₂SiO₄ was generated in the used NiO/HZSM‐5 catalysts during the high‐temperature pyrolysis process.     

生物质三组分与低密度聚乙烯共催化热解制取轻质芳烃的协同作用机理

生物质与废塑料共催化快速热解是制取轻质芳烃的重要途径。 采用不同种类的分子筛催化剂,首先研究了分子筛种类对杨木、生物质三组分和低密度聚乙烯（LDPE）单独催化快速热解轻质芳烃产率的影响,其次研究了生物质三组分与LDPE在共催化热解过程中的协同作用机理。结果表明：在杨木、生物质三组分和LDPE单独催化快速热解时,HZSM-5（25）催化剂体现出最高的轻质芳烃产率;在杨木和LDPE共催化快速热解时,随着LDPE质量的增加,轻质芳烃的产率呈先升高后降低趋势;在生物质三组分和LDPE共催化快速热解时,纤维素和半纤维素热解的呋喃类中间产物与LDPE热解的轻烯烃中间产物易发生“双烯合成”反应,表现出较强的协同催化作用,促进轻质芳烃的生成,而木质素则抑制轻质芳烃生成。     

Effects of catalyst acidity and HZSM-5 channel volume on polypropylene cracking

Effects of catalyst acidity and the restricted reaction volume afforded by HZSM-5 on the catalytic cracking of polypropylene are described. Polypropylene cracking by silica—alumina and HZSM-5 catalysts yields olefins as primary volatile products. In addition, HZSM-5 channels restrict carbenium ion rearrangements and facilitate formation of significant amounts of propene and alkyl aromatic volatile products. The higher acidity of sulfated zirconia compared to the other catalysts results in an increase in the frequency of hydride abstractions, resulting in the formation of significant yields of saturated hydrocarbons and organic residue for this catalyst. Primary polypropylene cracking products can be derived from carbenium ion reaction mechanisms. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 341–348, 1998     

Feedstock recycling of agriculture plastic film wastes by catalytic cracking

Feedstock recycling by catalytic cracking of a real plastic film waste from Almeria greenhouses (Spain) towards valuable hydrocarbon mixtures has been studied over several acid catalysts. The plastic film waste was mostly made up of ambient degraded low-density polyethylene (LDPE) and ethylene-vinyl acetate (EVA) copolymer, the vinyl acetate content being around 4 wt.%. Nanocrystalline HZSM-5 zeolite (crystal size 60 nm) was the only catalyst capable of degrading completely the refuse at 420 °C despite using a very small amount of catalyst (plastic/catalyst mass ratio of 50). However, mesoporous catalysts (Al-SBA-15 and Al-MCM-41), unlike it occurred with virgin LDPE, showed fairly close conversions to that of thermal cracking. Nanocrystalline HZSM-5 zeolite led to 60 wt.% selectivity towards C₁---C₅ hydrocarbons, mostly valuable C₃---C₅ olefins, what would improve the profitability of a future industrial recycling process. The remarkable performance of nanocrystalline HZSM-5 zeolite was ascribed to its high content of strong external acid sites due to its nanometer dimension, which are very active for the cracking of bulky macromolecules. Hence, nanocrystalline HZSM-5 can be regarded as a promising catalyst for a feasible feedstock recycling process by catalytic cracking.     

Catalytic pyrolysis of biomass for biofuels production

Fast pyrolysis bio-oils currently produced in demonstration and semi-commercial plants have potential as a fuel for stationary power production using boilers or turbines but they require significant modification to become an acceptable transportation fuel. Catalytic upgrading of pyrolysis vapors using zeolites is a potentially promising method for removing oxygen from organic compounds and converting them to hydrocarbons. This work evaluated a set of commercial and laboratory-synthesized catalysts for their hydrocarbon production performance via the pyrolysis/catalytic cracking route. Three types of biomass feedstocks; cellulose, lignin, and wood were pyrolyzed (batch experiments) in quartz boats in physical contact with the catalysts at temperature ranging from 400 °C to 600 °C and catalyst-to-biomass ratios of 5-10 by weight. Molecular-beam mass spectrometry (MBMS) was used to analyze the product vapor and gas composition. The highest yield of hydrocarbons (approximately 16 wt.%, including 3.5 wt.% of toluene) was achieved using nickel, cobalt, iron, and gallium-substituted ZSM-5. Tests performed using a semi-continuous flow reactor allowed us to observe the change in the composition of the volatiles produced by the pyrolysis/catalytic vapor cracking reactions as a function of the catalyst time-on-stream. The deoxygenation activity decreased with time because of coke deposits formed on the catalyst.