Ca1-xPrxFeO3催化热解甘蔗渣木质素制备酚类化合物

采用溶胶-凝胶法合成了一系列镨掺杂的铁酸钙氧化物(Ca_1-xPr_xFeO₃, 简称CPF-x), 优化了其焙烧机制, 研究了其对甘蔗渣木质素(BL)的催化热解作用, 考察了其再生性能. 研究结果表明, CPF-x适宜的合成及焙烧参数分别为: x=0.5, 焙烧温度为800 ℃, 焙烧时间为6 h, 在该条件下得到的CPF-0.5-800-6呈立方晶相, 为疏松多孔结构; 掺杂Pr后, 其比表面积提高了近3倍. CPF-0.5-800-6对BL催化热解最佳工艺参数为: m(CPF-0.5-800-6)∶m(BL)=1∶3, 热解温度为650 ℃, 液相收率最大可达20.73%, 其中主要产物为紫丁香酚类、 苯酚类及愈创木酚类, 其总选择性为63.21%. 以CPF-0.5-800-6为催化剂, 紫丁香酚类化合物选择性由20.60%增大到29.59%, 实现了提高BL催化热解中某种单酚化合物的选择性. CPF-0.5-800-6经5次催化热解-再生循环反应后, 仍具有良好的反应活性和结构稳定性.     

钙钛矿结构B位掺杂化合物LaCO1-xFexO3的光催化活性研究

用柠檬酸溶胶-凝胶法制备了钙钛矿型LaCo1-xFexO3系列化合物,使用XRD、XPS、红外和紫外等手段对其进行了表征和测定,并测定了其对活性艳红水溶性染料脱色的光催化活性．实验结果表明在B位掺杂Fea 后使LaCoO3光催化活性明显提高,当x=0．05时,即LaCo1-xFexO3的光催化活性最佳。     

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。     

Ce1-xFexO2复合氧化物催化剂的制备及其对甲烷的催化燃烧性能

采用柠檬酸溶胶-凝胶法和微波技术制备了Ce1-x Fex O2复合氧化物,以甲烷催化燃烧为探针反应测定了催化剂的活性及XRD、DRS、BET和TPR进行了表征。结果表明,Ce1-x Fex O2复合氧化物为介孔材料,所制得的复合氧化物在x≤0．2时以单一立方萤石结构的Ce1-x Fex O2固溶体存在,x〉0．2时形成了立方萤石结构Ce1-x Fex O2固溶体和少量的CeFeO3混合相。Ce1-x Fex O2固溶体的甲烷催化燃烧活性高于单组分CeO2,且随着x的不同而变化,其中以Ce0.9 Fe0.1 O2固溶体的催化活性最高。     

毛竹酶解/温和酸水解木质素的快速热解研究

采用热裂解-气相色谱/质谱仪联用技术,研究毛竹酶解/温和酸水解木质素(简称EMAL)的热解特性和热解产物的分布与形成规律.以温度为重要因素,研究其对木质素快速热裂解产物的影响,并通过主要的热解产物推断热解反应途径.研究结果表明,EMAL的热解产物主要是2,3-二氢苯并呋喃、酚类、脂类和少量乙酸.热解温度对热解产物组分的相对含量有显著影响,250~400 ℃时,产物主要是2,3-二氢苯并呋喃,320 ℃时其相对含量最高,达到66.26%;400~800 ℃时,热解产物主要是酚类,600 ℃时其相对含量最高,达到62.58%;800 ℃时出现了少量的乙酸.     

玉米芯与低密度聚乙烯混合物在氢气气氛下的催化热解研究

本文研究了在氢气氛围及HZSM-5、H-Beta、NaY和TiO2催化剂作用下玉米芯与LDPE混合物(重量比2∶8)的共热解情况。通过催化热解所得油相液体的烃族分析及碳数分布发现:在催化剂作用下,油相液体的碳数分布变窄,共同热解所得气体产率最高的是H-Beta催化体系,液体产率最高的是NaY,残渣量最多的是TiO2催化体系。催化共热解所得油相液体的碳数分布主要集中在C4~C19之间,使用NaY可获得高品位的油相液体,其研究法辛烷值(RON)为97.5;水相液体中的主要物质是醋酸,加入催化剂后其含量明显增加。四种催化剂中,醋酸生成量最多的是NaY催化剂,其次是HZSM-5,最后是H-Beta和TiO2。其中在NaY催化体系作用下生成的水相液体组分中,醋酸含量为57.8%。     

La0.7Sr0.3Co1-xFexO3催化剂氮氧化物储存及抗硫性能

采用溶胶-凝胶法通过在静态空气中700°C焙烧制备了不同Fe掺杂量的La0.7Sr0.3Co1-xFexO3(x=0,0.2,0.6,1.0)系列钙钛矿催化剂.考察了Fe掺杂量对催化剂的结构、氮氧化物储存、抗硫及再生性能的影响.研究结果表明:在La0.7Sr0.3CoO3钙钛矿B位用Fe部分取代Co,可有效提高SrCO3物相的分散,X射线衍射(XRD)结果显示样品中基本为钙钛矿物相.随着Fe掺杂量的增加,催化剂的NOx储存量(NSC)下降.对预硫化样品进行NOx储存测试,发现La0.7Sr0.3CoO3催化剂由于表面沉积了硫酸盐,同时钙钛矿结构也遭到了部分破坏,使得NOx储存量和NO氧化能力均大幅度下降,NOx储存量下降了64.2%,NO-to-NO2转化率从72.8%降至43.4%.掺杂Fe元素后,催化剂的抗硫性能都有不同程度的提高,特别是Fe掺杂量为60%的样品具有最佳的抗硫性能和可再生性能.与新鲜样品相比较,再生后样品的NOx储存量仅下降16.6%,而NO-to-NO2转化率为69.1%,几乎与新鲜样品相同.     

超临界甲醇中Ce/Cu/Zn/Al催化木质素制备酚类化合物的研究

采用共沉淀法制备Ce/Cu/Zn/Al催化剂,并将其应用于超临界甲醇中木质素的催化液化.考察单因素条件对木质素转化率和生成酚类的影响,得到最佳反应条件:反应温度320℃,反应时间120 min,催化剂用量150 mg,初始压力2 MPa,木质素的转化率达到67.33%,酚类产率达到30.84%.同时,以苯酚及愈创木酚为模型物,比较有无催化剂对液化产物分布或选择性生成的影响. Ce/Cu/Zn/Al催化剂的加入促进了甲醇的重整及其与模型化合物苯酚、愈创木酚的烷基化反应,从而生成了大量的烷基苯酚.     

Ba0.4Sr0.6Ci1-xFexO3-δ系阴极材料的制备和表征

采用甘氨酸.硝酸盐(GNP)法合成了中温固体氧化物燃料电池阴极材料Ba0.4Sr0.6Co1-xFexO3-δ=0.0～0.8)系列粉体.利用XRD和SEM对材料的结构和微观形貌进行分析,用直流四端子法测量了烧结陶瓷体在中温(450～800℃)范围内的电导率.结果表明.制备的样品为单一钙钛矿相,随着Fe含量增加,XRD衍射峰值向高角度方向稍有偏移.电导率随着温度及Fe含量的变化出现极大值,在x<0.2时,Ba0.4Sr0.6Co1-xFexO3-δ系列烧结体在 (450～800℃)XE的电导率,随Fe掺入量的增大而增大,x=0.2样品的电导率最高,800℃时达244.7 S·cm-1,远超过文献报道值,进一步增大Fe含量导电性能变差.     

快速热解炭负载Cu-Zn对碱木质素热裂解生成单酚类化合物的催化性能

以具备丰富中孔和大孔结构的快速热解炭(FPC)为载体,采用共浸渍法制备了不同Cu/Zn摩尔比的CuxZny/FPC负载型催化剂.采用X射线衍射仪(XRD)、高分辨场发射扫描电子显微镜(FE-SEM)及电子能谱仪(EDX)对催化剂进行了表征,采用热重分析仪(TG)和热解气质联用仪(Py-GC/MS)评价了催化剂对碱木质素热裂解生成单酚类化合物的催化性能.结果表明,催化剂活性组分Cu O和Zn O晶相结构均一,很好地嵌入到FPC中孔和大孔结构中,未发生聚集状态或生成Cu Zn合金;随着Cu或Zn金属负载量的增大,相应的Cu或Zn金属氧化物衍射峰强度逐渐增强,平均晶粒尺寸逐渐增大.热重分析结果表明,催化剂降低了碱木质素热裂解残炭率和反应活化能,提高了热裂解反应效率.热解气质联用分析表明,CuxZny/FPC催化剂大幅度简化了碱木质素热裂解单酚类化合物种类(从23种减少到了10种),Cu0.67Zn0.33/FPC对单酚类化合物表现出最大的选择性(52.99%),与Cu/FPC相比选择性增加49.7%.     

Study on Diameter Controlled Growth of Carbon Nanotubes by LaAl1-xFexO3 Catalysts

A series of LaAl1-xFexO3 catalysts prepared with lanthanum nitrate, aluminium nitrate and iron nitrate was investigated in catalytical syntheses of carbon nanotubes with high yields and purity. The properties of carbon nanotubes prepared by the method of CVD(chemical vapor deposition) with n-hexane as the carbon resource were studied and it was shown that the diameter of carbon nanotubes can be controlled by the molar ratio of iron to aluminum in the catalysts and that the diameter of carbon nanotubes changes a little with the decrease of the iron content in the catalysts. From the TEM pictures of carbon nanotubes, it can be found that the LaAl1-xFexO3 catalysts have a significant influence on the wall thickness of the carbon nanotubes, whereas they have little influence on the inner diameter of the carbon nanotubes.     

Model for Kinetics of Vinyl Chloride Polymerization

This paper gives a critical review of recent models for the polymerization of vinyl chloride. In solution and bulk polymerization the effect of eventual degradative chain transfer to monomer, addition of chain transfer agents, and precipitation of polymer is discussed. A model for emulsion polymerization is described which includes particle formation and kinetics of polymerization where especially desorption and reabsorption of radicals in the particles are included.     

低温催化裂解烷烃法制备碳纳米管

低温催化裂解烷烃法制备碳纳米管陈萍，王培峰，林国栋，张鸿斌，蔡启瑞（厦门大学化学系固体表面物理化学国家重点实验室，厦门，３６１００５）关键词碳纳米管，催化裂解，甲烷碳纳米管的制备与研究是国际上新材料领域的探索热点［１］．由于具有纳米级的管径，碳纳米管...     

Screening acidic zeolites for catalytic fast pyrolysis of biomass and its components

Zeolites have been shown to effectively promote cracking reactions during pyrolysis resulting in highly deoxygenated and hydrocarbon-rich compounds and stable pyrolysis oil product. Py/GC-MS was employed to study the catalytic fast pyrolysis of lignocellulosic biomass samples comprising oak, corn cob, corn stover, and switchgrass, as well as the fractional components of biomass, i.e., cellulose, hemicellulose, and lignin. Quantitative values of condensable vapors and relative compositions of the pyrolytic products including non-condensable gases (NCG's) and solid residues are presented to show how reaction products are affected by catalyst choice. While all catalysts decreased the oxygen-containing products in the condensable vapors, H-ZSM-5 was most effective at producing aromatic hydrocarbons from the pyrolytic vapors. We demonstrated how the Si/Al ratio of the catalysts plays a role in the deoxygenation of the vapors towards the pathway to aromatic hydrocarbons.     

Transformation of Biomass into Aromatics with Zeolite Catalysts

Biomass is a nature renewable resource which can be used for the production of high value chemicals and bio-fuels. In the present work, the transformation of sawdust into aromat- ics such as benzene, toluene and xylenes was investigated over a series of zeolite catalysts （NaZSM-5, HZSM-5, ReY and HY catalysts）. Among the tested catalysts, the HZSM-5 catalyst shows the highest activity for the production of aromatics. The yield and carbon selectivity of aromatics reached about 26.5% and 62.5C-mo1%, respectively over the HZSM-5 catalyst under the optimal condition of T=450 ℃, f（N2）=300 cm^3/min, and catalyst/lignin ratio of 2. The effects of the reaction conditions including temperature, gas flow rate, and catalyst/sawdust ratio on the production of aromatics were investigated in detail and the formation of aromatics from lignocellulosic biomass was also addressed.