共查询到19条相似文献,搜索用时 78 毫秒
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《可再生能源》2015,(7)
利用管式炉热解装置在不同温度下对工业废弃的木质素进行热解制备焦炭的试验研究,对热解焦炭的产率和各项指标进行了分析。结果表明:当热解温度从300℃升高至700℃时,焦炭产率从72.94%下降至39.79%;焦炭中固定碳含量不断升高,热值从29.19 MJ/kg逐步升高至31.62 MJ/kg;当热解温度从300℃升高至600℃时,焦炭的比表面积从0.47 m2/g迅速升至13.63 m2/g,碘吸附值由185.51 mg/g增大到320.64 mg/g,而随着热解温度继续升至700℃时,焦炭的比表面积和碘吸附值迅速降低。因此,热解温度有利于焦炭品质和吸附性能的提高,但过高的热解温度会对焦炭的吸附性能起到一定的抑制作用。 相似文献
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<正>1 前言 为了减少水和能源的浪费,很多企业采用了冷凝水回收技术(包括开放式和密闭式回收方式)。不管采用了哪种冷凝水回收技术,经常会遇到一个共同问题:冷凝水系统中热力设备的酸性腐蚀。即冷凝水系统在运行时,颜色发红,铁含量高,造成水质不合格,冷凝水不能被利用。这样,冷凝水回收技术达不到预期的节能效果,也影响了热力设备的使用寿命。 能够造成热力设备腐蚀的原因有很多,比如氧腐蚀和二氧化碳酸性腐蚀等。对于连续运行的蒸汽间接加热设备,回收系统管网设计正常时,漏入空气的可能性就很小,冷凝水中含氧量会很低,冷凝水系统中产生的腐蚀主要是酸性腐蚀;对于间断运行的蒸汽间接加热设备,设备经常启停使容器处于正负压交替运行,导致空气的吸入,产生的腐蚀就会是氧腐蚀和酸性腐蚀。 相似文献
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《可再生能源》2013,(8)
研究了湿氧化爆破副产物甲酸、乙酸、糠醛对酿酒酵母生长、发酵过程、糖酵解和能量代谢以及细胞膜完整性的影响。通过研究发现,酿酒酵母对于甲酸、乙酸、糠醛的最大耐受浓度分别为1.8,6.0,2.0 g/L。抑制剂对酿酒酵母乙醇发酵毒性依次为甲酸>乙酸>糠醛。在1×IC80时,乙酸对酿酒酵母糖酵解和能量代谢影响最小,在2×IC80和3×IC80时,糠醛对酿酒酵母糖酵解和能量代谢影响最小,而甲酸不论在任何浓度对酿酒酵母糖酵解和能量代谢都会产生很大的影响。与乙醇相比,甲酸、乙酸、糠醛对细胞膜完整性无显著的影响,从1×IC80-3×IC80分别造成的镁离子百分比为11%-20%,5%-12%,4.5%-8.4%,对照物乙醇则为55%。 相似文献
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柴油机颗粒在氧化过程中拉曼光谱参数的变化 总被引:1,自引:0,他引:1
为研究柴油机排放颗粒在氧化过程中化学结构的变化规律,通过一台燃用国Ⅴ标准柴油的电控高压共轨增压中冷柴油机CY4102-CE4B上进行颗粒取样,对所得颗粒进行了热重处理,分别得到不同氧化程度的颗粒,采用拉曼光谱仪测取样品的拉曼光谱,比较了在氧化过程中颗粒随失重量变化的拉曼光谱特征.结果表明:颗粒的石墨化程度随着柴油机负荷的增大而增加;氧化催化剂(DOC)作用后,颗粒的结构有序性增强;随着氧化的进行,颗粒的石墨化程度整体呈现上升趋势.颗粒的氧化活性与其结构有一定的关系;小负荷时,颗粒表现出较高的氧化活性,其中颗粒所具有的无序结构具有较大影响.DOC作用后,颗粒的内部结构发生了变化,颗粒的氧化模式发生了改变,石墨化程度不再是影响氧化活性的主要因素. 相似文献
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酸水解木质素的结构及热解产物分析 总被引:1,自引:0,他引:1
采用木质纤维典型稀酸水解残渣为实验原料,对其理化特性进行分析.对酸水解木质素(简称AHL)进行分离提纯,通过定量31P-NMR及木质素衍生化后的还原降解(DFRC)技术研究分离得到的水解残渣木质素的官能团的含量.采用TG和DTG研究AHL的热分解特性.借助Py-GC-MS分析AHL热裂解产物的主要组成.研究结果表明,AHL的热解发生在一个宽泛的温度范围内,并且DTG曲线中可以看到两个明显的失重峰;AIL热裂解产物主要由木质素大分子β-0-4连接断裂所得产物及二次裂解产物构成. 相似文献
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使用热天平考察了5种半焦的本征氧化反应活性。这5种半焦是由大同煤、神木煤、蔚县煤、湔江煤和台湾石油焦在900℃下热解7min制得的.使用分布活化能模型(DAEM)描述了半焦在氧化过程中的活化能变迁。大同煤半焦初期活化能最小,随着碳损失率的增加,活化能增加(反应初期增加较快),反应后期达到峰值后下降。湔江煤半焦活化能则是在反应初期活化能很高(达250kJ/mol),其初始下降较快,在碳损失为0.2后其下降趋势变缓。而对于其它三种半焦,均在反应初期与反应后期其活化能分别经历两个峰,在此之间变化比较平缓。各种半焦活化能的变迁规律不同,反映了其内部性质的不同。与煤焦相比,石油焦半焦的内部结构比较均一。 相似文献
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首先利用木本类(硬木和软木)和禾本类不同生物质原料制备有机酸溶木质素,发现木本木质素的碳、氢元素含量和高位热值高于禾本木质素,软木木质素中β-O-4、β-β和β-5键含量高于硬木和禾本木质素。然后,通过不同种类木质素在乙醇/异丙醇中氢解实验发现,木本木质素氢解得到产物产率高于禾本木质素,其中杉木木质素的单酚产率最高,约为8.07%(质量分数)。此外,木本木质素解聚产生的单酚化合物以无侧链和三元碳侧链为主,而禾本木质素以二元碳侧链化合物为主。 相似文献
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通过比较处理前后紫外可见光谱、红外吸收光谱、凝胶过滤色谱(GPC)的变化和对降解产物的气质分析,研究了木质素磺酸钠在微波/H2O2体系中的降解行为。试验发现,微波/H2O2体系能有效促使木质素降解,降解过程中苯丙烷侧链和苯环都遭到了不同程度的破坏。在低浓度双氧水条件下,中间产物中含有大量芳香醛;在高浓度双氧水条件下,芳香醛含量减少,低分子量脂肪酸含量增多。降解后残渣的分子量减小,分布变窄。通过对木质素磺酸钠降解后的产物分析,推测了其在微波/H2O2体系中降解的可能机理,为木质素资源的高效综合利用寻找新的途径。 相似文献
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研究一氧化碳氧化反应的机理对于工业制氢具有重要意义,为了考察一氧化碳氧化反应的非线性行为,本文应用已有的几何学模型,得到了一氧化碳氧化反应突变边界的局部几何性质,并由此预测出一氧化碳氧化反应的几种较为特殊的非线性行为,希望为制氢过程中一氧化碳氧化反应的实验研究和工程应用研究提供指导。 相似文献
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木质素是自然界中丰富的可再生芳香碳资源,其解聚得到的单体可以作为重要的化工原料。以蒽醌-2-羧酸作为光催化剂,在硝基苯存在和LED光源照射下,5 h内木质素模型化合物中β-O-4键有80%的转化率。对于木质素β-O-4多聚体,该体系也表现出了光催化活性,将蒽醌-2-羧酸负载在非均相载体上,在光催化降解中也可以获得77%的底物转化率。该反应涉及了木质素β-O-4中Cα—Cβ键和Cβ—O键的断裂,在催化剂的作用下,首先发生Cα—OH的脱氢,随后经过分子内的断键和重新成键生成苯甲醛和愈创木酚。本研究加深了对光催化木质素氧化过程中C—C键断裂过程的认识,有助于理解木质素的解聚机制。 相似文献
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Ayhan Demirbas 《Energy Sources, Part A: Recovery, Utilization, and Environmental Effects》2013,35(5):413-422
This article deals with slow pyrolysis of oak wood and agricultural residues such as hazelnut shell and wheat straw at high temperature (950–1250 K) in a cylindrical reactor. The aim of this work is to study the effect of the treatment conditions such as temperature, particle size, and lignin and inorganic matter contents on bio-char yield and reactivity. When the pyrolysis temperature increased, the bio-char yield decreased. A high temperature and smaller particles increase the heating rate resulting in a decreased bio-char yield. The higher lignin content in hazelnut shell results in a higher bio-char yield in comparison with oak wood and wheat straw. Bio-chars from hazelnut shell and wheat straw are more reactive in gasification than bio-chars from oak wood because of the higher ash content. The bio-char obtained are carbon rich, with high heating value and relatively pollution-free potential solid biofuel. 相似文献
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《International Journal of Hydrogen Energy》2019,44(29):14808-14819
Successful commercialization of direct formic acid fuel cells (DFAFCs) is restricted because of its apparent instability in acidic medium and high cost of typically noble metal based anode catalyst. To adequately address these key issues, in this work, a series of palladium-copper alloy catalyst supported on nitrogen-doped reduced graphene oxide (N-rGO) were synthesized via wet chemical reduction process. Several microscopic and spectroscopic techniques were employed to determine the crystal pattern, particle size, composition and morphology of the synthesized material. Electro-catalytic performance of the synthesized catalysts was carefully verified with respect to formic acid oxidation. All N-doped reduced graphene oxide (N-rGO) supported catalyst show enhanced catalytic activity in comparison to commercial Pd/C catalyst. Electrochemical study reveals precisely that Pd75Cu25/N-rGO catalysts have highest electro catalytic activity 1738 mA mg−1pd among all synthesized catalyst which is 3.67 times higher than commercial Pd/C catalyst. Pd75Cu25/N-rGO catalyst show lowest Tafel slope (119 mV dec−1) and excellent stability after 250 potential cycles. These extensive studies signify that N-rGO support material can remarkably improve the catalytic activity and stability of the catalysts which may be due to outstanding electron transfer capability and synergy between PdCu metallic and N-rGO support. This work helps further design of alloy nanoparticles on N-rGO support as a highly active and stable catalyst for application in the fuel cell. 相似文献
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多晶硅在生长过程中,由于温度控制的不准确性,易导致硅芯/硅棒氧化而形成氧化夹层。针对以上问题,文章从热力学的角度揭示了氧化夹层形成的原因,提出了消除氧化夹层的具体措施。 相似文献
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Yuan-Hang Qin Zi-Yao Xiong Jiayu Ma Li Yang Zaikun Wu Weiliang Feng Tie-Lin Wang Wei-Guo Wang Cun-Wen Wang 《International Journal of Hydrogen Energy》2017,42(2):1103-1112
TiO2-modified nitrogen-doped carbon (TiO2-NC), prepared by a polymerization-pyrolysis process, is used to support the Pd catalyst for ethanol oxidation reaction (EOR) in alkaline media. X-ray photoelectron spectroscopy characterization indicates that the incorporation of TiO2 and nitrogen into the carbon matrix could improve the percentage of Pd0 in Pd/TiO2-NC catalyst. Electrochemical characterization shows that the Pd/TiO2-NC catalyst presents higher electrocatalytic activity and stability for EOR than the nitrogen-doped carbon-supported Pd (Pd/NC) catalyst and the carbon black-supported Pd (Pd/CB) catalyst, which can be mainly attributed to the high percentage of Pd0 in Pd/TiO2-NC catalyst (65%) than those in Pd/NC (48%) and Pd/CB (31%) catalysts. The results indicate that the Pd/TiO2-NC catalyst holds great potential as high-performance anode catalyst for direct ethanol fuel cells. 相似文献
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Levulinate compounds are the biomass derived important energy products which are primarily used as diesel-blending components. These levulinates are the oxygenated fuel additive which promote complete combustion of fuel and reduces emission of pollutants like particulate matters and nitrogen oxides. In the present study, we have investigated sustainable synthesis of biomass derived levulinate compounds catalyzed by Cal B lipase in supercritical carbon dioxide (SC-CO2) as a green biocatalyst in green reaction media which provided an excellent mass yield. Various reaction parameters were optimized in details such as butanol, levulinic acid, biocatalyst, co-solvent, temperature and pressure to obtain 99% mass yield of the desired product. Moreover various green metric parameters (e.g. E-factor, carbon efficiency and mass productivity) of present methodology were evaluated. The green metrics evaluation suggested that developed procedure is a promising and a greener alternative as compared to various reported conventional synthetic protocols. The biocatalyst was efficiently recycled up to the five cycles. Moreover, the developed protocol can be used for synthesis of various industrially important levulinate compounds which also provided excellent mass yield. Thus, the present protocol demonstrated (i) robust biocatalytic application for transformation of renewable biomass derived levulinic acid (LVA) into value added chemicals and (ii) various green metric evaluation study for the sustainability. 相似文献