Upgrading of liquid fuel from the vacuum pyrolysis of biomass over the Mo-Ni/gamma-Al2O3 catalysts

High amounts of acid compounds in bio-oil not only lead to the deleterious properties such as corrosiveness and high acidity, but also set up many obstacles to its wide applications. By hydrotreating the bio-oil under mild conditions, some carboxylic acid compounds could be converted to alcohols which would esterify with the unconverted acids in the bio-oil to produce esters. The properties of the bio-oil could be improved by this method. In the paper, the raw bio-oil was produced by vacuum pyrolysis of pine sawdust. The optimal production conditions were investigated. A series of nickel-based catalysts were prepared. Their catalytic activities were evaluated by upgrading of model compound (glacial acetic acid). Results showed that the reduced Mo-10Ni/gamma-Al2O3 catalyst had the highest activity with the acetic acid conversion of 33.2%. Upgrading of the raw bio-oil was investigated over reduced Mo-10Ni/gamma-Al2O3 catalyst. After the upgrading process, the pH value of the bio-oil increased from 2.16 to 2.84. The water content increased from 46.2 wt.% to 58.99 wt.%. The H element content in the bio-oil increased from 6.61 wt.% to 6.93 wt.%. The dynamic viscosity decreased a little. The results of GC-MS spectrometry analysis showed that the ester compounds in the upgraded bio-oil increased by 3 times. it is possible to improve the properties of bio-oil by hydrotreating and esterifying carboxyl group compounds in the bio-oil.

A new prototype of self-pressurizing fuel tank for micro and nano-satellites

To increase effective load, light-weight micro-propulsion system is necessary for micro-satellites. Traditional propulsion systems including large and heavy high-pressure vessels are difficult to be scaled down to fulfill the demand of micro-satellites. In this article, a novel self-pressurizing fuel tank without high-pressure gas vessel is proposed. When some liquid propellant is consumed, pressure is compensated with CO2 released by heating NH4HCO3 powder in the fuel tank. Comparing with other types of self-pressurizing liquid fuel tank, a gas generator with special and simple structure was designed to stop or continue the NH4HCO3 decomposition reaction easily, and consumed a small amount of energy to heat the powder effectively. Performance tests showed that this new prototype is very suitable for micro-thrusters.

Partial oxidation reforming of biomass fuel gas over nickel-based monolithic catalyst with naphthalene as model compound

With naphthalene as biomass tar model compound, partial oxidation reforming (with addition of O-2) and dry reforming of biomass fuel gas were investigated over nickel-based monoliths at the same conditions. The results showed that both processes had excellent performance in upgrading biomass raw fuel gas. Above 99% of naphthalene was converted into synthesis gases (H-2+CO). About 2.8 wt% of coke deposition was detected on the catalyst surface for dry reforming process at 750 degrees C during 108 h lifetime test. However, no Coke deposition was detected for partial oxidation reforming process, which indicated that addition of O-2 can effectively prohibit the coke formation. O-2 Can also increase the CH4 conversion and H-2/CO ratio of the producer gas. The average conversion of CH4 in dry and partial oxidation reforming process was 92% and 95%, respectively. The average H-2/CO ratio increased from 0.95 to 1.1 with the addition of O-2, which was suitable to be used as synthesis gas for dimethyl ether (DME) synthesis.

Conversion of Soybean oil to Biodiesel Fuel with Immobilized Candida Lipase on Textile Cloth

The characteristic of biodiesel fuel production from transesterification of soybean oil is studied. The reactant solution is the mixture of soybean oil, methanol, and solvent. A new lipase immobilization method, textile cloth immobilization, was developed in this study. Immobilized Candida lipase sp. 99-125 was applied as the enzyme catalyst. The effect of flow rate of reaction liquid, solvents, reaction time, and water content on the biodiesel yield is investigated. Products analysis shows that the main components in biodiesel are methyl sterate, methyl hexadecanoate, methyl oleate, methyl linoleate, and methyl linolenate. The test results indicate that the maximum yield of biodiesel of 92% was obtained at the conditions of hexane being the solvent, water content being 20 wt%, and reaction time being 24 h.

低甲醇透过直接甲醇燃料电池(Low Methanol Crossover Direct Methanol Fuel Cell)

直接甲醇燃料电池与间接甲醇燃料电池相比，体积更小，重量更轻，因此在一些领域有诱人的应用前景。但是，在它们实际应用之前，必须解决一些具体的技术难题。目前，甲醇从阳极透过到阴极是影响电池性能的主要难题之一，另外，催化剂和电极的制备方法也对电池的性能有重要的影响。本论文的主要目的在于研制低甲醇透过直接甲醇燃料电池并有效地提高电池的性能。为了减小甲醇在Nafion117膜中的透过，提出并研制了铭纳米粒子修饰的Nafion复合膜，该方法包括与[Pd(NH_4)_4]~(2+)离子的离子交换过程和化学还原过程。研究了一种制备高分散性铂基催化剂的方法。另外我们还研究并分析了不同的电池运行参数，例如温度、甲醇浓度等，刘一电池性能和甲醇透过的影响。主要结果如下：1.采用离子交换还原法在Nafionll7膜内部沉积纳米把粒子，制备成高聚物电解质复合膜。研究了镀把前后Nafion膜表面形态、甲醇透过和膜的电导的变化和对直接甲醇燃料电池的性能的影响等。由于把纳米粒子阻碍了甲醇透过，同时，由于它对氢离子的强吸引力，不但不对氢离子的透过产生影响，而且还提高了膜佩狗电导。所以镀把后电解质膜的甲醇透过减少，膜电导增加，无论在低电流密度区还是在高电流密度区，电池性能都有效地提高。2.研究了一种制备高分散性铂基催化剂的新方法一预沉淀还原法。并采用TEM,XRD和电化学等技术来表征催化剂中铂的粒径、晶态结构和催化活性：与传统的化学还原法相比，因为该方法在化学还原过程中反应物与载体的作用力得到增强，所以采用该方法制备的催化剂铂分散性更好、晶态结构更低、粒径更小并且催化活性更好。该方法在直接甲醇燃料一电池中有应用价值。3.研究并分析了不同的电池运行参数，例如温度、甲醇浓度等，对电池性能和甲醇透过的影响。研究发现当电池运行温度增加时，电池性能提高，甲醇透过增加；甲醇浓度增加时，甲醇透过增加，但是，甲醇浓度对电池性能有不同的影响，在低甲醇浓度区，甲醇浓度增加，电池性能提高；在高甲醇浓度区，甲醇浓度增加，电池性能降低；存在一个最佳甲醇浓度，在该甲醇浓度的条件下，电池的性能最高。实验结果为：采用Nafion117膜时，电池的最佳甲醇浓度为2. 0 mol/L，采用镀把Nafion117膜时，电池的最佳甲醇浓度高于4.0 mol/Lo

直接甲醇燃料电池甲醇替代燃料的研究

论文主要研究了直接甲醇燃料电池（DMFC）中三种甲醇替代燃料，二甲氧基甲烷（DMM）、乙醇和乙二醇及导致阳极催化剂中毒的吸附CO（COad）在光滑R电极及几种新的R基催化剂电极上的电氧化行为。结合对催化剂的X射线光电子能谱（xPS）、X衍射(XRD)、扫描电子显微镜（SEM）和热重分析（TG）表征，初步探讨了几种新催化剂对三种甲醇替代燃料的电催化活性要高于碳载R（PtC）催化剂的原因。另外，还研究了用表面活化处理来提高阳极催化剂对甲醇氧化的电催化活性的方法。本论文得到的主要结果如下：1．在研究DMM在不同条件下，在不同R基催化剂电极上的电化学氧化行为的基础上，发现碳载R和TiO2（Pt-TiO2／C）复合催化剂对DMM氧化的电催化活性要优于Pt/C电极。而Pt-TiO2／C催化剂在吸附Ho3+(Pt-TiO2-Ho3+/C)或Eu3＋（Pt-TiO2-Eu3＋/C）后，对DMM氧化的电催化活性比Pt-TiO2／C电极高。表明TiO2、Eu3+和Ho3+对DMM的氧化都有很好的促进作用，这主要是它们都能为DMM的氧化在电极表面提供更多的含氧物种。由于DMM本身在这些催化剂电极上的氧化性能不好，而且DMM容易在酸性溶液中水解，生成甲醇和甲醛，因此，DMM不是一种好的甲醇替代燃料。2．无论在中性介质中还是在酸性介质中，Eu3＋和Ho3＋对乙醇在R／C电极上的电化学氧化反应都有较好的促进作用，而Eu3＋的促进作用要大于H3+，Eu3＋和H3+在酸性溶液中的促进作用要大于在中性溶液中。无论是中性溶液还是酸性溶液中，吸附CO（COad）在Pt／C催化剂电极上在较正的电位处有一个很大的氧化峰，而在R-Eu3＋／C或R-H3＋／C催化剂电极上在较负电位处有两个小的氧化峰，表明吸附的Eu3＋和Ho3+对cood在R／C催化剂电极上的氧化都有很好的促进作用，主要表现在使Cood的吸附强度降低和吸附量减少。XPs测量表明，当R／C电极表面吸附了Eu3＋或H了十后，使催化剂中Pt和c土的电子云密度变小，因此使Pt对coad的吸附强度减弱。由于Eu3＋或H03＋在电极上吸附不是物理吸附，而是化学吸附，因此，它们与Pt的结合具有相对的稳定性。乙醇电氧化的中间产物，如COad等能强烈地吸附在R上，因此会使R中毒。而Eu3＋或H矿"能降低Coad在R上地吸附强度，因此，Eu3＋或H3+能促进乙醇在Pt／C电极上的电化学氧化反应。Pt-TiO2／C催化剂对乙醇氧化的电催化活性要高于R／C催化剂，表明TiO2对乙醇在R／C电极上的电化学氧化反应也有较好的促进作用。XPS的测量表明，TiO2的加入并不改变Pt的电子状态，因此，TiO2能促进乙醇电氧化反应的主要原因是TIOZ能为乙醇氧化提供含氧物种。实验结果表明，Eu3＋或H3+对乙醇在R-TiO2／C电极上的电化学氧化反应也有一定的促进作用。这是由于Eu3＋或H3+改变了R的电子状态，降低了乙醇电氧化中间产物，COod在Pt上的吸附强度，而TIOZ提供了COod的氧化所必须的含氧物种。3．无论是酸性溶液中还是中性溶液中，乙二醇在R-TiO2／C电极上的氧化活性比在R／C电极上高。这表明TIOZ能促进乙二醇在Pt上的电氧化反应。进一步的实验表明，TIOZ对COad在Pt催化剂电极上氧化的促进作用并不明显。XPS测量表明，这是由于TIOZ并不改变R的电子状态。所以，TiO2对乙二醇在Pt上的电氧化的促进作用只是基于提供乙二醇电氧化所需的含氧物种。无论是酸性溶液中还是中性溶液中，乙二醇在R-WO3／C电极上的氧化活性都比在R／C电极上高。这表明W03能促进乙二醇在R上的电氧化反应。进一步的实验表明，R-WO3／C电极对Coad氧化的电催化活性也要高于R／C电极，XPS测量表明，WO3会降低Pt的电子云密度。所以，WO3对乙二醇在R上的电氧化的促进作用除了提供含氧物种外，还由于它能降低R的电子云密度而降低了乙二醇电氧化中间产物。4．用四氢吠喃和丙酮混合溶液浸泡法对电极进行表面处理后能使Pt／C和Pt-WO3／C电极对乙醇和乙二醇氧化的电催化活性有很大的提高。其原因可能是Pt／C和Pt一w03／C电极在经表面处理后，在电极制备过程中带来的表面活性剂等杂质由于溶解在混合溶液中而被除去，Nafion也可能在用混合溶液浸泡后会发生一定程度的结构变化，因此，使活性中心的位点增加，从而增加了催化剂的电催化活性。另外，经表面处理后，Pt／C和Pt-WO3／C电极的活性中心的结构有一定的变化，使COad的吸附强度降低而容易氧化，降低了COad对催化剂的毒化作用，因而提高了电极对乙醇和乙二醇氧化的电催化活性。