SGER: Catalytic Reforming of Electrically Charged Glycerin Nano-droplets to Produce Hydrogen

为了解决目前生物质催化制氢的局限性，将研究一种替代的创新范式，即在直径在1-100纳米之间的带电粘性液滴进行重整，即纳米相重整。阻碍这项技术发展的因素是在正电荷衬底和负电荷催化剂/载体界面发生的化学知识的差距，以及粘性纳米级液滴如何与固体相互作用。实验研究和理论建模和模拟将在一个综合的研究中进行，以了解这种行为，最终目标是提高纳米相转化技术。脂类、碳水化合物及其衍生物等CO2中性的可再生原料具有高分子量和高粘性，现有的制氢技术，即蒸汽重整和水相重整（APR），在重整此类流体方面效果不高。然而，与蒸汽重整相比，APR在几个方面是有利的：APR 1)通过节省汽化潜热，需要更少的总能量；2)具有在较低温度下进行重整的能力，3)能够充分利用在蒸汽重整温度下被热力学抑制的水气转换反应的潜力。尽管有上述优点，但由于固体（催化剂）层周围的扩散阻力，导致APR的产氢速率缓慢，从而阻碍了APR的发展。蒸汽重整，虽然它在历史上导致了短链碳氢化合物的高氢产量，但由于从液体（100纳米的液滴）到气体（1纳米的颗粒）状态变化的传质限制，在粘性底物的重整中是无效的。这导致我们提出了催化重整1至100纳米直径的带电液体纳米液滴的研究。长期目标是开发一种重整技术，主要从生物可再生原料中生产氢气，这种原料的物理化学性质与石油基碳氢化合物明显不同。本应用程序的目的是提高对在接地的Ni/碳-石墨导电催化剂表面上催化重整带正电的衬底液滴的化学反应的基本理解。该研究的中心假设是，与传统的APR工艺相比，重组直径在1-100 nm之间的带电衬底液滴可以显著提高衬底转化率。我们假设的基本原理和知识价值在于，如果将反应物分裂成更细的液滴并带电，则可以降低反应物密度，同时允许带正电的反应物液滴被带负电的催化剂载体所吸引。因此，在催化剂活性位点激发了比apr高得多的底物可用性。我们已经使用我们的电分裂装置获得了初步数据，证明了从高粘性甘油中生产纳米颗粒是可能的。中心假设将通过追求以下具体目标来检验：生产具有一致轮廓的甘油纳米颗粒-输入参数：流体流速、流体密度、自由空间介电常数、表面张力和流体的电导率特性影响纳米喷雾的液滴尺寸分布。通过改变上述参数，可以得到由直径为50nm的液滴组成的液滴尺寸分布。2. 比较氢选择性、甘油转化率和副产物生成——这些参数将在APR、蒸汽重整和纳米相重整中进行测量，同时在所有实验运行中保持催化剂负载、催化剂表面积和进料流量恒定。3. 通过凝析油中产物的鉴定提出反应机理。凝析油的产物将通过GCMS、HPLC和LCMS进行分析，以确定反应机理。将进行量子化学计算并开发互补模拟，然后进行实验验证以筛选可能的催化剂。根据这些结果，可能会在实验设计中加入另一种催化剂，以更准确地评估这一概念。该结果应适用于广泛的其他液体生物产品，如碳质甘油三酯及其衍生物。这项研究可能有助于扩大未来氢能源系统的原材料选择。研究将纳入教育，一名博士生和一名少数民族和代表性不足的学生将得到培训。

Proposal Number: CBET-0708932Principal Investigator: Fernando, Sandun D. Institution: Mississippi State UniversityIn order to address present limitations of catalytic hydrogen production from biomass, there will be investigated an alternative, innovative paradigm where electrically charged viscous liquid droplets will be reformed when they are between 1-100 nm in diameter, i.e, nanophase reforming. The factors impeding development of this technology are the gap in the knowledge of the chemistry that occurs at the positively charged substrate and the negatively charged catalyst/support interface and how viscous nanoscale droplets interact with solids.Both experimental studies and theoretical modeling and simulation will be conducted in an integrated study to understanding this behavior, with the ultimate goal of enhancing the nanophase reforming technique. Renewable raw materials which are CO2 neutral such as lipids, carbohydrates and their derivatives have high molecular weights and are highly viscous and the existing hydrogen production technologies, i.e, steam reforming and aqueous phase reforming (APR), are not highly effective in reforming such fluids. However, APR is advantageous in several ways over steam reforming: APR 1) requires less overall energy by saving the latent heat of vaporization; 2) has the ability to reform at substantially lower temperatures and 3) has the ability to harness the full potential of the water gas shift reaction which is thermodynamically inhibited at steam reforming temperatures. Despite the above advantages, APR is hindered by slow hydrogen production rates mainly due to diffusion resistance around the solid (catalyst) layer. Steam reforming, although it has historically resulted in high hydrogen yields from short chained hydrocarbons, is ineffective in reforming of viscous substrates due to mass transfer limitations associated with changing the state from a liquid (droplets 100 nm) to a gas (particles 1 nm). This leads to our proposed study of catalytic reforming of charged liquid nanodroplets of 1 to 100 nm in diameter. The long-term goal is to develop a reforming technique to produce hydrogen primarily from biorenewable feedstock which has markedly different physiochemical properties than petroleum based hydrocarbons. The objective of this application is to improve the basic understanding of the chemistries involved in catalytic reforming of positively charged substrate droplets over a grounded Ni/carbon-graphite conducting catalyst surface. The central hypothesis of the study is that reforming electrically charged substrate droplets that are between 1-100 nm in diameter can significantly increase substrate conversion in comparison to the conventional APR process. The rationale and the intellectual merit of our hypotheses is that if the reactants are split into finer droplets and electrically charged, the reactant densities could be reduced while allowing the positively charged reactant droplets to be attracted to the negatively charged catalyst support, thus instigating much higher substrate availability at the catalyst active sites than that of APR. We have obtained preliminary data using our electrosplitting device to demonstrate that the production of nanoparticles from highly viscous glycerin is possible. The central hypothesis will be tested by pursuing the following specific aims: 1. Production of glycerin nanoparticles with a consistent profile - Input parameters: fluid flow rate, fluid density, permittivity of free space, surface tension and conductivity properties of the fluid affect the droplet size distribution of the nanospray. A droplet size distribution that consists of 50 nm diameter droplets will be obtained by changing aforementioned parameters. 2. Comparing the hydrogen selectivity, glycerin conversion and byproduct formation - These parameters will be measured for APR, steam reforming and nanophase reforming while keeping catalyst loading, catalyst surface area and feed flow rates constant through out all experimental runs. 3. Proposing reaction mechanisms with the help of product identification in the condensates - The products of the condensate will be analyzed through GCMS, HPLC and LCMS to determine the reaction mechanisms. Quantum chemical calculations will be performed and complementary simulations developed, followed by experimental validation to screen possible catalysts. Depending on these results, another catalyst might be added into the experimental design for a more accurate evaluation of this concept. The results should be applicable to a broad range of other liquid bio-products, such as carbonaceous triglycerides and their derivatives. This research may help broaden the raw material choices available for future hydrogen based energy systems. Research will be incorporated into education, and one doctoral student and one minority and underrepresented student will be trained.