Energy storage by plasma methane decarbonization for CO2-free synthesis of H2 & carbonaceous nanoparticles

天然气(甲烷)在加拿大能源组合中的份额迅速增加，阻碍了能源脱碳。需要新的工艺来利用甲烷资源，并将对环境的影响降至最低。等离子体分解是一种新兴的技术，可以在不直接排放二氧化碳的情况下打破C-H键，生成氢气和碳质纳米颗粒。这项技术将电能储存在氢气中，并生产出用于电池的有价值的碳质纳米颗粒，对环境的影响即使不是零，也是最小的。通过等离子体脱碳，大部分消耗的电能可以从氢气中回收，元素碳可以转化为有价值的纳米颗粒，而不会燃烧排放。这项技术尚未得到广泛应用，因为： 1.对于甲烷热解与等离子体化学的相互作用，人们基本上缺乏了解。建立了甲烷氧化的燃烧动力学模型，其中只有少数几个反应占主导地位。然而，等离子体合成是在没有氧气的情况下进行的，而其他重要的反应途径也是活跃的。这种非氧化路线对工艺设计有重大影响，并为新技术打开了可能性。 2.碳纳米颗粒的气相合成知识仅限于狭窄的火焰温度范围。有了等离子体，这一范围将超出燃烧的热力学限制，并可以制造出一系列新的有价值的功能纳米颗粒。等离子体合成的非氧化性导致颗粒具有完全不同的组成、表面功能和光学性质。由于认识上的差距和缺乏预测框架，目前无法预测这些参数如何随着高温粒子停留时间的变化而变化。 这项研究通过多尺度的实验和建模方法解决了许多问题，重点放在等离子体化学与以下几个方面的相互作用：a)甲烷热解动力学，b)高温气溶胶动力学和c)碳纳米颗粒的功能特性。具体地说，我们将把甲烷和等离子体动力学模型与粒子模拟结合起来，以预测热解条件下的物种和气溶胶测量。然后，我们对过程控制中激光诊断所需的预测粒子光学属性进行基准测试。最后，通过在模块化反应器中的实验，我们了解了碳纳米颗粒的功能性质是如何被控制的。主要目的是揭示高温颗粒停留时间等工艺条件对颗粒功能特性和产氢的影响。 这项研究使加拿大能够利用其巨大的碳氢资源的能源，将其转化为氢和功能纳米颗粒，这是无碳能源转换和储存的两种基本商品。它还有助于开发新的碳氢化合物重整技术以减少排放。

The share of natural gas (methane) in Canadian energy portfolio is rapidly increasing which hinders energy decarbonization. Novel processes are needed to use methane recourses with minimal environmental impact. Plasma decomposition is an emerging technology for breaking C-H bonds without direct CO2 emissions to produce hydrogen and carbonaceous nanoparticles. This technology stores electricity in hydrogen and produces valuable carbonaceous nanoparticles used in batteries with minimal, if not zero environmental footprint. With plasma decarbonization, most of the consumed electricity can be recycled from hydrogen and the elemental carbon can be converted to valuable nanoparticles without combustion emissions. This technique has not been widely used because: 1. There is a fundamental lack of understanding regarding the interaction of methane pyrolysis with plasma chemistry. Combustion kinetic models are developed for methane oxidation where only a handful of reactions dominate. However, plasma synthesis operates without oxygen for which other important reaction pathways are active. Such non-oxidative routes have major implications for process design and open possibilities for novel technologies. 2. Knowledge of gas phase synthesis of carbonaceous nanoparticles is limited to a narrow range of flame temperatures. With plasma, this range is extended beyond thermodynamic limitations of combustion and an array of new valuable functional nanoparticles can be made. The non-oxidizing nature of plasma synthesis results in particles with completely different compositions, surface functionalities and optical properties. It is not currently possible to predict how these parameters change with high temperature particle residence time due to gaps in understanding and lack of a predictive framework. This research addresses many of these issues through a multiscale experimental and modeling approach with a focus on the interaction of plasma chemistry with: a) methane pyrolysis kinetics, b) high temperature aerosol dynamics and c) functional properties of carbonaceous nanoparticles. Specifically, we will couple methane and plasma kinetic models with particle simulations to predict species and aerosol measurements in pyrolysis conditions. Then we benchmark predicted particle optical properties needed for laser diagnostics in process control. Finally, with experiments in a modular reactor, we understand how the functional properties of carbonaceous nanoparticles are controlled. The main goal is to reveal how process conditions such as high temperature particle residence time affect particle functional properties and hydrogen production. This research enables Canada to harness the energy of its vast hydrocarbon resources by converting them to hydrogen and functional nanoparticles, i.e. two essential commodities for carbon free energy conversion and storage. It also contributes to developing novel hydrocarbon reforming technologies to reduce emissions.