Nitrogenated Hydrocarbon Cross-Product Formation during Combustion of Ammonia Co-Fired with Regular Hydrocarbons

可以说，我们当今社会面临的最大挑战是满足我们的能源需求，同时减少使地球变暖的排放。 在这方面，氨作为一种无碳燃料正在受到关注，它可以燃烧而不会直接排放二氧化碳。 它可以在国内使用清洁电力从空气和水生产，并且比氢气更容易液化。 由于氨具有较差的燃烧特性，在许多应用中，它将与烃类燃料如天然气共燃。 这为基础燃烧化学的一个新领域打开了大门：将燃料中碳氢化合物部分的碳原子与氨中的氮原子结合在一起的氮化交叉产物的形成。 我们有初步的数据，验证了这种交叉产品的形成，并表明它们通过以不能生长成烟灰的形式螯合碳，在化学上抑制了燃料中碳氢化合物部分形成烟灰颗粒。 拟议项目的目标是系统地探索氨与常规燃料燃烧时交叉产物的形成，确定它们与烟尘形成的关系，并确定产生它们的化学机制。该项目将使用火焰取样和在线光电离质谱法，生成第一个用灵敏、在以氨+甲烷、乙烯和其它烃为燃料的火焰中的宽带诊断。它将测量相同火焰中的烟灰体积分数，并测试交叉产物形成化学抑制共烧碳氢化合物形成烟灰的假设。它将表征的形态，纳米结构和原子组成的烟尘颗粒从火焰中热迁移采样，以进一步确定交叉产品和烟尘之间的关系。测量将使用一种新的实验设计，通过将氨+烃火焰与相应的一组氮+烃火焰进行比较，将氨的化学效应与其物理效应区分开来。火焰将彻底的特点，相对于温度，主要物种，和边界条件，使他们可以计算模拟测试和改进详细的动力学机制的交叉产品。温度测量将进一步发展一种新的X射线荧光诊断，这种诊断具有独特的测量热边界条件和现场温度的能力，在所有区域的烟尘火焰与颗粒的干扰可以忽略不计。这一奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

Arguably the greatest challenge confronting our society today is to satisfy our energy needs while reducing emissions that warm the planet. In this regard, ammonia is gaining attention as a carbon-free fuel that can be burned with no direct carbon dioxide emissions. It can be produced domestically from air and water using clean electricity and is much more easily liquified than hydrogen. Since ammonia has poor burning characteristics, in many applications it will be co-fired with hydrocarbon fuels such as natural gas. This opens the door to a novel area of fundamental combustion chemistry: the formation of nitrogenated cross-products that combine carbon atoms from the hydrocarbon portion of the fuel with nitrogen atoms from the ammonia. We have preliminary data that verifies the formation of such cross-products and suggests that they chemically suppress formation of soot particles from the hydrocarbon portion of the fuel by sequestering carbon in a form that cannot grow to soot. The objective of the proposed project is to systematically explore the formation of cross-products when ammonia is burned with conventional fuels, determine their relationship to soot formation, and identify the chemical mechanisms that produce them.This project will use flame sampling and online photoionization mass spectrometry to generate the first database of trace hydrocarbon concentration profiles measured with a sensitive, broadband diagnostic in flames fueled with ammonia + methane, ethylene, and other hydrocarbons. It will measure soot volume fractions in the same flames and test the hypothesis that cross-product formation chemically suppresses soot formation from the co-fired hydrocarbons. It will characterize the morphology, nanostructure, and atomic composition of soot particles sampled thermophoretically from the flames to further determine the relationship between cross-products and soot. The measurements will use a novel experimental design to distinguish the chemical effects of ammonia from its physical effects by comparing the ammonia + hydrocarbon flames with a corresponding set of nitrogen + hydrocarbon flames. The flames will be thoroughly characterized with respect to temperature, major species, and boundary conditions so that they can be computationally simulated to test and improve detailed kinetic mechanisms for cross-products. The temperature measurements will further the development of a novel X-ray fluorescence diagnostic that is uniquely capable of measuring thermal boundary conditions and in-situ temperatures in all regions of sooting flames with negligible interferences from particles.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.