CAREER: Theory-guided design of a novel chemical looping process for methane coupling using hydrogen storage materials

1454384 - grabowa将主要由甲烷（CH4）组成的丰富天然气转化为高价值产品（如乙烷或乙烯）的经济上可行的工艺可能会彻底改变化学工业。在使用CH4原料的所有过程中，主要的挑战是激活强C-H键，这通常是在氧化剂存在的情况下完成的，并且需要高温来激活，从而导致非选择性反应途径。该项目的主要目标是开发一种新的化学环工艺，用于在无氧条件下使用储氢材料进行选择性CH4偶联。第一性原理计算将指导有前途的储氢材料的选择，随后的反应/扩散模型将进一步缩小候选材料的范围。实验室规模的实验测试用于验证模型预测和优化操作条件。最近在水力压裂生产页岩气方面的技术发展，为开发商业上可行的甲烷转化工艺提供了巨大的动力，从而使美国经济受益。美国和世界上许多其他地区对大型页岩和致密气藏的利用，导致对其主要成分甲烷（CH4）的兴趣增加。截至2011年，全球已探明天然气储量总计208.4万亿立方米，其中7.72万亿立方米位于美国。天然气也是石油生产过程中的重要副产品，估计每年有1500亿立方米被燃烧。甲烷的传统用途包括发电（燃烧）和转化为合成气（CO和H2的混合物），在镍基催化剂上使用蒸汽重整。然而，甲烷作为生产液态碳氢化合物和有用化学品的原料的潜力尚未完全实现，经济上可行的甲烷到更高价值化学品的升级过程可能会彻底改变能源部门和化学工业。使用CH4作为原料的普遍挑战是激活非常强的C-H键（435 kJ/mol）。目前实施的利用CH4的工艺需要高温和含氧物质（如O2、H2O、CO2）的存在。这些过程对合成气的产生效果很好，这些合成气随后可以在费托合成反应器中转化为高级碳氢化合物。然而，将CH4直接转化为C2+仍然是化学工业面临的巨大挑战之一。甲烷氧化偶联（OCM）有可能解决这一挑战，但数十年的深入研究仍未能解决碳选择性问题。竞争燃烧反应消耗了大量的CH4原料，而CH3中间体在O2存在下的高反应性是一个不可逾越的障碍。本课题提出了一种新的甲烷偶联工艺，该工艺利用化学环和储氢材料分离碳和氧原子，以避免产生不需要的一氧化碳（CO）或二氧化碳（CO2）。拟议的研究活动将与K-12、本科、研究生和专业水平的广泛教育工作相结合，以扩大少数民族学生的参与，并增加有风险学生的留校率。与Marlo Diosomito和PI监督的赛普拉斯费尔班克斯ISD的两所经济状况不佳的第一高中的合作伙伴关系，将激发人们对STEM学科的更多兴趣，并增加低收入家庭学生的代表性。UH是一所指定的西班牙裔服务机构，拥有美国所有主要研究机构中种族最平衡的学生群体

1454384 - GrabowAn economically viable process to transform abundant natural gas, primarily composed of methane (CH4), to higher value products (e.g. ethane or ethylene) could revolutionize the chemical industry. The prevailing challenge in all processes using CH4 feedstock is activating the strong C-H bond, which is typically done in the presence of an oxidizing agent and requires high temperatures for activation coincidentally leading to unselective reaction pathways. The primary goal of this project is to develop a new chemical looping process for selective CH4 coupling in the absence of oxygen using hydrogen storage materials. First principles calculations will guide the selection of promising hydrogen storage materials and subsequent reaction/diffusion modeling will further narrow down the group of candidate materials. Laboratory scale experimental testing is used to verify the model predictions and to optimize the operating conditions. Recent technological developments in hydraulic fracturing (fracking) to produce shale gas provide a huge incentive to develop commercially viable methane conversion processes to benefit the U.S. economy. Utilization of large shale and tight gas reservoirs in the U.S. and many other parts of the world have led to an increased interest in its main component, methane (CH4). As of 2011 the proven natural gas reserves total 208.4 trillion cubic meters worldwide, of which 7.72 trillion cubic meters are located in the U.S. Natural gas is also a significant byproduct during oil production and an estimated 150 billion cubic meters are being flared annually.Traditional uses of methane include electricity generation (combustion) and conversion to syngas, a mixture of CO and H2, using steam reforming over Ni-based catalysts.However, the potential for methane as a feedstock for the production of liquid hydrocarbons and useful chemicals has not yet been fully realized and an economically viable methane to higher value chemicals upgrade process could revolutionize the energy sector and chemical industry. The pervasive challenge of using CH4 as feedstock is activating the very strong C-H bond (435 kJ/mol). Currently implemented processes utilizing CH4 require high temperatures and the presence of oxygen-containing species (e.g. O2, H2O, CO2). These processes work well for the generation of syngas, which can subsequently be converted to higher hydrocarbons in a Fischer-Tropsch synthesis reactor. However, the direct conversion of CH4 to C2+ species remains one of the grand challenges in the chemical industry. Oxidative coupling of methane (OCM), could potentially address this challenge, but decades of intensive research have not been able to solve the issue of carbon selectivity. The competing combustion reaction consumes a large fraction of the CH4 feedstock and the high reactivity of the CH3 intermediates in the presence of O2 presents an insurmountable obstacle. In this research project a new process for methane coupling is proposed, which uses chemical looping and hydrogen storage materials to separate the carbon and oxygen atoms in order to avoid the formation of undesired carbon monoxide (CO) or carbon dioxide (CO2). The proposed research activities will be integrated with broad-reaching educational efforts at the K-12, undergraduate, graduate and professional level to broaden the participation of minority students and increase the retention of at-risk students. Partnerships with Marlo Diosomito and two economically disadvantaged Title-1 high schools in the Cypress Fairbanks ISD that the PI supervises will be leveraged to generate more interest in STEM disciplines and increase the representation of students from low-income families. UH is a designated Hispanic-Serving Institution and has the most ethnically balanced student body of all major research institutions in the U.S.