Collaborative Research: SusChEM: Rational Design of Non-precious Metal Catalysts for a Future Biorefining Industry

使用诸如废木材产品和玉米秸秆等生物质作为燃料和化学原料的潜在来源是有吸引力的。 多相催化剂常用于将生物质转化为有用的化学品，但已知最有效的催化剂由稀有且昂贵的铂族金属组成。 南卡罗来纳州大学的海登博士和哥伦比亚大学的陈博士正在合作开发一种廉价而丰富的材料，碳化钼（Mo 2C）作为铂的替代品。 他们正在研究如何通过添加铁，铜，钴和镍来增强Mo 2C的催化性能，以实现生物质转化的可持续化学。该团队正在阐明开发高选择性非贵金属催化剂所需的基础科学，用于升级一种来自生物质的特定化学品甘油（C3 H8 O3）。 甘油已被确定为可以从糖中提取并转化为高价值生物基化学品和材料的十二种主要化学物质之一。 此外，甘油是通过植物油的酯交换生产生物柴油的主要副产物，并且衍生自甘油的产品的多样化已被确定为生物柴油生产的关键问题。 他们研究的一个主要重点是评估由于甘油和水中存在氧而导致的表面氧化程度，以及了解催化剂的氧改性如何影响反应。 研究活动还通过在陈博士和海登博士的实验室为本科生设立暑期研究实习机会，形成更广泛的影响，他们指导学生，鼓励他们在可再生能源和化学生产方面进行研究生学习和职业生涯。 陈博士和海登博士还积极参与将研究成果融入哥伦比亚大学和南卡罗来纳大学的本科生和研究生化学工程课程。在化学部化学催化项目的资助下，哥伦比亚大学的陈博士和南卡罗来纳州大学的海登博士正在开发高度选择性的，用于生物质衍生多元醇的加氢脱氧（HDO）的非贵金属催化剂。目前的HDO催化剂主要基于铂族金属催化剂，但其高成本和有限的丰度是生产成本有效的生物质基燃料和化学品的潜在问题。特别地，碳化钼（Mo 2C）对C-O/C=O键断裂（C =碳和O =氧）具有高度选择性，并且还可以通过非贵3d金属（铁、钴、镍和铜）改性以增强目标HDO反应的催化活性、选择性和稳定性。为了确定Mo 2C和3d-金属改性Mo 2C中的活性位点以及生物质衍生多元醇在这些活性位点上的HDO反应机理，Chen和Heyden博士采用了基于单晶模型表面上的密度泛函理论（DFT）计算的计算和实验相结合的研究方法。 他们还使用单晶模型表面的超高真空（UHV）实验来验证DFT预测的趋势，相应粉末催化剂的反应器评估，各种实验反应条件下的微动力学反应器建模，以及实验数据与计算模型的系统相关性。从拟议的研究中获得的知识为设计非贵金属催化剂提供了指导方针，特别是甘油和生物质衍生分子的选择性转化。 通过将研究成果融入哥伦比亚大学和南卡罗来纳州大学核心化学工程课程的本科生和研究生选修课，对教育产生了更广泛的影响。

The use of biomass such as waste wood products and corn stalks is attractive as a potential source of fuel and chemical feedstocks. Heterogeneous catalysts are often used in the transformation of biomass to useful chemicals, but the most effective known catalysts are composed of rare and expensive platinum group metals. Dr. Heyden of the University of South Carolina and Dr. Chen of Columbia University are collaborating to develop a cheap and abundant material, molybdenum carbide (Mo2C) as a replacement for platinum. They are studying how the catalytic properties of Mo2C can be enhanced by the addition of iron, copper, cobalt and nickel for sustainable chemistry of biomass transformation. The team is elucidating the underlying science needed for the development of highly selective, non-precious metal catalysts for upgrading a specific chemical derived from biomass called glycerol (C3H8O3). Glycerol has been identified as one of the top twelve building block chemicals that can be derived from sugar and converted to high-value bio-based chemicals and materials. Also, glycerol is a major by-product of the biodiesel production by transesterification of vegetable oils and the diversification of products derived from glycerol has been identified as a key issue for biodiesel production. A major focus of their research lies in evaluating the degree of the surface oxidation due to the presence of oxygen in the glycerol and in water, and in developing the understanding of how oxygen modification of the catalyst affects the reaction. Research activities also form broader impacts through the establishment of summer research internships for undergraduate students in the laboratories of Drs. Chen and Heyden, who mentor students to encourage them to pursue graduate studies and careers in renewable energy and chemical production. Drs. Chen and Heyden are also actively engaged in integrating research results into the undergraduate and graduate chemical engineering curriculum at Columbia University and the University of South Carolina.With funding from the Chemical Catalysis Program of the Chemistry Division, Dr. Chen of Columbia University and Dr. Heyden of the University of South Carolina are developing highly selective, non-precious metal catalysts for the hydrodeoxygenation (HDO) of biomass-derived polyols. Current HDO catalysts are primarily based on platinum-group metal catalysts, but their high costs and limited abundance are potential concerns for the production of cost-effective, biomass-based fuels and chemicals. In particular, molybdenum carbide (Mo2C) is highly selective for C-O/C=O bond cleavage (C = carbon and O = oxygen) and can furthermore be modified by non-precious 3d-metals (iron, cobalt, nickel, and copper) to enhance the catalytic activity, selectivity, and stability for targeted HDO reactions. To identify the active sites in Mo2C and 3d-metal modified Mo2C and the reaction mechanism of the HDO of biomass-derived polyols on these active sites, Drs. Chen and Heyden apply a combined computational and experimental research approach that is based on density function theory (DFT) calculations on single crystal model surfaces. They also use ultrahigh vacuum (UHV) experiments on single crystal model surfaces to validate DFT-predicted trends, reactor evaluations over the corresponding powder catalysts, microkinetic reactor modeling under various experimental reaction conditions, and systematic correlation of experimental data with computational models. Knowledge from the proposed research provides guidelines for designing non-precious metal catalysts for the selective transformation of glycerol in particular and of biomass-derived molecules in general. Broader impacts in education are included by integrating research findings into undergraduate and graduate electives in the core chemical engineering curriculum at Columbia University and the University of South Carolina.