A simple, cheap material for carbon capture, perhaps from tailpipes

一种简单、廉价的碳捕获材料,可能来自排气管

作者:Robert Sanders     来源:berkeley     阅读模式:只看译文

Using an inexpensive polymer called melamine — the main component of Formica — chemists have created a cheap, easy and energy-efficient way to capture carbon dioxide from smokestacks, a key goal for the United States and other nations as they seek to reduce greenhouse gas emissions. The process for synthesizing the melamine material, published this week in the journal Science Advances, could potentially be scaled down to capture emissions from vehicle exhaust or other movable sources of carbon dioxide. Carbon dioxide from fossil fuel burning makes up about 75% of all greenhouse gases produced in the U.S. The new material is simple to make, requiring primarily off-the-shelf melamine powder — which today costs about $40 per ton — along with formaldehyde and cyanuric acid, a chemical that, among other uses, is added with chlorine to swimming pools. “We wanted to think about a carbon capture material that was derived from sources that were really cheap and easy to get. And so, we decided to start with melamine,” said Jeffrey Reimer, Professor of the Graduate School in the Department of Chemical and Biomolecular Engineering at the University of California, Berkeley, and one of the corresponding authors of the paper. The so-called melamine porous network captures carbon dioxide with an efficiency comparable to early results for another relatively recent material for carbon capture, metal organic frameworks, or MOFs. UC Berkeley chemists created the first such carbon-capture MOF in 2015, and subsequent versions have proved even more efficient at removing carbon dioxide from flue gases, such as those from a coal-fired power plant. But Haiyan Mao, a UC Berkeley postdoctoral fellow who is first author of the paper, said that melamine-based materials use much cheaper ingredients, are easier to make and are more energy efficient than most MOFs. The low cost of porous melamine means that the material could be deployed widely. “In this study, we focused on cheaper material design for capture and storage and elucidating the interaction mechanism between CO2 and the material,” Mao said. “This work creates a general industrialization method towards sustainable CO2 capture using porous networks. We hope we can design a future attachment for capturing car exhaust gas, or maybe an attachment to a building or even a coating on the surface of furniture.” The work is a collaboration among a group at UC Berkeley led by Reimer; a group at Stanford University led by Yi Cui, who is director of the Precourt Institute for Energy, the Somorjai Visiting Miller Professor at UC Berkeley, and a former UC Berkeley postdoctoral fellow; UC Berkeley Professor of the Graduate School Alexander Pines; and a group at Texas A&M University led by Hong-Cai Zhou. Jing Tang, a postdoctoral fellow at Stanford and the Stanford Linear Accelerator Center and a visiting scholar at UC Berkeley, is co-first author with Mao. Reimer is also a faculty scientist at Lawrence Berkeley National Laboratory. Carbon neutrality by 2050 While eliminating fossil fuel burning is essential to halting climate change, a major interim strategy is to capture emissions of carbon dioxide — the main greenhouse gas — and store the gas underground or turn CO2 into usable products. The U.S. Department of Energy has already announced projects totaling $3.18 billion to boost advanced and commercially scalable technologies for carbon capture, utilization and sequestration (CCUS) to reach an ambitious flue gas CO2 capture efficiency target of 90%. The ultimate U.S. goal is net zero carbon emissions by 2050. But carbon capture is far from commercially viable. The best technique today involves piping flue gases through liquid amines, which bind CO2. But this requires large amounts of energy to release the carbon dioxide once it’s bound to the amines, so that it can be concentrated and stored underground. The amine mixture must be heated to between 120 and 150 degrees Celsius (250-300 degrees Fahrenheit) to regenerate the CO2. In contrast, the melamine porous network with DETA and cyanuric acid modification captures CO2 at about 40 degrees Celsius, slightly above room temperature, and releases it at 80 degrees Celsius, below the boiling point of water. The energy savings come from not having to heat the substance to high temperatures. In its research, the Berkeley/Stanford/Texas team focused on the common polymer melamine, which is used not only in Formica but also inexpensive dinnerware and utensils, industrial coatings and other plastics. Treating melamine powder with formaldehyde — which the researchers did in kilogram quantities — creates nanoscale pores in the melamine that the researchers thought would absorb CO2. Mao said that tests confirmed that formaldehyde-treated melamine adsorbed CO2 somewhat, but adsorption could be much improved by adding another amine-containing chemical, DETA (diethylenetriamine), to bind CO2. She and her colleagues subsequently found that adding cyanuric acid during the polymerization reaction increased the pore size dramatically and radically improved CO2 capture efficiency: Nearly all the carbon dioxide in a simulated flue gas mixture was absorbed within about 3 minutes. The addition of cyanuric acid also allowed the material to be used over and over again. A new family of porous networks Mao and her colleagues conducted solid-state nuclear magnetic resonance (NMR) studies to understand how cyanuric acid and DETA interacted to make carbon capture so efficient. The studies showed that cyanuric acid forms strong hydrogen bonds with the melamine network that helps stabilize DETA, preventing it from leaching out of the melamine pores during repeated cycles of carbon capture and regeneration. “What Haiyan and her colleagues were able to show with these elegant techniques is exactly how these groups intermingle, exactly how CO2 reacts with them, and that in the presence of this pore-opening cyanuric acid, she’s able to cycle CO2 on and off many times with capacity that’s really quite good,” Reimer said. “And the rate at which CO2 adsorbs is actually quite rapid, relative to some other materials. So, all the practical aspects at the laboratory scale of this material for CO2 capture have been met, and it’s just incredibly cheap and easy to make.” “Utilizing solid-state nuclear magnetic resonance techniques, we systematically elucidated in unprecedented, atomic-level detail the mechanism of the reaction of the amorphous networks with CO2,” Mao said. “For the energy and environmental community, this work creates a high-performance, solid-state network family together with a thorough understanding of the mechanisms, but also encourages the evolution of porous materials research from trial-and-error methods to rational, step-by-step, atomic-level modulation.” The Reimer and Cui groups are continuing to tweak the pore size and amine groups to improve the carbon capture efficiency of melamine porous networks, while maintaining the energy efficiency. This involves using a technique called dynamic combinatorial chemistry to vary the proportions of ingredients to achieve effective, scalable, recyclable and high-capacity CO2 capture. Reimer and Mao have also closely collaborated with the Cui group at Stanford to synthesize other types of materials, including hierarchical nanoporous membranes — a class of nanocomposites combined with a carbon sphere and graphene oxide — and hierarchical nanoporous carbons made from pine wood, to adsorb carbon dioxide. Reimer developed solid-state NMR specifically to characterize the mechanism by which solid materials interact with carbon dioxide, in order to design better materials for carbon capture from the environment and energy storage. Cui developed a robust and sustainable solid-state platform and fabrication techniques for creating new materials to address climate change and energy storage. This work was partly supported by the U.S. Department of Energy (DE-AC02-76SF00515). RELATED INFORMATION A scalable solid-state nanoporous network with atomic-level interaction design for carbon dioxide capture (Science Advances) Jeffrey Reimer’s lab website Yi Cui’s lab website Hong-Cai “Joe” Zhou’s lab website

化学家们利用一种名为三聚氰胺的廉价聚合物——胶木的主要成分——创造了一种廉价、简单和节能的方法,从烟囱中捕获二氧化碳,这是美国和其他国家寻求减少温室气体排放的一个关键目标。
本周发表在《科学进展》(Science Advances)杂志上的合成三聚氰胺材料的过程,可能会被缩小,以捕捉汽车尾气或其他可移动二氧化碳来源的排放。化石燃料燃烧产生的二氧化碳约占美国产生的温室气体的75%。
这种新材料制作简单,主要需要现成的三聚氰胺粉末(如今每吨价格约为40美元),以及甲醛和三聚氰胺酸,三聚氰胺酸是一种与氯一起添加到游泳池的化学物质。
“我们想考虑一种碳捕获材料,这种材料来自非常便宜和容易获得的来源。因此,我们决定从三聚氰胺开始,“杰弗里·雷默说,他是加州大学伯克利分校化学和生物分子工程系研究生院教授,也是该论文的相应作者之一。
所谓的三聚氰胺多孔网络捕获二氧化碳的效率可与另一种相对较新的碳捕获材料——金属有机框架(简称MOFs)的早期结果相媲美。加州大学伯克利分校的化学家在2015年创造了第一个这样的碳捕获MOF,后来的版本被证明在从烟道气体(如燃煤发电厂)中去除二氧化碳方面更有效。
但这篇论文的第一作者、加州大学伯克利分校博士后毛海燕说,三聚氰胺基材料使用的成分要便宜得多,更容易制造,而且比大多数MOF更节能。多孔三聚氰胺的低成本意味着该材料可以广泛应用。
“在这项研究中,我们专注于更便宜的捕获和储存材料设计,并阐明二氧化碳和材料之间的相互作用机制,”毛说。“这项工作创造了一种利用多孔网络实现可持续二氧化碳捕获的通用工业化方法。我们希望我们可以设计一种未来的捕捉汽车尾气的附件,或者可能是一种建筑的附件,甚至是家具表面的涂层。“
这项研究是由雷默领导的加州大学伯克利分校的一个团队合作完成的;由斯坦福大学Precourt能源研究所所长、加州大学伯克利分校Somorjai Miller客座教授、前加州大学伯克利分校博士后崔毅领导的研究小组;加州大学伯克利分校研究生院教授亚历山大·派恩;以及德州农工大学周洪才(Hong-Cai Zhou)领导的一个小组。唐静,斯坦福大学和斯坦福线性加速器中心博士后,加州大学伯克利分校访问学者,与毛同为第一作者。雷默也是劳伦斯伯克大学的一名教员科学家
到2050年实现碳中和
虽然消除化石燃料燃烧对遏制气候变化至关重要,但一项重要的临时战略是捕获二氧化碳(主要的温室气体)的排放,并将其储存在地下或将二氧化碳转化为可用的产品。美国能源部已经宣布了总额达31.8亿美元的项目,以推动先进的、商业上可扩展的碳捕获、利用和封存(CCUS)技术,以实现烟气二氧化碳捕获效率达到90%的宏伟目标。美国的最终目标是到2050年实现零碳排放。
但碳捕获在商业上远非可行。当今最好的技术是通过液体胺将烟道气输送,液体胺能结合二氧化碳。但这需要大量的能量来释放二氧化碳,一旦它与胺结合,这样它就可以浓缩并储存在地下。胺混合物必须加热到120到150摄氏度(250到300华氏度)才能再生二氧化碳。
相比之下,三聚氰胺多孔网络与DETA和三聚尿酸修饰捕获二氧化碳约40摄氏度,略高于室温,并释放它在80摄氏度,低于水的沸点。节省能源来自于不必将物质加热到高温。
在他们的研究中,伯克利/斯坦福/德州团队关注的是常见的聚合物三聚氰胺,它不仅用于胶木,还用于廉价的餐具和餐具、工业涂料和其他塑料。用甲醛处理三聚氰胺粉末——这是研究人员按千克量进行的——在三聚氰胺中产生纳米级的孔,研究人员认为这些孔可以吸收二氧化碳。
毛说,测试证实,甲醛处理过的三聚氰胺对二氧化碳有一定的吸附作用,但添加另一种含胺的化学物质DETA(二乙烯三胺)来结合二氧化碳,可以大大提高吸附效果。她和她的同事随后发现,在聚合反应中加入三聚酸会显著增加孔径,并从根本上提高二氧化碳捕获效率:模拟的烟气混合物中几乎所有的二氧化碳都在大约3分钟内被吸收。
三聚尿酸的加入也允许材料一遍又一遍地使用。
一族新的多孔网络
毛和她的同事进行了固态核磁共振(NMR)研究,以了解三聚尿酸和DETA是如何相互作用使碳捕获如此有效的。研究表明,三聚尿酸与三聚氰胺网络形成强大的氢键,这有助于稳定DETA,防止它在碳捕获和再生的反复循环中从三聚氰胺孔隙中浸出。
雷默说:“海燕和她的同事们能够用这些优雅的技术展示的是这些基团是如何混合的,CO2是如何与它们反应的,在这种开孔的三聚尿酸的存在下,她能够以非常好的容量多次循环CO2。”“相对于其他一些材料,二氧化碳的吸附速度实际上相当快。因此,这种材料在实验室范围内捕获二氧化碳的所有实用方面都得到了满足,而且非常便宜,容易制造。“
“利用固态核磁共振技术,我们以前所未有的原子级细节系统地阐明了非晶网络与二氧化碳反应的机制,”毛说。“对于能源和环境界来说,这项工作创造了一个高性能的固态网络家族,以及对机理的透彻理解,但也鼓励了多孔材料研究从试错方法向合理的、逐步的、原子级调制的进化。”
Reimer和Cui团队正在继续调整孔隙大小和胺基,以提高三聚氰胺多孔网络的碳捕获效率,同时保持能源效率。这涉及到使用一种称为动态组合化学的技术来改变成分的比例,以实现有效的、可扩展的、可回收的和高容量的二氧化碳捕获。
雷默和毛还与斯坦福大学的崔小组密切合作,合成了其他类型的材料,包括分级纳米孔膜–一种由碳球和氧化石墨烯结合的纳米复合材料–以及由松木制成的分级纳米孔碳,以吸附二氧化碳。Reimer专门开发了固态核磁共振来表征固体材料与二氧化碳相互作用的机制,以便设计更好的材料从环境中捕获碳和储存能量。崔开发了一个坚固和可持续的固态平台和制造技术,用于创造新材料来应对气候变化和能源储存。
这项工作得到了美国能源部(DE-AC02-76SF00515)的部分支持。
相关信息
可扩展的固态纳米孔网络,原子级相互作用设计用于二氧化碳捕获(科学进展)
杰弗里·雷默实验室网站
易翠的实验室网站
周宏才的实验室网站