艾姆斯國家實驗室、愛荷華州立大學、弗吉尼亞大學和哥倫比亞大學的科學家們日前開發出了一種將二氧化碳轉化為乙烯的新型混合催化劑

新型混合催化劑只使用地球上儲量豐富的材料，如鎳和銅，這種催化劑反應所需的能量更少

新型混合催化劑的多孔結構和兩種催化劑的組合使其在二氧化碳還原為一氧化碳和一氧化碳還原為乙烯反應中具有高效性和選擇性

據油價網2023年1月31日報道，愛荷華州立大學艾姆斯國家實驗室日前宣布了一種新型混合催化劑，可以在一個罐子里將二氧化碳轉化為乙烯。這種新型混合催化劑是由來自艾姆斯國家實驗室、愛荷華州立大學、弗吉尼亞大學和哥倫比亞大學的科學家們開發的。這種催化劑通過將二氧化碳回收作為高效乙烯生產的原料，支持世界凈零排放碳倡議。

這個團隊的報告論文日前已經發表在《美國化學學會雜志》上。

乙烯是一種作為大宗商品的化學制品，用于制造從塑料到防凍劑的各種產品。乙烯的大規模生產是能源密集型的，嚴重依賴化石資源。二氧化碳電催化制乙烯是一種很有前途的方法。這種新型混合催化劑只由地球上儲量豐富的材料組成，如鎳和銅，它們的化學反應所需的能量更少。

艾姆斯國家實驗室的科學家齊龍（音譯）解釋了新型混合催化劑的工作原理。

原子分散的鎳錨定在氮組裝碳(NAC)上，在低電壓和大電流下催化二氧化碳生成一氧化碳。這種新型混合催化劑在寬電壓范圍內有效，在更高電流下的有效性意味著更高的一氧化碳生產速率。

齊龍指出：“由于這種新型混合催化劑在非常寬的電壓范圍內保持活性，因此很容易與第二種催化劑耦合。所以我們使用第二種催化劑，這是一種銅納米線，通過結合這兩種催化劑，我們有一個非常具選擇性的過程，在一個罐子里從二氧化碳到乙烯的效率高達60%。”

催化劑的另一個重要方面是它的結構。艾姆斯國家實驗室科學家、愛荷華州立大學教授黃文宇(音譯)指出，這種新型混合催化劑的多孔結構增強了其有效性。他說：“我們的催化劑具有有序的介孔結構，有利于傳質。因為它是高度多孔的，你有一個非常大的表面積來暴露大量的鎳的活性位點，這使得我們的催化劑在將二氧化碳轉化為一氧化碳方面非常有效。”

黃文宇說，這項研究最令人興奮的方面是團隊如何結合兩種催化劑來簡化過程。他說：“我們基本上把兩種最好的催化劑單獨結合在一起，它們一起工作，所以我們可以在一個系統中把二氧化碳連接到一氧化碳以及把一氧化碳連接到乙烯的反應。”

齊龍強調了使用二氧化碳作為這種反應的原料的重要性，因為它解決了全球減少二氧化碳排放到大氣中的需求。他解釋說，這個過程可以使用從化學或工業過程中回收的二氧化碳，或者從空氣捕獲中回收的二氧化碳。齊龍說：“我們可以在沒有任何貴金屬的情況下做到這一點，只需鎳、銅、碳和氮，就可以實現大規模的工業應用。”“此外，我們可能不再使用化石燃料來生產乙烯。” 

看起來總有一天二氧化碳供應會出現競爭。這是另一個利用二氧化碳的突破性技術。早在去年12月，就有一篇關于廢氣捕集器用來制造乙烯的報道。

新聞稿中缺少的是氫氣的來源。這篇論文的摘要提供了催化劑在堿性流動池中運行，這可能需要補水。

但如上所述，乙烯是一種作為大宗商品的化學制品，幾乎在任何地方都有成千上萬噸的用量。然而，多樣化的供應看起來是一件好事。就目前而言，乙烯既不短缺，也不特別昂貴。看看什么才是真正具有經濟競爭力并獲得一些市場份額的產品，將是一件很有趣的事情。

李峻 編譯自 油價網

原文如下：

New Carbon Conversion Tech Could Boost Net-Zero Initiative

·     A new hybrid catalyst for converting carbon dioxide into ethylene has been developed by Ames Laboratory, Iowa State University, University of Virginia, and Columbia University. 

·     The catalyst uses only earth-abundant materials such as nickel and copper and requires less energy for chemical reactions. 

·     The catalyst's porous structure and combination of two catalysts make it highly effective and selective in CO2 reduction to CO and CO to ethylene reactions.

The Ames Laboratory at Iowa State University has announced a new hybrid catalyst that converts carbon dioxide into ethylene in one pot. The catalyst was developed by scientists from Ames National Laboratory, Iowa State University, University of Virginia, and Columbia University. This catalyst supports the world net-zero carbon initiative by using carbon dioxide (CO2) recycling it as a feedstock for efficient ethylene production powered by electricity.

The team’s reporting paper has been published in the Journal of the American Chemical Society.

Ethylene is a commodity chemical used to manufacture a wide range of products from plastics to antifreeze. The large-scale production of ethylene is energy intensive and relies heavily on fossil resources. Electrocatalytic production of ethylene from CO2 is emerging as a promising method. This new catalyst consists of only earth-abundant materials, such as nickel and copper, and requires less energy for chemical reaction.

Long Qi, a scientist at Ames Lab, explained how the catalyst works.

Atomically dispersed nickel anchored on nitrogen assembly carbon (NAC) works to catalyze CO2 to CO at low voltage and high current. The catalyst is effective over a wide range of voltages and its effectiveness at higher currents means a higher rate of CO production.

Qi noted, “Since this catalyst remains active over a very wide voltage range, that allows easy coupling with a second catalyst. So we use the second catalyst, which is a copper nanowire, and by combining these two we have a very selective process that has up to 60% efficiency going from CO2 to ethylene in one pot.”

Another important aspect of the catalyst is its structure. Wenyu Huang, an Ames Lab scientist and Iowa State University professor from the team, noted that the catalyst’s porous structure enhances its effectiveness. “Our catalyst has an ordered mesoporous structure that is beneficiary for mass transfer,” he said. “Because it’s highly porous, you have a very high surface area to expose a lot of nickel’s active sites, making our catalyst very effective in CO2 reduction to CO.”

For Huang, the most exciting aspect of this research was how the team combined the two catalysts to streamline the process. “We basically combine the two best catalysts on their own, and they work together so we can connect the CO2 to CO and the CO to ethylene reactions in one system,” he said.

Qi emphasized the importance of using CO2 as a feedstock for this reaction, because it addresses the global need to reduce the amount of CO2 released into the atmosphere. He explained that this process can use CO2 recovered from chemical or industrial processes, or from air capture. “And we can do this without any precious metal, simply the nickel, copper, carbon, and nitrogen, to permit large-scale industrial applications,” Qi said. “Also, we potentially eliminate the use of fossil resources to make ethylene.”

It looks like there will be some competition for CO2 supplies someday. This is another breakout technology to make use of CO2. Back in December there was a report about a flue gas trap set up to make ethylene.

What’s missing in the press release is the source for the hydrogen. The abstract for the paper offers that the catalyst operates in an alkaline flow cell, which presumably needs water replenishment.

But as noted, ethylene is a commodity chemical that is used by the thousands of tons almost everywhere. Yet a diversified supply looks like a good thing. For now, ethylene is hardly in short supply or particularly expensive. It will be interesting to see what is actually economically competitive and gets some market share.