PEREGRINE科學點滴 一些科學報導詳實譯文

828愛的鼓勵 0訂閱站台

Room-temperature, ambient-pressure conversion reaction for carbon monoxide could be part of a larger cascade strategy for efficiently turning atmospheric carbon dioxide (CO₂) into liquid fuel

一氧化碳於室溫、環境壓力下的轉化反應可能是，將大氣中二氧化碳(CO₂)，有效轉化成液體燃料之更大級聯策略的一部分。

  

圖1. 美國布魯克海文國家實驗室及北卡羅萊納大學教堂山分校的研究人員們發現了，可再生的有機氫化物，能有效地將一氧化碳(CO)轉化為甲醇(CH₃OH)。這些反應物可能成為，將大氣中的二氧化碳(CO₂)轉化成，易於運輸/儲存之液體燃料的部分級聯策略。

Brookhaven National Laboratory and University of North Carolina Chapel Hill researchers have identified renewable organic hydrides that can efficiently convert carbon monoxide (CO) to methanol (CH₃OH). These reagents could be part of a cascade strategy for converting atmospheric carbon dioxide (CO₂) into easily transportable/storable liquid fuel.

 

Scientists at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory and the University of North Carolina Chapel Hill (UNC) have demonstrated the selective conversion of carbon dioxide (CO₂) into methanol using a cascade reaction strategy.

美國能源部(DOE)所屬布魯克海文國家實驗室及北卡羅來納大學教堂山分校(UNC)的科學家們已經證實，使用一種級聯反應策略，選擇性將二氧化碳(CO₂)轉化成甲醇。

 

The two-part process is powered by sunlight, occurs at room temperature and at ambient pressure, and employs a recyclable organic reagent that’s similar to a catalyst found in natural photosynthesis.

這種有兩部分的變化過程是採用一種，類似在自然光合作用中，被發現之觸媒的可回收有機反應物，在室溫及環境壓力下，由陽光所驅動。

 

“Our approach is an important step toward finding an efficient way to convert CO₂, a potent greenhouse gas that poses a significant challenge for humanity, into an easily storable and transportable liquid fuel,” said Brookhaven Lab Senior Chemist Javier Concepcion, a lead author on the study.

該項研究主要撰文人，布魯克海文國家實驗室資深化學家，Javier Concepcion宣稱：「我們的方法是尋找一種，邁向將對人類構成重大挑戰之強有力的溫室氣體，二氧化碳轉化成易於儲存及運輸之液體燃料的重要一步。」

 

The research was conducted as part of the Center for Hybrid Approaches in Solar Energy to Liquid Fuels (CHASE), an Energy Innovation Hub based at UNC and funded by the DOE Office of Science. The study is published as the "front cover" article in the Journal of the American Chemical Society.

該項發表於《美國化學會雜誌》，作為"封面"文章之研究的進行，是總部位於北卡羅來納大學之太陽能與液體燃料混合方法中心(CHASE由美國能源部科學局資助之能源創新中心)的部分研究。

 

The room-temperature conversion of CO₂ into liquid fuels has been a decades-long quest. Such strategies could help achieve carbon-neutral energy cycles, particularly if the conversion is powered by sunlight. The carbon emitted as CO₂ by burning single-carbon fuel molecules such as methanol could essentially be recycled into making new fuel without adding any new carbon to the atmosphere.在室溫下，將二氧化碳轉化成液體燃料，已經是一個長達數十年的探索。此類策略可能有助於實現，碳中和的能源循環。特別是，倘若轉換是由陽光所驅動。由於燃燒諸如甲醇等，單一碳的燃料分子，而以二氧化碳形式排放的碳，本質上，能沒將任何新的碳添加到大氣中，被回收製造成新燃料。

 

Methanol (CH₃OH) is a particularly attractive target because it is a liquid that can be easily transported and stored. In addition to its usefulness as a fuel, methanol serves as a key feedstock in the chemical industry for making more complex molecules.

甲醇(CH₃OH)是一種特別吸引人的目標，因為它是一種易於運輸及儲存的液體。除了其用作燃料的用處外，在製造更複雜分子的化學工業中，甲醇也作為一種關鍵原料。

 

Also, because methanol contains just one carbon atom, like CO₂, it circumvents the need for making carbon-carbon bonds, which require energy-intensive processes.

However, key steps involved in the reactions required to selectively and efficiently generate solar liquid fuels like methanol remain poorly understood.

此外，由於甲醇與二氧化碳一樣，僅具有一個碳原子。因此，它規避了，形成需要能源密集過程之碳-碳鍵的需求。然而，在選擇性、有效產生，像甲醇等，太陽能液體燃料所需反應中，被涉及的關鍵步驟，仍然缺乏被瞭解。

 

“Converting CO2 to methanol is very difficult to achieve in a single step. It is energetically akin to climbing a very tall mountain,” Concepcion said. “Even if the valley on the other side is at lower altitude, getting there requires a lot of energy input.”

Concepcion宣稱：「於單一步驟中，很難實現，將二氧化碳轉換成甲醇。在能量上，這類似攀登一座非常高的山。即使，於另一邊的山谷處於較低海拔，到達那裡也需要大量的能量輸入。」

 

Instead of trying to tackle the challenge in a single “climb,” the Brookhaven/UNC team used a cascade, or multi-step, strategy that goes through several intermediates that are easier to reach. “Imagine climbing several smaller mountains instead of a big one — and doing so through several valleys,” Concepion said.

取代嘗試解決，於一次“攀登”中的挑戰。該布魯克海文國家實驗室及北卡羅萊納大學的團隊使用了一種，經過幾個較容易到達之居間物的級聯(也就是多重步驟)策略。Concepion宣稱：「想像一下，攀登幾座較小而不是一座大山。也就是，穿過幾個山谷來做到這一點。」

 

The valleys represent reaction intermediates. But even reaching those valleys can be difficult, requiring the stepwise exchange of electrons and protons among various molecules. To lower the energy requirements of these exchanges, chemists use molecules called catalysts.

此些山谷代表反應居間物。不過，即使達到那些山谷也會是困難的，需要電子及質子，在各種分子之間的逐步交換。為了降低此些交換的能量需求，化學家們使用被稱為觸媒的分子。

 

“Catalysts enable reaching the next valley through ‘tunnels’ that require less energy than climbing over the mountain,” Concepcion said.

Concepcion宣稱：「觸媒能透過，需要比攀越這座山更少能量的‘隧道’，來到達下一個山谷。」

 

For this study, the team explored reactions employing a class of catalysts called dihydrobenzimidazoles. These are organic hydrides — molecules that have two extra electrons and a proton to “donate” to other molecules. They are inexpensive, their properties can be easily manipulated, and previous studies have shown that they can be recycled, a requirement for a catalytic process.

為了這項研究，該研究團隊探索了，使用一類被稱為二氫苯並咪唑之觸媒的反應。此些是具有兩個額外電子及一個質子，來“捐贈”給其他分子的有機氫化物分子。它們是廉價、屬性能容易被控制的，且先前諸多研究已經證實，它們能被回收利用，這是催化過程的一項必要條件。

 

These molecules are similar in structure and function to organic cofactors responsible for carrying and delivering energy in the form of electrons and protons during natural photosynthesis.

在結構及功能上，此些分子與在自然光合作用期間，負責以電子及質子形式，攜帶及傳遞能量的有機輔因子相似。

 

“Photosynthesis itself is a cascade of many reaction steps that convert atmospheric CO₂, water, and light energy into chemical energy in the form of carbohydrates — namely sugars — that can later be metabolized to fuel the activity of living organisms. Our approach of using biomimetic organic hydrides to catalyze methanol as a liquid fuel can therefore be viewed as an artificial approach to photosynthesis,” said UNC co-lead author Renato Sampaio.

共同的首要撰文人，北卡羅來納大學教堂山分校的Renato Sampaio宣稱：「光合作用本身是一種，許多反應步驟的級聯，將大氣中的二氧化碳、水及光能轉化成，之後能被代謝來為生物體的活動，提供燃料之以碳水化合物形式(即醣類)的化學能。我們使用仿生之有機氫化物，來催化甲醇作為液體燃料的方法。因此，能被視為光合作用的一種人工方法。」

 

In the study, the chemists broke the conversion of CO₂ into methanol into two steps:  photochemical reduction of CO₂ to carbon monoxide (CO), followed by sequential hydride transfers from dihydrobenzimidazoles to convert the CO into methanol.

在該項研究中，此些化學家將二氧化碳成為甲醇的轉化，分為兩個步驟：CO₂的光化學還原成一氧化碳(CO)，隨後從二氫苯並咪唑連續的氫化物轉移，來將CO轉化成甲醇。

 

Their work describes the details of the second step, as the reaction proceeds through a series of intermediates, including a ruthenium-bound carbon monoxide (Ru-CO²⁺) group, a ruthenium formyl (Ru-CHO⁺) moiety, a ruthenium hydroxymethyl (Ru-CH₂OH⁺) group, and finally, light-induced methanol release.

他們的研究描述了第二步驟的細節，當反應透過一系列居間物進行時，包括結合了釕的一氧化碳(Ru-CO₂+)基團、釕甲醯基(Ru-CHO+)部分(組成部分中的一部分)、釕羥甲基(Ru- CH₂OH+)基團及最後，由光誘導的甲醇釋出。

 

While the first two steps of this scheme are “dark reactions,” the third step that results in free methanol is initiated by the absorption of light by the ruthenium hydroxymethyl (Ru-CH₂OH⁺) complex.

儘管此方案的前兩步驟是“暗反應”，不過導致游離之甲醇的第三步驟，是由釕羥甲基(Ru-CH₂OH+)複合物吸收光引發的。

 

The proposed mechanism by which this occurs is through an excited-state electron transfer between the Ru-CH₂OH⁺ and a molecule of organic hydride followed rapidly by a ground proton transfer that results in the generation of methanol in solution.

該藉以發生被提出的機制，是透過於Ru-CH₂OH+與有機氫化物分子間，激發態的電子轉移，然後快速進行導致，於溶液中產生甲醇的基本質子轉移。

 

“The ‘one-pot’ and selective nature of this reaction results in the generation of millimolar (mM) concentrations of methanol — the same range of concentrations as the starting materials — and avoids complications that have plagued previous efforts to use inorganic catalysts for these reactions,” said UNC co-author and CHASE Director Gerald Meyer.

合撰人，北卡羅來納大學教堂山分校兼CHASE(Center for Hybrid Approaches in Solar Energy to Liquid Fuels)主任的Gerald Meyer宣稱：「該反應之‘一鍋法’及選擇性的特質，導致產生毫摩爾(mM)濃度的甲醇(與起始材料相同範圍的濃度)，且避免了一直使先前諸多嘗試，難以使用無機觸媒進行此些反應的複雜狀況。

 

This work can therefore be viewed as an important step in the use of renewable organic hydride catalysts to the decades-long quest for room temperature catalytic methanol production from CO₂.”

因此，對長達數十年探索，於室溫下，從二氧化碳催化產生甲醇而言，該項研究能被視為，在使用可再生有機氫化物觸媒上的重要一步。」

 

 

網址：https://www.bnl.gov/newsroom/news.php?a=121740

翻譯：許東榮