To reduce the amount of carbon dioxide (CO) already emitted into the atmosphere, various carbon capture, utilization, and storage (CCUS) technologies have been developed for climate and economic reasons in recent years. However, the state of art CCUS techniques suffer from deficiencies such as high cost, low yield, and harsh and discontinuous production conditions. In this work, we report a new thermal reduction method for continuously conversing CO to methane (CH) by introducing sodium borohydride (NaBH) as a reductant under catalyst-free conditions. Experimental results show that CO can be fully captured and converted to CH and carbon monoxide (CO) and the selectivity efficiency of CO to CH can be achieved to be as high as 90% with the optimization of experimental conditions. Such a result originates from the high activity of NaBH and high selectivity of the thermal reduction of CO. To demonstrate one of the potential usages of the reduction products, we integrated the thermal reduction of CO with the production of carbon nanotubes (CNTs). As long as CO is supplied at the source end, the reduction products can undergo catalytic decomposition to produce a CNT fiber or film continuously at the final end. The present technique is featured with simple equipment setup, low cost, and continuous thermal reduction, thus providing a new pathway for the large-scale conversion of CO into high-valued products for wide applications.

中文翻译：

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CO2高效热还原为高价值碳纳米管


为了减少已经排放到大气中的二氧化碳 (CO) 量，近年来出于气候和经济原因开发了各种碳捕获、利用和储存 (CCUS) 技术。然而，最先进的 CCUS 技术存在成本高、产量低、生产条件恶劣和不连续等缺陷。在这项工作中，我们报告了一种新的热还原方法，通过在无催化剂条件下引入硼氢化钠（NaBH）作为还原剂，将CO连续转化为甲烷（CH）。实验结果表明，通过实验条件的优化，CO可以被充分捕获并转化为CH和一氧化碳(CO)，CO对CH的选择性效率可以达到90%以上。这样的结果源于NaBH的高活性和CO热还原的高选择性。为了证明还原产物的潜在用途之一，我们将CO热还原与碳纳米管（CNT）的生产结合起来。只要在源端供给CO，还原产物就可以进行催化分解，在末端连续生成碳纳米管纤维或薄膜。该技术具有设备设置简单、成本低廉、可连续热还原等特点，为CO大规模转化为高价值产品和广泛应用提供了新途径。