A ligand coordination approach for high reaction stability of an Au–Cu bimetallic carbon-based catalyst in the acetylene hydrochlorination process
A ligand coordination approach for high reaction stability of an Au–Cu bimetallic carbon-based catalyst in the acetylene hydrochlorination process
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DOI：
10.1039/c5cy01270h
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发表时间：
2016-02
影响因子：
5
通讯作者：
Hao Xu-;Kai Zhou;Jiangkun Si;Chunhua Li;Guohua Luo
中科院分区：
文献类型：
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作者：
Hao Xu-;Kai Zhou;Jiangkun Si;Chunhua Li;Guohua Luo
为中国所在的聚氯乙烯行业研发无汞催化剂迫在眉睫。负载在活性碳上的金(Au)是一种潜在的高活性的新型催化剂，被认为是汞的理想替代品。然而，乙炔导致的金催化剂在长期工业应用中的失活是一个巨大的挑战。在这项工作中，构建了一种新的金催化配体筛选和设计方法。三氯异氰尿酸(TCCA)被证明是一种很好的配体。此外，添加铜是一种良好的协同金属，使催化剂中金的含量进一步降低到0.2wt%(质量分数)。实验中，各组分的最佳配比为Au：Cu：TCCA=1：5：20。在温度180℃、空速90h−1的条件下，制备的0.2wt%Au催化剂在24 h内转化率达98%以上，选择性达99%以上。此外，结合DFT计算对催化剂进行了表征，结果表明，TCCA的引入使催化剂具有较高的稳定性，这可能是因为它具有较强的防止高价Au还原和抑制结焦效应的能力，而且Au和Cu之间的电子相互作用有利于Au的分散，从而提高了催化剂的催化活性。
The research and development of a non-mercury catalyst for China's PVC (polyvinyl chloride) industry is extremely urgent. Gold (Au) loaded on activated charcoal (AC), as a potential novel catalyst with high activity, has been regarded as an ideal substitute for mercury. However, the deactivation of a gold catalyst caused by acetylene for long-term industrial applications is a big challenge. In this work, a new methodology of ligand screening and design for gold catalysis was constructed. Trichloroisocyanuric acid (TCCA) was proved to be an excellent ligand. Besides, copper (Cu) was added and proved to be a favorable synergistic metal so that the content of Au in the catalyst could be further reduced to 0.2 wt% (weight percentage). Experimentally, the best ratio of each component was optimized to be Au : Cu : TCCA = 1 : 5 : 20. The prepared 0.2 wt% Au catalyst had a conversion of over 98% with over 99% selectivity during 24 h operation under the temperature of 180 °C and GHSV (gas hourly space velocity) of 90 h−1. Then, an over 6800 h pilot trial has been carried out to demonstrate its promising capability for practical applications. Moreover, several characterization methods accompanied by DFT calculations were used, and it was proved that the high stability after TCCA introduction may come from its high ability to prevent high valence Au from being reduced and to inhibit the coking effect and that the electron interaction between Au and Cu could facilitate the dispersion of Au and lead to higher catalytic activity.