Promoting effect of potassium over Pd/SiO2 catalyst for ambient formaldehyde oxidation

IF 5.9 2区 环境科学与生态学 Q1 ENVIRONMENTAL SCIENCES
Xiaofeng Liu , Chunying Wang , Xudong Chen , Jingyi Wang , Yaobin Li
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Abstract

Highly dispersed noble metals are acknowledged for its pivotal role in influencing the efficiency of catalysts during the HCHO oxidation process. Interestingly, in this work, an innovative approach was employed to augmenting the stabilization of noble metals on irreducible carriers supported noble metal catalyst (Pd/SiO2) by adding alkali metal potassium (K). A formidable promotion effect was observed when the K doping to Pd/SiO2 catalysts. It achieves a conversion rate of 93% for 270 ppmV of HCHO to harmless CO2 and H2O at a weight hourly space velocity (WHSV) of 300,000 mL/(g·hr) at 25°C. Multiple characterization results illustrated that a strong interaction between added K and Pd species was formed after K addition, which not only stabilized Pd species on the carrier surface but also markedly enhanced its dispersal on the SiO2 carrier. The increasing Pd dispersion induced more oxygen vacancies on the surfaces of the Pd/SiO2 catalysts. The formation of these oxygen vacancies can be attributed to the phenomenon of hydrogen spillover, which also contributed to elevating the electron density on the Pd sites. Meanwhile, the oxygen vacancies favored the O2 activation to form more reactive oxygen species participating in the HCHO oxidation reaction, thus improving the performance of Pd/SiO2 catalysts displayed for HCHO oxidation. This study provides a simple strategy to design high-performance irreducible carriers supported noble metal catalysts for HCHO catalytic oxidation.

Abstract Image

钾对 Pd/SiO2 催化剂在环境甲醛氧化中的促进作用
高度分散的贵金属在影响 HCHO 氧化过程中催化剂的效率方面发挥着关键作用,这一点已得到公认。有趣的是,在这项工作中,采用了一种创新方法,通过添加碱金属钾(K)来增强不可还原载体支撑贵金属催化剂(Pd/SiO2)上贵金属的稳定性。当 K 掺杂到 Pd/SiO2 催化剂中时,观察到了强大的促进作用。在 25°C 条件下,重量小时空间速度(WHSV)为 300,000 mL/(g-hr)时,270 ppmV 的 HCHO 转化为无害的 CO2 和 H2O 的转化率达到 93%。多重表征结果表明,添加 K 后,添加的 K 与钯元素之间形成了强烈的相互作用,这不仅使钯元素稳定在载体表面,还显著提高了钯元素在二氧化硅载体上的分散度。随着钯分散度的增加,Pd/SiO2 催化剂表面出现了更多的氧空位。这些氧空位的形成可归因于氢溢出现象,这也有助于提高钯位点上的电子密度。同时,氧空位有利于 O2 活化,形成更多的活性氧参与 HCHO 氧化反应,从而提高了 Pd/SiO2 催化剂在 HCHO 氧化中的性能。这项研究为设计用于 HCHO 催化氧化的高性能不可还原载体支撑贵金属催化剂提供了一种简单的策略。
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来源期刊
Journal of Environmental Sciences-china
Journal of Environmental Sciences-china 环境科学-环境科学
CiteScore
13.70
自引率
0.00%
发文量
6354
审稿时长
2.6 months
期刊介绍: The Journal of Environmental Sciences is an international journal started in 1989. The journal is devoted to publish original, peer-reviewed research papers on main aspects of environmental sciences, such as environmental chemistry, environmental biology, ecology, geosciences and environmental physics. Appropriate subjects include basic and applied research on atmospheric, terrestrial and aquatic environments, pollution control and abatement technology, conservation of natural resources, environmental health and toxicology. Announcements of international environmental science meetings and other recent information are also included.
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