Qingdao Energy Institute developed a nanoreactor strategy to synthesize supported bimetallic catalysts

[ Instrument network instrument research and development ] Supported bimetallic nano-catalysts are an important type of catalyst in the field of heterogeneous catalysis, which are widely used in various catalytic processes such as electrochemistry, biomass conversion, and fine chemicals. The impregnation method is a commonly used method for preparing supported metal catalysts. Although it is simple to operate, it has poor controllability. The resulting bimetallic nanoparticles have large size, wide particle size distribution, and low alloying degree, which may lead to poor catalytic performance and low metal utilization. The seed crystal growth method in the liquid phase can achieve precise control of the size, morphology and composition of the bimetallic nanoparticles, but when they are loaded on the carrier by the method of colloidal deposition, the distribution of metal nanoparticles is usually uneven, and some The phenomenon of regional agglomeration, and the weak interaction between the metal nanoparticles and the carrier, also leads to poor catalyst stability.

Recently, Wang Guanghui and Jiang Heqing, researchers at the Qingdao Institute of Bioenergy and Processes, Chinese Academy of Sciences, and Liu Jian, a researcher at the Dalian Institute of Chemical Physics, have developed a universal nanoreactor strategy for the synthesis of Pd-based bimetallic catalysts. This strategy successfully applies the seed crystal growth method in the liquid phase to the solid phase-through chemical coordination, the Pd nanocluster seed crystal and the secondary metal precursor are uniformly introduced into the solid phase carrier, and the double is achieved during the reduction process. The solid-phase seed crystal growth of the metal finally obtains the bimetallic nano-particle size, composition controllable and uniform bimetallic catalyst. The strategy is simple to operate and the process is simple and easy to scale up. It can synthesize a variety of Pd-based bimetallic nanocatalysts (size range of 2~3 nm), including PdAu, PdRu, PdCo, ​​PdNi, PdZn, PdAg, PdCu and other bimetallic nanocatalysts. Further research showed that compared with the corresponding single metal, the Pd1Au1/4 bimetallic catalyst showed enhanced catalytic performance in the decomposition of formic acid to hydrogen production, which proved the synergistic effect between Pd and Au. In addition, the catalyst carrier obtained by this strategy has a coral-like structure and is easy to shape; the formed catalyst still has good activity for the decomposition of formic acid to produce hydrogen, with a TOF value of 3684 h-1, and the catalytic activity has not changed significantly after five times of repeated use. This research work provides a new strategy for the design and preparation of supported bimetallic catalysts.

The bimetal reforming catalyst is a catalyst in which the metal component contains another metal besides platinum. White, cylindrical solid.

Bulk density U. 79-}}. 85g /crri3. During the high-temperature condensation and regeneration or reduction process of single platinum catalyst during operation, the effect of oxygen and moisture will cause platinum crystal grains to grow, and the exposed platinum atoms decrease and the activity decreases. Adding the second metal can prevent longer than boll crystal grains. Large, improve its stability, and also increase its allowable carbon deposit. The second metal used is Lei and Tin, followed by Ba and Iridium. This catalyst can carry out reforming operations under the conditions of low pressure and low hydrogen-to-oil ratio, which is beneficial to the aromatization reaction. The disadvantage is that the second metal has hydrocracking activity, so the hydrogen purity and liquid phase yield are both better than The single platinum catalyst is low.

Related results were published on Materials Today. The first author is Tian Zhengbin, a doctor from Qingdao Energy Institute. The research was funded by the National Natural Science Foundation of China and the Cooperation Fund of the Institute of Clean Energy Innovation of the Chinese Academy of Sciences.