Details

Autor(en) / Beteiligte

• Chen, Weimiao
• Song, Xiangen
• Ning, Lili
• Ding, Yunjie

Titel

CO Hydrogenation to C.sub.2 Oxygenates over SiO.sub.2 Supported Rh-Based Catalyst: The Effect of pH Value of Impregnation Solution

Ist Teil von

• Catalysis letters, 2021-09, Vol.151 (9), p.2775

Ort / Verlag

Springer

Erscheinungsjahr

2021

Link zum Volltext

Quelle

SpringerLink

Beschreibungen/Notizen

• The synthesis of C.sub.2 oxygenates including ethanol directly from coal-derived syngas is significant from both academic and practical points of view and SiO.sub.2 supported Rh-based catalysts are very effective for this conversion. However, the high price of Rh requires the improvement of its dispersion to maximize Rh efficiency. The adjustment of impregnation solution pH value can modify effectively the metal dispersion over the support. Herein, we reported the pH effect on catalytic performance of Rh-Mn-Li/SiO.sub.2 for CO hydrogenation to C.sub.2 oxygenates for the first time. A series of catalysts were prepared from different pH values of impregnation solutions, and were characterized by various techniques. With the increasing of solution pH value above zero point of charge (ZPC) of silica, Rh particle sizes increased with much wider size distribution and reduction of Rh species was restrained over the prepared catalysts owing to the stronger interaction between Rh and support. As a result, the active sites for CO insertion, especially for CO or H.sub.2 dissociation was lowered, leading to the depletion of the activity for the formation of C.sub.2 oxygenates from CO hydrogenation, and larger Rh particle size with wider size distribution favors the production of long chain hydrocarbons. On the contrary, when the catalyst was prepared using solution with pH below ZPC of silica, the dispersion and the reduction of Rh were promoted due to suitable Rh-support interaction, and in the CO hydrogenation reaction, the space time yield and selectivity of C.sub.2 oxygenates reached 679.4 g/kg-cat/h and 73.3%, respectively. Graphic The pH value of impregnating solution regulate the metal-support interaction and thus Rh particle sizes and its reduction, which effects strongly CO hydrogenation activity and selectivity.